KR100940763B1 - Projection screen - Google Patents

Abstract

The present invention relates to a projection type screen used as an image display medium, in particular a substrate made of a transparent material; A rear lens positioned on the light incident side of the substrate; A front lens having a light diffusing layer having a protrusion formed on a portion symmetrical with a valley portion of the rear lens, and a printing layer printed on an upper portion of the protrusion, coated with a bead and a binder resin on the light exit side of the substrate. It relates to a projection screen having a high luminance and a greatly improved viewing angle having a lenticular lens for a projection screen comprising a.

Description

Projection screen

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

2 is a diagram illustrating the operation of a projection screen having different incidence angles of red, green, and blue tricolor light.

3 is a diagram illustrating the operation of a projection screen having the same incident angle of red, green, and blue tricolor light.

4 is a diagram illustrating a structure of a lenticular lens of the present invention.

<Brief description of symbols used in the drawings>

11: screen 12: mirror 13, 23, 33: projector

21, 31: lenticular lens 22, 32: Fresnel lens

A: front lenticular lens B: rear lenticular lens

41 base material 42 primer layer 43 binding resin

44: Bead 45: Light Diffusion Layer 46: Printing Layer

The present invention relates to a projection type screen used as an image display medium, and more particularly, to a projection type screen suitable for a projection type display for a large screen. It also relates to a lenticular lens that forms a screen with a Fresnel lens.

The image projection type system of a product such as a projection television or a video projector is, as illustrated in FIG. 1, an image display such as a specially made small cathode ray tube (CRT) or a liquid crystal display (LCD). An image display system in which an image is generated by the projector 13 by 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.

As is well known, such an image projection system includes a front projection type called a front type and a rear projection type called a rear type according to a method of projecting an image on a screen. Light is projected forward along the projection axis towards the screen, forming an image on the surface of the screen and perceived by an observer in front of the screen.

In the image projection system as described above, the screen plays an important role in which the optical characteristics dominate the image quality, especially in the case of a large projection television that requires high image quality such as HD (High Definition) TV. Is very high.

As shown in FIG. 2, the Fresnel lens 22 constituting the projection screen has the brightness of the center part and the periphery of the image projected on the lenticular lens 21 on the front surface in parallel with the light projected from the projector 23. Has the ability to minimize the difference. The lenticular lens 21 diffuses the light incident from the Fresnel lens 22 to form an image, and minimizes the difference in the emission angles of the three-color light having different incidence angles, thereby changing color according to the observed position. It corrects (color shift). 3 illustrates the operation of a projection screen having the same incident angle of three colors of light. The conventional lenticular lenses 21 and 31 form a lens on the surfaces of the lenticular lenses 21 and 31 as shown in U.S. Patent No. 5,066,099, and then apply a light diffusing agent to the surface of the lenticular lens 21 and 31 to provide a light diffusion effect on the surface. It is shown. This not only makes the manufacturing process complicated, but also increases the luminance and viewing angle of the present invention. On the other hand, Korean Patent Laid-Open Publication No. 2000-0056232 proposes to coat the diffusing agent on the front surface without forming the front surface of the lenticular lenses 21 and 31, but even in this case, the color shift which is the original purpose of the lenticular lens is sufficiently removed. Not only is it impossible, but rather the result is an excessive use of the amount of the diffusing agent to reduce the brightness.

The present invention, in order to improve the problems of the prior art as described above, in the lenticular lens, the bead and the binder resin are mixed and provided with a light diffusing layer having a shape of a protrusion and a printing layer on top of the protrusion, the luminance is high and the viewing angle It is an object of the present invention to provide a greatly improved lenticular lens for a projection screen, a projection screen including the same, and a projection system employing the projection screen.

In the present invention to achieve the above technical problem,

a) a substrate made of a transparent material;

b) a rear lens positioned on the light incident side of the substrate;

c) a bead and a binder resin are mixed and coated on the light exit side of the substrate, the light diffusion layer having a protrusion formed on a portion symmetrical to the valley portion of the rear lens, and a printing layer printed on an upper position of the protrusion. Provided is a lenticular lens for a projection screen including a front lens.

In order to achieve the above another technical problem, the present invention also provides a projection screen including the lenticular lens.

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

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

4 schematically shows the structure of a lenticular lens according to a preferred embodiment of the present invention. Referring to FIG. 4, a photocurable resin is coated on a base 41 of a transparent polymer film to form a rear lenticular lens B on the base 41 through a mold in which a lens is formed in a conventional manner. On the opposite side of the substrate 41, a bead 44, which is used as a light diffusing agent, is mixed with the photocurable bonding resin 43 and coated to form a front lenticular lens A through a mold in which a lens is formed in a conventional manner. . In addition, the front and rear lenticular lens is formed to have a semi-circular cross section. At this time, the front and rear lenses may be formed on the upper and lower portions of the base film such as polyethylene terephthalate (PET) using a roll mold in the manufacturing process. According to an embodiment of the present invention, the primer layer 42 is disposed between the light diffusing layer 45 and the base 41 and / or the base 41 and the rear lens, which contain the transparent beads 44 used as the light diffusing agent. It is preferable to further provide.

The prism sheet according to the present invention, as shown in FIG. 4 for light diffusing effect and wide viewing angle, is made of a light composed of a bonding resin 43 containing a transparent bead 44 on the opposite side of the rear lenticular lens B. It is characterized by including the diffusion layer 45.

The bonding resin 43 may be transparent or translucent, and the same resin as the cured resin forming the lens portion, for example, polyesters, epoxy resins, polyester (meth) acrylates, epoxy (meth) acrylates, Resin, such as urethane (meth) acrylate, is used.

The beads 44 have a transparent spherical shape, and organic beads are used, and the organic beads are made of urethane resin, acrylic resin, vinyl chloride resin, or the like. In particular, a mixture of beads of various sizes rather than a single size of beads is effective to widen the effect of light diffusion and to widen the viewing angle and make the light source invisible. This is because the number of beads per unit area of the base sheet 23 can be increased by filling the voids between the beads with the larger diameter with the beads having the smaller diameter. The diameter of the beads suitable for the present invention is preferably 1 to 50 µm, particularly 5 to 50 µm. Beads having a diameter of 1 μm or less rapidly decrease in brightness, and beads having a diameter of 50 μm or more have a poor coating property, making it difficult to form a lens.

The content of the beads is suitably 0.5 to 10 parts by weight, in particular 1.5 to 3.0 parts by weight, based on 100 parts by weight of the binder resin. This is not preferable because the viewing angle is bad when the bead content is less than 0.5 parts by weight, and the luminance characteristic is poor when it exceeds 10 parts by weight.

Looking at the manufacturing method of the light diffusion layer 45 is as follows. The composition comprising the beads and the binder resin is dispersed using commonly used dispersers such as bead mills using glass or zirconium beads, roll mills using horizontal or vertical rolls. At this time, a dispersant containing a modified polysiloxane or polycarboxylic acid may be used in order to make the dispersion better. A binder resin solution in which beads are uniformly dispersed is applied over the primer layer 43 and then dried / cured to form a rough surface layer. The method of applying the bead composition on the primer layer is not particularly limited as long as it is a method commonly known in the art, and may be adopted depending on the material and shape of the substrate, for example, an air knife method, a gravure method, and a reverse method. A roll method, a spray method, or a blade method can be used. After apply | coating resin containing a bead on the primer layer of a base film, hot air, infrared rays, an ultraviolet-ray, etc. are irradiated, and the light-diffusion layer 45 is formed.

The base material 41 used by this invention will not be specifically limited if it is a material which permeate | transmits active energy, such as an ultraviolet-ray, visible light, an electron beam. Specifically, for example, sheets and films of transparent resins such as flexible polyester resins, acrylic resins, polycarbonate resins, vinyl chloride resins, and polymethacrylamide resins are preferable. Particularly, polymethyl methacrylate, a mixture of polymethyl acrylate and polyvinylidene fluoride-based resin, polycarbonate-based resin, polyethylene terephthalate, and the like, which have a lower refractive index than the refractive index of the lens part on the front and rear surfaces, are low. It is preferable that it consists of ester resin. As for the thickness of the said base material, 100-500 micrometers is preferable.

The active energy ray curable resin for forming a pattern layer such as the front lens portion A, which is the light incident shape layer, and the rear lens portion B, which is the light exit side according to the present invention, may be used as active energy rays such as ultraviolet rays or electron beams. It will not specifically limit, if it is hardened | cured. For example, (meth) acrylate type resins, such as polyester, epoxy resin, polyester (meth) acrylate, epoxy (meth) acrylate, and urethane (meth) acrylate, etc. are mentioned. Especially, (meth) acrylate type resin is especially preferable from a viewpoint of an optical characteristic.

As the active energy ray curable composition used for such a cured resin, polyhydric acrylate and / or polymethacrylate (hereinafter referred to as polyvalent (meth) acrylate), monoacrylate and / or It is preferable to have monomethacrylate (hereinafter, referred to as mono (meth) acrylate) and a photopolymerization initiator based on an active energy ray as a main component. As typical polyvalent (meth) acrylate, polyol poly (meth) acrylate, polyester poly (meth) acrylate, epoxy poly (meth) acrylate, urethane (meth) acrylate, etc. are mentioned. These are used alone or as a mixture of two or more kinds. Moreover, as mono (meth) acrylate, a monoalcohol mono (meth) acrylic acid ester, the mono (meth) acrylic acid ester of a polyol, etc. are mentioned, In the latter case, when using a metal type, the influence of a free hydroxyl group is used. In order to reduce the mold release difficulty with the metal mold considered to be, it is good to use in small quantities. In the case of using a metal mold, it is preferable to use a small amount because it has a high polarity with respect to (meth) acrylic acid and its metal salt.

Molds having transfer patterns on the circumference are usually made of metals such as aluminum, brass, steel, or synthetic resins such as silicone resins, polyurethane resins, epoxy resins, ABS resins, fluorocarbon resins, polymethylfetene resins, and Ni electroforming methods. And the like are used. The pattern suitable for a light control sheet is formed in the roll surface, and it is preferable to plate chromium (Cr) etc. on it.

In order to increase the contrast of external light, a black printed layer 46 is formed on the layer containing the transparent beads 44. The print layer 46 is located at a protrusion formed in a portion symmetrical with the valley of the front lens, and is made of black polyurethane-based photocurable resin, the thickness is 5 to 50㎛.

On the other hand, the primer layer 42 is made of polyurethane, the thickness thereof is 0.001 to 1㎛, the content of the polyurethane in the primer layer is preferably 0.01 to 0.5g / m ² . When the thickness of the primer layer is less than 0.001 μm, the coating property is poor, whereas when the thickness of the primer layer is more than 1 μm, the adhesion to the laminated or coated polymer resin may be deteriorated. If the primer layer is not formed, the adhesive force is weak at the time of forming the lens using the photocurable resin on the film, and the lens layer is easily separated from the film.

<Example 1>                     

The front lens was prepared by dispersing the first bead and the second bead into the photocurable resin with the following composition while stirring. The front lens was coated on the surface of the primer-treated substrate according to the following method, and the front and rear surfaces of the lens were changed by a mold. After forming and photocuring, the front lens unit was printed in black to form a print layer, which is a light absorption layer. The rear lens was coated on the surface of the substrate primed with only photocurable resin containing no beads and the lens was formed by a mold. Luminance and viewing angle were evaluated in the dark room using TOPCON's BM-7 luminance measurement instrument and the results were shown.

[Front Lens]

Photocurable resin: 100 parts by weight of urethane acrylate resin

1 bead: acrylic beads diameter 5㎛ 1.5 parts by weight

2nd bead: acrylic bead diameter 10㎛ 1.5 parts by weight

Base material: polyester film

[Rear lens]

Photocurable resin: 100 parts by weight of urethane acrylate resin

Material: Polyester film, SKC product

<Example 2>

Example 2 was prepared according to the same apparatus and method as described in Example 1 except that the content of the first and second beads contained in the front lens was 2.5 parts by weight, respectively, based on 100 parts by weight of the photocurable resin. Was evaluated.

<Example 3>                     

Example 3 was prepared according to the same apparatus and method as described in Example 1 except that the content of the first and second beads contained in the front lens was 3.0 parts by weight, respectively, based on 100 parts by weight of the photocurable resin. Was evaluated.

<Example 4>

Example 4 was prepared according to the same apparatus and method as described in Example 1 except that the content of the first and second beads contained in the front lens was 3.5 parts by weight, respectively, based on 100 parts by weight of the photocurable resin. Was evaluated.

Example 5

Example 5 was prepared according to the same apparatus and method as described in Example 1 except that the content of the first and second beads contained in the front lens was 4.5 parts by weight, respectively, based on 100 parts by weight of the photocurable resin. Was evaluated.

<Example 6>

Example 6 was prepared according to the same apparatus and method as described in Example 1 except that the content of the first and second beads contained in the front lens was 6.0 parts by weight based on 100 parts by weight of the photocurable resin. Was evaluated.

Comparative Example 1

Comparative Example 1 was prepared according to the same apparatus and method as described in Example 1 except that the front lens portion was formed only of a photocurable resin containing no beads, and the characteristics thereof were evaluated.

division Brightness (cd / m ² ) Normal direction Normal + 30 degree direction Example 1 111.7 62 Example 2 111.7 63 Example 3 115.5 67.97 Example 4 111.8 59 Example 5 98.07 46.61 Example 6 82.53 35.93 Comparative Example 1 111 48.26

In the brightness measurement results of Table 1, the beads of Examples 1 to 4 including 1.5 parts, 2.5 parts, 3.0 parts, and 3.5 parts by weight based on 100 parts by weight of the binder resin on the front surface of the lenticular lens of the present invention, the beads A larger value was shown than in the case of Comparative Example 1 not containing. This can be seen that when the light diffusing layer forming the front lens portion contains a bead of the appropriate range, the light transmittance is increased to improve the brightness while improving the light diffusivity at the same time to widen the wide viewing angle. In addition, as can be seen in Example 3, the case containing 3.0 parts by weight of the beads showed the most preferable results.

As described above, the lenticular lens of the present invention includes a light diffusing layer having a transparent or semi-transparent protrusion including a bead and a binder resin having a particle diameter of 1 to 50 μm, and a protrusion, which is located on the opposite side of the rear lens. By providing the printing layer on the upper side, the light transmittance is increased to improve the brightness while simultaneously improving the light diffusivity, thereby widening the wide viewing angle.

Claims (8)

A substrate made of a transparent material; A rear lens positioned on the light incident side of the substrate; A front lens having a light diffusion layer having a protrusion formed on a portion symmetrical with a valley portion of the rear lens and a printing layer printed on an upper position of the protrusion, wherein the bead and the binder resin are mixed and coated on the light exit surface side of the substrate; Including but not limited to: The beads are organic based on mixing different beads having a diameter of 5 to 50㎛, The lenticular lens for a projection screen, characterized in that the content of the beads is 1.5 to 3.0 parts by weight based on 100 parts by weight of the binder resin. delete delete The lenticular lens for a projection-type screen as claimed in claim 1, further comprising a primer layer on at least one surface between the substrate and the lens. 5. The lenticular lens for a projection screen as claimed in claim 4, wherein the primer layer is 0.001 to 1 mu m thick. 5. The lenticular lens for a projection screen as claimed in claim 4, wherein the primer layer comprises 0.01 to 0.5 g / m ² of polyurethane. A projection screen comprising the lenticular lens of claim 1. A projection type system using a cathode ray tube or a liquid crystal display as an image generating device in the projection type screen of claim 7.

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