Abstract:
A dual switchable LCD display is disclosed that allows the juxtaposition of a front and rear image. A rear switchable screen is in proximity to the projector system. The rear image is projected on the rear screen at a first time interval. The rear switchable screen has an open state allowing light transmission through the rear screen and a closed translucent state obscuring the rear screen. A front switchable screen overlays the rear switchable screen. The projector system projects the front image on the front screen at a second time interval. The front switchable screen has an open state allowing light transmission through the front screen and a closed translucent state obscuring the front screen. A controller periodically cycles the respective closed and open states between the first and second time intervals to present a juxtaposition of the front image and the rear image to a viewer.

Description:
PRIORITY CLAIM AND CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a U.S. national stage of International Application No. PCT/US2010/049834 filed on Sep. 22, 2010, which is related to and claims priority to U.S. Provisional Application No. 61/246,800, filed on Sep. 29, 2009, each of which is incorporated herein its entirety. 
    
    
     COPYRIGHT 
     A portion of the disclosure of this patent document contains material which is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent disclosure, as it appears in the Patent and Trademark Office patent files or records, but otherwise reserves all copyright rights whatsoever. 
     TECHNICAL FIELD 
     The present invention relates generally to switchable transmissive displays and more particularly relates to a transmissive display having dual liquid crystal shutter screens that allows display of two juxtaposed images. 
     BACKGROUND 
     Gaming terminals, such as slot machines, video poker machines, and the like, have been a cornerstone of the gaming industry for several years. Generally, the popularity of such machines with players is dependent on the likelihood (or perceived likelihood) of winning money at the machine and the intrinsic entertainment value of the machine relative to other available gaming options. 
     LCDs (liquid crystal displays) have long been incorporated into gaming machines to enhance the flexibility of the displayed wagering games. However, some players prefer to see mechanical reels rather than a video rendering of a slot machine game, in part due to the more traditional appearance and perceived trustworthiness of the rotating mechanical slot reels. Utilization of mechanical reels makes the wagering game more enjoyable for such players, but limits the ability of the wagering game machine to present computer graphics and animation to enhance the theme of the wagering game or to provide other information, and so may be less entertaining to players than a wagering game utilizing a touchscreen LCD wagering game system. 
     Video-based slot machines allow for flexibility in game design and do not require any additional hardware for implementing different games, such as bonus games. With respect to flexibility in game design, the video display of a video-based slot machine can depict complex and entertaining graphical images, animations, and play sequences that cannot be employed in mechanical slot machines. Video-based slot machines do not require any additional hardware for implementing bonus games because the bonus game may be depicted on the primary video display and executed by the same game controller used to execute the video slot game. 
     Video-based slot machines and mechanical slot machines generally appeal to different segments of the market. Although many players are attracted to the complex and entertaining graphical images, animations, and play sequences afforded by video-based slot machines, many players are still drawn to mechanical slot machines because they are simplistic machines that often only pay on a single pay line and only require a pull of a handle to initiate a spin of the reels. Part of the reason that these players avoid video-based slot machines is that the simulated reels on the video-based machines are different in looks than standard mechanical reels. This is primarily due to the nature of the video screen displaying the images. 
     It would be beneficial to incorporate some of the features of the video-based slot machines into a traditional mechanical slot machine because of the flexibility that these video-based machines offer. A need exists for a slot machine having video-based capabilities, while still preserving the simplistic rotation of mechanical reels that traditionalists appreciate in the traditional mechanical slot machine. One type of display imposes an image on an underlying display by use of a transmissive liquid crystal display over a window which provides viewing of the underlying display which may be a mechanical reel or a simulated mechanical reel. Such a display system produces a bright front image, but the underlying display is problematic. The current generation of LCD&#39;s used to build such a display panel block more than 90% of the light in the window area under the best of conditions. This necessitates a very bright underlying display to project a marginally acceptable image in the window. 
     SUMMARY 
     According to one example, a gaming system display is disclosed. The gaming system display includes a projector system projecting a front image associated with a game and a rear image associated with the game at different times. A rear switchable screen is in proximity to the projector system. The rear image is projected on the rear screen at a first time interval. The rear switchable screen has an open state allowing transmittal of light through the rear screen and a closed translucent state obscuring the rear screen. A front switchable screen overlays the rear switchable screen. The projector system projects the front image on the front screen at a second time interval. The front switchable screen has an open state allowing transmittal of light through the front screen and a closed translucent state obscuring the front screen. A controller is coupled to the projector system and front and rear switchable screens to periodically cycle the respective closed and open states between the first and second time intervals to present a juxtaposition of the front image and the rear image to a viewer. 
     According to another example, a method of juxtaposing a front image associated with a game on a rear image associated with the game on a gaming system display is disclosed. A projector system is positioned relative to a front switchable screen and rear switchable screen. The front switchable screen is switched to a closed translucent state obscuring the front screen during a first time interval. A front image from the projector device is projected on the front switchable screen during the first time interval. The rear switchable screen is switched to an open transparent state allowing the viewing of the front image during the first time interval. The rear switchable screen is switched to a closed translucent state during a second time interval. A rear image is projected from the projector device on the rear switchable screen during the second time interval. The front switchable screen is switched to an open transparent state allowing the viewing of the rear image during the second time interval. The screens are cycled between the first and second time intervals to create a juxtaposition of the front and rear images. 
     Another example disclosed is a wagering game system including a wagering game controller for operating a wagering game. A wagering game display is coupled to the wagering game controller. The wagering game display includes a projector system projecting a front wagering game image and a rear wagering game image at different times. A rear switchable screen is in proximity to the projector system. The rear wagering game image is projected on the rear screen at a first time interval and the rear switchable screen has an open state allowing transmittal of light through the rear screen and a closed translucent state obscuring the rear screen. A front switchable screen overlays the rear switchable screen. The projector system projects the front wagering game image on the front screen at a second time interval. The front switchable screen has an open state allowing transmittal of light through the front screen and a closed translucent state obscuring the front screen. A display controller is coupled to the projector system and front and rear switchable screens to periodically cycle the respective closed and open states between the first and second time intervals to present a juxtaposition of the front wagering game image and the rear wagering game image to a viewer. 
     Another example disclosed is a wagering game system display including a projector system projecting a front image relating to a wagering game and a rear image relating to the wagering game at different times. A rear switchable screen has a curved surface and is in proximity to the projector system. The rear image is projected on the rear screen at a first time interval. The rear switchable screen has an open state allowing transmittal of light through the rear screen and a closed translucent state obscuring the rear screen. A front switchable screen overlays the rear switchable screen. The projector system projects the front image on the front screen at a second time interval. The front switchable screen has an open state allowing transmittal of light through the front screen and a closed translucent state obscuring the front screen. A controller is coupled to the projector system and front and rear switchable screens to periodically cycle the respective closed and open states between the first and second time intervals to present a juxtaposition of the front image and the rear image to a viewer. 
     Another example disclosed is a wagering game system display including a projector system projecting a plurality of wagering game images at different time intervals. A plurality of switchable screens are each in fixed position relative to the projector system. Each of the switchable screens has an open state allowing viewing through the screen and a closed translucent state. A controller is coupled to the projector system and the plurality of switchable screens to periodically cycle the respective closed and open states between the different time intervals to present a juxtaposition of the plurality of wagering game images to a viewer. 
     Additional aspects will be apparent to those of ordinary skill in the art in view of the detailed description of various embodiments, which is made with reference to the drawings, a brief description of which is provided below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a free-standing gaming terminal according to one example. 
         FIG. 2  is a schematic view of a gaming system. 
         FIG. 3  is an image of a basic-game screen of a wagering game that may be displayed on a gaming terminal. 
         FIG. 4  is an image of a bonus-game screen of a wagering game that may be displayed on a gaming terminal, according to an embodiment of the present invention. 
         FIG. 5  is a cross-section view of a prior art example of a projection display used with a transmissive LCD. 
         FIG. 6   a  is a cross-section view of a first example of a dual shutter display having dual projectors. 
         FIGS. 6   b  and  6   c  are cross-section views of the liquid crystal shutter screens of the display in  FIG. 6   a.    
         FIG. 7  is a cross-section view of a second example of a dual shutter display having a single projector. 
         FIG. 8  is a block diagram of a dual video image projector that may be used for the projector in  FIG. 7 . 
         FIG. 9  is a block diagram of an alternative dual video image projector that may be used for the projector in  FIG. 7 . 
     
    
    
     While the invention is susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and will be described in detail herein. It should be understood, however, that the invention is not intended to be limited to the particular forms disclosed. Rather, the invention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims. 
     DETAILED DESCRIPTION 
     While this invention is susceptible of embodiment in many different forms, there is shown in the drawings and will herein be described in detail preferred embodiments of the invention with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the broad aspect of the invention to the embodiments illustrated. 
     Referring to  FIG. 1 , there is shown a gaming terminal  10  similar to those used in gaming establishments, such as casinos. With regard to the present invention, the gaming terminal  10  may be any type of gaming terminal and may have varying structures and methods of operation. For example, the gaming terminal  10  may be an electro-mechanical gaming terminal configured to play mechanical slots, or it may be an electronic gaming terminal configured to play a video casino game, such as slots, keno, poker, blackjack, roulette, craps, etc. It should be understood that although the gaming terminal  10  is shown as a free-standing terminal of the upright type, it may take on a wide variety of other forms such as a free-standing terminal of the slant-top type, a portable or handheld device primarily used for gaming as shown in  FIG. 1   b , a mobile telecommunications device such as a mobile telephone or personal digital assistant (PDA), a counter-top or bar-top gaming terminal, or other personal electronic device such as a portable television, MP3 player, entertainment device, etc. 
     The illustrated gaming terminal  10  comprises a cabinet or housing  12 . For output devices, the gaming terminal  10  may include a primary display area  14 , a secondary display area  16 , and one or more audio speakers  18 . The primary display area  14  and/or secondary display area  16  may display information associated with wagering games, non-wagering games, community games, progressives, advertisements, services, premium entertainment, text messaging, e-mails, alerts or announcements, broadcast information, subscription information, etc. For input devices, the gaming terminal  10  may include a bill validator  20 , a coin acceptor  22 , one or more information readers  24 , one or more player-input devices  26 , and one or more player-accessible ports  28  (e.g., an audio output jack for headphones, a video headset jack, a wireless transmitter/receiver, etc.). While these typical components found in the gaming terminal  10  are described below, it should be understood that numerous other peripheral devices and other elements may exist and may be used in any number of combinations to create various forms of a gaming terminal. 
     The primary display area  14  may include a mechanical-reel display, a video display, or a combination thereof in which a transmissive video display in front of the mechanical-reel display portrays a video image superimposed over the mechanical-reel display. Further information concerning the latter construction is disclosed in U.S. Pat. No. 6,517,433 to Loose et al. entitled “Reel Spinning Slot Machine With Superimposed Video Image,” which is incorporated herein by reference in its entirety. The video display may be a cathode ray tube (CRT), a high-resolution liquid crystal display (LCD), a plasma display, a light emitting diode (LED), a DLP projection display, an electroluminescent (EL) panel, or any other type of display suitable for use in the gaming terminal  10 . The primary display area  14  may include one or more paylines  30  (see  FIG. 3 ) extending along a portion thereof. In the illustrated embodiment, the primary display area  14  comprises a plurality of mechanical reels  32  and a video display  34  such as a transmissive display (or a reflected image arrangement in other embodiments) in front of the mechanical reels  32 . If the wagering game conducted via the gaming terminal  10  relies upon the video display  34  only and not the mechanical reels  32 , the mechanical reels  32  may be removed from the interior of the terminal and the video display  34  may be of a non-transmissive type. Similarly, if the wagering game conducted via the gaming terminal  10  relies upon the mechanical reels  32  but not the video display  34 , the video display  34  may be replaced with a conventional glass panel. The mechanical reels  32  may be replaced with a simulated mechanical reel display such as those described in U.S. Publication No. 2008/0113755 entitled “Wagering Game With Simulated Mechanical Reels Having An Overlying Image Display,” U.S. Publication No. 2008/004104 entitled “Wagering Game With Simulated Mechanical Reels” and U.S. Publication No. 2009/0075721 entitled “Wagering Game With Simulated Mechanical Reels” all of which are incorporated herein by reference in their entirety. Further, the underlying mechanical-reel display may be replaced with a video display such that the primary display area  14  includes layered video displays, or may be replaced with another mechanical or physical member such as a mechanical wheel (e.g., a roulette game), dice, a pachinko board, or a diorama presenting a three-dimensional model of a game environment. 
     An example of a simulated reel system  500  where projected images may serve as an underlying simulated mechanical reel display is shown in  FIG. 5 .  FIG. 5  is a cross-section view of the simulated reel system  500 . The simulated reel system  500  includes a projector  502 , a curved projection screen  504  and a front transparent LCD panel  506 . The front transparent LCD panel  506  has a backlight layer  508  that includes an aperture  510 . The aperture  510  allows viewing of an underlying display of images projected on the projection screen  504 . The simulated reel system  500  allows an underlying display that is the simulated image of mechanical reels created with the projector  502  and a front image on the transparent LCD panel  506  juxtaposed over the underlying display. A significant disadvantage of this approach is that the front LCD panel  506  is only about 5% transmissive at best. The lack of transmissivity severely limits the brightness of the underlying display such as the projected reels on the screen  504 . 
     Video images in the primary display area  14  and/or the secondary display area  16  may be rendered in two-dimensional (e.g., using Flash Macromedia™) or three-dimensional graphics (e.g., using Renderware™). The images may be played back (e.g., from a recording stored on the gaming terminal  10 ), streamed (e.g., from a gaming network), or received as a TV signal (e.g., either broadcast or via cable). The images may be animated or they may be real-life images, either prerecorded (e.g., in the case of marketing/promotional material) or as live footage, and the format of the video images may be an analog format, a standard digital format, or a high-definition (HD) digital format. 
     The player-input devices  26  may include a plurality of buttons  36  on a button panel and/or a touch screen  38  mounted over the primary display area  14  and/or the secondary display area  16  and having one or more soft touch keys  40 . The player-input devices  26  may further comprise technologies that do not rely upon touching the gaming terminal, such as speech-recognition technology, gesture-sensing technology, eye-tracking technology, etc. 
     The information reader  24  is preferably located on the front of the housing  12  and may take on many forms such as a ticket reader, card reader, bar code scanner, wireless transceiver (e.g., RFID, Bluetooth, etc.), biometric reader, or computer-readable-storage-medium interface. Information may be transmitted between a portable medium (e.g., ticket, voucher, coupon, casino card, smart card, debit card, credit card, etc.) and the information reader  24  for accessing an account associated with cashless gaming, player tracking, game customization, saved-game state, data transfer, and casino services as more fully disclosed in U.S. Patent Publication No. 2003/0045354 entitled “Portable Data Unit for Communicating With Gaming Machine Over Wireless Link,” which is incorporated herein by reference in its entirety. The account may be stored at an external system  46  (see  FIG. 2 ) as more fully disclosed in U.S. Pat. No. 6,280,328 to Holch et al. entitled “Cashless Computerized Video Game System and Method,” which is incorporated herein by referenced in its entirety, or directly on the portable medium. To enhance security, the individual carrying the portable medium may be required to enter a secondary independent authenticator (e.g., password, PIN number, biometric, etc.) to access their account. 
     Turning now to  FIG. 2 , the various components of the gaming terminal  10  are controlled by a central processing unit (CPU)  42 , also referred to herein as a controller or processor (such as a microcontroller or microprocessor). The CPU  42  can include any suitable processor, such as an Intel® Pentium processor, Intel® Core 2 Duo processor, AMD Opteron™ processor, or UltraSPARC® processor. To provide gaming functions, the controller  42  executes one or more game programs stored in one or more computer readable storage media in the form of memory  44  or other suitable storage device. The controller  42  uses a random number generator (RNG) to randomly generate a wagering game outcome from a plurality of possible outcomes. Alternatively, the outcome may be centrally determined using either an RNG or pooling scheme at a remote controller included, for example, within the external system  46 . It should be appreciated that the controller  42  may include one or more microprocessors, including but not limited to a master processor, a slave processor, and a secondary or parallel processor. 
     The controller  42  is coupled to the system memory  44  and also to a money/credit detector  48 . The system memory  44  may comprise a volatile memory (e.g., a random-access memory (RAM)) and a non-volatile memory (e.g., an EEPROM). The system memory  44  may include multiple RAM and multiple program memories. The money/credit detector  48  signals the processor that money and/or credits have been input via a value-input device, such as the bill validator  20 , coin acceptor  22 , or via other sources, such as a cashless gaming account, etc. These components may be located internal or external to the housing  12  of the gaming terminal  10  and connected to the remainder of the components of the gaming terminal  10  via a variety of different wired or wireless connection methods. The money/credit detector  48  detects the input of funds into the gaming terminal  10  (e.g., via currency, electronic funds, ticket, card, etc.) that are generally converted into a credit balance available to the player for wagering on the gaming terminal  10 . The credit detector  48  detects when a player places a wager (e.g., via a player-input device  26 ) to play the wagering game, the wager then generally being deducted from the credit balance. The money/credit detector  48  sends a communication to the controller  42  that a wager has been detected and also communicates the amount of the wager. 
     As seen in  FIG. 2 , the controller  42  is also connected to, and controls, the primary display area  14 , the player-input device  26 , and a payoff mechanism  50 . The payoff mechanism  50  is operable in response to instructions from the controller  42  to award a payoff to the player in response to certain winning outcomes that might occur in the base game, the bonus game(s), or via an external game or event. The payoff may be provided in the form of money, redeemable points, services or any combination thereof. Such payoff may be associated with a ticket (from a ticket printer  52 ), portable data unit (e.g., a card), coins (from a coin outlet  54  shown in  FIG. 1 ), currency bills, accounts, and the like. The payoff amounts distributed by the payoff mechanism  50  are determined by one or more pay tables stored in the system memory  44 . 
     Communications between the controller  42  and both the peripheral components of the gaming terminal  10  and the external system  46  occur through input/output (I/O) circuit  56 , which can include any suitable bus technologies, such as an AGTL+ frontside bus and a PCI backside bus. Although the I/O circuit  56  is shown as a single block, it should be appreciated that the I/O circuit  56  may include a number of different types of I/O circuits. Furthermore, in some embodiments, the components of the gaming terminal  10  can be interconnected according to any suitable interconnection architecture (e.g., directly connected, hypercube, etc.). 
     The I/O circuit  56  is connected to an external system interface  58 , which is connected to the external system  46 . The controller  42  communicates with the external system  46  via the external system interface  58  and a communication path (e.g., serial, parallel, IR, RC, 10 bT, etc.). The external system  46  may include a gaming network, other gaming terminals, a gaming server, a remote controller, communications hardware, or a variety of other interfaced systems or components. 
     Controller  42 , as used herein, comprises any combination of hardware, software, and/or firmware that may be disposed or resident inside and/or outside of the gaming terminal  10  and may communicate with and/or control the transfer of data between the gaming terminal  10  and a bus, another computer, processor, or device and/or a service and/or a network. The controller  42  may comprise one or more controllers or processors. In  FIG. 2 , the controller  42  in the gaming terminal  10  is depicted as comprising a CPU, but the controller  42  may alternatively comprise a CPU in combination with other components, such as the I/O circuit  56  and the system memory  44 . The controller  42  is operable to execute all of the various gaming methods and other processes disclosed herein. 
     The gaming terminal  10  may communicate with external system  46  (in a wired or wireless manner) such that each terminal operates as a “thin client” having relatively less functionality, a “thick client” having relatively more functionality, or with any range of functionality therebetween (e.g., a “rich client”). In general, a wagering game includes an RNG for generating a random number, game logic for determining the outcome based on the randomly generated number, and game assets (e.g., art, sound, etc.) for presenting the determined outcome to a player in an audio-visual manner. The RNG, game logic, and game assets may be contained within the gaming terminal  10  (“thick client” gaming terminal), the external systems  46  (“thin client” gaming terminal), or distributed therebetween in any suitable manner (“rich client” gaming terminal). 
     Referring now to  FIG. 3 , an image of a basic-game screen  60  adapted to be displayed on the primary display area  14  is illustrated, according to one embodiment of the present invention. A player begins play of a basic wagering game by providing a wager. A player can operate or interact with the wagering game using the one or more player-input devices  26 . The controller  42 , the external system  46 , or both, in alternative embodiments, operate(s) to execute a wagering game program causing the primary display area  14  to display the wagering game that includes a plurality of visual elements. 
     The basic-game screen  60  may be displayed on the primary display area  14  or a portion thereof. In  FIG. 3 , the basic-game screen  60  portrays a plurality of simulated movable reels  62   a - e . Alternatively or additionally, the basic-game screen  60  may portray a plurality of mechanical reels. The basic-game screen  60  may also display a plurality of game-session meters and various buttons adapted to be actuated by a player. 
     In the illustrated embodiment, the game-session meters include a “credit” meter  64  for displaying a number of credits available for play on the terminal; a “lines” meter  66  for displaying a number of paylines to be played by a player on the terminal; a “line bet” meter  68  for displaying a number of credits wagered (e.g., from 1 to 5 or more credits) for each of the number of paylines played; a “total bet” meter  70  for displaying a total number of credits wagered for the particular round of wagering; and a “paid” meter  72  for displaying an amount to be awarded based on the results of the particular round&#39;s wager. The user-selectable buttons may include a “collect” button  74  to collect the credits remaining in the credits meter  64 ; a “help” button  76  for viewing instructions on how to play the wagering game; a “pay table” button  78  for viewing a pay table associated with the basic wagering game; a “select lines” button  80  for changing the number of paylines (displayed in the lines meter  66 ) a player wishes to play; a “bet per line” button  82  for changing the amount of the wager which is displayed in the line-bet meter  68 ; a “spin reels” button  84  for moving the reels  62   a - e ; and a “max bet spin” button  86  for wagering a maximum number of credits and moving the reels  62   a - e  of the basic wagering game. While the gaming terminal  10  allows for these types of player inputs, the present invention does not require them and can be used on gaming terminals having more, less, or different player inputs. 
     Paylines  30  may extend from one of the payline indicators  88   a - i  on the left side of the basic-game screen  60  to a corresponding one of the payline indicators  88   a - i  on the right side of the screen  60 . A plurality of symbols  90  is displayed on the plurality of reels  62   a - e  to indicate possible outcomes of the basic wagering game. A winning combination occurs when the displayed symbols  90  correspond to one of the winning symbol combinations listed in a pay table stored in the memory  44  of the terminal  10  or in the external system  46 . The symbols  90  may include any appropriate graphical representation or animation, and may further include a “blank” symbol. 
     Symbol combinations may be evaluated as line pays or scatter pays. Line pays may be evaluated left to right, right to left, top to bottom, bottom to top, or any combination thereof by evaluating the number, type, or order of symbols  90  appearing along an activated payline  30 . Scatter pays are evaluated without regard to position or paylines and only require that such combination appears anywhere on the reels  62   a - e . While an embodiment with nine paylines is shown, a wagering game with no paylines, a single payline, or any plurality of paylines will also work with the present invention. Additionally, though an embodiment with five reels is shown, a gaming terminal with any plurality of reels may also be used in accordance with the present invention. 
     Turning now to  FIG. 4 , a bonus game that may be included with a basic wagering game is illustrated, according to one embodiment. A bonus-game screen  92  includes an array of markers  94  located in a plurality of columns and rows. The bonus game may be entered upon the occurrence of a special start-bonus game outcome (e.g., symbol trigger, mystery trigger, time-based trigger, etc.) in or during the basic wagering game. Alternatively, the illustrated game may be a stand-alone wagering game. 
     In the illustrated bonus game, a player selects, one at a time, from the array of markers  94  to reveal an associated bonus-game outcome. According to one embodiment, each marker  94  in the array is associated with an award outcome  96  (e.g., credits or other non-negative outcomes) or an end-game outcome  98 . In the illustrated example, a player has selected an award outcome  96  with the player&#39;s first two selections (25 credits and 100 credits, respectively). When one or more end-game outcome  98  is selected (as illustrated by the player&#39;s third pick), the bonus game is terminated and the accumulated award outcomes  96  are provided to the player. 
       FIG. 6   a  is a cross section view of a dual shutter LCD system  600  that allows the interposition of a front image on a rear image. The dual shutter LCD system  600  has a front projector  602  and a rear projector  604 . Corresponding front and rear liquid crystal (LC) shutter screens  606  and  608  each provide a surface for the projection of images from the projectors  602  and  604  respectively. It is not necessary that screens  606  and  608  be flat and parallel to each other. The front shutter screen  606  is shown as a flat surface, while the rear shutter screen  608  has a curved central area which approximates the curved face of a mechanical reel. Other combinations of flat, curved or other shaped screens  606  and  608  are possible for other applications. The front and rear shutter screens  606  and  608  are arranged in parallel to allow a combined display of a rear image and a front image. The projectors  602  and  604  and the screens  606  and  608  are coupled to a controller module  610 . The liquid crystal (LC) shutter screens  606  and  608  have a transparent mode allowing transmission of light and a translucent mode that prevents transmission of light that may be voltage controlled. Examples of switchable screens for the switchable LC shutter screens  606  and  608  are available from Pro Display Ltd. of Wakefield, UK or LC-TEC Displays AB, Borlänge, Sweden. 
       FIGS. 6   b  and  6   c  are cross section views of the front LC shutter screen  606  in  FIG. 6   a .  FIG. 6   b  shows the front screen  606  in the translucent mode and  FIG. 6   c  shows the front screen  606  in the transparent mode. It is to be understood that the rear LC shutter screen  608  functions in a similar manner as the front LC shutter screen  606 . As shown in  FIGS. 6   b  and  6   c , the front LC shutter screen  606  has a rear glass plate  622  and a front glass plate  624 , a rear interlayer film  626  and a front interlayer film  628 , a rear liquid crystal film  630  and a front liquid crystal film  632 , a rear conductive coating  634  and a front conductive coating  636 . Liquid crystals  640  are located between the rear conductive coating  634  and the front conductive coating  636 . 
     Without voltage applied to the rear and front conductive coatings  634  and  636  as shown in  FIG. 6   b , the front screen  606  is normally translucent and white in appearance. The liquid crystals  640  are randomly aligned, and scatter the incident light as shown in  FIG. 6   b . The random alignment scattering the light causes a translucent appearance. When in the translucent state the LC shutter front screen  606  makes a suitable projection screen. 
     When a suitable voltage is applied across the conductive coatings  634  and  636  of the LC shutter front screen  606 , the liquid crystals  640  are aligned perpendicularly with the LC shutter front screen  606  allowing incoming light to be transmitted through as shown in  FIG. 6   c . Thus, the LC shutter front screen  606  becomes essentially transparent with voltage applied. The state of the LC shutter front screen  606  can be switched rapidly, in just a few milliseconds, by applying the proper voltage to conductive coatings  634  and  636  of the front screen  606 . 
     In the dual shutter LCD system  600  shown in  FIG. 6   a , the separate projectors  602  and  604  are used to project front and rear images respectively on each of the front and rear screens  606  and  608 . In this figure the rear screen  608  is curved to better simulate a mechanical reel when a reel image is projected on it from the rear projector  604 . Of course, both screens  606  and  608  could be flat and parallel, or in other combinations of shapes. Only one of the two projectors  602  and  604  is on at a time. The projectors are turned off by either removing power to their illumination source, or by causing the projector to project a totally black image. Removing power requires a projector modification to provide an enable/disable input for the illumination source. Causing the projector to project a black image requires a mechanism for switching the input video signal. This can be done with relatively simple electronic circuitry and has the advantage of utilizing standard projectors. Thus, during a first interval when the front projector  602  is on, a front image is projected on the front screen  606  which is switched to translucent mode. The rear screen  608  is switched to the transparent mode, allowing the front image projected on the front screen  606  to be viewed in the first interval. When the rear projector  604  is turned on, a rear image is projected on the rear screen  608  in the first interval. During a second interval, the front projector  602  is turned off and stops projecting the front image. The rear screen  608  is switched to the translucent mode to allow the projection of the rear image in the second interval. The front screen  606  is switched to the transparent mode to allowing viewing of the rear image projected on the rear screen  608  in the second interval. The projector enable timing signals for controlling the front projector  602  and the rear projector  604  and the LC shutter enable timing for the front screen  606  and the rear screen  608  are coordinated by a timing routine on the controller module  610 . The timing diagram for of the various components in the display  600  in  FIG. 6   a  during the first and second intervals is shown in the below table. 
     
       
         
               
             
               
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                 Timing Diagram 
               
             
          
           
               
                 Component 
                 INTERVAL 1 
                 INTERVAL 2 
               
               
                   
               
               
                 Front Projector 602 
                 On 
                 Off 
               
               
                 Rear Projector 604 
                 Off 
                 On 
               
               
                 Front Screen 606 
                 Translucent (showing 
                 Transparent 
               
               
                   
                 front image) 
               
               
                 Rear Screen 608 
                 Transparent 
                 Translucent (showing 
               
               
                   
                   
                 front image) 
               
               
                   
               
             
          
         
       
     
     In this example, the projection switching between the two projectors  602  and  604  is done sequentially, probably at 15 times per second or faster, fast enough that the eye does not perceive any flicker in the front and rear images. In such a manner, the images projected by the front projector  602  and the rear projector  604  appear to be juxtaposed with each other. Thus, the player will perceive this as a composite of the two images at the same time, with no noticeable flicker. The rear image will be visible through the front image since the front image is only displayed 50% of the time it will appear to be 50% transparent, even when a fully saturated image is being projected on it. To create fully saturated black (for instance), care must be taken to project black (no light) on the rear screen in the desired areas behind the front screen. 
     The projectors  602  and  604  are enabled and disabled rapidly through an external control signal, shown originating from the controller module  610 . In this example, the projectors  602  and  604  use an LED based light source and therefore the required enable signal may be coupled to the light source of the projectors which may be switched rapidly. The controller module  610  also provides the voltage driver signals to the LC shutter screens  606  and  608 . The switching from one mode to the other does not need to be synchronous to the input video signals with this approach; the two projectors  620  and  604  may thus be running at different resolutions and frame rates. Using two projectors  602  and  604  will also double the amount of light available to provide a bright image on the display  600 . 
     The superimposed front and rear images presented on the display  600  may serve any number of other functions. For example, the front image presented on the front screen  606  may be used to highlight winning combination(s) (e.g., “7,” “7,” “7”), associated pay line(s,) and/or depict the award for that winning combination on the rear image on the rear screen  608 . Such rear images may simulate a mechanical reel system with various symbols. Alternatively, the front image may appear to obscure all symbols not appearing on an active pay line or not part of a winning outcome when the rear image on the rear screen  608  is a simulated mechanical reel. The front image may further include special effects such as flashing the winning pay line(s) and/or the award and providing desired themed graphics in the mechanical reel mode. In certain examples, the display  600  may be outfitted with a touch screen, and the front image on the front screen  606  portrays touch keys wherein a player can then enable a desired function by touching the touch screen at an appropriate touch key. Thus, the superimposed front image, along with a touch screen, may be used to implement side betting, such as is disclosed in United States Patent Publication No. 2004/0219968 entitled “Gaming Machine with Interactive Pop-Up Windows,” which is hereby incorporated by reference in its entirety herein. In some examples, the superimposed front image may provide foreground elements that interact with the rear image on the rear screen  608 . The superimposed video image may be used to provide additional games instead of or in addition to interacting with a wagering game display on a primary game display. 
     Basic wagering games and/or bonus games may also be played, in whole or in part, using the front and rear images on the display. For example, a bonus game may be shown on the front screen  606 . Further, the front image may be used to modify one or more symbols on one or more of an image of stopped mechanical reels on the rear screen  608  or to display a symbol over a blank symbol field (i.e., solid white area) on an underlying simulated reel on the rear screen  608 . 
     A cross-section view of an alternate dual shutter display  700  is shown in  FIG. 7 . The dual shutter LCD system  700  has a projector  702  positioned relative to a front liquid crystal (LC) shutter screen  704  and a rear LC shutter screen  706 . The projector  702  and the screens  704  and  706  are coupled to a controller module  710 . As in the previous example, the liquid crystal (LC) shutter screens  704  and  706  have a transparent mode allowing transmission of light and a translucent mode that prevents transmission of light. The projector  702  is used to project images on the two different screens  704  and  706 . In this example, the rear screen  706  is curved to simulate a mechanical reel. However, both screens  704  and  706  could be flat and parallel, or other combinations of shapes. The timing diagram of the various components in the display  700  in  FIG. 7  is shown in the below table. 
     
       
         
               
             
               
               
               
             
           
               
                 TABLE 2 
               
             
             
               
                   
               
               
                 Timing Diagram 
               
             
          
           
               
                 Component 
                 Interval 1 
                 Interval 2 
               
               
                   
               
               
                 Projector 702 
                 Rear image 
                 Front image 
               
               
                 Front Screen 704 
                 Transparent 
                 Translucent (showing 
               
               
                   
                   
                 front image) 
               
               
                 Rear Screen 706 
                 Translucent (showing 
                 Transparent 
               
               
                   
                 rear image) 
               
               
                   
               
             
          
         
       
     
     In this example, the projector  702  projects a rear image for the rear screen  706  during a first interval. During the first interval, no voltage is applied to the rear screen  706 , so it is translucent and allows the rear image to be seen projected on the rear screen  706 . A voltage from the controller  710  is applied to the front screen  704 , making it transparent during the first interval. Therefore, during this time interval a player will see the rear image projected onto the rear screen  706 . 
     During the second time interval the projector  702  projects a front image for the front screen  704 . In the second time interval, a voltage is applied to the rear screen  706  from the controller  710 , making it transparent. This allows the projected front image to pass through undisturbed to the front screen  704 , which is now translucent because no voltage is applied to it. 
     The controller  710  cycles the video signal to the projector  702  and the screens  704  and  706  between the two time intervals. The player will perceive this effect as the front and rear image being shown at the same time on the display  700 , with no noticeable flicker. The rear first image will be visible through the front image. Since the front image is only displayed 50% of the time it will appear to be 50% transparent, even when a fully saturated image is being projected on it. To create fully saturated black (for instance), care must be taken to project black (no light) on the rear screen in the desired areas behind the front screen. In this example, the input video at the projector  702  must be switched between the two images without creating image artifacts. This requires that the switching be synchronous with the video refresh rate of the projection device  702 , which may be set at 60 Hz. 
     One example of providing the proper video signal to the projector  702  in  FIG. 7  may be the video device  800  shown in  FIG. 8 .  FIG. 8  is a block diagram of the video device  800  that accepts video input signals from a first video source  802  and a second video source  804  and includes a video switch  806 . Each of the video sources  802  and  804  may be video signal output sources such as graphic computers, image processors, etc. The first video source  802  provides image data for the front image on the front screen  704  through a first video stream  812  and the second video source provides image data for the rear image on the rear screen  706  through a second video stream  814 . The video switch  806  has dual video inputs coupled to the video sources  802  and  804  and an output video stream  816 . The video streams  812  and  814  from the video sources  802  and  804  are transmitted to the dual video inputs of the video switch  806 . One or the other video streams  812  or  814  are selected by the video switch  806  to be sent to the output video stream  816 . The output video stream  806  is sent to the projector  702 . The video switch  806  is controlled through the controller  710 , which also controls the signals which enable the LC shutter screens  704  and  706 . The timing generator which determines the timing of the switching signal for the video switch  806  gets its timing information from the frame rate data in the incoming video streams  812  and  814  from the video sources  802  and  804 . The video switching occurs synchronously with the input video data to avoid image breakup, etc. This requires that the incoming video streams  812  and  814  must be at the same frame rate exactly and in phase. In this example, a dual-head video output card including a field programmable gate array (FPGA)  820  may be used for the video switch  806  which insures the video steams  812  and  814  are at the same frame rate and in phase. The FPGA  820  allows for rapid image processing and switching, ensuring that the video streams  812  and  814  stay in sync with each other. Of course other mechanisms to provide rapid switching such as high-speed analog circuitry may be used. 
       FIG. 9  shows an alternate video device  900  which may be used to provide the proper video signal for the projector device  702  in  FIG. 7 . The projector device  900  has a video buffer  902  that has enough digital storage for twice the image size required for a single image. An input video source  904  writes an incoming video stream  906  to the video buffer  902 . In this example, the incoming video stream  906  has two images that are to be projected on the front and rear screens  704  and  706  in  FIG. 7 . For example, if the images in the incoming video stream  906  are each 800×600 pixels, the video buffer  902  would thus be 1600×600 pixels in order to store two images. In this example, the video buffer  902  has a rear frame area  924  and a front frame area  926  that are used to store the two images from the incoming video stream  906 . 
     A video selector  908  is coupled to the video buffer  902  and may read pixels from the two frame areas  924  and  926 . The video selector  908  chooses one half of the video buffer  902  to be sent to an output video stream  910  as part of the timing interval described above to cycle the front and rear images. The output video stream  910  is coupled to the projector  702 . The timing from the input video source  904  is extracted by the timing generator in the controller  710  to ensure that the switching between the images does not affect the video quality. 
     The advantage of this approach is that it only requires one input video stream which generates switching from one input video channel to ensure synchronization. One video stream also reduces the system video requirements. 
     One of the major benefits of the dual shutter type displays as shown in  FIG. 6   a  and  FIG. 7  is image brightness. The LC shutters in  FIG. 6   a  and  FIG. 7  transmit about 85% of the light, either transparent or translucent. Factoring in two LC shutters, and the fact that either screen is translucent 50% of the time gives a light transmission to the user of about 36%. This is an improvement over the best case 10% for the transmissive LCD display in  FIG. 5 . In addition, this approach allows either screen to be tailored to different size, aspect ratios, shapes, etc. 
     Each of these embodiments and obvious variations thereof is contemplated as falling within the spirit and scope of the claimed invention, which is set forth in the following claims.