Abstract:
An image projection system capable of projecting images to multiple screens or viewing surfaces. The system uses a moveable mirror to direct the projected images to the screens. The moveable mirror may work in concert with one or more fixed mirrors to reflect the projected images to screens in a variety of configurations relative to the projector.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]    This application claims the benefit of U.S. Provisional Application No. 60/351,295, filed Jan. 23, 2002.  
         [0002]    The present invention is also related to U.S. patent application Ser. No. 09/876,400, which is a continuation-in-part of Ser. No. 09/519,537. 
     
    
     
       TECHNICAL FIELD  
         [0003]    The invention is generally related to the field of image projection systems, and more particularly to image projectors capable of projecting images to multiple screens or viewing surfaces.  
         BACKGROUND INFORMATION  
         [0004]    When projecting images into an audience space, it may be desired to project images onto more than one screen. This may be due to increasing the audience capacity of the image demonstration or to present more information than can be presented on only screen. Typically, multiple images are presented by utilizing as many projectors as the desired number of screens. However, multiple projectors are expensive and it can be difficult to coordinate the presentation between the multiple projectors.  
           [0005]    Accordingly, there exists a need to provide a low-cost way to multiplex the images of a single projector; that is, using one projector to present images on multiple screens. In addition to being relatively inexpensive, the multiplexing means should also be sufficiently flexible to allow for different viewing configurations.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]    For a more complete understanding of the present invention, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:  
         [0007]    [0007]FIGS. 1A and 1B illustrate a top view of a multiple-image projection system in accordance with an embodiment of the present invention;  
         [0008]    [0008]FIG. 1C illustrates a top view of an alternative embodiment of a multiple-image projection system;  
         [0009]    [0009]FIG. 2 illustrates a top view of an alternative embodiment of a multiple-image projection system showing projection of the images onto one of two sides of a screen;  
         [0010]    [0010]FIG. 3 illustrates a top view of an alternative embodiment of a multiple image projection system for projecting holographic images;  
         [0011]    [0011]FIGS. 4A and 4B illustrate a top and side view, respectively, of a rotating mirror mount on a motor for use with the present invention; and,  
         [0012]    [0012]FIGS. 5A and 5B illustrate side views of an alternative rotating mirror mount on a motor for use with the present invention.  
     
    
     DETAILED DESCRIPTION  
       [0013]    In the following description, numerous specific details are set forth such as specific screen materials to provide a thorough understanding of the present invention. However, it will be obvious to those skilled in the art that the present invention may be practiced without such specific details. In other instances, well-known circuits have been shown in block diagram form in order not to obscure the present invention in unnecessary detail. For the most part, details concerning timing considerations and the like have been omitted in as much as such details are not necessary to obtain a complete understanding of the present invention and are within the skills of persons of ordinary skill in the relevant art.  
         [0014]    While the specification concludes with claims defining the features of the invention that are regarded as novel, it is believed that the invention would be better understood from a consideration of the following description in conjunction with the drawing figures, in which like reference numerals are carried forward.  
         [0015]    Referring to FIGS. 1A and 1B, a multiple-image projection system  100  embodying principles of the present invention is representatively illustrated. A single projector  101  projects an image at moveable mirror  102  along the path indicated by the arrows. Any well-known projector of images can be used. In the position shown in FIG. 1A, the moveable mirror  102  reflects the projected image toward fixed mirror  103  (as shown by the arrows), which is angled such that mirror  103  further reflects the image toward a display screen  106 . FIG. 1B illustrates that moveable mirror  102  can be positioned to reflect the projected image to other fixed mirrors such as illustrated mirror  104 , which further reflects the image toward other display screens such as illustrated screen  105 .  
         [0016]    The means for moving the moveable mirror  102 , which is not illustrated in FIGS. 1A and 1B, may be any well-known means for changing the position of a planar object, for example, a motor attached to the non-reflecting side of the mirror. FIGS. 4A, 4B,  5 A, and  5 B illustrate two possible mirror-motor configurations. In FIGS. 4A and 4B, a motor spindle  403  is connected along a portion of its length to a non-reflecting surface of a mirror  401 . The motor  402  rotates the mirror along an axis that is parallel to the plane of the mirror  401 . In FIGS. 5A and 5B, a motor spindle  503  is connected at its end to a non-reflecting surface of a mirror  501 . The mirror is mounted at an angle desired to properly reflect a projected image. The motor  502  rotates the mirror to reflect the projected image where desired.  
         [0017]    The means for moving the moveable mirror  102  could be controlled by any well-known means for controlling the means for moving, such as by an electronic signal provided by a wired, wireless, or networked system. Further, the moveable mirror may be continuously rotated to bring the projected image to each fixed mirror or moved in a flip-flop manner from mirror to mirror. In addition, a moveable mirror with more than one reflecting surface could be used to decrease the movement necessary to provide an image to a particular screen. An alternative embodiment includes continuously rotating the moveable mirror as stated above so that it repositions the projected light image onto each fixed mirror sequentially in a loop at a cycle frequency such that the image projected to the screen appears constant to a viewer of the image.  
         [0018]    It will be readily apparent to a person of ordinary skill that a multiple image projection system is not restricted to the illustration in FIGS. 1A and 1B. It is envisioned that a system including more than two screens, variable numbers of fixed mirrors, or more than one moveable mirror could be utilized. FIG. 1C illustrates an alternative multiple-image projection system that includes no fixed mirrors, instead reflecting the projected image directly to a screen  105  or  106  from the movable mirror  102 .  
         [0019]    Referring now to FIG. 2, an alternative multiple image projection system  200  is illustrated. As in FIGS. 1A and 1B, the light image from projector  201  is projected towards moveable mirror  202 , which is positioned by a moving means similar to that described for FIGS. 1A and 1B. The projected image is then reflected from moveable mirror  202  toward one of a first set of fixed mirrors, either  203  or  204 . The first set of fixed mirrors  203  and  204  are positioned so that they reflect the light image toward a second set of fixed mirrors  205  and  206  respectively. The second set of fixed mirrors further reflect the projected image to a side of screen  207  making it possible to view an image on either side of screen  207 . Screen  207  may be opaque, translucent, or switchable as described in U.S. patent application Ser. No. 09/876,400, which is a continuation-in-part of Ser. No. 09/519,537, both of which are incorporated by reference herein. It will be readily appreciated that this system of projecting an image onto either side of a screen alleviates the problem of reversed images typically created when viewing an image through a translucent screen.  
         [0020]    It should be understood that many types of mirrors may be used within the present invention, such as grating mirrors, metallic mirrors, and cold mirrors, and also the shape of the mirror may vary, i.e., parabolic or flat. The mirrors may also be made of many different types of materials. Referring to FIG. 3, fixed, parabolic, holographic mirrors  302  and  303  are utilized in projection system  300  to reflect images from moveable mirrors  304  and  305  from projector  301  to a holographic display medium  306 . Holographic mirrors are designed utilizing holography by imprinting the material, such as plastic, with an interference pattern suitable for a specific optical function. A reflective substrate may then be designed to work in conjunction with the interference imprinted material by knowing the location of the source of light illuminating the interference pattern and using well-known holographic calculations. By using holography for the specific system shown one can achieve better efficiency, and if needed, even make the mirrors smaller in dimensions.  
         [0021]    Although the present invention and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.