Abstract:
A curvilinear projection screen and acoustic system includes a curvilinear structural frame having a first side and a second side, a plurality of glass fiber reinforced gypsum (GRG) surface panels secured to the first side of the curvilinear structural frame, and a plurality of acoustic panels secured to the first side of the structural frame and interspersed between the plurality of GRG surface panels. In addition, the system includes a projection coating over the pluralities of GRG surface panels and acoustic panels to define a curvilinear projection surface.

Description:
TECHNICAL FIELD 
     The present invention relates to the field of projections screens, and, more particularly, to a curvilinear projection screen and acoustic system. 
     BACKGROUND 
     Acoustic systems often use stereophonic reproduction in an attempt to achieve an approximation to spatial reality of sound. For example, two groups of speakers are typically located on either side of a stage at a large stadium for a music concert. However, this orientation provides a poor spatial approximation to the actual performance. In other words, the listeners are not provided with an amplified version of the performance as if they were located in front of the stage and near enough to hear the music live. Instead, the listeners are looking at the performers but hearing the sound from either side of the stage. 
     Another example is where an audience is being provided with a projected visual image in addition to the audio at a movie theater. It is preferred to approximate spatial reality by having the audio emanate from the projected image that the viewers are observing rather than from the sides. 
     There have been attempts to address these shortcomings by placing the speakers behind the projection screen itself. However, the projection screen requires perforations in order to allow an adequate portion of the sound to pass through the screen. A shortcoming of the perforated screens is that they limit the high frequency response of the speakers. In addition, the perforated screen must also serve as the projection screen so that the resolution of the image and the percentage of reflected light are undesirably reduced. This shortcoming is particularly exacerbated with large curvilinear projection screens. 
     Accordingly, what is needed in the art is a curvilinear projection screen and acoustic system that increases the spatial approximation of the sound to the visual image being projected without diminishing the resolution of the image. 
     SUMMARY 
     In view of the foregoing background, it is therefore an object of the present invention to provide a curvilinear projection screen and acoustic system. 
     This and other objects, features, and advantages in accordance with the present invention are provided by a system including a curvilinear structural frame having a first side and a second side, a plurality of glass fiber reinforced gypsum (GRG) surface panels secured to the first side of the curvilinear structural frame, and a plurality of acoustic panels secured to the first side of the structural frame and interspersed between the plurality of GRG surface panels. The system also includes a projection coating over the pluralities of GRG surface panels and acoustic panels to define a curvilinear projection surface. 
     A method aspect is directed to a method of constructing a curvilinear projection screen and acoustic system including connecting a plurality of vertical metal trusses using a plurality of horizontal wood purlins, and securing a plurality of glass fiber reinforced gypsum (GRG) surface panels to the plurality of horizontal wood purlins, where the GRG surface panels having a curvature defined by an installation location on the curvilinear projection screen. In addition, the method includes forming a plurality of acoustic panels with a randomized perforated portion therein configured to allow sound waves to pass, and securing the plurality of acoustic panels to the plurality of horizontal wood purlins between the pluralities of GRG surface panels. The method also includes installing a projection coating over the pluralities of GRG surface panels and acoustic panels to define a curvilinear and seamless projection surface. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is front perspective view of the curvilinear projection screen and acoustic system according to an embodiment of the invention; 
         FIG. 2  is a rear perspective view of a curvilinear structural frame of the system shown in  FIG. 1 ; 
         FIG. 3  is a front perspective view of the GRG surface panels being installed on the curvilinear structural frame; 
         FIG. 4  is an exploded view of the main components of the system; 
         FIG. 5  is a section view of the GRG surface panel; 
         FIG. 6  is a detail front view of the connections of the purlins to the curvilinear structural frame; 
         FIG. 7  is a side section view of the connections of the GRG surface panels to the curvilinear structural frame shown in  FIG. 6 ; 
         FIG. 8  is a top section view of the connections of the GRG surface panels to the curvilinear structural frame shown in  FIGS. 6 and 7 ; 
         FIG. 9  is an exploded view of an acoustic panel of an embodiment of the invention; 
         FIG. 10  is a front view of the acoustic panels with a speaker installed; 
         FIG. 11  is an exploded section view of the acoustic panel; and 
         FIG. 12  is a partial detail view of the acoustic panel. 
     
    
    
     DETAILED DESCRIPTION 
     The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. 
     Referring now to  FIG. 1 , the curvilinear projection screen and acoustic system  100  generally includes four main components. These components include a curvilinear structural frame  102 , a projection screen  104  comprising of glass fiber reinforced gypsum (GRG) panels  112  and acoustic panels (e.g., randomized faded perforated panels)  140 , and utilizing a projection coating  105  thereon. 
     The overall geometric shape of the curvilinear projection screen  104  (e.g., compound curve or curvilinear) is typically determined by a “projection study.” The projection study may provide a lens shape, pixel map, lumens, minor radius, major radius, and degrees in plan for a particular application. The particular application could be for a virtual reality type amusement ride, for example. The projection screen  104  may be an up scaled version of the optical characteristics of a lens. There is virtually no limit to size, geometry, shape or orientation in which the projection screen  104  may be orientated to the earth&#39;s plane. Most curvilinear projection screens  104  are typically a horizontal/vertical torus (toroidal) or section of a sphere or hemisphere. 
     The curvilinear structural frame  102  includes a series of vertical trusses  106  that are arrayed from the plan radius center point, as shown in  FIG. 2 . The vertical trusses  106  are typically spaced four feet on center at the equator line of the projection screen  104 . The structural framework  102  may include light to medium gauge metal studs/track that overlap one another (web to web connection) to be mechanically fastened with self-drilling screws. The front edges of the vertical trusses  106  include vertical roll chords  110  that are curved to match the section radius of the geometry. The procedure in which the metal track is bent into the vertical roll chords  110  is known as crimp rolling. Crimp rolling is a series of micro crimps that make short facets to produce a desired radius. Horizontal members, identified as purlins  108 , connect the vertical trusses  106  together. The purlins  108  are typically three layers (glued and screwed together to make one unit) of CNC cut 1″ thick fire rated (FR) plywood. The wood isolates sound from one vertical truss  106  to the next. 
     When the curvilinear structural frame  102  is complete, there are a series of lines similar to longitude and latitude lines on a globe formed by the vertical trusses  106  and purlins  108 . The GRG surface panels  112  overlap onto the vertical and horizontal roll chords and can be mechanically fastened with wood to metal self-drilling screws. 
     As shown in  FIG. 3 , the GRG surface panels  112  are being installed on the curvilinear structural frame  102 . The horizontal edges  116  and vertical edges of the GRG surface panels  112  are secured to the purlins  108  and to the roll chords  110  of the vertical trusses  106 . The acoustic panels  140  are installed to the curvilinear structural frame similarly to that of the GRG surface panels  112 . The GRG surface panels  112  may be tapered  118  around the perimeter to allow for finishing compound to be added at the seams (seamless). 
     Referring now to  FIG. 4 , the GRG surface panels  112  are typically 4′ wide×8′ tall. The GRG surface panels  112  may be cast in a series of molds (made on a 5-axis CNC machine) with each having a slightly different geometry and shape depending on the install location of the screen geometry. A typical curvilinear projection screen will have approximately 3-6 molds per screen, for a combination typically ranging from 30-160 GRG surface panels  112  and acoustic panels  140  to be assembled for the overall geometry of the projection screen  104 . 
     For example, the perimeter of the GRG surface panels  112  may be approximately 1″ thick and include a wood coring material  116  embedded therein to allow for mechanical fastening to the structural framework with minimal tear out as shown in  FIG. 5 . Approximately 80% of the GRG surface panel  112  towards the center may be approximately ¼″ thick with no wood coring. In addition, the GRG surface panels  112  (and acoustic panels  140 ) may have a slight taper  118  around their perimeter (approximately 3″ wide, 2 panels next to each other 6″ wide v-groove) to allow for mesh tape and drywall mud finishing compound. CNC cut drywall knives and screeds are produced with the same arc geometry as the projection screen  104  to be finished properly for a constant seamless radius. 
     Referring now to  FIGS. 6-8 , which show exemplary connections of the GRG surface panels  112  and acoustic panels  140  to the curvilinear structural frame  102 .  FIG. 6  illustrates a front view of the connections of the purlin  108  and adjacent purlin  108   a  to the curvilinear structural frame  102 . This includes a top L-shaped bracket  120  having a first leg being secured to the inside surface of the roll chord  110  with metal screws  122  above a purlin  108 , and a second leg secured to a top surface of the purlin  108  using wood screws  124 . A bottom L-shaped bracket  126  is connected to an adjacent purlin  108   a  by first leg secured to the outside surface of the roll chord  110  below the purlin  108  using metal screws  130  and a second leg secured to a bottom surface of the purlin  108  using the wood screws  128 . 
       FIG. 7  is a section view of the same location shown in  FIG. 6  showing the connections of the GRG surface panels (and acoustic panels) to the curvilinear structural frame  102 . The GRG surface panels  112  are secured to the purlin  108  using wood screws  132  passing through the wood coring material  116  and into the purlin  108 . The top L-shaped bracket  120  is also shown in  FIG. 7 . 
       FIG. 8  is a top section view of the same location shown in  FIGS. 6 and 7 . As can be seen in  FIG. 8 , the GRG surface panels  112  and acoustic panels  140  may be connected to the roll chord  110 . The purlin  108   a  also includes a notch  134  between the inside leg of the roll chord  110  to allow for clearance for the crimps in the roll chord  110 . Wood screws  138  are used to secure the layers of the purlins  108 ,  108   a  together. Wood to metal screws  136  are used to secure the GRG surface panels  112  and acoustic panels  140  along their respective vertical edges  114  to the roll chord  110 . 
     The acoustic panels  140  shown in  FIGS. 9-12  are similar in size and shape to the GRG surface panels  112  described above. An objective of the acoustic panels  140  is for it not to be visible under projection but to allow the passing of sound waves through the projection screen. The acoustic panels  140  include an organically shaped and progressively fading hole pattern or randomized faded perforated portion  146  which makes it difficult for anyone to see under projection, while maintaining high quality sound penetration through the screen surface  104 . 
     The acoustic panels  140  comprise a GRG panel  142  having an aperture therein. A randomized faded perforated portion  146  is installed within the aperture. The randomized faded perforated portions  146  may be produced in a mold similar to the GRG surface panels  112  except they are a different material such as carbon fiber or formed aluminum sheet material. The thickness of the randomized faded perforated portions  146  is an important factor to maintain a range between 60-90 thousands in order to keep the structural integrity due to the thousands of holes in the randomized faded perforated portion  146  but keeping the smooth open cell speaker fabric  150  as close to the backside as possible. The speaker fabric  150  and retaining ring  148  are coated with a higher gain projection coating (+2.0, +2.5 gain) than the surface of the main projection screen  104  to brighten the hole cavities in the randomized faded perforated panel  146  due to light loss and darker shadowing effect that occurs prior to higher gain coating. 
     After the projection screen  104  is finished (to a level 5 smoothness rating, for example), installation of the projection coating  105  begins. Two or three layers of a high build primer, e.g., a sandable primer, is sprayed onto a front surface of the projection screen  105 . Each coat of primer is sanded in-between coats to maintain a smooth finish. The next step is the projection coating  105 . Two coats of base and two coats of finish may be sprayed on to the front surface of the projection screen  104  with airless spray rigs. Most projection screens utilize max contrast (0.7 gain) or ultramax contrast (0.5 gain). 
     Benefits of the curvilinear projection screen and acoustic system includes that it is seamless (high importance), can be a compound curve projection screen, non-combustible materials, high resolution, durable, maintenance friendly, repairs quickly, allows rear mounted speakers (randomized faded speaker perforated panels), passes seismic load analysis, thermal rated, and sound deadening characteristics. 
     Many modifications and other embodiments of the invention will come to the mind of one skilled in the art having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is understood that the invention is not to be limited to the specific embodiments disclosed, and that modifications and embodiments are intended to be included within the scope of the appended claims.