Patent Publication Number: US-11385534-B2

Title: Transparent screen, transparent screen assembly, manufacturing method of transparent screen, and manufacturing method of transparent screen assembly

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application is a continuation of U.S. application Ser. No. 15/905,880, filed on Feb. 27, 2018, which is a continuation application filed under 35 U.S.C. 111(a) claiming benefit under 35 U.S.C. 120 and 365(c) of PCT International Application No. PCT/JP2016/073892 filed on Aug. 16, 2016 and designating the U.S., which claims priority of Japanese Patent Application No. 2015-173639 filed on Sep. 3, 2015. The entire contents of the foregoing applications are incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The disclosure herein generally relates to a transparent screen, a transparent screen assembly, a manufacturing method of a transparent screen, and a manufacturing method of a transparent screen assembly. 
     2. Description of the Related Art 
     A typical screen displays video images projected from a front side of the screen or from a rear side of the screen to a user on the front side of the screen. Because the screen is dedicated for displaying video images, the user cannot view a rear background behind the rear side of the screen (See Japanese Unexamined Patent Application Publication No. 2012-032513). 
     SUMMARY OF THE INVENTION 
     Technical Problem 
     There is a problem that in the process of development of a transparent screen, through which a user can view a rear background behind a rear side of the screen, when a shape of the transparent screen is changed from a flat shape to a curved shape, a great difference in extent occurs on an end surface of the transparent screen. 
       FIG. 1  is a cross-sectional view of a transparent screen according to a related art. A side of the transparent screen  120  closer to a user  110  will be referred to as a front side, and a side of the transparent screen  120  farther from the user  110  will be referred to as a rear side. A left part of  FIG. 1  is the front side, and a right part of  FIG. 1  is the rear side. The left part may be the rear side and the right part may be the front side. That is, in  FIG. 1 , the user  110  is present on the left side of the transparent screen  120 . The user  110  may be present on the right side of the transparent screen  120 . 
     The transparent screen  120  displays video images projected from the front side of the screen or from the rear side of the screen to the user  110  on the front side of the screen, and causes the user  110  to view a rear background behind the rear side of the screen. The transparent screen  120  has, for example, a rectangular shape viewed in a front-rear direction. 
     The transparent screen  120  has a curved shape. In  FIG. 1 , the transparent screen  120  has a convex shape toward the user  110 . However, the transparent screen  120  may have a concave shape toward the user  110 . 
     As illustrated in  FIG. 1 , in a cross section orthogonal to a part of an outer edge of the transparent screen  120 , the transparent screen  120  has a curved shape. Here, the “curved shape” includes a shape of arc, a shape of elliptical arc, and the like. 
     The transparent screen  120  includes a plurality of transparent plates  130 ,  140  arranged in the front-rear direction, and a screen main body  150  interposed between the plurality of transparent plates  130 ,  140 . The plurality of transparent plates  130 ,  140  hold the screen main body  150  from both sides in the front-rear direction, to protect the screen main body  150  from both sides in the front-rear direction. The screen main body  150  displays video images projected from the front side of the screen or from the rear side of the screen to the user  110  on the front side of the screen, and causes the user  110  to view a rear background behind the rear side of the screen. The transparent screen  120  is held by a holding member  160 . 
     The holding member  160  includes an exterior side surface holding part  161  and an interior side surface holding part  162 . The exterior side surface holding part  161  holds an exterior main surface of the transparent screen  120  in the curvature radius direction. The term “exterior surface in the curvature radius direction” means a surface, out of two surfaces in a direction normal to the transparent screen  120 , which is farther from a center of curvature. The interior side surface holding part  162  holds an interior main surface of the transparent screen  120  in the curvature radius direction. The term “interior surface in the curvature radius direction” means a surface, out of two surfaces in a direction normal to the transparent screen  120 , which is closer to the center of curvature. 
     The plurality of transparent plates  130 ,  140  are obtained by bending a plurality of transparent flat plates having main surfaces of the same size into curved shapes on heating. The size of the main surface can be read as a size of a center plane in a plate thickness direction. Because there is only little tensile stress and compression stress applied to the center plane in the plate thickness direction when the transparent plates are bent in curved shapes, the size of the center plane in the plate thickness direction little changes before and after the bending. 
     In the cross section, illustrated in  FIG. 1 , the transparent screen  120  has a curved shape, and a length of a center line in the plate thickness direction  131  of the transparent plate  130  on an exterior side in the curvature radius direction is the same as a length of a center line in the plate thickness direction  141  of the transparent plate  140  on an interior side in the curvature radius direction. A center line in a plate thickness direction is a line that bisects a plate in a plate thickness direction. The length of the center line in the plate thickness direction is measured along the center line in the plate thickness direction having a curved shape. 
     In the cross section illustrated in  FIG. 1 , when the lengths of the center lines in the plate thickness direction  131 ,  141  of the plurality of transparent plates  130 ,  140  are the same, a great difference in extent D occurs on end surfaces of the plurality of transparent plates  130 ,  140 . In this case, when both main surfaces of the transparent screen  120  are held equally, as illustrated in  FIG. 1 , the exterior side surface holding part  161  reduces the rear background which can be viewed through the transparent screen  120 . In this case, when the exterior side surface holding part  161  is made shorter in order to secure a sufficient size of the rear background which can be viewed through the transparent screen  120 , sufficient size of the main exterior surface of the transparent screen  120  in the curvature radius direction cannot be secured, and the transparent screen  120  becomes unstable. 
     The present invention was made in view of the aforementioned problem, and mainly aims at providing a curved transparent screen, through which a sufficient size of a rear background can be viewed, and which can be held with stability. 
     Solution to Problem 
     In order to solve the aforementioned problem, an aspect of the present invention provides 
     a transparent screen including 
     a plurality of transparent plates arranged in a front-rear direction; and 
     a screen main body, interposed between the plurality of transparent plates, configured to display video images projected from a front side of the transparent screen or from a rear side of the transparent screen to a user on the front side, and configured to enable a rear background to be visually recognized by the user. 
     In a cross section orthogonal to a part of an outer edge of the transparent screen, the transparent screen having a curved shape, and a length of a center line in a plate thickness direction of the transparent plate on an external side of the screen main body in a curvature radius direction of the curved shape being greater than a length of a center line in a plate thickness direction of the transparent plate on an internal side of the screen main body in the curvature radius direction. 
     Effect of Invention 
     According to an aspect of the present invention, a curved transparent screen, through which a sufficient size of a rear background can be visually recognized, and which can be held with stability is provided. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cross-sectional view depicting a transparent screen according to a related art; 
         FIG. 2  is a cross-sectional view depicting a transparent screen according to an embodiment; 
         FIG. 3  is a cross-sectional view depicting the transparent screen illustrated in  FIG. 2 , cut along a III-III line; 
         FIG. 4  is a flowchart depicting a manufacturing method of the transparent screen according to the embodiment; 
         FIG. 5  is a cross-sectional view depicting a transparent screen assembly according to the embodiment; 
         FIG. 6  is a flowchart depicting a manufacturing method of a screen assembly according to the embodiment; 
         FIG. 7  is a cross-sectional view depicting a reflection-type transparent screen according to the embodiment; 
         FIG. 8  is a cross-sectional view depicting in detail a reflection-type screen main body illustrated in  FIG. 7 ; 
         FIG. 9  is a cross-sectional view depicting a transmission-type transparent screen according to the embodiment; 
         FIG. 10  is a cross-sectional view depicting in detail a transmission-type screen main body illustrated in  FIG. 9 ; and 
         FIG. 11  is a cross-sectional view depicting a transmission-type transparent screen according to a variation. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In the following, with reference to drawings, embodiments for implementing the present invention will be described. In each drawing, the same or corresponding reference numeral is assigned to the same or corresponding component, and an explanation will be omitted. 
       FIG. 2  is a cross-sectional view depicting a transparent screen according to an embodiment.  FIG. 3  is a cross-sectional view depicting the transparent screen cut along a III-III line, illustrated in  FIG. 2 . A side of the transparent screen  20  closer to a user  10  will be referred to as a front side, and a side of the transparent screen  20  farther from the user  10  will be referred to as a rear side. In each of  FIGS. 2 and 3 , a left part of the drawing is the front side, and a right part of the drawing is the rear side. The left part may be the rear side and the right part may be the front side. That is, in each of  FIGS. 2 and 3 , the user  10  is present on the left side of the transparent screen  20 . The user  10  may be present on the right side of the transparent screen  20 . 
     The transparent screen  20  displays video images projected from the front side of the screen or from the rear side of the screen to the user  10  on the front side of the screen, and enables the rear background to be visually recognized by the user  10 . The transparent screen  20  is only required to be capable of enabling the rear background to be visually recognized at least in the case where video images are not projected. In the case where video images are projected, the transparent screen  20  may enable the rear background to be visually recognized by the user  10 , or may not enable the rear background to be visually recognized by the user  10 . The transparent screen  20  has, for example, a rectangular shape visually recognized in a front-rear direction. 
     Note that, the transparent screen  20  according to the embodiment has an approximately front-rear shape visually recognized in the front-rear direction. For example, the shape may be an approximately triangular shape, a circular shape, or the like. The shape may be of great variety. 
     The transparent screen  20  has a curved shape. In  FIG. 2 , the transparent screen  20  has a convex shape toward the user  10 . However, the transparent screen  20  may have a concave shape toward the user  10 . 
     As illustrated in  FIG. 2 , in a first cross section orthogonal to a part of an outer edge of the transparent screen  20 , the transparent screen  20  has a curved shape. In the specification of the present application, the “outer edge” is an outer edge of a main surface. Moreover, the “curved shape” includes a shape of arc, a shape of elliptical arc, and the like. 
     As illustrated in  FIG. 3 , in a second cross section orthogonal to another part of the outer edge of the transparent screen  20 , the transparent screen  20  has a flat shape. The first cross section illustrated in  FIG. 2  and the second cross section illustrated in  FIG. 3  are cross sections orthogonal to each other. 
     The transparent screen  20  includes a plurality of transparent plates  30 ,  40  arranged in the front-rear direction, and a screen main body  50  interposed between the plurality of transparent plates  30 ,  40 . The transparent screen  20  is held by a holding member  60 . 
     Each of the plurality of transparent plates  30 ,  40  has a main surface and an end surface orthogonal to the main surface. Each of the plurality of transparent plates  30 ,  40  may have an oblique surface (not shown) in a boundary portion between the main surface and the end surface. The oblique surface is formed by a chamfering or the like, and is oblique with respect to both the main surface and the end surface. 
     The plurality of transparent plates  30 ,  40  hold the screen main body  50  from both sides in the front-rear direction, to protect the screen main body  50  from both sides in the front-rear direction. The plurality of transparent plates  30 ,  40  are, for example, glass plates, respectively. A laminated glass can be configured of a plurality of glass plates, and a screen main body  50  interposed between the glass plates. 
     Each of the plurality of glass plates, in which the screen main body  50  is interposed, may be a non-strengthened glass or may be a strengthened glass. The non-strengthened glass is obtained by forming a molten glass into a shape of plate, and cooling the glass slowly. The method of forming includes a float method, a fusion method and the like. The strengthened glass may be a physically strengthened glass or a chemically strengthened glass. The physically strengthened glass is obtained by rapidly cooling a uniformly heated glass plate from a temperature around a softening temperature so that a compression stress is generated on a glass surface according to a difference between a temperature of the glass surface and a temperature inside the glass, and thereby the glass surface is strengthened. The chemically strengthened glass is obtained by generating a compression stress on a glass surface according to an ion exchange process or the like, and thereby the glass surface is strengthened. 
     When at least one glass plate of the plurality of glass plates, in which the screen main body  50  is interposed, is a strengthened glass, a durability of the transparent screen  20  can be enhanced. 
     In the case where among the plurality of glass plates, in which the screen main body  50  is interposed, a glass plate arranged on the front side of the screen main body  50  is a strengthened glass, and a glass plate arranged on the rear side of the screen main body  50  is a non-strengthened glass, when the non-strengthened glass is broken by a flying object from the rear side, the screen function can be maintained. This is because the non-strengthened glass is less likely to shatter into small pieces as compared to the strengthened glass. 
     In the case where among the plurality of glass plates, in which the screen main body  50  is interposed, a glass plate arranged on the rear side of the screen main body  50  is a strengthened glass, and a glass plate arranged on the front side of the screen main body  50  is a non-strengthened glass, when the non-strengthened glass is broken by a flying object from the front side, the screen function can be maintained. This is because the non-strengthened glass is less likely to shatter into small pieces as compared to the strengthened glass. 
     Note that when each of the plurality of glass plates, in which the screen main body  50  is interposed, is a strengthened glass, a probability of breakage by a flying object can be minimized. 
     Note that the transparent plates  30 ,  40  according to the embodiment are glass plates, respectively. However, the transparent plates  30 ,  40  may be resin plates. Moreover, among the plurality of transparent plates  30 ,  40 , one plate may be a glass plate and the other plate may be a resin plate. 
     The screen main body  50  displays video images projected from the front side of the screen or from the rear side of the screen to the user  10  on the front side of the screen, and enable a rear background to be visually recognized by the user  10 . A configuration of the screen main body  50  will be specifically described later. 
     The holding member  60  has an exterior side surface holding part  61  and an interior side surface holding part  62 . The exterior side surface holding part  61  holds an exterior main surface of the transparent screen  20  in the curvature radius direction. The term “exterior surface in the curvature radius direction” means a surface, out of two surfaces in a direction normal to the transparent screen  20 , which is farther from a center of curvature. The interior side surface holding part  62  holds an interior main surface of the transparent screen  20  in the curvature radius direction. The term “interior surface in the curvature radius direction” means a surface, out of two surfaces in a direction normal to the transparent screen  20 , which is closer to the center of curvature. 
     The plurality of transparent plates  30 ,  40  are prepared by bending a plurality of transparent flat plates having different sizes of main surfaces into curved shapes on heating. The size of the main surface can be read as a size of a center plane in a plate thickness direction. Because there is only little tensile stress and compression stress applied to the center plane in a plate thickness direction when the transparent plates are bent in curved shapes, the size of the center plane in the plate thickness direction little changes before and after the bending. 
     In the first cross section, illustrated in  FIG. 2 , the transparent screen  20  has a curved shape, and a length of a center line in the plate thickness direction  31  of the transparent plate  30  on an exterior side in the curvature radius direction is greater than a length of a center line in the plate thickness direction  41  of the transparent plate  40  on an interior side in the curvature radius direction. A center line in a plate thickness direction is a line that bisects a plate in a plate thickness direction. The length of the center line in the plate thickness direction is measured along the center line in the plate thickness direction having a curved shape. 
     As a result, compared with the case of the plurality of transparent plates  130 ,  140  obtained by bending a plurality of transparent flat plates having main surfaces of the same size into curved shapes on heating, as illustrated in  FIG. 1 , end surfaces of the plurality of transparent plates  30 ,  40  can be aligned. Thus, while maintaining functions of both main surfaces of the transparent screen  20 , in the same way as the case illustrated in  FIG. 1 , a size of a rear background viewable through the transparent screen  20  can be increased compared with the case illustrated in  FIG. 1 . Therefore, a sufficient size of a rear background viewable through the transparent screen  20  can be secured, and the transparent screen  20  can be held with stability. 
     In the first cross section, illustrated in  FIG. 2 , the transparent screen  20  has a curved shape, and a difference in extent between the end surfaces of the plurality of transparent plates  30 ,  40  is, for example, 5 mm or less (in  FIG. 2 , the difference is 0 mm). The difference in extent is measured along the screen main body  50  having the curved shape. In the first cross section, when the difference in extent is 5 mm or less, a sufficient size of rear background viewable through the transparent screen  20  can be secured, and the transparent screen  20  can be held with stability. In the first cross section, the size of the difference in extent is preferably 2 mm or less. The size of the difference in extent preferably falls within the above-described range over the entire outer periphery of the transparent screen  20 . 
     In the second cross section illustrated in  FIG. 3 , the transparent screen  20  has a flat shape, and the lengths of center lines in the plate thickness direction  31 ,  41  of the plurality of transparent plates  30 ,  40  are the same. In the second cross section, the size of difference in extent between the end surfaces of the plurality of transparent plates  30 ,  40  is preferably 5 mm or less (in  FIG. 3 , the difference is 0 mm). 
     Note that although the transparent screen  20  according to the embodiment has a flat shape in the second cross section, the transparent screen  20  may have a curved shape in the same way as in the first cross section. In this case, in the second cross section, the length of the center line in the plate thickness direction of the transparent plate  30  on an exterior side in the curvature radius direction may be greater than the length of the center line in the plate thickness direction of the transparent plate  40  on an interior side in the curvature radius direction. Moreover, in this case, in the second cross section, the size of the difference in extent between the end surfaces of the plurality of transparent plates  30 ,  40  may be, for example, 5 mm or less, and preferably 2 mm or less. 
       FIG. 4  is a flowchart depicting a manufacturing method of a transparent screen according to the embodiment. The manufacturing method of the transparent screen  20  includes a bending formation process (step S 10 ) and a laminating process (step S 20 ). 
     In the bending formation process (step S 10 ), a plurality of transparent flat plates are bent in curved shapes on heating, and thereby the plurality of transparent plates  30 ,  40  are prepared. The plurality of transparent flat plates may be laminated and bent simultaneously in curved shapes, or may be bent separately. For the bending formation, a gravity formation, a press formation or the like is used. 
     In the bending formation process (step S 10 ), a glass surface may be strengthened by rapidly cooling a uniformly heated glass plate from a temperature around a softening temperature so as to generate a compression stress on a glass surface according to a difference between a temperature of the glass surface and a temperature inside the glass. A physically strengthened glass is obtained. Note that a chemically strengthened glass is obtained by generating a compression stress on a glass surface according to an ion exchange process or the like, after the bending formation process (step S 10 ) and before the laminating process (step S 20 ). 
     In the laminating process (step S 20 ), the plurality of transparent plates  30 ,  40  are laminated via the screen main body  50 . The screen main body  50  may have adhesion layers on both ends in the laminating direction, and may be fixed to the transparent plate  30  by an adhesion force. Note that the screen main body  50  may be deposited on any one of the plurality of transparent plates  30 ,  40 . 
     In the laminating process (step S 20 ), typically, after holding the screen main body  50  with the plurality of transparent plates  30 ,  40 , heating and pressuring processes are performed using an autoclave. Before the heating and pressuring processes using the autoclave, a degassing process for degassing using a vacuum bag or the like, or a clamping process for clamping using pressing rolls or the like may be performed. Moreover, the degassing process or the clamping process may be performed under a heating condition. In the laminating process (step S 20 ), when a laminated body is formed so that stress is not concentrated at an end portion of the laminated body, a deformation of an end portion of the screen main body  50  can be controlled and distortion of projected video images can be reduced, and it is preferable. 
     In the bending formation process (step S 10 ), the plurality of transparent plates  30 ,  40  are prepared by bending a plurality of transparent flat plates having different sizes of main surfaces into curved shapes on heating. The sizes of the main surfaces of the transparent flat plates are adjusted in advance so that the end surfaces of the plurality of transparent plates  30 ,  40  are aligned after the bending formation process (step S 10 ). Thus, it becomes possible to reduce time and labor in processing, such as in cutting, grinding, or chamfering, and it also becomes possible in some cases to eliminate the time-labor of these processes. Note that the time-labor in processing a flat plate is markedly less than the time-labor in processing a curved plate. Moreover, by eliminating processing after the laminating process (step S 20 ), the screen main body  50  can be prevented from being damaged. 
       FIG. 5  is a cross-sectional view depicting a transparent screen assembly according to the embodiment. The transparent screen assembly includes a plurality of transparent screens  20 , and a holding member  60  that successively holds the plurality of transparent screens  20 . 
     Each of the transparent screens  20  has a curved shape. In a cross section orthogonal to a part of an outer edge of each of the transparent screens  20 , the plurality of curved transparent screens  20  are arranged successively. 
     According to the embodiment, on the outer periphery of each of the transparent screens  20 , as described above, end surfaces of the plurality of transparent plates  30 ,  40  are aligned. Thus, there is little gap between the adjacent transparent screens  20 . Therefore, there is little interference of video light leaked from gaps on both sides of the transparent screens, and blurring of video images is not observed. Moreover, when curvatures of the adjacent transparent screens  20  are the same, the transparent screens  20  are connected to each other smoothly, the blurring of video images is further controlled. 
       FIG. 6  is a flowchart depicting a manufacturing method of a screen assembly according to the embodiment. The manufacturing method of the screen assembly includes a transparent screen manufacturing process (step S 30 ) and a transparent screen connecting process (step S 40 ). 
     In the transparent screen manufacturing process (step S 30 ), a plurality of transparent screens  20  are manufactured. The manufacture of transparent screens  20  is performed by the bending formation process step S 10  and the laminating process S 20 , illustrated in  FIG. 4 . 
     In the transparent screen connecting process (step S 40 ), the plurality of transparent screens  20  are connected successively. For the connection, the holding member  60  is used. 
       FIG. 7  is a cross-sectional view depicting a reflection-type transparent screen according to the embodiment. The reflection-type transparent screen displays video images projected from a projector  70  on the front side of the screen to the user  10  on the front side, and enable a rear background to be visually recognized by the user  10 . The reflection-type transparent screen includes a screen main body  50 A interposed between the plurality of transparent plates  30 ,  40 . 
       FIG. 8  is a cross-sectional view illustrating in detail the reflection-type screen main body illustrated in  FIG. 7 . The screen main body  50 A includes, for example, a plurality of adhesion layers  51 A,  52 A and a screen sheet  53 A interposed between the plurality of adhesion layers  51 A,  52 A. 
     In  FIG. 8 , a plate thickness of the transparent plate  30  and a plate thickness of the transparent plate  40  can each be selected as desired according to strength of the screen assembly or design property. A thickness of the adhesion layer  51 A and a thickness of the adhesion layer  52 A are not limited, respectively, and preferably fall within a range of, for example, 0.01 to 1.5 mm, and more preferably fall within a range of 0.05 to 0.5 mm. A thickness of the screen sheet  53 A can be set as desired depending on the manufacturing method of the screen sheet  53 A, a visibility for projected video images, or the like, and preferably fall within a range of, for example, 0.02 to 1.5 mm. 
     The plurality of adhesion layers  51 A,  52 A, bond the plurality of transparent plates  30 ,  40  with the screen sheet  53 A. One adhesion layer  51 A bonds one transparent plate  30  with the screen sheet  53 A, and the other adhesion layer  52 A bonds the other transparent plate  40  with the screen sheet  53 A. The adhesion layers  51 A,  52 A are formed of, for example, a thermoplastic resin, a thermosetting resin, or an ultraviolet curable resin. The adhesion layers  51 A,  52 A are preferably formed of one or more selected from a vinyl polymer, an ethylene-vinyl monomer copolymer, a styrene copolymer, a polyurethane resin, a urethane acrylate resin, a fluorinated resin, and an acrylic resin. The thermoplastic resin includes typically a polyvinyl butyral resin (PVB), an ethylene-vinyl acetate copolymer (EVA). The thermosetting resin includes typically a urethane acrylate resin. In the case of the thermoplastic resin or the thermosetting resin, the bonding is performed by a thermal process. In the case of the ultraviolet curable resin, the bonding is performed by an irradiation with ultraviolet rays. The urethane acrylate resin can cure by ultraviolet rays. 
     According to the embodiment, compared with the case illustrated in  FIG. 1 , because the end surfaces of the plurality of transparent plates  30 ,  40  are aligned, in the laminating process (step S 20 ), a dilamination due to a change in temperature in the laminating process (step S 30 ) can be controlled against. The dilamination includes at least one dilamination of a dilamination between one transparent plate  30  and the screen sheet  53 A and a dilamination between the other transparent plate  40  and the screen sheet  53 A. Because the dilamination can be controlled against, it becomes possible to control against generation of bubbles, and to control against disturbance in video images. 
     The reason why the aforementioned dilamination can be controlled against when the end surfaces of the plurality of transparent plates  30 ,  40  are aligned is that a bonding state of one adhesion layer  51 A and a bonding state of another adhesion layer  52 A transition to the same degree when the temperature varies in the laminating process (step S 20 ). The bonding states of the respective adhesion layers  51 A,  52 A vary according to expansion and contraction of the respective layers. The respective adhesion layers  51 A,  52 A expand with a rise in temperature and contract with a fall in temperature. Moreover, the respective adhesion layers  51 A,  52 A contract according to a reaction or the like of resin compositions when the layers are heated. 
     Assume the case where, as illustrated in  FIG. 1 , there is a great difference in extent D between the end surfaces of the plurality of transparent plates  130 ,  140 ; and, the end surface of the transparent plate  130 , which is on an exterior side in the curvature radius direction, and the end surface of the screen main body are aligned. In this case, with a rise in temperature, an adhesion layer protrudes from the transparent plate  130  that is an object to be bonded, but another adhesion layer does not protrude from the transparent plate  140  that is an object to be bonded. Thus, the bonding state of one adhesion layer and the bonding state of another adhesion layer are not likely to transition to the same degree. Therefore, a stress that is asymmetric with respect to the center plane in the plate thickness direction of the transparent screen is liable to occur, and a dilamination easily occurs. 
     Note that at a time before the rising in temperature in the laminating process (step S 20 ), the adhesion layer  51 A is arranged at an inner position relative to the outer edge of the transparent plate  30  that is an object to be bonded, thus it is possible to control the protrusion of the adhesion layer  51 A from the outer edge of the transparent plate  30  when the adhesion layer  51 A expands. Therefore, when the adhesion layer  51 A contracts afterwards, drawn in air between the transparent plate  30  and the screen sheet  53 A can be restricted, and it is possible to suppress generation of bubbles. The adhesion layer  51 A may be processed into a size smaller than the transparent plate  30  before holding the screen main body  50 A with the plurality of transparent plates  30 ,  40 . But, the adhesion layer  51 A is preferably processed into a size smaller than the transparent plate  30  after holding the screen main body  50 A with the plurality of transparent plates  30 ,  40 . The adhesion layer  51 A may be processed by moving a cutter along an oblique surface formed in a boundary portion between the main surface and the end surface on the transparent plate  30 . 
     Similarly, before the rising in temperature, in the laminating process (step S 20 ), the adhesion layer  52 A is arranged at a position inner than the outer edge of the transparent plate  40  that is an object to be bonded, it is possible to control the protrusion of the adhesion layer  52 A from the outer edge of the transparent plate  40  when the adhesion layer  52 A expands. Therefore, when the adhesion layer  52 A contracts afterwards, involving air between the transparent plate  40  and the screen sheet  53 A can be restricted, and it is possible to suppress generation of bubbles. The adhesion layer  52 A may be processed into a size smaller than the transparent plate  40  before holding the screen main body  50 A with the plurality of transparent plates  30 ,  40 . But, the adhesion layer  52 A is preferably processed into a size smaller than the transparent plate  40  after holding the screen main body  50 A with the plurality of transparent plates  30 ,  40 . The adhesion layer  52 A may be processed by moving a cutter along an oblique surface formed in a boundary portion between the main surface and the end surface on the transparent plate  40 . 
     The screen sheet  53 A is not required to have flexibility, but preferably has flexibility. When the screen sheet  53 A has flexibility, the screen sheet  53 A can be bent to be deformed along the transparent plates  30 ,  40 . The screen sheet  53 A includes a base material  54 A, an irregular layer  55 A, a reflection film  56 A, a covering layer  57 A, and a protection sheet  58 A, in this order.  FIG. 8  illustrates the base material  54 A on the left and the protection sheet  58 A on the right. However, the base material  54 A may be on the right and the protection sheet  58 A may be on the left. A total thickness of the irregular layer  55 A, the reflection film  56 A and the covering layer  57 A can be selected as desired depending on a manufacturing method, and preferably falls within a range of 1 to 100 μm, for example. Thicknesses of the base material  54 A and the protection sheet  58 A can be selected as desired depending on the manufacturing method, respectively, and preferably fall within a range of 0.01 to 0.5 mm, for example, and more preferably fall within a range of 0.05 to 0.3 mm. Note that the protection sheet  58 A may not be present and the adhesion layer may be formed on the covering layer  57 A. 
     The base material  54 A may be any one of a glass sheet and a resin sheet. But in terms of flexibility, the resin sheet is preferable. The resin sheet is formed of, for example, a polycarbonate, a PET (polyethylene terephthalate), a PEN (polyethylene naphthalate), a cycloolefin polymer, or a polyester. 
     The irregular layer  55 A is formed on the base material  54 A, and has an irregular pattern on a surface opposite to the base material  54 A. The irregular layer  55 A may be formed of a resin. A formation method of the irregular layer  55 A includes, for example, use of an imprint method. For a resin material in the imprint method, any of a light curing resin, a thermoplastic resin and a heat curing resin may be used. For a mold used in the imprint method, a resin sheet, a glass sheet or a metal sheet can be used. The irregular pattern on the mold is formed by an etching, a sandblast, an extrusion molding, or the like. 
     The reflection film  56 A is formed along the irregular pattern on the surface of the irregular layer  55 A. The reflection film  56 A reflects a part of light incident from the front side to the front side, and transmits a part of light incident from the rear side to the front side. The reflection film  56 A may be formed of, for example, a metal, a metal oxide, or a metal nitride. For a formation method of the reflection film  56 A, for example, a vacuum deposition method or a sputtering method may be used. For a metal material in the vacuum deposition method or the sputtering method, for example, aluminum (Al) or silver (Ag) may be used. 
     The covering layer  57 A embeds the irregular pattern of the reflection film  56 A. The covering layer  57 A may be formed of a resin, and is preferably formed of the same resin as the irregular layer  55 A. 
     The protection sheet  58 A covers the covering layer  57 A. The protection sheet  58 A may be any one of a transparent glass sheet and a transparent resin sheet. But in terms of flexibility, the transparent resin sheet is preferable. The resin sheet is formed of, for example, a polycarbonate, a PET, a PEN, a cycloolefin polymer, or a polyester. 
     Note that the irregular layer  55 A according to the embodiment is formed on the base material  54 A. However, the irregular layer  55 A may be formed on any one of the plurality of transparent plates  30 ,  40 . Moreover, the covering layer  57 A according to the embodiment is covered with the protection sheet  58 A. However, the covering sheet  57 A may be covered with another one of the plurality of transparent plates  30 ,  40 . In this case, the plurality of adhesion layers  51 A,  52 A, the base material  54 A and the protection sheet  58 A are not required. 
     Note that the irregular structure of the irregular layer  55 A may be, in addition to the structure illustrated in  FIG. 8 , a micro lens array, a hologram, or the like. 
     As optical characteristics of the reflection type transparent screen, the transmittance is preferably 5% or more and 90% or less, the reflectance is preferably 5% or more and 70% or less, and the forward haze is preferably 20 or less. The transmittance, the reflectance and the forward haze are measured by using the D65 light source defined in JIS 28720 (2012) “standard illuminant (standard light) for color measurement and standard light source”, respectively. 
       FIG. 9  is a cross-sectional view depicting the transmission type transparent screen according to the embodiment. The transmission type transparent screen displays video images projected from a projector  70  on the rear side of the screen to a user  10  on the front side, and enables a rear background to be visually recognized by the user  10 . The transmission type transparent screen includes a screen main body  50 B interposed between a plurality of transparent plates  30 ,  40 . 
       FIG. 10  is a cross-sectional view depicting in detail the transmission-type screen main body illustrated in  FIG. 9 . The screen main body  50 B includes, for example, a plurality of adhesion layers  51 B,  52 B, and a screen sheet  53 B interposed between the plurality of adhesion layers  51 B,  52 B. 
     In  FIG. 10 , a plate thickness of the transparent plate  30  and a plate thickness of the transparent plate  40  can be selected as desired according to strength of the screen assembly or design property, respectively. A thickness of the adhesion layer  51 B and a thickness of the adhesion layer  52 B are not limited, respectively, and preferably fall within a range of, for example, 0.01 to 1.5 mm, and more preferably fall within a range of 0.05 to 0.5 mm. A thickness of the screen sheet  53 B can be set as desired depending on the manufacturing method of the screen sheet  53 B, a visibility for projected video images, or the like, and preferably fall within a range of, for example, 0.02 to 1.2 mm. 
     The plurality of adhesion layers  51 B,  52 B, bond the plurality of transparent plates  30 ,  40  with the screen sheet  53 B. One adhesion layer  51 B bonds one transparent plate  30  with the screen sheet  53 B, and the other adhesion layer  52 B bonds the other transparent plate  40  with the screen sheet  53 B. For the adhesion layers  51 B,  52 B, the same layers as the adhesion layers  51 A,  52 A, described with reference to  FIG. 8 , can be used. The adhesion layers  51 B,  52 B are the same as the adhesion layers  51 A,  52 A, including also the preferable embodiment. 
     The screen sheet  53 B is not required to have flexibility, but preferably has flexibility. When the screen sheet  53 B has flexibility, the screen sheet  53 B can be bent deformed along the transparent plates  30 ,  40 . The screen sheet  53 B includes a base material  54 B, and a light scattering layer  55 B.  FIG. 10  illustrates the base material  54 B on the right and the light scattering layer  55 B on the left. However, the base material  54 B may be on the left and the light scattering layer  55 B may be on the right. A thickness of the light scattering layer  55 B can be selected as desired depending on a manufacturing method of the light scattering layer  55 B, and preferably falls within a range of 1 to 200 μm, for example. A thicknesses of the base material  54 B can be selected as desired depending on the manufacturing method of the base material  54 B, and preferably falls within a range of 0.01 to 0.5 mm, for example, and more preferably falls within arrange of 0.05 to 0.3 mm. 
     The base material  54 B may be any one of a glass sheet and a resin sheet. But in terms of flexibility, the resin sheet is preferable. The resin sheet is formed of, for example, a polycarbonate, a PET, a PEN, or a cycloolefin polymer. Especially, a PET or a PEN is preferable on the point that a wrinkle or a distortion due to a bending stress is not likely to occur when the transparent screen having a curved shape is manufactured. 
     The light scattering layer  55 B includes a transparent resin and a light scattering material. For the transparent resin used in the light scattering layer  55 B, a light curing resin such as an acrylic resin or an epoxy resin, a heat curing resin, a thermoplastic resin or the like can be used. For the light scattering material, fine particles of a high refractive index material such as titanium oxide (refractive index falls within a range of 2.5 to 2.7), zirconium oxide (refractive index is 2.4), or aluminum oxide (refractive index is 1.76), fine particles of a low refractive index material such as porous silica (refractive index is 1.25 or less), or hollow silica (refractive index is 1.25 or less), a resin material having a low compatibility with the aforementioned transparent resin and a refractive index different from that of the aforementioned transparent resin, a crystallized resin material including crystals with a size of 1 μm or less, or the like can be used. A fraction of the light scattering material occupied in the light scattering layer  55 B is, for example, 0.01 volume percent or more and 5 volume percent or less, and is preferably 0.05 volume percent or more and 1 volume percent or less. 
     The light scattering layer  55 B may further include a light absorbing material. For the light absorbing material, a carbon black, a titanium black or the like can be used. A fraction of the light absorbing material occupied in the light scattering layer  55 B is, for example, 0.01 volume percent or more and 5 volume percent or less, and is preferably 0.1 volume percent or more and 3 volume percent or less. The light absorbing material can enhance a contrast of video images displayed on the screen main body  50 B. 
     Note that the light scattering layer  55 B may be a layer, illustrated in  FIG. 11 , in which a plurality of light scattering parts  57 B are arranged at intervals in a transparent resin part  56 B. This arrangement is referred to as a louver structure. The light scattering part  57 B includes a light scattering material and a transparent resin. In the transparent resin part  56 B, the same material as the transparent material used in the light scattering layer  55 B, illustrated in  FIG. 10 , can be used. 
     Note that the light scattering layer  55 B according to the embodiment is formed on the base material  54 B. But the light scattering layer  55 B may be formed on any one of the plurality of transparent plates  30 ,  40 . Moreover, the light scattering layer  55 B according to the embodiment is covered with the adhesion layer. But the light scattering layer  55 B may be covered with another one of the plurality of transparent plates  30 ,  40 . In this case, the plurality of adhesion layers  51 B,  52 B, and the base material  54 B are not required. 
     As optical characteristics of the transmission-type transparent screen, the transmittance is preferably 5% or more and 90% or less, the forward haze is preferably 4 or more and 40 or less, and the rear haze is preferably 0 or more and 60 or less. The transmittance, the forward haze and the rear haze are measured by using the D65 light source defined in JIS 28720 (2012) “standard illuminant (standard light) for color measurement and standard light source”, respectively. 
     As described above, embodiments and the like of the transparent screen have been described. The present invention is not limited to the embodiments or the like. Various variations and enhancements may be made without departing from the scope of the present invention. 
     For example, the transparent screen according to the aforementioned embodiment includes two transparent plates. However, the transparent screen may include three or more transparent plates. 
     Moreover, the reflection type screen main body  50 A according to the aforementioned embodiment includes the adhesion layers  51 A,  52 A and the screen sheet  53 A. But the screen main body may include other functional layers. 
     Similarly, the transmission type screen main body  50 B according to the aforementioned embodiment includes the adhesion layers  51 B,  52 B and the screen sheet  53 B. But the screen main body may include other functional layers. 
     The functional layers include, for example, an antireflection layer having a solid shape or a layer configuration for reducing reflection of light, a light attenuation layer for attenuating a part of light, an infrared ray shielding layer for preventing infrared ray from transmitting through the screen main body, and the like. In the configuration of the reflection type screen main body  50 A or the transmission type screen main body  50 B, one layer or two or more layers of the functional layer may be present at any position. Moreover, two or more different functional layers may be present. 
     REFERENCE SIGNS LIST 
     
         
           10  user 
           20  transparent screen 
           30  transparent plate 
           40  transparent plate 
           50  screen main body 
           50 A reflection type screen main body 
           51 A adhesion layer 
           52 A adhesion layer 
           53 A screen sheet 
           54 A base material 
           55 A irregular layer 
           56 A reflection film 
           57 A covering layer 
           58 A protection sheet 
           50 B transmission type screen main body 
           51 B adhesion layer 
           52 B adhesion layer 
           53 B screen sheet 
           54 B base material 
           55 B light scattering layer 
           60  holding member 
           61  exterior side surface holding part 
           62  interior side surface holding part