Abstract:
A foldable screen is disclosed, which can be used continuously over a long period without distortion, allows writing thereon, and is resistant against physical damages. The screen comprises a resin impregnated paper sheet. The screen may be made into a front screen or a rear screen. The screen may further comprise a thermoplastic resin sheet integrally provided on the resin impregnated paper sheet. The screen may be mounted over a glass pane to provide an advertising media or made into a partition screen. An information board system is also provided utilizing a glass pane type screen and a projector.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to a front screen and a rear screen as well as their applied products.  
           [0003]    2. Related Art  
           [0004]    A conventional projection screen board comprises a PMMA or vinyl chloride board on which a resin layer such as an urethane layer is integrated to provide a reflection surface as disclosed in Japanese Laid-Open Patent Publication No. 8-43948 or an acrylic board containing diffusion particles.  
           [0005]    Those screen boards are rigid and do not fold for storage when not in use. In addition, due to the thermoplastic nature of PMMA and vinyl chlorides those conventional screen boards warp when used continuously for an extended period of time, deflecting the screen images. Furthermore, letters written or drawings depicted on those screen boards will not be readily and cleanly erased. In addition, a pointer can easily damage the surface of those screen boards.  
           [0006]    Screen boards or screens are expected to faithfully reproduce the original colors, for which it is required to reproduce blue light and red light in practically equal contrast, for which again excellent whiteness of the screen surface is indispensable.  
           [0007]    Conventional screens such as those described above do not provide a desired degree of surface whiteness or equal contrast between blue and red lights.  
           [0008]    It is conventionally practiced to utilize show windows or glass walls as advertisement media. Posters are affixed on shop windows or glass walls of shops to attract pedestrians&#39; attention. However, such advertisement media have become so conventional and less effective.  
           [0009]    Naturally, it is required to prepare new posters or the like and replace the old ones with the new ones when change of the advertisement contents is desired. It is understood that peeling off old posters from shop windows and affixing new ones in replacement requires some work. The cost of producing new posters cannot be neglected.  
           [0010]    There exists a demand for a new way of utilizing shop windows or glass walls as advertisement media.  
           [0011]    Conventionally, a display apparatus such as an electronic bulletin board or plasma vision board is put up on a building wall for various purposes.  
           [0012]    Such an display apparatus becomes exponentially expensive as its size increases, which prevents wide utilization of such external display apparatuses.  
           [0013]    Demands for utilization of building windows and glass walls in alternative and less costly ways are steadily growing.  
         SUMMARY OF THE INVENTION  
         [0014]    The present invention offers an answer to the above-mentioned demands.  
           [0015]    It is an object of the present invention to provide a screen which can be easily stored, can be used continuously for an extended period of time, allows direct writing and drawing, and is resistant to surface damages.  
           [0016]    It is another object of the present invention to provide an excellently bright screen which is capable of reproducing the colors faithful to original images as well as equally contrasting blue light and red light.  
           [0017]    It is another object of the present invention to provide a screen to be used on a shop window or building window as an advertisement or information medium.  
           [0018]    It is still another object of the present invention to provide products which utilize screens of the present invention.  
           [0019]    The term “front screen” as used herein is a projection screen onto which images are to be projected with a projector from the viewers&#39; side and the term “rear screen” is a screen onto which images are to be projected from the rear side. The term “screen” is directed to either “front screen” or “rear screen”.  
           [0020]    A screen of the present invention comprises a resin impregnated paper sheet comprising a paper substrate which is preferably transparent paper having an ash content of equal to or less than 5% and a thickness of about 10 μm to 200 μm. The transparent paper is preferably 30 g/m 2 -180 g/m 2 . Polyolefin or polyester fibers may be blended in the paper.  
           [0021]    The resin is preferably a thermosetting resin. Two or more different types selected from melamine, diallyl phthalate and phenol resins may be used. Melamine and diallyl phthalate resins having a high transparency are preferred. A plasticized modified melamine resin is preferred. Thermoplastic resins having high melting points may also be used. For example, polyethylene phthalate, polyester and olefin resins may be used.  
           [0022]    A brightening material may be advantageously blended in the resin impregnated paper sheet or in the resin to be impregnated. The former is preferred, which makes the screen surface more resistant to physical damages. The brightening material may be an inorganic material such as silica, alumina, zirconia, titanium oxides glass powders calcium carbonate or barium sulfate. The inorganic material powder preferably has a mean particle size 0.1 μm to 1000 μm.  
           [0023]    A rear screen of the present invention preferably has a visible light transmittance of 30% to 80% and is light dispersive. A front screen of the present invention has excellent brightness.  
           [0024]    In an embodiment, the resin impregnated paper is placed between hot press stainless plates and pressed and then cooled to provide a screen of the present invention.  
           [0025]    A rear projector system incorporating a rear screen of the present invention is provided comprising a projector with a slide unit to slide a film or liquid crystal panels and a light source.  
           [0026]    A front screen according to an embodiment of the present invention can be obtained by integrally adhering a thermoplastic resin layer on a side of a resin impregnated paper sheet. The front screen provides a total reflectance equal to or greater than 90% and whiteness equal to or greater than 80% (JIS-L-1015, Japanese industrial standard), which reflects blue light and red light in equal contrast and provides substantially equal reflection over a visible light wavelength range 400 nm (blue light) to 700 nm (red light). Images are reflected on the bonded portion of the resin impregnated paper sheet and resin layer.  
           [0027]    In assistance to realize the reflectance greater than 90% and whiteness greater than 80% the thermoplastic resin may contain inorganic particles. Alternatively the resin layer may be provided with pores. It is preferable that the mean pore size is 1 μm to 100 μm.  
           [0028]    A plurality of thermoplastic resin layers selected from polyethylene terephthalate, vinyl chloride, polymethyl methacrylate, polyolefin and polyester resins may be advantageously used.  
           [0029]    The front screen or rear screen of the present invention may be applied on a glass pane directly or indirectly. Also, the screen of the present invention can be utilized in a variety of ways.  
           [0030]    The screen of the present invention can be rolled up for storage or transportation. The screen can be framed or used as a partition to name a few.  
           [0031]    The screen manufactured through a hot-press process can be used as a writing board while used as a projection screen. The resin impregnated paper of the screen does not chemically react with water or solvents, letters written or pictures drawn on the screen can be easily erased. The screen surface is resistant to physical damages.  
           [0032]    The screen of the present invention as applied on a glass pane or wall provides a novel information board system comprising a projector and a projector control device. The system further comprises image transmitting means, memory means, computation means, input means and storage means.  
           [0033]    The information board system may be either a front screen system or rear screen system. The front screen system will facilitate people to view the screen from inside the building or shop while the rear screen system will facilitate people to view the screen from outside the building or shop.  
           [0034]    The screen of the front screen type information board system possesses an excellently bright projection surface, while the screen of the rear screen type information board system possesses an excellent light dispersing. In order to provide excellent brightness for the front screen and excellent light scattering property for the rear screen, a brightening material or materials are blended in their resin impregnated paper sheets.  
           [0035]    When brightening materials are blended in the resin impregnated paper sheet (not coated), excellency of projected images will not be materially damaged even if the screen surface is somehow physically damaged to a degree.  
           [0036]    As set forth earlier, the screen of the rear type information board system possesses an excellent light transmittance property, Such as 30% to 80%. When the resin impregnated paper sheet is to be bonded to a glass pane using an adhesive, such an adhesive need be highly transparent.  
           [0037]    The information board system of the present invention may be used with a shop window or building window, e.g., as an advertisement medium for projecting a still image or moving images having advertising contents. Such advertising media are novel and it is naturally expected that the screened images of the present invention powerfully attract pedestrians and the effects of the advertisement are exceptional.  
           [0038]    Unlike similar conventional devices, the information board system of the present invention does not require removal of old advertisement materials. Only simple change of films or the like is required by changing image data. Such changes are simple and easy. Therefore, the present invention holds advertisement costs very low while providing improved advertising effects.  
           [0039]    The information board system of the present invention is light weight. Change of size does not materially affect the weight or price, which is a great advantage over the prior art screen of similar nature. Even a large size information board system can be installed very easily with a low cost. Change of the system is also easy.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0040]    [0040]FIG. 1 is a partial sectional view of a screen according to an embodiment of the present invention;  
         [0041]    [0041]FIG. 2 is a partial sectional view of a screen according to another embodiment of the present invention;  
         [0042]    [0042]FIG. 3 is a partial sectional view of a front screen according to an embodiment of to the present invention;  
         [0043]    [0043]FIG. 4 is a partial sectional view of a front screen according to another embodiment of the present invention;  
         [0044]    [0044]FIG. 5 is a front view of a screen product according to an embodiment of the present invention;  
         [0045]    [0045]FIG. 6 shows how a rear type screen of the present invention is used;  
         [0046]    [0046]FIG. 7 shows the structure of a rear-type screen projector according to an embodiment of the present invention;  
         [0047]    [0047]FIG. 8 is a partial sectional view of the structure of a screen according to an embodiment of the present invention;  
         [0048]    FIGS.  9 (A) and  9 (B) are partial sectional views of the structures of screen devices according to other embodiments of to the present invention;  
         [0049]    [0049]FIG. 10 is a schematic view of an information board system according to an embodiment of the present invention;  
         [0050]    [0050]FIG. 11 is a block diagram of a projector control device according to an embodiment of the present invention; and  
         [0051]    [0051]FIG. 12 is a schematic view of an information board system according to an embodiment of to the present invention.  
     
    
     DESCRIPTION OF TERMS USED IN THE DRAWINGS:  
       [0052]    [0052] 1  . . . resin impregnated paper sheet;  2  . . . substrate paper;  3  . . . resin;  4  . . . thermoplastic resin layer;  5  . . . glass pane;  6  . . . adhesive layer;  7  . . . attachment member;  8  . . . suction disk;  9  . . . dual adhesion tape;  10  . . . screen;  10   a  . . . front screen;  10   b  . . . rear screen;  21  . . . frame;  22  . . . support leg;  30  . . . . partition;  40  . . . projector;  60  . . . housing;  61  . . . base;  62  . . . light source;  63  . . . slide device;  64  . . . rear projector;  70   a ,  70   b  . . . information board system;  71  . . . rear projector;  80  . . . . projector controller  
       DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0053]    Screens and products incorporating the screens of the present invention together with their manufacture will be described in detail hereunder according to various embodiments depicted in the accompanying drawings without limiting the scope of the present invention.  
         [0054]    Embodiment 1  
         [0055]    In FIG. 1 is shown a screen  10  comprising a resin impregnated paper sheet  1  comprising a substrate paper  2  and a resin impregnated in the substrate paper  2 .  
         [0056]    A transparent paper “MOL-D-100” (manufactured by DAIFUKU PAPER M.F.G. CO., LTD.) having an ash content of less than 5% and a weight 100 g/m 2  was used as the substrate paper  2 , and a plasticized modified melamine resin  3  was used as the resin  3 . The melamine resin was prepared: blending 1.7 mol 37% formaldehyde aqueous solution with 1 mol melamine; adjusting the blend to pH 9.0 with sodium hydroxide; and leaving the blend to chemically react for 60 minutes under 90° C.  
         [0057]    The resin impregnated paper sheet  2  was placed between hot-press stainless plates with fine surface irregularities. The paper sheet  2  was subjected to hot press at 140° C. and pressure at 7.85 MPa for about 10 minutes, and then subjected to cold press for about 10 minutes. A hardened resin impregnated paper sheet  1  or screen  10  was obtained.  
         [0058]    Embodiment 2  
         [0059]    In FIG. 2 is shown another screen  10   a  comprising a resin impregnated paper sheet  1  comprising a substrate paper  2  and a resin  3  impregnated in the substrate paper  2 , which was similar to the paper sheet  1  of embodiment 1, except that 30 wt % inorganic powder or titanium nitride powder having a mean diameter of 0.1 μm to 1000 μm was further blended as a brightening material The other respects are the same as those in the first embodiment. This screen can be used as a front screen.  
         [0060]    Tests and measurement were conducted on the screen  10   a  with regards thickness, light resistance, spectral reflectance, solvent resistance, contamination resistance, hot-water resistance, thermal resistance, moisture resistance, dimensional change and surface hardness. The results and the conditions of the tests and measurement are shown in Table 1. For comparison, a white screen (silica containing polyvinyl chloride) was used.  
                                                 TABLE 1                       Evaluation       Embodiment           Item   Test Condition   2   Comparison                                Thickness       mm   0.12   0.4       Light resistance   Mercury Lamp   ΔE   1.7       48 hrs   Carbon Lamp   ΔE   0.8   1.0       Projection       Spectral   total   %   98   96       Reflection   Dispersal   %   96   90       Solvent   Acetone,       No Change   Whitened       Resistance   Toluene, etc.       Contamination   JIS-K-6902       No Change   Changed to 2%       Resistance               mercurochrome                       aqueous                       solution                       and crayon       Hot-Water   JIS-K-6902       No Change   Softened       Resistance       Thermal   60° C., 48 hs.       No Change   Deformed       Resistance       Moisture   40° C.,       No Change   No Change       Resistance   90% RH,           168 hs.       Dimensional   20° C.,   %   0.82   0.10       Change   95%-30% RH,           24 hs.       Surface   Handwriting by       2H   B       Hardness   pencil                  
 
         [0061]    Embodiment 3  
         [0062]    In FIG. 3 is shown a front screen  10   a  comprising a porous thermoplastic resin sheet  4  and a resin impregnated paper sheet  1  bonded together.  
         [0063]    The thermoplastic resin sheet  4  was a 0.26 mm thick porous polyethylene terephthalate resin sheet  4  of MCPET (manufactured by Furukawa Electric Co., Ltd.).  
         [0064]    The resin impregnated paper sheet  1  was a transparent paper sheet of MOL-D-100 (manufactured by DAIFUKU PAPER M.F.G. CO., LTD.) having an ash content of less than 5% and weighing 100 g/m 2 . Further, 30 wt % inorganic powder of titanium oxide having a mean diameter of 0.1 μm to 1000 μm was blended as a brightening material  
         [0065]    The resin  3  impregnated in the paper sheet  2  was a plasticized modified melamine resin  3 .  
         [0066]    The resin impregnated paper sheet  1  was integrated with the thermoplastic resin sheet  4  after coming through a hardening process: hot press step between hot-press stainless plates at 140° C. and 7.85 MPa for about 10 minutes; and cold press step about 10 minutes. The resin impregnated paper sheet  1  was integrated with the thermoplastic resin sheet  4  (MCPET) with an urethane adhesive to provide a front screen  10   a.    
         [0067]    Embodiment 4  
         [0068]    In FIG. 4 is shown a front screen  10   a  comprising a thermoplastic resin sheet  4   a  which was “Lumirror R E20#188” (manufactured by Toray Industries, Inc.) and a resin impregnated paper sheet  1 . In the thermoplastic resin sheet  4   a  which was polyethylene terephthalate were blended inorganic particles of titanium oxide (shown in exaggerated size for convenience). The resin impregnated paper  1  was identical with that of embodiment 1.  
         [0069]    Product quality tests were conducted on the front screens  10   a  of Embodiments 3 and 4. The test results are shown in Table 2.  
                                                               TABLE 2                                       Measurement                    Embodiment   Embodiment       Test items   Test Condition   3   4                    Thickness       mm   1.20   0.30       Optical   Screen Gain,       0.92   0.91       Property   View Angle 5°           1/2 Screen       0.47   0.47           Gain       Surface   Handwriting   JIS-K-   2H   2H       Hardness   by Pencil   5400       Cl.2 Dipping/   70° C. -   JAS   No Peel   No Peel       Peeling   Water (2 hs.)   Plywood           60° C. -           Dry (3 hs.)       Cool-Hot   80° C. -   JAS   No Change   No Change       Repetition   Dry (2 hs.)   Plywood           20° C. -           Cold (2 hs.)           2 c/c       Hot-Water   Against   JIS-K-   No Change   No Change       Resistance   Hot Water   6902           Pot (20 min.)       Light   Carbon Arc   JIS-K-   ΔE = 0.6   0.6       Resistance   (48 hs.)   6902           Mercury Lamp   JIS-K-   ΔE = 0.9   0.9           (48 hs.)   6902       Solvent   Methanol       No Change   No Change       Resistance   (24 hs.)           Ethanol       No Change   No Change           (24 hs.)           Acetone       No Change   No Change           (24 hs.)           Toluene       No Change   No Change           (24 hs.)           Window       No Change   No Change           Cleaner           (24 hs.)       Contamination   2% Mercuro-       Changed   Changed       Resistance   chrome           1% Iodine       Slight   Slight           Alcohol       Change   Change           Tea, Coffee,   JIS-K-   No Change   No Change           Vinegar, 10%   6902           Citric Acid,           Soy Sauce,           Gasoline, Olive           Oil, 10%           Ammonia, 5%           Carbolic Acid,           Crayon, Shoe           Cream, Red           Dye 102, 5%           Carbolic Acid-           Acidified           Sulfurous Soda       Dimensional   20° C., 30%   *1   0.1%   0.1%       Change   RH, 48 hr.           20° C. 95%           RH 48 hr.                  
 
         [0070]    *l The test pieces (13 mm×130 mm) were left for 48 hs. at 20° C. humidity 30% and measured with a dial gauge (measurements “a” which were then left for 48 hs. at 20° C., humidity of 95% and again measured (measurements “b”). The change in dimension was obtained following the equation:  
           lb−al/a× 100=Dimension Change (%)  
         [0071]    Using embodiments 1-4 and the following comparison samples, comparison tests were conducted with respect to color reproducibility. The tests were carried out by 10 persons by visually examining color impression. Optical property testing was also conducted in relation to total reflectance and diffusion reflectance against a barium sulfate white board.  
         [0072]    Comparison 1  
         [0073]    Urethane resin was coated on a PMMA board, which was subjected to hot press at 140° C. for about 10 minutes.  
         [0074]    Comparison 2  
         [0075]    A solution of 20% silica blended in melamine resin was coated on a PMMA board, which was hardened at 120° C.  
         [0076]    Comparison 3  
         [0077]    An MCPET board.  
         [0078]    Comparison 4  
         [0079]    A white steel board.  
         [0080]    Comparison 5  
         [0081]    An aluminum mirror board.  
         [0082]    Comparison 6  
         [0083]    An LumirrorR-E20#188 board (manufactured by Toray Industries, Inc.) (containing titanium oxide in polyethylene phthalate)  
         [0084]    All ten testers concluded that the color impression of the projected image each received was practically the same as that of the original image with regard to embodiments 1 and 2. They reported that the projected image was redder than the original image with regard to comparison 1, that the projected image was bluer than the original image with regard to comparison 2, and that the images were unclear because the screen reflected the projected light itself with regard to comparisons 3-6.  
         [0085]    The results of the optical property tests (total reflectance and diffusion reflectance) conducted on embodiment 4 and comparison 3-5 are shown in Tables 3 and 4.  
               TABLE 3                                                                                                                
 
         [0086]    [0086]               TABLE 4                                                                                                                  
         [0087]    Embodiment 5  
         [0088]    Products or systems utilizing the screens of the present invention are described hereunder.  
         [0089]    In FIG. 5 is shown a partition incorporating a front screen or rear screen of the present invention. The front screen  10   a  or rear screen  10   b  is fixedly mounted on a frame  21  which is supported by support legs  22 . The partition  30  with the screen  10   a  or  10   b  can serve two purposes, as a partition and a projection screen. This panel screen  30  possesses all advantageous features of the screens  10   a ,  10   b  of the present invention thus far described.  
         [0090]    Embodiment 6  
         [0091]    [0091]FIG. 6 shows an embodiment use of a rear screen  10   b  of embodiment  1 . A picture is projected with a projector  40  onto the rear screen  10   b  to be viewed by a person on the opposite side. As the rear screen  10   b  of embodiment  1  comprises a resin impregnated paper sheet, the screen  10   b  is flexible and can be rolled up for storage when not in use. The screen will not be softened in use and will not distort images. When a brightening material is blended as taught in embodiment  5 , the screen surface is physically resistant. The thermosetting resin will not dissolve against a solvent or water, facilitating writing and drawing on the screen.  
         [0092]    Embodiment 7  
         [0093]    [0093]FIG. 7 shows a rear projector  64  comprising a rear screen  10   b , a base  61 , a light source  62  mounted on the base  61 , a slide device  63  positioned between the light source  62  and the rear screen  10   b , all which are housed in a housing  60 . A film or a slide is inserted into the slide device  63  (an image can be provided utilizing a liquid crystal panel as well). A copy image is provided on the rear screen  10   b . Any type of rear projector  64  may be utilized.  
         [0094]    The rear screen  10   b  will not distort even if used for an extended period of time because it is impregnated with a thermosetting resin such as a melamine resin.  
         [0095]    Embodiment 8  
         [0096]    [0096]FIG. 8 shows an embodiment of a screen product  10   c  comprising a resin impregnated paper sheet  1  bonded to a surface of a transparent glass pane  5  with an adhesive  6 .  
         [0097]    It is not necessarily required to apply the adhesive  6  on the entire surface of the resin impregnated paper sheet  1  or the glass pane  5 . The adhesive  6  may be only partially applied as long as it can adequately hold the resin impregnated paper sheet  1  and the glass pane  5  securely together.  
         [0098]    The adhesive  6  may be an urethane-based adhesives epoxy-based adhesive or synthetic rubber-based adhesive. Alternatively, the adhesive  6  may be a pressure sensitive adhesive. which facilitates the resin impregnated paper sheet  1  to be removed from the glass pane  5  easily as desired.  
         [0099]    Embodiment 9  
         [0100]    [0100]FIGS. 9A and 9B show other types of screen products  10   d  utilizing a glass panes which comprises a resin impregnated paper sheet  1  attached to a surface of a glass pane  5  by means of attachment members  7 . It is to be noted that there is created a space between the glass pane  5  and the resin impregnated paper sheet  1 .  
         [0101]    [0101]FIG. 9A shows use of a suction cup or disk  8  as the attachment member  7 , and FIG. 9B shows use of a dual type adhesive tape  9  as the attachment member  7 . It is very easy to remove the resin impregnated paper sheet  1  from the glass pane  5 .  
         [0102]    Embodiment 10  
         [0103]    [0103]FIG. 10 shows an information board system  70   a  in which a front screen is used, comprising a front screen  10   c  (or  10   d ), a projector  71  and a projector control device  80 .  
         [0104]    The screen  10   c  or  10   d  is attached to a glass wall of a building or shop (not shown) (e.g., show window, shop window, glass window, glass door or fixed sash glass wall). In order to protect the resin impregnated paper sheet  1  from damages, the glass wall  5  is positioned outside.  
         [0105]    The projector  71  is positioned at an appropriate location outside of the building or shop. An image (or a picture) projected from the projector  71  onto the screen  10   c  or  10   d  is seen through the glass wall  5 . People walking on the street facing the screen  10   c  or  10   d  can view the image projected onto the screen  10   c  or  10   d.    
         [0106]    [0106]FIG. 11 is a block diagram of the projector control device  80 . The control device  80  comprises a control section  81  which transmits images to the projector  71 , memory section  82 , computation section  83  and input section. Image data inputted into the control device  80  via the input section  84  is stored in the memory section  82 . The image data retrieved from the memory section  82  is processed into a control data by the computation section  63 . The control section  81  controls the projector  71  in accordance with the control data.  
         [0107]    Embodiment 11  
         [0108]    [0108]FIG. 12 shows another type of an information board system  70   b  in which a rear screen is used, comprising a rear screen  10   c  (or  10   d ), projector  71  and projector control device  80  which can be identical with the one for the information board system  70   a  of embodiment  10 .  
         [0109]    Embodiment 11 differs from embodiment  10  in that the projector  71  is positioned at inside a building or shop whereby images projected from the projector  71  onto the screen  10   c  or  10   d  are seen from outside the building or shop.  
         [0110]    According to the present invention which has been described in details the screen of the present invention can be folded and stored, and can be used for a long period of time without distortion. Letters written or pictures drawn on the screen can be cleaned easily. A pointer will not damage the screen.  
         [0111]    The total reflectance of 99% and diffusion reflectance of 95% can be attained. Blue light and red light can be reflected in equal contrast. Equal reflection in a visible light range 400 to 700 nm is possible. The resin impregnated paper sheet can be attached to a glass pane to provide a front-type or rear-type screen board The information board system provides an excellent advertisement medium.  
         [0112]    When the advertisement content is to be changed, mere change of image films will do. Such a change is quite simple and easy. Further, it is not necessary to replace the whole screen with another. Therefore, advertisement costs can be kept minimal.