WO2003102687A1

WO2003102687A1 - Surface-reflective projection screen with curved surface and method of manufacturing the same

Info

Publication number: WO2003102687A1
Application number: PCT/KR2002/001046
Authority: WO
Inventors: In-Hwan Lee
Original assignee: G.B. Light Co., Ltd
Priority date: 2002-06-01
Filing date: 2002-06-01
Publication date: 2003-12-11
Also published as: AU2002306132A1

Abstract

Disclosed is a curved surface-reflective projection screen, in which moving pictures are clearer than those provided by a conventional flat-type projection screen, when viewing at a side, and the definition and resolution are too improved in accordance with increased viewing area in the same region on the screen.

Description

SURFACE-REFLECTIVE PROJECTION SCREEN WITH CURVED SURFACE AND METHOD OF MANUFACTURING THE SAME

Technical Field

The present invention relates to a surface -reflective projection screen, and in particular, to a curved surf ace -reflective projection screen, in which moving pictures are clearer than those provided by a conventional flat -type projection screen, when viewing at a side, and the definition and resolution are too improved in accordance with an increased viewing area in the same region on the screen.

Background Art

A conventional screen used for projection is a lamination of a dark backing sheet and a white polyvinyl chloride (PVC) film. The conventional screen has a low reflectivity and therefore a dark projected image. In addition, the conventiona 1 screen has a low diffusing power.

A projection screen have been developed before several decades, in which glass beads having a diameter of micron unit are bonded to the PVC film to enhance the reflectivity and the diffusing power. Since a technique of depositing glass beads is incomplete, the glass beads are readily scraped off when the contaminants are wiped off from the surface thereof, which is a defect of such a screen.

In order to solve the above drawback, a screen comprising the dark backing sheet and the white PVC film as described above is disclosed in Japanese Laid -Open Utility Model Publication No. Sho 64 -40835. A metallized layer is provided as a reflection layer on the white PVC film. A translucent PVC film containing a pearl pigment is laminated thereon, and a specific emboss is provided on the outer surface thereof. However, the prior screen has too high light reflectivity and too many components of specular reflection, so that a halation is caused to present a dull image projected.

In order to address the drawback and problem of the prior projection screen as described above, the development of a projection screen utilizing a reflective film with the glass beads deposited thereon have been attempted. However, since a technique of depositing glass beads is incomplete, it was impossible to manufacture a high quality of an article.

Another projection screen having an emboss formed on a surface of a light diffusing layer without utilizing the reflective film is proposed in PCT application No. PCT/JP 92/00715. A fibrous sheet of glass fibers is provided on the surface of a light absorbing layer which is a dark plastic sheet, and a white, opaque base material sheet made with a plastic sheet is laid on the fibrous sheet. And then, a light diffusing layer of a translucent plastic is formed on the base material sheet. The emboss is formed on the outer surface of the light diffusing layer, which is a copy of the operation of the glass beads of the conventional projection screen. The PCT application proposed to solve the poor durability of the glass bead and the drawback of the projection screen having the metallized layer has some problems in that the reflectivity and diffusing power are low relative to a manufacturing cost thereof, that a distinct picture is not provided from a side, and the picture is more and less dark.

Considering the above description, the inventor arrives at the conclusion in that it is most preferable to manufacture the projection screen by using the reflective film for satisfying the economical efficiency and the functionality. Recently, the high development of the glass beads depositing technique causes the separating phenomenon of the glass beads to be highly improved, so that a projection screen made of a reflective film as shown in Fig. 7 is developed and is commercially available. In other words, Fig. 1 is a cross sectional view of a photograph of Fig. 7, and Fig. la shows an alternative example of Fig. 1, in which its construction is substantially similar to that of Fig. 1.

Specifically, the projection screen includes a fibrous sheet 100 of glass woven fabric provided on a black PVC sheet 140, a white shielding film 120 coated on the fibrous sheet, a white reflective resin layer 240 formed on the white shielding film, and glass beads 230 attached on the reflective resin layer. The example shown in Fig. la is characterized in that a white shielding film 120 is further formed between the fibrous sheet 100 and the black PVC sheet 140. These projection screens are most widely used at present. Since they employ the PVC, which is not an environment -friendly material, it is impossible at present to use it in every country. In view of the diffusing power and reflectivity of the light, the functional side such as image discrimination of the image when viewing at a side, and the economical efficiency, it will be popularized, but there is a problem in that the functional side is not favorable. Referring to Figs. 1 and la, when the white shielding film 120 is formed on the fibrous sheet 100 with the emboss formed thereon, a thickness of the white shielding film is different at every position (e.g., d and d '). In other words, since a surface of the white shielding film 120 is horizontally maintained as shown in Figs. 1 and la, the thickness (d and d') should be different from each other on the basis of the fibrous sheet 100. Since the white reflective resin layer 240 is formed on the white shielding film, and glass beads 230 are attached on the reflective resin layer, the distance D and D' between the glass beads and the fibrous sheet 100 should be different from each other. Accordingly, the diffusing power of the light is not uniform, and the reflectivity is also not uniform. As will be seen from Figs, la and 7, the glass bead 23 0 is horizontally fixed.

In conclusion, the entire surface of the projection screen has a horizontal construction. There is a problem in that the light transferred to the screen through a light source is not properly reflected toward the right source, bu t is dispersed, thereby adversely influencing the discrimination, the reflectivity, the diffusing power, the brightness of the picture and so forth. Referring to Fig. 5, since the surface of the screen is horizontally maintained, the definition and resolu tion of the picture are lowered when viewing at the side.

Disclosure of the Invention

Therefore, an object of the present invention is to solve the problems involved in the prior art, and to provide a curved surface -reflective projection screen capable of achieving a lot of curved -surface reflection from a screen by forming a curved glass beads on the entire surface of the screen along a curvature relative to a curve of a fibrous sheet of glass woven fabric.

Another object of the present invention is to pr ovide a projection screen utilizing urethane resin and urethane pigment, which are environment -friendly material.

In order to accomplish the above mentioned objects, the present invention provides a method of manufacturing a curved surface -reflective projection screen, the method comprising the steps of: forming white urethane resin layers on an upper and lower surface of a white fibrous sheet of glass woven fabric to form an emboss along a curvature of the white urethane resin layer; forming a black uretha ne pigment layer on a surface of the white urethane resin layer along its curvature to form a substrate; rigidly integrating the white urethane resin layer and a hot melt urethane adhesive of a reflective film including a poly ethylene resin formed on a polyethylene film, glass beads fixed on the polyethylene resin, a reflective resin layer formed on the glass beads, and the hot melt urethane resin adhesive formed on the reflective resin layer; and detaching the polyethylene film and the polyethylene resin from the glass beads to expose the glass beads repeatedly and uniformly forming a curved surface along the curvature of the white urethane resin layer.

It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the present invention as claimed.

Brief Description of the Drawings

The above objects, other features and advantages of the present invention will become more apparent by describing the preferred embodiment thereof with reference to the accompanying drawings, in which:

Figs. 1 and la are cross sectional views illustrating a conventional projection screen utilizing glass beads.

Figs. 2 and 2a are cross sectional views illustrating a process of manufacturing a projection screen according to one preferred embodiment of the present invention.

Fig. 3 is a side view illustrating a reflective action of a conventional projection screen.

Fig. 4 is a side view illustrating a reflective action of a projection screen according to the present invention. Fig. 5 is a side view illustrating an image viewing action of a conventional projection screen.

Fig. 6 is a side view illustrating an image viewing action of a proje ction screen according to the present invention.

Fig. 7 is a photograph of a cross section of a conventional projection screen. Fig. 8 is a photograph of a cross section of a projection screen according to the present invention. Best Mode for Carrying Ou t the Invention

Reference will now be made in detail to the preferred embodiments of the present invention.

The present invention is characterized in that a substrate 5 is made of an environment -friendly material and a continuously curved surface is formed on a surface of a screen.

The present invention includes a fibrous sheet 10 of glass woven fabric having a thickness of about 0.18 mm (specification: 67TEX g/1,000 m, density: 42 ± 2 numbers/inch of warp, and 32 ± 2 numbers/inch, and weight: 208 ± 12 g/m²), but is not limited to the above conditions.

The white fibrous sheet 10 of glass woven fabric is dipped into a solution of a white urethane resin at a temperature of 100 to 120 °C, so that white urethane resin layers 12 and 12' are formed an upper and lower surface of the white fibrous sheet 10 of glass woven fabric, and its thickness is about 0.01 mm. Even though the thickness of the white urethane resin layer will be increased or reduced, in case of unnecessarily increasing the thickness of the white urethane resin layer, the performance of the projection screen is not improved, and it brinks about an uneconomical problem. On the Contrary, in case of considerably reducing the thickness of the projection screen in relative to 0.01 mm, the diffusing po wer of the light and the brightness of the picture are adversely affected. According to an experiment, preferably, the thickness of the white urethane resin layers 12 and 12 ' are about 0.01 mm.

The white urethane resin layer 12 ' formed under the lower surface is to prevent a black urethane pigment of a black urethane pigment layer 14 from permeating into the white fibrous sheet 10 of glass woven fabric and to increase a durability of a reflective layer formed on the surface of the screen. And then, the white urethane resin layer 12 ' is treated with fire retardant and deadening to prevent decolorizing and yellowing phenomenon. Also, a black urethane pigment layer 14 is coated on the surface of the urethane resin layer 12 ' to improve a masking force of the substrate relative to the light (light source) irradiated on the surface of the screen. At that time, preferably, a thickness of the coating is about 0.035 mm. If the thickness is above it, the coating is of no significance, while the thickness is below it, its function is lowered. According to the experiment, preferably, the thickness of the black urethane pigment layer is about 0.035 mm.

It is noted that when the white urethane resin layers 12 and 12 ' and the black urethane pigment layer 14 are formed, they are naturally curved along a curvature of the white fibrous sheet 10 of glass woven fabric, as shown in the accompanying drawings. Specifically, the present invention employs a new technique, which is substantially different from that of forming the white shielding film 120 and the black PVC layer 140 on the white fibrous sheet according to the conventional projection screen as shown in Figs. 1 and la. The present invention forms the white urethane resin layers 12 and 12 ' having a uniform thickness d" on the upper and lower surface of the white fibrous sheet 10, as shown in Fig. 2a. Accordingly, the black urethane pigment layer 14 is also formed with a manner similar to the above process.

And then, the reflective film 20 is attached to the substrate 5 as shown in Fig. 2a, in which the white urethane resin layer 12 and a hot melt urethane adhesive 25 are rigidly integrated by a heat adhesion. Meanwhile, it is noted that the reflective film 20 recently manufactured has no the separating or poor phenom enon of the glass beads due to the improvement of the glass bead, the development of the adhesive of outstandingly improving the fixing performance of the glass beads, and the epoch-making advance of the heat adhesion technique. After rigidly integrating the white urethane resin layer 12 and the hot melt urethane adhesive 25, if a polyethylene film 21 is detached from the glass beads, a polyethylene resin 22 for holding the glass beads 23 is also detached from the glass beads, thereby exposing the glass beads. Since the reflective film is attached to the substrate 5 with a heat and pressure being received from a hot press or other unit, the glass beads 23 are formed to form a curved surface along the curvature of the white urethane resin layer 12 as shown in Fig. 2a.

Referring to Fig. 2a, a distance D " between the white urethane resin layer 12 and the glass beads 23 is constantly maintained, with the glass beads formed in a curved shape, contrary to the prior art.

Supposing that one region consisting of a c urved surface is referred to as "P" as shown in Fig. 8, the light radiated from the light source is properly reflected toward the light source, and the curved surface P is continuously formed in all directions, thereby improving the discrimination and refl ectivity, brightening the picture, and increasing the diffusing power of the light. Furthermore, when viewing at the center and the side of the screen of the present invention on the basis of the curved surface P, as shown in Fig. 6, a viewing distance L ' of the present invention is shorter than a viewing distance 1 ' of the conventional screen (Fig. 5), and a view angle θ' of the present invention is wider than a viewing angle θ of the conventional screen, so that a viewing area at the region P " is wide in relative to that of the conventional screen. Accordingly, the definition and resolution are improved, the discrimination at the side is outstandingly increased, and the reflectivity and the diffusing power of the light are also increased.

As apparent from the above description, the present invention provides a method of manufacturing the projection screen utilizing the reflective film, the method catching the point passed over and technically solving it.

Claims

1. A method of manufacturing a curved s urf ace -reflective projection screen, the method comprising the steps of: forming white urethane resin layers 12 and 12 ' on an upper and lower surface of a white fibrous sheet 10 of glass woven fabric to form an emboss along a curvature of the white urethane resin layer; forming a black urethane pigment layer 14 on a surface of the white urethane resin layer 12' along its curvature to form a substrate 5; rigidly integrating the white urethane resin layer 12 and a hot melt urethane adhesive 25 of a reflective film 20 including a polyethylene resin formed on a polyethylene film 21, glass beads 23 fixed on the polyethylene resin, a reflective resin layer 24 formed on the glass beads, and the hot melt urethane resin adhesive 25 formed on the reflective resin lay er; and detaching the polyethylene film 21 and the polyethylene resin 22 from the glass beads 23 to expose the glass beads repeatedly and uniformly forming a curved surface along the curvature of the white urethane resin layer 12.

2. A curved surface -reflective projection screen manufactured according to the method claimed in claim 1.