Abstract:
A method of manufacturing a multi-layer panel having a curved reflective and/or transmitting facing layer that includes the steps of increasing and/or decreasing pressure on a side of a thin membrane to form a pressure differential across the thin membrane that causes the thin membrane to deform to a required shape; applying a first layer of material to an outer surface of the thin membrane while the thin membrane is maintained in the required shape by the increase and/or decrease in pressure, and allowing the first layer of material to cure for a pre-determined time.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to U.S. Provisional Patent Application No. 61/080,411, entitled “Live Teleporting System and Apparatus” filed on Jul. 14, 2008. The foregoing provisional is incorporated by reference herein. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to a multi-layer panel and in particular a method of manufacturing such a panel. 
       BACKGROUND OF THE INVENTION 
       [0003]    Parabolic reflectors (or paraboloids) and mirrors are a spherical cap with a polished, well-reflecting surface. The paraboloid has the property that an on-axis parallel beam of radiation will be reflected by the surface and concentrated at its focus (or conversely, a point source located at the focus will produce a parallel beam on reflection). 
         [0004]    Parabolic mirrors form two types of images of objects: real and virtual images. If the object is placed on the axis of revolution and further from the surface of the mirror than the focal point, the image formed is the real image. If the object is between the mirror and the focal point a virtual image is formed. If the object is placed at the focal point no image is formed. 
         [0005]    Mirrors constituted by a glass sheet having a reflective coating of, for example, silver or black are of course very well known. Particularly in the case of large mirrors, they suffer from the disadvantage that they must often be made unduly heavy in order to reduce the risk of their breaking, and the weight and thickness of glass required can make such mirrors unsuitable for use in some circumstances. 
         [0006]    It has been recognized that it has been difficult to mechanically deform a rigid mirror into a precise concave shape and maintain it in that concave shape without it having defects which might vary the focal point of the mirror. This problem is particularly prevalent in constructing paraboloid shaped mirrors. Consequently, in constructing concave mirrors, particularly of large focal length, the most frequently suggested construction techniques have been to either mold a reflective facing layer and a holding layer into the desired shape, or to apply a reflective layer as a coating on a surface which has already been formed in the desired configuration. 
         [0007]    Accordingly, it is desirable to develop a method of manufacturing a parabolic mirror with a large focal length without it having defects which might vary the focal point of the mirror. 
       SUMMARY OF THE INVENTION 
       [0008]    According to a first aspect, the present invention provides a method of manufacturing a multi-layer panel having a curved reflective and/or transmitting facing layer, the method comprising the steps of: increasing and/or decreasing the pressure on a side of a thin membrane to form a pressure differential across the thin membrane that deforms the thin membrane to a required shape; and applying a first layer of material to an outer surface of the thin membrane whilst the thin membrane is maintained in the required shape by the increase and/or decrease in pressure, and allowing the first layer of material to cure for a pre-determined time. 
         [0009]    The thin membrane may comprise a thin plastic film or a thin foil. The method may further comprise applying a second layer of material to the first layer of material whilst the thin membrane is maintained in the required shape by the increase and/or decrease in pressure and allowing the second layer of material to cure for a pre-determined time, the second layer of material used to reinforce the multi-layer panel. Forming the pressure differential may further comprise sealing the thin membrane to a pressure chamber, the pressure chamber being pressurised or de-pressurised to deform the thin membrane to the required shape. A sealing device may be placed on the thin membrane to assist in sealing the pressure chamber to the thin membrane. The method may further comprise at least one frame to which the thin membrane is attached to, the at least one frame attached to the pressure chamber by at least one clamp to form a seal between the at least one frame and the pressure chamber. Sealing either the thin membrane to the pressure chamber or the at least one frame to the pressure chamber may comprise attaching an o-ring to either the thin membrane or the at least one frame. The method may further comprise when the pressure chamber is pressurised the thin membrane forms a concave shape and when the pressure chamber is depressurised the thin membrane forms a convex shape. The required shape of the thin membrane may be a parabolic shape. The method may further comprise abrading the outer surface of the thin membrane whilst still under a pressure differential to provide a mechanical key to the outer surface of the thin membrane. 
         [0010]    The first layer of material may comprise a plastic that is cured by the application of a catalyst or very low heat. These materials are generally from the thermosetting category of plastics, such materials could be polyesters, epoxies, silicones or polyurethanes. The first layer of material may be a slow curing material. The first layer of material may further comprise aluminium or other suitable filler to increase the viscosity of the first layer material. The first layer of material may further comprise a black dye added to the first layer of material to enhance the reflectivity of the multi-layer panel. 
         [0011]    The second layer of material may comprise a fibre glass mat impregnated with a polyester resin, the polyester resin cured by mixing the polyester resin with a suitable catalyst. The predetermined time for cure of either the first or second layer of material may be from a few minutes up to at 24 hours. 
         [0012]    According to a further aspect, the present invention provides a mirror comprising: a concave thin foil membrane stiffened by a first layer placed on an outer surface of the thin foil membrane to provide structural rigidity to the mirror. 
         [0013]    The required shape of the thin membrane may be a parabolic shape. comprise a plastic that is cured by the application of a catalyst or very low heat. These materials are generally from the thermosetting category of plastics, such materials could be polyesters, epoxies, silicones or polyurethanes. The first layer of material may be a slow curing material. The first layer of material may further comprise aluminium or other suitable filler to increase the viscosity of the first layer material. The first layer of material may further comprise a black dye added to the first layer of material to enhance the reflectivity of the mirror. The mirror may further comprise a second layer of material, the second layer of material used to reinforce the mirror. The second layer of material may comprise a fibre glass mat impregnated with a polyester resin, the polyester resin cured by mixing the polyester resin with a suitable catalyst. 
         [0014]    According to a still further aspect, the present invention provides an apparatus for producing a multi-layer panel having a curved reflective and/or transmitting facing layer, the apparatus comprising: at least one frame to which a thin membrane is attachable; a pressure chamber adapted to allow a seal to form between the at least one frame and the pressure chamber; and wherein the pressure chamber is arranged to create a pressure differential across the thin membrane to deform the thin membrane to a required shape, when the frame containing the thin membrane is attached to the pressure chamber; and a means for applying a first layer and a second layer to the thin membrane to form the multi-layer panel whilst the multi-layer panel is maintained in the pressure differential state by the pressure chamber. 
         [0015]    To be effective in delivering a highly realistic and immersive experience, the virtual image should be HD video and if a human figure, life size. This is produced by using a foil which is vacuum blown to form a shape in a purpose built housing, to adopt and then retain the shape used in the cast of curved reflectors. The advantage of using foil is not just the ease of construction there is also the fact that the film will potentially be lighter weight than a solid polymer bowl of similar size. The key advantage is size. Optically clear/semi transparent fire retardant antistatic foil of widths 6-8 meters would provide the necessary sheet size enabling a mirror to reflect virtual images sized up to 2 m high×2 m wide. 
         [0016]    The various features of novelty which characterize the present invention are pointed out with particularity in the claims annexed to and forming part of this disclosure. For a better understanding of the present invention, its operation, advantages and specific objects attained by its use, reference should be had to the accompanying drawings and descriptive matter in which preferred embodiments of the invention are illustrated and described. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]      FIG. 1  is a schematic of a parabolic mirror used for projecting a virtual image in accordance with an embodiment of the present invention; 
           [0018]      FIG. 2  is a flow diagram of a method of manufacturing a parabolic mirror in accordance with an embodiment of the present invention; 
           [0019]      FIG. 3  is a perspective illustration of a multi-layer panel manufactured in accordance with an embodiment of the present invention; and 
           [0020]      FIG. 4  shows a block diagram of the manufacturing process in accordance with an embodiment of the present invention. 
       
    
    
     DESCRIPTION OF PREFERRED EMBODIMENT 
       [0021]    A limiting factor for parabolic mirrors is the size of the mirror itself—being limited to the limited size of casting tools used in the parabolic ‘bowl’ or mirror manufacture. 
         [0022]      FIG. 1  shows a multi-layer parabolic mirror  100  used for producing a virtual image or hologram  134 . The distance between the position of the virtual image  134  and the multi-layer panel or parabolic mirror  100  and a reflective or transmitting surface  124  (i.e. how far image appears in front of the mirror  100 ) is determined by the depth of the mirror  100  or bowl&#39;s concavity as well as its actual size and the distance between a direct video source  132  and mirror centre.  FIG. 1  shows the parabolic bowl or mirror  100 , configured with the direct video source  132  such as a monitor or LED screen as well as a projector (not shown) beaming onto a rear projection screen directed towards the central area of the parabolic mirror  100 . Direct video source  132  can be moved up and down, left and right, and in and out relative to the mirror  100  using adjustable arm  130 . The parabolic mirror  100  is supported by legs  122 ,  123  and the display device  132  and legs  122 ,  123  are masked from the viewer by masks  126 ,  128  and  138 . The perceived hologram or virtual image  134  is viewed by the viewer  140  placed in front of the parabolic mirror  100 . 
         [0023]    To be effective in delivering a virtual image  134 , the image to be projected into the parabolic mirror  124  and reflected as a virtual image  134  should be projected as high definition (HD) video and if the projected image is to be a human figure, then the mirror must be capable of producing a life size virtual image  134 . 
         [0024]    To produce such an experience a multi-layer panel  100  having a curved reflecting or transmitting facing layer  124  is produced by blowing a thin plastic membrane  10  held in a circular frame  20  and then backed by a polyurethane layer  700  supported by fibre glass  800  to retain the shape of the parabola while being either pressurised or de-pressurised by a pressure chamber  30  as shown in  FIGS. 3 and 4 . 
         [0025]    A thin plastic film, foil or membrane  10  is clamped between an inner and an outer circular frame  20 . One of the frames  20  contains a sealing “O” ring (not shown). The two parts of the frame  20  can be held together by screws or bolts. The frame  20  with the thin membrane  10  is then placed on top of a pressure box or chamber  30  and temporary sealed to the box or chamber  30  by release clamps. The object of the clamps is to ensure an airtight seal between the frame  20  and the pressure chamber  30  and subsequently the thin membrane  10 . 
         [0026]    Air is then blown into the sealed chamber  30  and under pressure or a pressure differential the membrane  10  is blown up to form the shape of the multi-layer parabolic mirror  100 . If the air is turned off the membrane  10  will collapse as it is unsupported. To produce a multi-layer mirror  100  it is necessary to support the membrane  10  to retain the original parabolic shape. 
         [0027]    Whilst under pressure  40  the top surface of the membrane  10  which becomes the back surface of the multi-layer mirror  100  is lightly abraded with sandpaper to provide a mechanical key to the thin membrane  10  backing structure. Whilst under pressure  40  the abraded surface of the membrane  10  is coated with a first layer  700  of preferably a two component polyurethane (PU) and allowed to cure for up to 24 hours. The first layer may comprise any suitable plastic material that is cured by the application of a catalyst or very low heat. The plastic material may be any one of the group of materials comprising polyesters, epoxies, silicones or polyurethanes. 
         [0028]    It is important to use a slow curing PU resin as a fast curing resin creates an exothermic heat reaction which causes the thin membrane  10  to wrinkle and lose its curvature. The PU is filled with aluminium or other suitable filler to increase the viscosity of the PU to aid its application and also to reduce the exothermic reaction. A black dye is also added to the PU to enhance the reflectivity of the multi-layer mirror  100 . 
         [0029]    Whilst still under pressure  40  and after the curing of the first layer  700  PU backing the multi-layer mirror  100  structure is reinforced by adding a second layer  800  of fibre glass mat which is impregnated with a polyester resin, the polyester resin cured by mixing the polyester resin with a suitable catalyst. The reinforced multi-layer mirror  100  is left for a further 24 hours to complete the curing process. 
         [0030]    On completion of the backing curing process the air is turned off, the clamps released and the multi-layer parabolic mirror  100  in its circular frame  20  is removed from the pressure box  30 . 
         [0031]    A typical mirror is formed of a thin membrane  10 , for example, a 100 micron PET foil, the first layer  700  PU backing of 2 mm thick, and a second layer  800  of fibreglass backing which is 4 mm thick. The circular frames  20  are constructed from plywood 25 mm thick. The multi-layer mirror  100  is 500 mm in diameter. 
         [0032]    As described above a foil or thin membrane  10  is vacuum blown to form a required shape in purpose built housing (circular frame)  20 , to adopt and then retain the shape used in the cast of parabolic reflectors or multi-layer mirrors  100 . This is achieved by tensioning a foil (thin membrane)  10  vertically at the front of the structure  20 , much as a screen faces a monitor. The foil edges  10  are sealed so that a vacuum applied  30  to the box behind the foil eventually sucks the foil into a pre determined parabolic shape. The foil depth of concavity could be varied according adjustment using variable vacuum pressure. 
         [0033]    In a further embodiment the foil shape (multi-layer panel)  100  could be retained in operation by vacuum  30 . Another method of forming from foil (thin membrane)  10  a parabolic shape for permanent use is to simultaneously feed a solidifying liquid substance into the box whilst the foil&#39;s correct parabolic shaped is retained under vacuum suction  30 . Once the foam solidifies, the shape remains permanent. The foam is coloured black so once set the foil surface appears to be a shiny reflective black parabolic mirror  100 . 
         [0034]    The advantage of using foil is not just the ease of construction and potentially lighter weight than a solid polymer bowl of similar size. The key advantage is size. Optically clear/semi transparent fire retardant antistatic foil of widths 6-8 meters would provide the necessary sheet size enabling a parabolic mirror to reflect virtual images sized up to 2 m high×2 m wide. 
         [0035]    Various configurations are suited to a variety of applications where virtual interactive figures would be of benefit. For stage applications the mirrors  100  may be used effectively face on to the live stage talent  140 . The angle of view is such live talent  140  can simply reference themselves to interactive virtual images  134  for spatial distance as well as left right movement over reasonably large stage areas, yet the audience  140  do not see the virtual image  134  emitting from the foil parabolic mirror  100 . 
         [0036]    In other applications such as retail shop windows or museums the parabolic mirror  100  is arranged to face on the viewing audience  140 . 
         [0037]      FIG. 2  shows the different steps involved in producing a multi-layer parabolic mirror panel  100 . The first step involves constructing a frame  200  in this case a circular frame  20 . A thin membrane  10  is placed between the two circular frames  20  and the combined frame  20  and thin membrane  10  are placed in a pressure chamber  30 . The pressure chamber  30  being pressurised or de-pressurised  300  to form the thin membrane  10  to a required shape. Once the membrane  10  has formed the required shape a first layer  700  of material is applied  400  to an outer surface of the thin membrane  10  whilst still under pressure  40 . The first layer  700  is then allowed to cure for a pre-determined time, the predetermined time being approximately 20 hours. Once the first layer  700  has cured a second layer  800  is applied  500  to the surface of the first layer  700 . The second layer  800  of material being applied  500  to the first layer  700  of material whilst still under pressure  40  and allowing the second layer  800  of material to cure for a pre-determined time, the second layer of material used to reinforce the multi-layer panel. The predetermined time is approximately 20 hours. Once the second layer  800  has cured the completed multi-layer mirror  100  is removed from the pressure chamber  600 . 
         [0038]    It will be understood that the predetermined time for curing the first and second layer is chosen such that wrinkling of the thin membrane and loss of curvature is avoided. In other embodiments, the predetermined time may be from a few minutes up to 24 hours. 
         [0039]    Although the present invention has been illustrated and described with respect to exemplary embodiment thereof, it should be understood by those skilled in the art that the foregoing and various other changes, omission and additions may be made therein and thereto, without departing from the scope of the invention. Therefore the present invention should not be understood as limited to the specific embodiment set out above but to include all possible embodiments which can be embodied within a scope encompassed and equivalent thereof with respect to the features set out in the appended claims.