WO2009041747A1

WO2009041747A1 - Screen improved every side viewing angle

Info

Publication number: WO2009041747A1
Application number: PCT/KR2007/004772
Authority: WO
Inventors: Young Tae Kim
Original assignee: Vulite
Priority date: 2007-09-28
Filing date: 2007-09-28
Publication date: 2009-04-02
Also published as: CN101878450A; KR20090032704A; KR100893942B1

Abstract

The present invention related to a front reflective screen in which glass beads having a particle size ranging from 20μm to 80μm are adhered to a panel to make the surface from which light is reflected uneven considering that the brightness caused by specular reflection is high but the brightness caused by side reflection is low because the diameters of the glass beads formed fixed on the screen are identical. The present invention provides a screen with enlarged side viewing angles, including: a panel; glass beads fixed on the panel to diffusely reflect light incident to the glass beads and to improve brightness, the glass beads having a spherical or elliptical shape and having a particle size of 20 ~ 80μm; and an adhesive used to fix glass beads on the panel, the adhesive having a thickness of 100 ~ 400μm, wherein the particles sizes of the glass beads impregnated into the adhesive are different from each other, so that a surface of the panel is uneven, thereby enlarging the side viewing angles of the screen.

Description

Description SCREEN IMPROVED EVERY SIDE VIEWING ANGLE

Technical Field

[1] The present invention relates to a front reflective screen with enlarged side viewing angles, and, more particularly, to a front reflective screen with enlarged side viewing angles, in which, in consideration of the narrow side viewing angles of a flat screen having the same incident angle and reflection angle, the surface of a panel is formed to be irregularly uneven in order to diffuse light, the panel is formed of a fabric in order to minimize the difference between the front view angle and side view angle of the screen and to increase brightness, an adhesive is applied on the panel, heated and then sprayed with glass beads having different particle sizes, and the thickness and viscosity of the adhesive are adjusted depending on the particle size of the glass beads, thus maximizing diffuse reflection. Background Art

[2] Generally, an image projection system including a projection television, a video projector and the like is an image display system in which an image generated from a projector is reflected by a mirror and then enlarged and projected on a screen. Recently, the demand for an image projection system is increasing because the image projection system has an advantage in that a large image which can meet the requirements of consumers can be displayed on a screen.

[3] Such an image projection system includes a front reflective screen, called a front type screen, and a rear projective screen, called a rear type screen, according to the method of enlarging and projecting an image onto a screen. In the image projection system, light emitted from an image source is transmitted toward a screen along an incidence axis, and thus an image is formed on the screen, and the image is recognized by an observer located in front of the screen.

[4] Generally, a front projector screen is a display panel used to realize an image using optical techniques related to a beam projector, and is made of white or gray resin or paper. Here, an image beam emitted from the beam projector is projected onto the front projector screen and reflected from the front projector screen, and thus an observer can recognize the image displayed on the front projector screen.

[5] When a screen for receiving an image projected from a projector is manufactured, in order to improve brightness, a screen is coated with aluminum powder to induce light diffusion and light reflection, or is fabricated by forming a light reflection layer on the surface of the screen and then placing a light diffusion layer on the light reflection layer formed by dispersing a granular light diffusing agent in a transparent resin layer.

[6] Meanwhile, Korean Patent Registration M>s. 10-0289787 and 10-0289788 disclose a retroreflective textile including retroreflective materials such as glass beads which are used to exhibit beautiful colors even in the daytime and to improve brightness.

[7] However, according to the above conventional technologies, when a screen is fabricated by dispersing glass beads 20 or aluminum powder on the surface of a panel 10 as shown in FIG. 1, the diameters of the glass beads or aluminum powder are constant. Consequently, the screen reflects light in the front direction of the screen, and thus the screen has high brightness in the front direction thereof. However, since the viewing angles of the screen are narrow in horizontal and vertical directions, it is difficult to see the picture on the screen from the side thereof. Further, when a viewer sees the screen, the screen acts as a light source, so that the viewer's eyes are dazzled by the glare of the light emitted from the light source, and the difference in the viewing angles of the screen is great yet.

[8] That is, in the front reflective screen, while a projector projects an image on the screen at one point using a single light source, the incidence angle of a projected image projected onto the central portion of the screen is different from the incidence angle at the left and right portions of the screen, and thus the brightness of the central portion of the screen is also greatly different from those of the left and right portions of the screen. Further, even when a high-brightness reflector is manufactured by sequentially forming a glass bead layer, a microlens, a microprism and a glass hemisphere lace on the surface of the screen to enable the screen to have retroreflectivity, there are also problems in that the viewing angles of the screen are narrow, and a clear image can be realized only on a specific region of the screen.

[9] Further, in a conventional screen manufactured by adhering a film or layer onto a fabric or sheet, there are problems in that the film or layer is separated from the fabric or sheet by the heat emitted from a beam projector or the environmental factors, or the screen becomes wrinkled, thereby decreasing the lifespan of the screen. Disclosure of Invention Technical Problem

[10] Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a screen with enlarged side viewing angles, which can ensure wide viewing angles over both a central portion and side portions of the screen.

[11] Another object of the present invention is to provide a screen with enlarged side viewing angles, the surface of which is uneven and curved, thus increasing the brightness of the screen.

[12] Still another object of the present invention is to provide a screen with enlarged side viewing angles, in which a fabric or sheet is integrated with beads by impregnating a bridging material into the fabric or sheet, not by adhering a film or layer onto the fabric or sheet. Technical Solution

[13] In order to accomplish the above objects, an aspect of the present invention provides a screen with enlarged side viewing angles, including: a panel; glass beads fixed on the panel to diffusely reflect light incident to the glass beads and to improve brightness, the glass beads having a spherical or elliptical shape and having a particle size of 20 ~ 80μm; and an adhesive used to fix glass beads on the panel, the adhesive having a thickness of 100 ~ 400μm, wherein the particles sizes of the glass beads impregnated into the adhesive are different from each other, so that a surface of the panel is uneven, thereby enlarging the side viewing angles of the screen.

[14] Another aspect of the present invention provides a screen with enlarged side viewing angles, including: a panel; glass beads fixed on the panel to diffusely reflect light incident to the glass beads and to improve brightness, the glass beads having a spherical or elliptical shape and having a particle size of 20 ~ 80μm; and an adhesive used to fix glass beads on the panel, the adhesive having a thickness of 100 ~ 400μm, wherein the particles sizes of the glass beads impregnated into the adhesive are equal, and the depths of the glass beads impregnated into the adhesive are different from each other, so that a surface of the panel is uneven, thereby enlarging the side viewing angles of the screen.

[15] Another aspect of the present invention provides a screen with enlarged side viewing angles, including: a panel; glass beads fixed on the panel to diffusely reflect light incident to the glass beads and to improve brightness, the glass beads having a spherical or elliptical shape and having a particle size of 20 ~ 80μm; and an adhesive used to fix glass beads on the panel, the adhesive having a thickness of 100 ~ 400μm, wherein the particles sizes of the glass beads impregnated into the adhesive are different from each other, and the depths of the glass beads impregnated into the adhesive are different from each other even when the particle sizes thereof are equal, so that a surface of the panel is uneven, thereby enlarging the side viewing angles of the screen. [16] Meanwhile, still another aspect of the present invention provides a screen, comprising: a panel; glass beads which are irregularly applied on the panel according to the particle size thereof in order to diffusely reflect light incident on the panel; and an adhesive which tightly fixes the glass bead on the panel to make a surface of the panel uneven. [17] In the screen, a plurality of irregular recesses and protrusions may be integrally formed on the panel. [18] Further, the panel may be formed of a fabric, and the fabric may be composed of many strands connected with each other in an annular shape, and recesses and protrusions may be formed on a surface of the panel by adjusting the thickness of the strands and the intervals between the strands. [19] Further, the panel may be formed of a film or glass, and a plurality of irregular recesses and protrusions may be formed on the film or glass. [20] Further, the glass beads may have a spherical shape or a cubic shape approximate to the spherical shape, such as an elliptical, hexagonal or diamond shape. [21] Further, the glass beads may be made of a transparent material selected from among transparent glass, transparent acrylate and transparent PVC. [22] Further, the glass beads may have a particle size of 20 ~ 80μm.

[23] Further, the glass beads may have a particle density of 300 ~ 400 g/m².

[24] Further, the adhesive may be prepared by dissolving a transparent polyurethane resin and a polyisocyanate compound, serving as a crosslinking agent, in an organic solvent. [25] Further, the adhesive may have a thickness of 100 ~ 400μm.

[26] Further, the glass beads may be each differently immersed into the adhesive, and thus the entire surface of the glass beads may be more uneven.

Advantageous Effects

[27] The present invention has the following advantages.

[28] First, since the surface of the screen is irregularly concave and convex, the light incident on the screen is diffusely reflected and the viewing angle of the screen is remarkably enlarged, so that a wide-angle screen can be easily realized and the convenience of users can be increased.

[29] Second, since the surface of the screen can be easily changed into a concavo-convex shape by adjusting the size of glass beads and the thickness of an adhesive for fixing the glass beads onto a panel, an additional light diffusion agent or light diffusion lens is not required, thus reducing production costs and simplifying production processes. Brief Description of the Drawings

[30] FIG. 1 is a sectional view showing a conventional screen;

[31] FIG. 2 is a sectional view showing a screen with enlarged side viewing angles according to the present invention;

[32] FIGS. 3 and 4 are sectional views showing a process of manufacturing a screen with enlarged side viewing angles according to the present invention;

[33] FIG. 5 is a sectional view showing a screen with enlarged side viewing angles according to the present invention; and

[34] FIG. 6 is a sectional view showing a screen with enlarged side viewing angles according to the present invention;

[35] <Description of the elements in the drawings>

[36] 100: screen

[37] 110: panel

[38] 120: adhesive

[39] 130: glass beads

Best Mode for Carrying Out the Invention

[40] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[41] As shown in FIG. 2, a screen 100 according to the present invention includes a flat panel 110 which is made of a fabric such as wool or a sheet and has predetermined thickness and area, glass beads 130 which are irregularly applied on the panel 110, and an adhesive 120 for fixing the glass beads 130 on the panel 110.

[42] The panel 110 is made of a flat fabric or sheet whose surface is uneven. In the present invention, since diffuse reflection is induced by irregularly forming the glass beads 130 on the surface of the panel 110, the irregularity of the glass beads 130 is further increased by irregularly forming the glass beads 130 themselves as well as by unevenly forming the surface of the panel 110 on which the glass beads 130 are placed. The reason for this is that diffuse reflection in which light can be reflected in all directions is induced in order to overcome the disadvantage of specular reflection in which the angle of reflected light to incident light becomes narrow when light is incident on a plane mirror and in which brightness is weakened as the angle of reflected light to incident light is enlarged.

[43] When the panel 110 is formed of a fabric or sheet, the fabric is composed of a great number of strands connected with each other in an annular shape, and thus its surface becomes an uneven surface having different heights. In particular, the uneven shape may be changed by adjusting the intervals between the strands and the thickness of the strands, thus increasing reflection efficiency.

[44] The present invention relates to a fabric or sheet having an uneven shape, but is not limited thereto. Even when the panel is formed of a material having a flat surface, such as film or glass, the panel itself is formed into a panel having an uneven shape such as a spherical shape, a cubic shape or the like, thus obtaining the same effects as the fabric composed of a great number of strands connected with each other in an annular shape.

[45] The glass beads 130 are used to overcome the problem that the screen 110 cannot have a wide viewing angle because its side angles are narrow even though its front brightness is very high. A conventional screen has a front brightness of 2.0 ~ 3.0 gains and a side brightness of 0.8 ~ 0.9 gains. Therefore, the conventional screen is problematic in that the front brightness thereof is three times or more of the side brightness thereof, and thus the difference between the front brightness and the side brightness is very large. For this reason, in order to minimize the difference between front brightness and side brightness, the present invention provides a screen having front brightness of 1.5 ~ 1.8 gains and a side brightness of 1.5 ~ 1.8 gains. The brightness of 1.5 ~ 1.8 gains corresponds to international certification standards and is a brightness level suitable to minimize the fatigue of eyes. Accordingly, the screen of the present invention is most characterized in that it is configured such that the particle diameters of the glass beads 130 are different from each other.

[46] Generally, glass beads 130 have a spherical shape, but the present invention is not limited thereto. The surface of the glass beads 130 may be rough as long as they have a cubic shape approximate to a spherical shape. Further, the glass beads 130 may have an elliptical, hexagonal or diamond shape, but may not have an amorphous polygonal shape having many edges.

[47] Glass beads 130 may be made of transparent glass, transparent acrylic resin or transparent PVC. The glass beads is generally adhered onto a panel 110 using an adhesive 120 after spraying glass bead particles onto the panel 110, but may be adhered onto the panel 110 using the adhesive 120 after engraving the glass beads in a predetermined shape. Further, the glass beads may be adhered onto the panel 110 by form the glass beads into a film and then adhering the film onto the panel 110 using the adhesive 120.

[48] The particle size of the glass beads 130 may be in a range of 1 ~ lOOμm, preferably 20 ~ 80μm. For example, from FIG. 2, it can be seen that glass beads 130 having various particle sizes of 80μm, 40μm, 30μm, 25 μm and 20 μm are irregularly mixed with each other.

[49] When the particle size of the glass beads is less than lμm, foci are formed not in the glass beads but in the panel 110 or the backside thereof, thereby decreasing reflection efficiency. In contrast, when the particle size thereof is more than lOOμm, foci are formed in the glass beads, so that front reflection efficiency is increased but side reflection efficiency is decreased, with the result that the diffusion of light does not occur.

[50] The density of the glass beads 130 may be may be in a range of 50 ~ 1000 g/m², preferably 300 ~ 400 g/m². When the density of the glass beads 130 is more than 1000g/m², reflection efficiency is increased, but the weight of the screen 100 is excessively increased. In contrast, when the density of the glass beads 130 is less than 50g/ m², diffusion effects hardly occur.

[51] The adhesive 120 functions to prevent the glass beads from being separated from the panel 110. That is, the adhesive 120 functions to adhere the glass beads 130 on the panel 110 such that the glass beads 130 is not detached from the panel 110 even when the panel is stood on end or rolled. Secondarily, the adhesive 120 secondarily functions to accelerate the diflusion of light and to increase brightness. Therefore, the viewing angle of the screen 100 can be remarkably enlarged even when the screen 100 is viewed from various angles.

[52] The adhesive 120 is prepared by dissolving a thermoplastic resin, such as a transparent polyurethane resin, and a polyisocyanate compound, serving as a crosslinking agent, in an organic solvent. Here, it is preferred that the amount of the crosslinking agent be 4 ~ 8 parts by weight based on 100 parts by weight of the thermoplastic resin.

[53] As described above, the surface of the screen 100 can be uneven by irregularly applying the glass beads having various particle sizes onto the panel 110 using the adhesive 120. In addition, the surface of the screen 100 can also be uneven by adjusting the thickness and viscosity of the adhesive 120 impregnated with the glass beads 130.

[54] Hereinafter, a method of manufacturing the screen according to the present invention will be described in detail with reference to the accompanying drawings.

[55] First, a panel 110 formed of a fabric or sheet is provided. The surface of the panel

110 is uneven regardless of the kinds of the materials constituting the panel 110, such as natural fiber, synthetic fiber, film, glass and the like. The panel 110 is cut at a predetermined size.

[56] As shown in FIG. 3, an adhesive 120 is applied on the panel 110. Subsequently, the panel 110 coated with the adhesive 120 is heated to a predetermined temperature, and then glass beads 130 are sprayed thereon.

[57] The method of applying the adhesive 120 on the panel 110 may be conducted by spraying, rolling or printing, and may be repeatedly conducted several times.

[58] It is preferred that the panel 110 coated with the adhesive 120 be heated to a temperature of 90 ~ 11O⁰C. When the heating temperature is less than 8O⁰C, the viscosity of the adhesive 120 becomes low, so that the glass beads 130 are not sufficiently impregnated into the adhesive 120, thereby losing the adhesion between the glass beads 130 and the adhesive 120. In contrast, when the heating temperature is more than 18O⁰C, the adhesive 120 is almost liquefied, so that the glass beads 130 are excessively impregnated into the adhesive 120, with the result that the glass beads 130 are completely immersed under the adhesive 120, thereby losing reflectivity.

[59] As shown in FIG. 5, although the adhesive 120 may be heated or the viscosity of the adhesive 120 may be adjusted to such a degree that the glass beads 130 are immersed in the adhesive 120 to a depth of half their diameters, as shown in FIG. 6, in order to make the surface shape of the panel 110 irregular, the thickness and viscosity of the adhesive 120 may be adjusted such that the glass beads 130 are immersed in the adhesive to different depths even if the sizes of the glass beads 130 are equal.

[60] The thickness of the adhesive 120 is properly determined in consideration of the size of the glass beads. It is preferred that the thickness of the adhesive 120 be determined within the range of 100 ~ 400μm.

[61] When the thickness of the adhesive 120 is less than lOOμm, considering that the diameter of the glass beads 130 is 20 ~ 80μm, the glass beads 130 cannot be immersed in the adhesive 120 to a sufficient depth, so that the adhesion between the adhesive 120 and the glass beads 130 is weakened, the heights of the glass beads 130 fixed on the panel are very different from each other because the adhesive layer is thin, and the surface of the panel 110 is excessively uneven.

[62] In contrast, when the thickness of the adhesive 120 is more than 400μm, most of the glass beads 130 are immersed in the bottom of the adhesive layer, so that the surface of the panel 110 does not become uneven at all.

[63] The adhesive 120 is sprayed with the glass beads 130, heated, and then dried at a predetermined temperature using a hot air dryer. It is preferred that the adhesive 120 sprayed with the glass beads 130 be dried at a temperature of 100⁰C for 30 minutes or more in order to strongly fix the glass beads 130 on the panel 110 and increase the unevenness of the surface of the panel 110.

[64] When the drying temperature is less than 100⁰C, the adhesion between the adhesive

120 and the glass beads 130 is weakened, and, when the drying temperature is more than 100⁰C, the glass beads are immersed in the bottom of the adhesive layer. It is preferred that hot air be applied to the lateral side of the panel 110.

[65] After the drying, the adhesive layer is aged at a temperature of 4O⁰C for one week or more. It takes much time to completely dry the adhesive layer to the bottom thereof although the adhesive layer has been dried at a temperature of 100⁰C for 30 minutes or more using hot air.

[66] As described above, in order to overcome the disadvantage that the brightness of the light reflected from the center of a flat screen is high but the brightness of the light reflected from the sides of the flat screen is low because the diameter of the glass beads fixed on the flat screen in order to increase the brightness of the flat screen is constant, the present invention provides a technical idea in which glass beads having different particle sizes are sprayed on a panel and then fixed on the panel using an adhesive, and in which the thickness and viscosity of the adhesive are adjusted according to the particle size of the glass beads to make the surface of a screen uneven, and thus the glass beads are differently immersed into the adhesive when the liquid adhesive is dried. Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Claims

[1] A screen with enlarged side viewing angles, comprising: a panel; glass beads fixed on the panel to diffusely reflect light incident to the glass beads and to improve brightness, the glass beads having a spherical or elliptical shape and having a particle size of 20 ~ 80μm; and an adhesive used to fix glass beads on the panel, the adhesive having a thickness of 100 ~ 400μm, wherein the particles sizes of the glass beads impregnated into the adhesive are different from each other, so that a surface of the panel is uneven, thereby enlarging the side viewing angles of the screen. [2] A screen with enlarged side viewing angles, comprising: a panel; glass beads fixed on the panel to difiusely reflect light incident to the glass beads and to improve brightness, the glass beads having a spherical or elliptical shape and having a particle size of 20 ~ 80μm; and an adhesive used to fix glass beads on the panel, the adhesive having a thickness of 100 ~ 400μm, wherein the particles sizes of the glass beads impregnated into the adhesive are equal, and the depths of the glass beads impregnated into the adhesive are different from each other, so that a surface of the panel is uneven, thereby enlarging the side viewing angles of the screen. [3] A screen with enlarged side viewing angles, comprising: a panel; glass beads fixed on the panel to difiusely reflect light incident to the glass beads and to improve brightness, the glass beads having a spherical or elliptical shape and having a particle size of 20 ~ 80μm; and an adhesive used to fix glass beads on the panel, the adhesive having a thickness of 100 ~ 400μm, wherein the particles sizes of the glass beads impregnated into the adhesive are different from each other, and the depths of the glass beads impregnated into the adhesive are different from each other even when the particle sizes thereof are equal, so that a surface of the panel is uneven, thereby enlarging the side viewing angles of the screen. [4] A screen, comprising: a panel; glass beads which are irregularly applied on the panel according to the particle size thereof in order to diffusely reflect light incident on the panel; and an adhesive which tightly fixes the glass bead on the panel to make a surface of the panel uneven. [5] The screen according to claim 4, wherein a plurality of irregular recesses and protrusions are integrally formed on the panel. [6] The screen according to claim 4, wherein the panel is formed of a fabric, and the fabric is composed of many strands connected with each other in an annular shape, and recesses and protrusions are irregularly formed on a surface of the panel by adjusting the thickness of the strands and the intervals between the strands. [7] The screen according to claim 4, wherein the panel is formed of a film or glass, and a plurality of irregular recesses and protrusions are formed on the film or glass. [8] The screen according to claim 4, wherein the glass beads have a spherical shape or a cubic shape approximate to the spherical shape, such as an elliptical, hexagonal or diamond shape. [9] The screen according to claim 8, wherein the glass beads are made of a transparent material selected from among transparent glass, transparent acrylate and transparent PVC. [10] The screen according to claim 4, wherein the glass beads have a particle size of

20 ~ 80μm. [11] The screen according to claim 4, wherein the glass beads have a particle density of 300 ~ 400 g/m². [12] The screen according to claim 4, wherein the adhesive is prepared by dissolving a transparent polyurethane resin and a polyisocyanate compound, serving as a crosslinking agent, in an organic solvent. [13] The screen according to claim 4, wherein the adhesive has a thickness of 100 ~

400μm. [14] The screen according to claim 13, wherein the glass beads are each differently immersed into the adhesive, and thus the entire surface of the glass beads is more uneven.