Abstract:
An apparatus and method for forming images visible to audiences includes a system for forming virtual images and creating visual effects in a stage setting. This system may include a stage and first and second flat panel video displays. The first flat panel video display is visible to the audience through a portal mirror. The second flat panel video display is not visible to the audience; however, images displayed thereon are reflected off of the portal mirror and outwardly to the audience. Finally, a performance area between the back display and the portal mirror is provided for a person or object whereby the audience may see the composite image of the images from the first and second flat panel video displays and the person or object in the performance area on-stage.

Description:
This invention relates to an apparatus and method for forming images visible to audiences in live stage performances. More specifically, the invention relates to a relatively compact system for forming virtual images and creating visual effects in a stage setting. 
     BACKGROUND OF THE INVENTION 
     The art of staging presentations that incorporate optical illusions has been practiced for many years. One of the most popular illusions is created through use of projectors and screens and results in apparent three-dimensional images that a viewing audience sees on-stage during a show or presentation. 
     These prior art illusion systems can be generally categorized as follows: projections onto gauze or other transparent surfaces; projections on live smoke; three-dimensional film technique; and multiple Blue Room techniques. The categories of systems are discussed in substantial detail in U.S. Pat. No. 4,805,985 to Rogers. The discussion includes detailed explanations of the various different Blue Room techniques. 
     More recently, changes in technology have allowed for more sophisticated systems with computerized lighting coordinated with projectors. There has even been teaching of combining projection systems with object tracking devices to tie live performances in with the projection system. These types of techniques are described in U.S. Pat. Nos. 5,685,625 and 5,528,425 to Beaver. 
     Drawbacks with existing technologies noted above include the possible logistic nightmare of a projection system. A screen and projector combination typically requires substantial space between a screen and projector. The combination is also a concern with respect to the registration of the projector itself in relation to the screen. The process of projection convergence and screen alignment is time consuming and requires a skilled technician. In any event, when performing on-stage and using two screens like in Beaver, there must be space between the rear projector and the rear screen as well as space between the second projector and the overhead screen. In smaller auditoriums or meeting places, it is very difficult to try to stage these systems such as, for instance, the Beaver system. Space limitations may require a substantial reduction in the size of the effects area that can be created. 
     In addition to the foregoing, there are fundamental limitations to projection systems generally. First, the use of lighting on-stage to illuminate a person or actor can wash out the images being projected on the various screens, particularly a back screen. Also, in order to achieve some effects, the screens are movable. Moving screens will require moving projectors and the resulting logistical drawbacks coordinating the projector/screen movement. 
     Another problem with live presentations is coordinating a live performance with images shown on various screens. The Beaver reference discloses object tracking devices to try to solve this problem, but known tracking systems may not always be reliable. Known tracking systems may also be subject to interference from adjacent metal structures (especially if moving) and from adjacent electrical equipment systems. Tracking systems are also very expensive and difficult to integrate with multiple graphics, video, lighting and other equipment system control software. Rather than using a tracking device, an actor giving a live performance usually must look at an off-stage monitor to see what the audience sees and react accordingly. These side glances can take away from the overall visual effect of a performance. In other words, it is difficult for an actor to see the same composite imagery as the audience, because the actor is in the middle of the composite. 
     SUMMARY OF THE INVENTION 
     It is an objection of the present invention, therefore, to overcome the foregoing drawbacks and provide an improved apparatus and method for forming images during live performances. 
     In one embodiment, an apparatus for displaying visual effects for live presentations involves a stage and a viewing area in which is seated an audience. The stage comprises a foreground side and a background side wherein the foreground side is adjacent the viewing area and the background side is on the side of the stage opposite the foreground side. A back display is comprised of a first flat panel video display wherein the back display is mounted toward the background side of the stage and the first flat panel video display is visible to the audience. A partially-silvered portal mirror is mounted toward the foreground side of the stage at an angle to a vertical plane in front of the audience. A performance area is provided between the back display and the portal mirror. A second flat panel video display that is not visible to the audience displays images that are reflected off of the portal mirror and create a virtual image visible to the audience. The apparatus may further include the portal mirror mounted at an angle so that it is inclined upwardly away from the foreground side of the stage with the second flat panel video display mounted above the stage and above the portal mirror. Alternatively, the portal mirror may be mounted at an angle so that it inclines upwardly toward the foreground side of the stage and a second flat panel video display is mounted below the portal mirror. The apparatus may further include a monitor mirror mounted parallel to the second flat panel video display and on the opposite side of the portal mirror from the second flat panel video display. In a still further embodiment, the apparatus may include an off-stage set including a video camera, a background and a second performance area. The video camera records images from the background and second performance area and feeds those images into the first or second flat panel video displays. 
     The invention also includes a method for creating visual effects during live presentations comprising a number of steps. First, it includes providing a stage and a viewing area in which an audience is seated. This stage comprises a foreground side and a background side wherein the foreground side is adjacent the viewing area and background side is on the side of the stage opposite the foreground side. A back display comprised of a first flat panel video display is mounted toward the background side of the stage and the first flat panel video display is visible to the audience. The stage further includes a partially-silvered portal mirror wherein the portal mirror is mounted toward the foreground side of the stage and further wherein the portal mirror is mounted at an angle to a vertical plane in front of the audience. A performance area between the back display and the portal mirror is provided. A second flat panel video display that is not visible to the audience displays images that are reflected off the portal mirror and create a virtual image visible to the audience. The method further includes the steps of sending signals to the first and second flat panel video displays that form images thereon visible to the audience. The method further includes placing a person or object in the performance area and directing lights on them so that they are visible to the audience. In this method, the audience simultaneously sees the composite image made up of the images from the first and second flat panel video displays and the person or object placed in the performance area. In a further alternative, the method further includes providing a monitor mirror mounted parallel to the second flat panel video display and on the opposite side of the portal mirror from the second flat panel video display. The method also includes in a further variation of providing an off-stage set comprising a video camera, a background and a second performance area wherein the video camera records images from the background and the second performance area and further wherein those images recorded by the video camera are fed into the first or second flat panel video displays. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 a schematic side elevation view of an apparatus embodying the present invention. 
     FIG. 2 is a flow chart diagram of the sound, lighting and video systems used to actuate the present invention. 
     FIG. 3 is a side elevation schematic view of an off-stage set that may be used in connection with the present invention. 
     FIG. 4 is a side elevation schematic view of an apparatus embodying the present invention. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     FIG. 1 illustrates a schematic view of a preferred embodiment the present invention. There is shown a stage  10  having a foreground side  11  and background side  12 . The foreground side  11  is adjacent the viewing area  27  in which is seated an audience  26 . Toward the background side  12  there is mounted a back display  15 . The back display  15  is a flat panel video display. The images that are shown on the back display  15  are visible to the audience  26 . 
     Portal mirror  17  is mounted toward the foreground side  11  of the stage  10 . The portal mirror  17  is inclined upwardly away from the foreground side  11  of the stage  10  at an angle to the vertical plane in front of the audience. The portal mirror  17  is only partially silvered. In the preferred embodiment, the portal mirror  17  is 50% silvered thus allowing 50% of light (images) to pass through the mirror  17  such that the audience  26  can see through the portal mirror  17  to see the images on the back display  15 . 
     In between the portal mirror  17  and back display  15  is the portion of the stage  10  referred to as the performance area  13 . The performance area  13  is wide enough to allow a person  20  or other object to act or perform on-stage before the audience  26 . The person  20  is visible to the audience  26  through the partially-silvered portal mirror  17 . The performance area  13  will also typically include a stage monitor loudspeaker  23  and one or more stage microphones  22 . Stage lighting  21  illuminates the person  20  or object in the performance area  13 . 
     FIG. 1 further illustrates a second flat panel video display  16  that is mounted above the stage  10  and above the portal mirror  17 . The second flat panel video display  16 , or overhead display, is further mounted behind a proscenium drape  19  or other curtain so that the audience  26  cannot observe the overhead display. Images that are displayed on the overhead display  16  are reflected off of the portal mirror and outwardly towards the audience  26 . The apparatus further includes a monitor mirror  18  that is mounted underneath the portal mirror and parallel to the overhead display  16 . The monitor mirror  18  is fully silvered. Because the portal mirror  17  is only partially silvered, a portion of the intensity of the image projected on the overhead display  16  reflects out to the audience, and the remaining intensity of the image passes through the portal mirror  17  and is reflected back upwardly by the monitor mirror  18 . A portion of that reflection is then reflected backwardly to the person  20  acting or performing in the performance area  13 . 
     Preferably, the partially silvered mirror is 50% silvered. Therefore, 50% of the light (image) striking the surface of the portal mirror  17  is reflected off the mirror and changed in direction according to the angle of inclination of the mirror, i.e., outwardly towards the audience  26 . The other 50% of the light passes straight through the half-silvered mirror. In operation, therefore, this one-half of the image from the overheard display  16  passes straight through the portal mirror  17  hitting the floor underneath it where the monitor mirror  18  is placed. This one half of the image brightness bounces straight back up and hits the underside of the portal mirror  17  and is one half reflected back toward the person on-stage. The image from the background display  15  does the same thing as the image from overhead display  16 . Fifty percent of the light (image) goes straight through the portal mirror  17  and out to the audience  26 . The other 50% is bounced onto the monitor mirror  18  and back into the underside of the portal mirror  17 . Fifty percent of that reflected image can then also be seen by the performer. The light  21  illuminating the person on-stage also passes 50% out towards the audience  26  while the other half is directed onto the monitor mirror  18  and reflected back up off of the underside of the portal mirror  17  back to the performer. With this system, therefore, the person  20  in the performance area  13  is able to see the same image that the audience  26  sees. The only difference is that the person  20  only sees half of the brightness of the composite image that the audience  26  sees. The composite image is a combination of reflections from the monitor mirror  18  including the overhead display  16 , background display  15  and stage person/object  20 . The obvious benefit of the monitor mirror  18 , therefore, is that the person  20  in the performance area  13  is able to follow exactly how everything is appearing to the audience without having to view an off-stage monitor or otherwise guess what the composite images looks like. 
     FIG. 2 demonstrates schematically the sound, lighting and video systems that may be used in connection with a preferred embodiment of the image forming apparatus. The sound system can be made up of a series of different microphones  30  and playback devices  31  that are fed into a mixer and amplifier system  32 . The mixer and amplifier  32  then sends the music out through various loudspeakers  33 . The microphones  30  may be placed in the performance area  13 , before an off-stage announcer, and/or in an off-stage set. Obviously, the playback device  31  or devices may play prerecorded messages. The loudspeakers  33  may be positioned for the audience to hear, as a stage monitor speaker, and/or at an off-stage set. 
     The lighting system is made up of a lighting controller and dimmer system  41  connected to the various lighting hardware  40 . The lighting controller  41  may control both on-stage and off-stage lighting elements. 
     The video system may incorporate several different input components. These components may include an off-stage camera  50 , a video playback  51 , a graphics video device  52 , and/or an audience view camera  53 . The system may also include more than one of each of these input components. Those signals are observed by operators on the source monitors  54  prior to or contemporaneous with utilizing the signals in the video controllers  55  and  56 . The overhead video display controller  55  receives input from one or more of the graphics video source  32 , video playback source  51 , or off-stage camera  50 . Likewise, the back panel display video controller  56  receives input from one or more of the same components. Those controllers  55  and  56  are connected to video monitors  57  and  58  that are likewise connected to the overhead display  16  and background display  15 . The audience camera  53  is fed to a stage monitor  59  and/or to an off-stage set monitor  60 . 
     FIG. 3 illustrates a schematic of an off-stage set  72 . The off-stage set includes video camera  50  that captures what is going on the off-stage set  72  so that it may be optionally input onto one or both of the display panels  15  and  16  on the stage  10 . The off-stage set includes an off-stage person  70  and, optionally, a background  71 . The background  71  will often be a primary color which is then subtracted from the final signal in a well-known process called “keying” that is familiar to those of skill in the art. The off-stage set  72  further includes a microphone  30  and lighting  40  as well as an off-stage set speaker  33 . A monitor  60  allows the person  70  to see what is happening on-stage  10 , because the monitor  60  is receiving input from the audience view camera  53 . 
     Loudspeakers and microphone placements on both the main stage and the off-stage set are positioned so that offstage performers and on-stage performers may interact together in real time in addition to whatever playback sources may also be utilized. Also, the lighting on the off-stage set is carefully controlled so that the transmitted off-stage image will appear similar to the images seen on the main stage to better carry off the virtual image seen by the audience. 
     FIG. 4 sets forth in more structural detail the stage  10 . The back display  80  includes the panel display  81  on a frame and roller  82 . This allows the display  80  to be moved laterally and forward and backwards with respect to the audience. The rollers  82  also allow for easy access to placing large objects on and off the performance area  83 . In a preferred embodiment, the flat panel video display  81  is nine feet tall and 12-16 feet wide. Typically, the screen is approximately 4-24 inches thick. Manufacturers of suitable video displays include Sony and Lighthouse Technologies, Inc. Preferably, the surface of the video display  81  includes a surface that diffuses or scatters incident light from the stage or elsewhere and does not reflect off of the display surface. 
     The second flat panel video display  85 , also referred to as the overhead display, is suspended from and supported by frame  84 . Frame  84  is attached to trusses  86  that allows for the overhead display  85  to move up and down in the vertical direction in planes parallel to the plane defined by the display itself. Alternatively, not shown, the overhead display  85  may be suspended from the frame  84  so that the display  85  may move about within the plane defined by the video display  85  itself. In other words, the vertical height of the display would not change, but the horizontal position could be varied. In a further alternative, not shown, the display  85  may be moved about to planes not parallel to the plane of the display shown. Various asymmetrical or unbalanced images may be reflected to the audience. The total height that the overhead display  85  may move and is equal to at least the depth of the performance area  83  of the stage such that the images perceived by the audience  26  from the displays  15  and  16  may be arranged, when desired, to appear superimposed in the same virtual place. In a preferred construction, the performance area is twelve feet deep. Therefore, the overhead display  85  can move upward and downward twelve feet. The truss columns  86  are spaced fifteen feet apart on their outside edges. Finally, a proscenium drapery  87  covers the front of the apparatus so that the overhead display  85  and supporting framework  84  can not been seen by the audience viewing from audience area  100 . The length and width of the overhead display  85  are preferably comparable to the dimensions of the back display  81 . 
     The portal mirror  90  is tilted at approximately a 45° angle to the vertical plane in front of the audience. The height of the portal mirror  90  is 14 feet, 4 inches. The portal mirror is comprised of stretched optical films that have been metalized to the point that they are 50% silvered. Fifty percent silvered is preferable, because many desirable effects rely heavily on the fact that images on either the overhead display or background display cannot be readily discerned from each other. The stretched optical films allows the mirror to be light weight and relatively easily replaceable. Certainly, it is easier to handle then an actual glass mirror. The portal mirror  90  is fitted with a hinged mounting and articulation mechanism  91 , so that the mirror  90  can be rotated upwardly. As the portal mirror swings up, persons or things can move onto and off of the stage and into the audience area. The monitor mirror  95  is also made up of stretched optical film. It has the same dimensions as the overhead display  85 . The monitor mirror film is 100% silvered to reflect all the light that it receives. Acceptable films that may be used include Mylar polyester 
     The height of the portal mirror  90  and the height of the back display  80  may vary at the preference of a presentation designer. With respect to the height of the back display  80 , it should be no less than six feet to accommodate the height of an average person in the performance area  83 . Similarly, the length of the portal mirror  90  should be no less than about 9½ feet in order to be vertically high enough (when mounted at a 45° angle) to be as tall as an average six feet tall person. Alternatively, if a portal mirror is mounted other than at the 45° angle shown, the length of the portal mirror can be adjusted with the angle in order to cover the preferable minimum six foot height. Actors or objects in the performance area that are taller than six feet (as described) or even nine feet (as shown in FIG. 4) will require proportionate adjustments to the height and length of a back display and portal mirror. 
     The system described herein can be adapted to various different situations depending on the locational requirements. For instance, if there is little or no overhead space in which to mount a truss frame work, then the second flat panel video display can be mounted parallel to or below the floor of the stage. In that case, the portal mirror would be mounted so that it inclines toward the audience and reflects the images from underneath outwardly towards the audience. Further alternatively, if the location requirements demanded, then the second flat panel video display could be placed vertically like the back display but in the right or left hand wing of the stage. In this way, the portal mirror would be vertical in the side elevation yet angled in a top or bottom view. 
     In further variations of the invention, the degree of silvering of the portal mirror can be varied so that images that are reflected off of the portal mirror can be given a different “look” or “texture” to the audience. Further, although the preferred embodiments illustrated in the drawings show the overhead panel display parallel to the plane of the stage, the second flat panel display could be at an angle and the portal mirror angle adjusted accordingly. This could provide further flexibility with respect to the auditorium or location where the images will be formed. 
     While the invention has been described with reference to specific embodiments thereof, it will understood that numerous variations, modifications and additional embodiments are possible, and accordingly, all such variations, modifications, and embodiments are to be regarded as being within the spirit and scope of the invention.