KR100420650B1 - Rear projection screen - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screen of a rear projection type system for enlarging and viewing an image formed on a small CRT, LCD, etc., and more particularly, to a lenticular lens constituting a screen together with a Fresnel lens. . The lenticular lens according to the present invention includes a support film made of a transparent material; An aspheric incident layer formed on the light incident surface of the support film and formed of a photocurable resin; A light diffusing layer in which a light diffusing agent and a diffusing agent binder resin are mixed and coated in a single row on the light exit surface of the support film; And a printing layer printed at a position on the light diffusion layer symmetrical with the valley portion of the incident surface shape of the incident shape layer. The lenticular lens of the present invention reduces the color shift by minimizing the exit angle of the light emitted by the light diffusing layer at various angles without the conventional exit lens shape, and reduces the color shift, and the three-color light rear projection type system having the same incident angle or It can be used for all systems with different angles of incidence.

Description

Rear Projection Screen {REAR PROJECTION SCREEN}

[Industrial use]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screen of a rear projection system that allows an enlarged view of a screen formed by a projector such as a small cathode ray tube (CRT) and a liquid crystal display (LCD). In particular, it relates to a lenticular lens constituting the screen with a Fresnel lens.

[Prior art]

1 is a diagram illustrating the operation of a projection screen having different incidence angles of red, green, and blue tricolor light. The Fresnel lens 2 constituting the rear projection screen connects the light projected from the projector 3 to the inside to minimize the difference in brightness between the center part and the peripheral part of the image projected on the lenticular lens 1. Has the function to 2 is a diagram illustrating the operation of a projection screen having the same incident angle of three colors of light. The lenticular lens 1 diffuses the light incident from the fennel lens 2 so that the image is imaged, and the image is imaged by minimizing the difference in the exit angles of the three-color light having different incidence angles. By minimizing the difference in the emission angle of the color light has a function of minimizing the color shift (color shift) depending on the viewing position and the white uniformity phenomenon that the color is different for each position of the screen.

3 is a diagram illustrating a conventional lenticular lens. Conventional lenticular lenses 1 need to form optically spherical or non-spherical lenses not only at the entrance face but also at the exit face in order to minimize color shift, making it difficult to align the optical axes of the entrance and exit lenses. In addition, two molding dies were required, which resulted in high manufacturing costs and difficulty in producing a product having a pitch and thickness of 0.5 mm required for high resolution. 4 is a view illustrating the light diffusing action of a conventional lenticular lens, such a lenticular lens (US Patent No. 5,066,099) is disordered light diffusing agent (5) to image the image as illustrated in FIG. There is a difficulty in that a separate randomly mixed light diffusing layer (4).

In the prior art, a case of a lenticular lens provided with a light diffusing layer 4 in which an incident surface forms a spherical lens and an exit surface has no lens shape and randomly mixed light diffusing agent 5 (Japanese Laid-Open Patent Publication) 9-269546). Such a conventional lenticular lens can be used when blue, green, and red light are incident at the same incident angle in the projector 3 as illustrated in FIG. 2, but different incident angles are illustrated as illustrated in FIG. 1. When used as a screen in a rear projection system, color shifting problems occur, making it difficult to use.

The present invention can be used for three-color and monochromatic light projectors having the same or different incidence angles by adding a light diffusing layer having a light diffusing and optical connection function to the lenticular lens exit surface of the rear projection type screen. Provides a projection screen that is easy and greatly reduces color shift.

In order to achieve the above object, the lenticular lens of the present invention uses a thin film as a support, and the lenticular lens is formed into an aspherical shape by using a photocurable resin and an exit side without a lens shape. It can be prepared by mixing and diffusing the light diffusing agent and the diffusing agent bonding resin having a particle size to a thickness corresponding to the light diffusing agent particle diameter and curing.

1 illustrates the operation of a projection screen having different incidence angles of three colors of light;

2 illustrates the operation of a projection screen having the same incident angle of three colors of light.

3 illustrates a conventional lenticular lens.

4 is a diagram illustrating a light diffusion effect of a conventional lenticular lens.

5 illustrates the present invention.

6 is a diagram illustrating the light diffusion and the connecting action of the lenticular lens of the present invention.

7 is a view illustrating a process of forming a printing layer on the lenticular lens of the present invention.

8 illustrates another embodiment of the present invention.

9 illustrates another embodiment of the present invention.

10 is a graph showing the relationship between the incident angle versus the exit angle measured using the lenticular lens of the present invention.

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

1, 10: Lenticular lens

2, 26: Fresnel lens

3: projector

4, 16: light diffusing layer

5, 20: light diffusing agent

6, 12: support

7, 18: printed layer

8, 22: Diffusion agent binder resin

14: incident shape layer

24: printing roll

Hereinafter, the present invention will be described in detail.

FIG. 5 is a view illustrating the present invention, wherein the lenticular lens 10 of the present invention is used in combination with a fennel lens (not shown) and is incident on the light incident side around the support 12. It consists of the shape layer 14, the light-diffusion layer 16 located in the light emission side, and the printing layer 18 located on the light-diffusion layer 16. As shown in FIG.

The support 12 supports the light diffusing layer 16 and the incident shape layer 14 as a transparent film having good light transmittance. The support 12 has a thickness of 10 to 300 μm, a total light transmittance of 75% or more, and is surface-treated with a primer, plasma, corona, or the like to improve adhesion to the light diffusing layer 16 and the incident shape layer 14. desirable.

The transparent film used as the support 12 is polyester, polyvinyl chloride, polymethyl methacrylate, polycarbonate, polyamide 6, polyamide 66, polyester sulfone, polyether ketone, polyetherimide polyacrylate resin Films prepared by one type alone or by mixing two or more types may be used.

The incident shape layer 14 is designed to have an aspherical shape satisfying Equation 1 below to secure the viewing angle of the screen and minimize the color shift, and can be cured by irradiating light such as ultraviolet rays or electron beams. Made of chemical resin, It is preferable that it is made of photocurable resin whose total light transmittance is 70% or more.

[Equation 1]

Where C is the curvature of the lens, Is the cone coefficient and X and Z are the coordinate determination dependent variables.

The photocurable resin used for the above-mentioned incident shape layer 14 may be used alone or in combination of two or more of urethane acrylate, epoxy acrylate, ester acrylate and ether acrylate resin.

The light diffusing layer 16, which is a feature of the present invention, has a very important function of focusing incident light to minimize the angle of emitted light, thereby reducing color shift and simultaneously allowing an image to be imaged.

6 is a view illustrating the light diffusion and focusing action of the lenticular lens of the present invention, the light diffusing layer 16 after mixing the spherical light diffusing agent 20 with the diffusion agent bonding resin 22, the thickness 10 It may be prepared by coating a single layer on the support 12 to be to 100 ㎛. The spherical light diffusing agent 20 scatters light by refraction and reflection at the same time while each particle acts like a fine lens to focus light at a predetermined angle. It is preferable that each particle of the light diffusing agent 20 has an average particle diameter of about 3 to 70 μm, and the amount of the light diffusing agent is about 30 to about 100 vol% of the diffusing agent binder resin 22 and the light diffusing agent 20. It is preferably 80% by volume.

The light diffusing agent 20 has a spherical shape of a transparent glass, aluminum hydroxide, alumina, silica, polymethacrylate, polycarbonate, polystyrene, epoxy, unsaturated polyester, or a mixture of two or more kinds of raw materials. It is preferable that the refractive index difference from the diffusing agent bonding resin 22 is 0.02 to 0.1.

The diffusing agent bonding resin 22 has a function of fixing and supporting the light diffusing agent 20, It may be made of the same photocurable resin as the incident shape layer 14, and it is preferable to use a photocurable resin having a total light transmittance of 70% or more. In addition, the diffusion agent binder resin may be prepared including an organic and inorganic powder having an average particle diameter of 0.1 to 5㎛. It can be prepared by adding pigments or pigments to improve contrast or by additionally using spherical or amorphous fillers to increase diffusion efficiency.

The present invention forms the printed layer 18 in order to prevent glare and lowering of contrast caused by reflected light in the presence of an external light source. The printing layer 18 is produced by printing black ink on the light emitting side light diffusing layer 16 which is symmetrical to the valleys of the lens of the incident shape layer 14.

7 is a view illustrating a process of forming a printing layer on the lenticular lens of the present invention. In the manufacture of the lenticular lens 10 according to the present invention, first, the incident shape layer 14 is coated with a photocurable resin on a roll mold formed in the same manner as the incident shape layer as described in US Patent No. 3,689,346. Together it can be easily prepared through ultraviolet or electron beam curing. The light diffusing layer 16 may be prepared by coating with a known method such as roll coating, reverse roll coating, knife coating and the like followed by photocuring. The printing layer 18 can be easily produced by penetrating ink into the printing roll 24 and then transferring and photocuring the light diffusion layer 16.

FIG. 8 is a further embodiment of the present invention, which may be manufactured by adding a pigment into the diffusion agent binder resin 22 of the light diffusing layer 16 to exclude the printing layer for contrast control.

FIG. 9 illustrates another embodiment of the present invention, in which a shape of the Fresnel lens 26 is formed without the incident shape layer of the lenticular lens 10.

FIG. 10 is a graph showing the relationship between the incident angle versus the exit angle measured using the lenticular lens of the present invention. It can be seen that the color shift phenomenon is greatly reduced by refracting the incident light inward to have an exit angle smaller than the incident angle. Can be.

The present invention will be described in more detail with reference to the following examples and comparative examples.

Example 1

A polyester film was used as the support 12, and the incident shape layer 14 was UV-cured photocurable urethane acrylate resin, and the spherical polystyrene light diffuser 20 and the photocurable urethane acrylate on the support 12. The light diffusion layer 16 was formed by mixing and coating the diffusion binder resin 22. It finished by forming the printing layer 18 on the light-diffusion layer 16 using black ink. The raw materials used and the molding conditions are shown in Table 1.

Comparative Example 1

A product used in the prior art was prepared by co-extrusion of polymethacrylate mixed with a light diffusing agent. The performance compared with the Example is shown in Table 2.

TABLE 1

division Item standard Remarks Support Furtherance Polyester SK products thickness 250 ± 2 μm Total light transmittance 90% Incident Shape Layer Furtherance Urethane Acrylate Viscosity 700 ± 100 cps 25 ℃ Printed layer Furtherance Urethane Acrylate color black * Light diffusing agent Furtherance polystyrene Average particle diameter 8 μm Refractive index 1.59 * Diffuser Bonded Resin Furtherance Urethane Acrylate Refractive index 1.52

(* The mixing ratio of binder resin (22) to light diffusing agent (20) is 1: 1.5 by volume)

TABLE 2

Item Example 1 Comparative Example 1 pitch 0.3 mm 0.67 mm Full thickness 0.5 mm 0.97 mm Light Diffusion Layer 16 Thickness 18 μm 200 μm Contrast Dark room 70: 1 60: 1 Persons 60: 1 55: 1 Color shift 3.5 4.2

The present invention eliminates the spherical lens shape of the exit surface side of the conventional lenticular lens as shown in Figure 10 and Table 2, and the light diffusion layer is opened to collect the light incident at an angle to minimize the exit angle of the emitted light Providing a lenticular lens reduces color shift and can be used in all three-color back-projection systems with the same or different angles of incidence.

Claims (13)

In the lenticular lens for the rear projection screen, a) a support film made of a transparent material; b) formed on the light incident side of the support film and molded of a photocurable resin An aspheric incidence layer; And c) a light diffusing agent and a diffusing agent bonding resin on the light exit side of the support film; Light diffusing layer mixed and coated with light diffusing agent particles arranged in a single layer Lenticular lens comprising a. The method of claim 1, The lenticular lens of the incident shape layer is made of a photocurable resin having a total light transmittance of 70% or more. The method of claim 1, The lenticular lens of the support is made of a transparent film having a total light transmittance of 75% or more and a thickness of 10 to 300 μm. The method of claim 1, The light diffusing layer is a lenticular lens in which the spherical light diffusing agent is mixed in 30 to 80% by volume with respect to the diffuser binder resin and 100% by volume of the light diffusing agent. The method of claim 4, wherein The light diffusing agent is a transparent spherical particle having an average particle diameter of 3 to 70 ㎛, and has a refractive index difference of 0.02 to 0.1 with the diffusion agent bonding resin. The method of claim 4, wherein The diffuser binder resin is a lenticular lens made of organic and inorganic powder having an average particle diameter of 0.1 to 5 ㎛. The method of claim 6, The lenticular lens of the diffusion agent binder resin further comprises a pigment. The method of claim 4, wherein The lenticular lens of the diffusing agent binder resin is made of a photocurable resin having a total light transmittance of 70% or more. The method of claim 1, A lenticular lens in which a Fresnel lens is molded and manufactured in the incident shape layer. In projectors and rear projection systems, a) a support film made of a transparent material; b) formed on the light incident side of the support film and molded of a photocurable resin An aspheric incidence layer; And c) a light diffusing agent and a diffusing agent bonding resin on the light exit side of the support film; Light diffusing layer mixed and coated with light diffusing agent particles arranged in a single layer Rear projection type system comprising a lenticular lens comprising a. The method of claim 10, A rear projection type system wherein said projector is a cathode ray tube or a liquid crystal display. 10. The lenticular lens of claim 1, further comprising: d) a printed layer printed at a location on the light diffusing layer that is symmetric to the valley portion of the incident surface shape of the incident shape layer. Lenticular lens, characterized in that. 12. The back surface according to claim 10 or 11, wherein the lenticular lens further comprises a printing layer printed at a position on the light diffusion layer symmetric with the valley portion of the incidence surface shape of the incidence layer. Projective system.