Abstract:
An apparatus, system, and method for a dual front/rear projection screen having a first exterior surface and a second exterior surface are disclosed herein. The second exterior surface may be shaped to facilitate transmission and reflection of a portion of light and enable viewing an image from both sides of the projection screen.

Description:
RELATED APPLICATION 
     The present application claims priority to provisional application No. 60/703,160, filed on Jul. 27, 2005, entitled “DUAL FRONT/REAR PROJECTION SCREEN.” The specification of said provisional application is also hereby fully incorporated by reference in its entirety, except for those sections, if any, that are inconsistent with this specification. 
    
    
     FIELD 
     Embodiments of the invention relate generally to the field of projection screens, and more particularly to a dual front/rear projection screen. 
     BACKGROUND 
     Projection systems project images from a small display, or light valve, found in a projection device, onto a projection screen for viewing. Prior art projection systems are based on either front projection or rear projection. A front-projection system uses a projection device to project an image onto a screen which is then reflected back towards a viewer. In a rear-projection system, the projection device projects the image onto the screen, which transmits the image for viewing from the opposite side. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the invention are illustrated by way of example and not by way of limitation in the figures of the accompanying drawings, in which like references indicate similar elements and in which: 
         FIG. 1  illustrates a projection system, in accordance with an embodiment of the present invention; 
         FIG. 2  illustrates a cross-section view of a portion of a projection screen, in accordance with an embodiment of the present invention; 
         FIG. 3  illustrates a cross-section view of a portion of a projection screen, in accordance with another embodiment of the present invention; 
         FIG. 4  illustrates a cross-section view of a portion of a projection screen, in accordance with another embodiment of the present invention; and 
         FIG. 5  illustrates a cross-section view of a portion of a projection screen, in accordance with another embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Illustrative embodiments of the present invention include a dual front/rear projection screen and methods practiced thereon. 
     Various aspects of the illustrative embodiments will be described using terms commonly employed by those skilled in the art to convey the substance of their work to others skilled in the art. However, it will be apparent to those skilled in the art that alternate embodiments may be practiced with only some of the described aspects. For purposes of explanation, specific materials and configurations are set forth in order to provide a thorough understanding of the illustrative embodiments. However, it will be apparent to one skilled in the art that alternate embodiments may be practiced without the specific details. In other instances, well-known features are omitted or simplified in order not to obscure the illustrative embodiments. 
     Further, various operations will be described as multiple discrete operations, in turn, in a manner that is most helpful in understanding the present invention; however, the order of description should not be construed as to imply that these operations are necessarily order dependent. In particular, these operations need not be performed in the order of presentation. 
     The phrase “in one embodiment” is used repeatedly. The phrase generally does not refer to the same embodiment; however, it may. The terms “comprising,” “having,” and “including” are synonymous, unless the context dictates otherwise. 
       FIG. 1  illustrates a projection system  100  in accordance with an embodiment of the present invention. In this embodiment, a projection device  104  may project an image onto a projection screen  108 . The projection screen  108  may have a shaped surface to facilitate the reflection of a reflected portion  112  of the projected image back for viewing on the same side of the projection screen  108  as the projection device  104 . The shaped surface of the projection screen  108  may also facilitate the transmission of a transmitted portion  116  through the projection screen  108  to be viewable from the side opposite the side that the projection device  104  is located. 
     The projection screen  108  being viewable from both sides may allow for flexibility in the placement of the projection screen  108 . For example, the projection screen  108  may be placed more towards the center of a room, rather than a perimeter placement required by one-sided prior art projection screens. This may, in turn, facilitate deployment of the projection system  100 , or parts thereof, in ways which may be impractical for prior art projection systems. For example, in one embodiment, the projection system  100  may be integrated with a housing  120  that is away from the perimeter of the room, e.g., a coffee table or the center of a conference table. The housing  120  may securely dispose one or more of the components of the projection system  100  relative to one another. 
     In various embodiments, the projection system  100  may be employed in any number of applications including, but not limited to, home theater, videoconferencing, and/or gaming applications. 
       FIG. 2  illustrates a cross-section view of a portion of a projection screen  200  in accordance with an embodiment of the present invention. The projection screen  200  may be substantially interchangeable with the projection screen  108  described above. In this embodiment, the projection screen  200  may have a surface  204  and a shaped surface  208  on opposite sides of a transparent substrate  212 . In various embodiments the surface  204  may be shaped or substantially planar. 
     The shaped surface  208  may have one or more features, e.g., feature  216 , formed directly into the substrate  212 . In another embodiment, the feature  216 , may be formed independent of the substrate  212  and subsequently coupled thereto. 
     The feature  216  of the shaped surface  208  may be formed by stamping, rolling, or by any other suitable manufacturing process. In one embodiment, the feature  216  may be cured following formation in order to provide for the desired material properties. In other embodiments, this curing step may not be used. The projection screen  200  may be constructed from materials having suitable mechanical, formable, and optical properties. Such materials could include, but are not limited to, a transparent polymer, glass, or plastic. 
     In one embodiment, the substrate  212  may include light-scattering particles suspended throughout the substrate  212 . These particles may diffuse the light as it travels through the substrate  212  in order to lessen the occurrence of speckle. 
     In one embodiment, the feature  216  may include a face  220 . A light ray  224  from a projection device may be incident upon the surface  204  at an angle Θ. The angle Θ and the point of incidence may be such that the light ray  224  is transmitted through the projection screen  200 . More particularly, and in accordance with this embodiment, the light ray  224  may be transmitted through the substrate  212  toward the face  220 . At the face  220  the light ray  224  may be incident at an angle η, which may be of such a degree to allow the light ray  224  to be transmitted through the projection screen  200 . 
     In one embodiment, the feature  216  may also include a face  228  which intersects the face  220  at an angle Φ. A light ray  232  from the projection device may also be incident upon the surface  204  at an angle Θ (approximately). The angle Θ and the point of incidence may be such that the light ray  232  is reflected from the projection screen  200 . More particularly, and in accordance with this embodiment, the light ray  232  may be transmitted through the substrate  212  toward the face  228 . At the face  228 , the light ray  232  may be incident at an angle δ, which may be of such a degree to internally reflect, e.g., by total internal reflection, the light ray  232  towards the face  220 . The reflected light ray  232  may also be internal reflected from the face  220  and be emitted out from the surface  204 . 
     In various embodiments, reflections may be facilitated by reflective coatings. 
     In various embodiments, faces, e.g., the face  220  and/or face  228 , may be any of a number of shapes including, but not limited to, substantially planar, as shown in  FIG. 2 , conical, cylindrical, spherical, and free-form. In one embodiment, a non-planar face may be implemented to spread light upon reflection and/or refraction of the light rays. 
     The dimensions of the face  220  and the face  228 , as well as the angle Φ, may be adjusted to accommodate parameters of various embodiments. One such parameter may be the projection angle that corresponds to the initial incident angle Θ. Because this incident angle may change over the face of the projection screen, the dimensions and angles of the features may change correspondingly over the face. For example, in an embodiment having the projection device set at or below the projection screen  200 , the faces of the features corresponding to face  220  may get smaller towards the top of the screen, while the faces corresponding to face  228  may get larger. The particular dimensions/angles may be determined based on optical properties such as index of refraction of the substrate  212 , angle of projection, etc. 
     In this embodiment, features, which may or may not be similar to the feature  216 , may be repeated over the shaped surface  208 . 
       FIG. 3  illustrates a cross-section view of a portion of a projection screen  300  in accordance with another embodiment of the present invention. The projection screen  300  may be substantially interchangeable with the projection screen  108  discussed above with reference to  FIG. 1 . In this embodiment, the projection screen  300  may have a surface  304  on one side and a shaped surface  308 , with one or more features, e.g. feature  312 , on an opposite side. Unlike the above embodiment, this embodiment may be configured to receive light from a projection device with the shaped surface  308  having the one or more features. This embodiment may accommodate steep projection angles from a projection device placed relatively close to the base of the projection screen  300 . 
     In one embodiment, the feature  312  of the projection screen  300  may include a face  316 . The face  316  of the feature  312  may be configured such that a light ray  320 , from a projection device, may be transmitted through the projection screen  300 . More particularly, and in accordance with this embodiment, the light ray  320  may be transmitted through the face  316  towards a face  324  where it may be reflected internally towards the surface  304 . The light ray  320  may then be emitted from the surface  304 . 
     In one embodiment, the feature  312  may also include a face  328 . The face  328  may be configured such that a light ray  332 , from the projection device, may be reflected from the projection screen  300 . More particularly, and in accordance with this embodiment, the light ray  332  may be transmitted through the reflecting face  328  towards the surface  304  in a manner to facilitate internal reflection at the surface  304 . The light ray  332  may then be emitted from the face  324 . 
     In this embodiment, features, which may or may not be similar to the feature  312 , may be repeated over the shaped surface  308 . 
       FIG. 4  illustrates a projection screen  400  in accordance with another embodiment of the present invention. The projection screen  400  may be substantially interchangeable with the projection screen  108  described above. In the present embodiment, the projection screen  400  may have a feature  404  with a face  408  adjacent to a curved face  412 . In this embodiment, the curved face  412  may be mirrored to reflect a light ray  416  received from a projection device, while the face  408  may transmit a light ray  420  received from the projection device. In this embodiment, the projection screen  400  may have a substrate  424  with diffusive properties. 
     While the above embodiments include a feature having faces to facilitate appropriate reflection and transmission of light rays, other embodiments may have a feature configured to facilitate transmission of light rays, while another feature is configured to facilitate reflection of light rays.  FIG. 5  illustrates a cross-section view of a portion of a projection screen  500  in accordance with another embodiment of the present invention. The projection screen  500  may be substantially interchangeable with the projection screen  108  described above. In this embodiment, the projection screen  500  may have a surface  504  on one side and a shaped surface  508  on an opposite side. 
     In the present embodiment, the shaped surface  508  may include a feature  512  configured in such a manner as to facilitate the transmission of light rays through the projection screen  500 . More particularly and in accordance with this embodiment, a light ray  516 , from a projection device, may be incident upon the surface  504  in such a manner as to be transmitted to, and emitted from, the feature  512 . 
     In one embodiment, the shaped surface  508  may also include a feature  520  configured in such a manner as to facilitate the reflection of light rays from the projection screen  500 . More particularly, and in accordance with this embodiment, a light ray  524 , from the projection device, may be incident upon the surface  504  in such a manner as to be transmitted to the feature  520  at an angle sufficient to cause the light ray  524  to go through a series of internal reflections at faces of the feature  520 . The light ray  524  may ultimately be emitted from the surface  504 . In this embodiment, transmitting features and reflecting features may be alternated over the face of the shaped surface  508 . 
     In various embodiments, features configured to transmit and/or reflect, may be designed to accommodate incident angles typical for an area of a projection screen in which a particular feature is employed. For example, features at the top edge of the projection screen may be configured to accommodate steeper projection angles than features towards the bottom of the projection screen. 
     Although specific embodiments have been illustrated and described herein for purposes of description of the preferred embodiment, it will be appreciated by those of ordinary skill in the art that a wide variety of alternate and/or equivalent implementations calculated to achieve the same purposes may be substituted for the specific embodiment shown and described without departing from the scope of the present invention. Those with skill in the art will readily appreciate that the present invention may be implemented in a very wide variety of embodiments. This application is intended to cover any adaptations or variations of the embodiments discussed herein. Therefore, it is manifestly intended that this invention be limited only by the claims and the equivalents thereof.