Abstract:
A system displays a collection of stationary images as a motion picture to passengers travelling in a vehicle along a pathway. In a first embodiment, the vehicle moves at a known speed and known distance from the images. The system includes an image illumination system including stroboscopic lighting for each image. The images, placed in parallel along the walls of the pathway of the vehicle, are adapted in number, size, and spacing for a vehicle travelling at the known speed and at the known distance from images on one or both sides of the vehicle such as to maintain an approximately constant viewing rate and perceived size of the images. Glare due to interior lighting in the vehicle is reduced or eliminated by selecting the appropriate illumination intensity for the stroboscopic lighting. In an alternate configuration, a speed sensor monitors speed of the vehicle to determine the appropriate cycling rate of the images. Also, the images themselves may be cycled intermittently with a blank image while remaining steadily illuminated.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application is a continuation-in part of application Ser. No. 10/332,100, filed Jan. 3, 2003, which is a 371 of PCT/CA/01/00999, filed Jul. 5, 2001 which claims priority from U.S. application Ser. No. 09/628,333 filed Jul. 28, 2000. 
     
    
     FIELD OF THE INVENTION  
       [0002]     This invention relates to an apparatus for displaying a collection of stationary images as a motion picture to passengers in a vehicle, for example a train, travelling along a pathway in the vicinity of the images.  
       DESCRIPTION OF THE PRIOR ART  
       [0003]     It is known to provide a motion picture system for viewing from a vehicle traveling along a fixed path. A known form of such a system comprises a plurality of static images, image mounts mounting the images along one side of the fixed path and an illumination system for illuminating each of the images intermittently. The proposed uses of these systems include commercial advertising, entertainment, and information provision. A variety of illumination methodologies, triggering mechanisms, and display mountings have been proposed.  
         [0004]     The systems disclosed in U.S. Pat. Nos. 4,383,742 and 4,179,198 use electromagnetic triggers to sense the velocity of the moving vehicle and to synchronize the intermittent illumination of the images according to the vehicle speed and the image dimensions. Thus, the frequency of the motion picture varies with the speed of the train. Furthermore, the necessary synchronizing mechanism is quite complicated and therefore expensive. In the second patent, light flash emitting devices are installed on the vehicle at regular intervals. The traveling light source results in a blurring of the image, particularly at the edges. Installation requires modifications to the vehicle, which may prove expensive and undesirable.  
         [0005]     U.S. Pat. No. 5,108,171, discloses, in one embodiment, a trigger mechanism responsive to a light signal from each window of the vehicle. In another embodiment, a reflector is associated with each window to reflect light from stationary light sources. This latter arrangement is another form of traveling light source with consequent image blurring. This system requires modifications to and regular maintenance of the vehicle, which is expensive and undesirable.  
         [0006]     U.S. Pat. No. 6,016,183 discloses the use of individual sets of screens and stroboscopic liquid crystal projectors for the display of images. Image signals are sent to the liquid crystal projectors from an image source such a digital video player. This combination is expensive.  
         [0007]     U.S. Pat. No. 3,951,529 discloses a system using a rear stroboscopic backlight for each image to illuminate the images, but provides scant guidance on the size and placement of the images. Thus to an observer in the vehicle there is the undesirable possibility that only a partial view of an image is perceived through the closest vehicular window.  
         [0008]     Additional prior art which fail to provide an effective motion picture appearance include GB 2 241 813 A to Helcke and U.S. Pat. Nos. 6,564,486 to Spodek et al, 3,694,062 to Koenig and 6,343,468 to Howard et al.  
         [0009]     All of the patents referred to above are incorporated herein by reference.  
         [0010]     One common problem with all of these patented inventions is the possible of loss of synchronicity in illumination. In this case, the observer sees flashing black images, which detracts from the esthetic appeal of the motion picture. Another problem is the failure to account for a change in the perceived size of the image if the distance between the vehicle and the wall changes. Therefore, for a passenger travelling in a vehicle through different areas where such a system is installed, there may be a great variation in perceived image size corresponding to differing cross-sectional width of the relevant pathways. The prior art displays are further limited in their ability to vary the images being displayed due to costly and labor intensive manual replacement of the images being required.  
       SUMMARY OF THE INVENTION  
       [0011]     According to one aspect of the present invention there is provided a moving picture system for viewing from a vehicle traveling along a fixed path at a substantially constant speed V, the system comprising:  
         [0012]     a plurality of display panels, each for displaying a static image on a viewable surface of the panel;  
         [0013]     image mounts mounting the display panels along one side of the fixed path;  
         [0014]     a static illumination system for only illuminating each display panel for viewing the static images;  
         [0015]     an image cycling system for cycling the viewability of the static images at a fixed frequency viewing rate of images R; and  
         [0016]     a single trigger responsive to the approach of the vehicle to initiate the image cycling system to cause the viewability of all of the images to be cycled simultaneously;  
         [0017]     wherein each image has a width W p  and is spaced from the adjacent images by a spacing W i  and the dimensions W p  and W i  are related to the vehicle speed by
 
( W   p   +W   i )≧ V/R 
 
 where R is greater than or equal to 24 images per second. 
 
         [0018]     The images, of minor variation in successive content, give to an observer the illusion of a motion picture when viewability is rapidly cycled. The advantages of the apparatus over the prior art include its moderate cost, the relatively simple construction, installation, and maintenance of the constituent elements, and the improved view offered to passengers in the vehicle. With this system at least twenty four images per second pass a stationary passenger in the moving vehicle regardless of the speed of the vehicle.  
         [0019]     According to a second aspect of the present invention there is provided a moving picture system for viewing from a vehicle traveling along a fixed path at a substantially constant speed V, the system comprising:  
         [0020]     a plurality of static images;  
         [0021]     image mounts mounting the images along one side of the fixed path; and  
         [0022]     a static illumination system for illuminating each of the images intermittently,  
         [0000]     characterized in that:  
         [0023]     each image has a width W p  and is spaced from the adjacent images by a spacing W i  and the dimensions W p  and W i  are related to the vehicle speed by
 
( W   p   +W   i )≧ V/R 
 
 where R is the viewing rate of the images and is greater than or equal to 24 images per second; and 
 
         [0024]     the illumination system includes a single trigger responsive to the approach of the vehicle to cause all of the images to be illuminated simultaneously at a fixed frequency greater than 24 Hz.  
         [0025]     According to a third aspect of the present invention there is provided a moving picture system for viewing from a vehicle traveling along a fixed path, the system comprising:  
         [0026]     a plurality of display panels, each having a viewable surface which is cyclable between an active state in which a static image is displayed and an inactive state in which a blank image is displayed, the viewable surface being cyclable between the first and second states at a fixed frequency viewing rate which is greater than 24 cycles per second and which is dependent upon speed of the vehicle;  
         [0027]     image mounts mounting the display panels along one side of the fixed path;  
         [0028]     an illumination system for providing illumination to the display panels for viewing the static images; and  
         [0029]     a single trigger responsive to the approach of the vehicle to cause the viewable surfaces of all of the display panels to be simultaneously cycled between their respective first and second states.  
         [0030]     When cycling the images themselves, cycling is similarly governed by:
 
( W   p   +W   i )≧ V/R 
 
 where R is the fixed frequency viewing rate and is greater than or equal to 24 images per second. 
 
         [0031]     A speed sensing device may be provided fixed in relation to the fixed path of the vehicle for measuring speed of the vehicle and for using this speed to calculate the viewing rate of the images. In the preferred embodiment, the speed sensing device comprises spaced apart interruptable IR beams spanning across the path of the vehicle to determine speed using elapsed time between interruption of thee beams. The beams may also serve as the trigger to initiate cycling of the images.  
         [0032]     The display panels may be divided into consecutive banks, each bank comprising a plurality of the display panels, in which the viewability of one bank can be controlled independently of the remaining banks by the image cycling system. In this arrangement, the image cycling system can control viewability of the display panels in a stepped manner by sequentially activating or sequentially deactivating the banks.  
         [0033]     In one advantageous embodiment, the viewable surface comprises a layer of charged particles supported on a control layer in which the charged particles vary in orientation depending upon various electrical charges applied to the control layer to cycle the image between the static image and the blank image. The set of images being displayed can thus be instantly varied to a different set of displayed images electronically or at a preprogrammed time according to the controller programming.  
         [0034]     In one embodiment, the image cycling system cycles the illumination system, dependent upon sensed vehicle speed, regardless of the configuration of the display panels.  
         [0035]     Alternatively, the image cycling system cycles the viewable surface of each panel simultaneously, dependent upon sense vehicle speed, between a first state in which the static image is displayed and a second state in which a blank image is displayed. In this instance it is desirable for the illumination system to provide steady illumination to the display panels, for example using light emitting diodes.  
         [0036]     The viewable surface may comprise a non light emitting surface in which the blank image displayed by each panel in the inactive state is darker than the respective static image displayed in the active state.  
         [0037]     Each display panel may be cyclable between the inactive state and a selected one of plural different active states, each corresponding to a different static image being displayed as programmed by the controller.  
         [0038]     In embodiments where the distance from the vehicle to an adjacent wall carrying the images varies along the path, the ratios of the image width and height to the vehicle to image spacing are maintained constant, either by varying the positioning of the images relative to the wall or varying the image size. This maintains the perceived size of the images fairly constant. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0039]     Embodiments of the invention will be described by way of example and with reference to the drawings in which:  
         [0040]      FIG. 1  is a perspective view of an installation of a system according to the present invention;  
         [0041]      FIG. 2  is a perspective view of a panel mounting device:  
         [0042]      FIG. 3  is a schematic front view of a section of mounted panels;  
         [0043]      FIG. 4  is a schematic side view illustrating a system compensating for variations in the vehicle to image spacing; and  
         [0044]      FIG. 5  is a schematic representation of the illumination system.  
         [0045]      FIG. 6  is a perspective view of a second embodiment of an installation of a system according to the present invention.  
         [0046]      FIG. 7  is a schematic representation of the controller connections to the illumination system.  
         [0047]      FIG. 8  is a schematic side elevational view of the panel according to the second embodiment. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0048]     Referring to the accompanying drawings, there is illustrated a moving picture system for viewing from a vehicle traveling along a fixed path, for example a subway train  10 . While various embodiments are described in the following, the common features of each will first be described herein.  
         [0049]     A subway train  10  travels along a pathway defined by track  12 . Along one side of the vehicle&#39;s pathway are placed image panels  14 , each of which displays one image. The image covers the whole of the image panel. Typically, solid walls  16  line the sides of the pathway, but this is not required for proper functioning of the invention. Each image panel  14  is mounted on the wall  16  by a panel mount  18 . Each image panel  14  is Illuminated by a light  20  directed towards the image on the front face of the panel. The lights and an associated system for cycling viewability of the images are operated by a common controller  22 .  
         [0050]     Turning now to the first embodiment of  FIG. 1 , the display panels each illustrate a static image which remains displayed. The lights  20  illuminating each panel comprise stroboscopic lights controlled by the controller  22  to cycle at the desired viewing rate. The lights may comprise light emitting diodes (LED&#39;s) or any other type of lighting capable of providing precise control of the illumination.  
         [0051]     As illustrated in  FIG. 5 , the controller  22  includes an infrared (IR) motion detector  24  positioned to detect the approach of the train  10 . On detection of the train, the IR detector starts a timer  26 , which in turn actuates a strobe power supply  28 . The power supply is connected to an AC mains power supply  30  and produces an output wave at mains frequency, either 50 or 60 Hz depending on location. This minimizes the complexity of the controller and eliminates any synchronization of the image illumination with either train speed or window position. After a preset time, the timer  26  counts out and the power supply is turned off. The time of operation is selected to be sufficient to allow passage of the subway train.  
         [0052]     It is known that where the frequency at which images of minor variation are flashed to an observer at or in excess of about 24 cycles per second, the perception is that of smooth motion. The human mind fills in the intervening blank spaces to create an illusion of continuous motion. Furthermore, a separation of the still images is necessary. For example, on television, diagonal black bars are scanned at a rate of one-eighth to one-thirtieth per second; and cinematic films frames are separated by a fine black border.  
         [0053]     If the frequency falls below this threshold of about 24 cycles per second, the psychological perception of continuous motion is not achieved; instead, any movements are seen as “jerky” and the images flash.  
         [0054]     Referring to  FIGS. 3 and 4  of the drawings, each panel has a panel width W p  and a height H p . It is spaced from each adjacent panel by a spacing W i . The image is spaced from the side of the train by a distance D. The speed at which a subway vehicle (or any conventional means of mass vehicular transport) travels during cruising speed is generally consistent from day to day. This is to permit detailed scheduling as well as for safety reasons. It is therefore an acceptable assumption, in some embodiments, that the speed of a subway train is relatively constant, consistent, and known in the region where the system is installed. Given that the threshold image viewing rate is about 24 cycles per second, this imposes an upper limit on the width W p  of each image panel plus the spacing W i  associated with the separation between images. The relationship is such that the minimum speed of the vehicle V is the multiplicative product of the panel width plus separating distance, and the continuous motion threshold (about 24):
 
 V≦ ( W   p   +W   i ) R, 
 
         [0055]     where R is the viewing rate of the images and is ≧24.  
         [0056]     To maintain the largest possible image size, the viewing rate should be kept as close to 24 as possible.  
         [0057]     If the speed of the vehicle increases, then the panel size plus separating distance must proportionately increase if the viewing rate by the observer in the vehicle is to remain at about 24 cycles per second. Considerations of aesthetic appeal mandate an increase of the size of each image panel with a concomitant decrease in the separating distance between the image panels. On the other hand, a decrease in the speed of the vehicle requires that the image panel size plus separating distance decrease. In fact, the image panel size actually decreases whereas the separating distance increases, again, for aesthetic reasons. Studies show that a maximum of five centimeters (two inches) is imposed on the separating distance between image panels. This upper limit works also to eliminate the possibility of loss of synchronicity so prevalent in other attempts at creating the same effect. In general, the cruising speed of a vehicle is unlikely to vary by a significant amount, and variations in panel size and interval tend to be minimal.  
         [0058]     A desirable characteristic of a motion picture apparatus is to keep constant the dimensions of the image as perceived by the observers. As illustrated in  FIG. 4 , the size of an image as seen by an observer inside the vehicle is inversely proportional to the perpendicular distance from the observer (in practice the window of a vehicle) to the image panels. If this distance increases, in order to keep the perceived size constant, the absolute size of an image as carried by an image panel must increase proportionally. The ratios of image width W p  and height H p  to the distance from the train to the wall remain constant. The consequent expansion or contraction in image panel size is compensated by a decrease or increase in the separating distance so as to leave unperturbed the viewing rate.  
         [0059]     Therefore, the dimension and placement of the image panels are specified as a function of the speed of the travelling vehicle and the distance from the image panels to the train. For example, if the vehicle travels at about 80 kilometers per hour (50 miles per hour), which is equivalent to about 22.22 meters per second (73.35 feet per second), in order to afford a viewing rate of about 24 images per second, the width of each image panel plus the interval spacing is approximately one meter (three feet). Typically, the interval spacing on each size of an image is chosen as one-twelfth the size of the panel plus interval spacing, 8.3 centimeters (3 inches). If the distance to the wall increases by five percent, then the image panel size increases proportionately to 96.2 centimeters meters (2 feet 10.7 inches), and the interval spacing should be set at about 3.8 centimeters (1.3 inches).  
         [0060]     As illustrated most particularly in  FIG. 2 , the image panels  14  are constructed of rigid materials so as to avoid movement on the passage of a vehicle due to the displacement of air. Image mounts  18  affix the image panels  14  to the wall  16  of the vehicle&#39;s pathway. The panel holder  34  includes a U-shaped frame  36  with upright arms  38  and a base  40  configured as channels to receive the side and bottom edges of an image panel. Each of the arms  38  is connected to two angle brackets  42  by fasteners  44  fixed to the arms and slots  46  in the brackets. Tightening the fasteners fixes the position of the arms along the slots. The angle brackets have base flanges  48  mounted on the wall, so that the flanges  50  in which the slots are formed project forwardly from the wall. Thus, the image panels may be each positioned vertically at a generally uniform distance from the train, regardless of the contour of the supporting wall. Of course minor variations may exist due to serious defects in the wall or general conditions.  
         [0061]     Illumination of each image panel is provided through the strobe lights  20  which are attached to the wall and located immediately above the image mounts  32 . The orientation of each light is preferably adjustable, using a rotating light head and “barn door” flaps. In order to reduce or practically eliminate the effect of glare from other light sources on the inside windows of a vehicle, the intensity of strobe illumination should be such that 75 per cent of illumination perceived by an observer on passing through the region of the image panels derives from the external strobe lighting and the balance from sources within the vehicle. A further option is to reduce the internal lighting of the vehicle on entering into a vicinity of the image panels.  
         [0062]     Each set of lights is preferably connected to the next set by interlocking receptacles. This produces modularity, resulting in ease of extension and maintenance.  
         [0063]     Turning now to the embodiment of  FIGS. 6 through 8 , a plurality of the panels  14  are similarly mounted side by side along a fixed wall  16  of a subway tunnel. As in the previous embodiment, an individual light  20  is provided in association with each panel and is directed at the panel for substantially only illuminating the respective panel.  
         [0064]     The controller  22  in this instance includes a speed monitor to monitor the speed of the vehicle using a pair of sensors  64 . Each sensor  64  is statically mounted adjacent the path of the vehicle to emit an infra-red beam to an opposing receiver, wherein the beams cross the path of the vehicle. The sensors are capable of detecting when the respective beam is broken and interrupted by the train passing therethrough so that the controller can determined the speed of the train based on the amount of elapsed time it takes for the train to break the second beam once the first beam has been broken. For effective operation the sensors  64  are mounted at spaced apart positions along the path of the vehicle ahead of the panels on the wall when the vehicle is traveling in direction  66  as shown in  FIG. 6 . The sensors  64  may also be used as the trigger for indicating when the train is approaching and when the simultaneous cycling of the viewability of the images should begin. Once the beam is broken, a timer determines the length of operation of the image cycling and illumination as described above.  
         [0065]     Similarly to the previous embodiment, the controller according to the second embodiment uses the speed to determine the panel size and the viewing rate of the images using the relationship: V≦(W p +W i )R. Panel size is selected to ensure the viewing rate R of the images and is ≧24. To maintain the largest possible image size, the viewing rate should be kept as close to 24 as possible.  
         [0066]     As shown schematically in  FIG. 7 , the images and associated lighting may be divided into banks  58 , each comprising ten images and lights. The controller  22  is then coupled to the banks  58  by addressable digital relays which are associated with the banks  58  respectively. The digital relays thus permit the controller to operate activation and deactivation of the banks independently of one another in a stepped manner by sequentially turning on or turning off the banks at any programmed time in the vehicle&#39;s transit.  
         [0067]     With reference to  FIG. 8 , each of the panels  14  according to the second embodiment has a viewable surface  60  on a flat front face thereof which is generally rectangular in shape and substantially spans the full dimensions of the panel  14 . The viewable surface  60  is formed of millions of charged micro particles suspended in a first layer overlapping a control layer  62  which spans the full area of the panel underneath the viewable surface.  
         [0068]     The particular configuration of the particles is similar to what is described in U.S. Pat. No. 6,333,754 to Fuji Xerox Company Limited, or in an alternate configuration, the viewable surface  60  may be configured in the manner described in various US patents owned by E Ink Corporation of Cambridge, Mass. All patents referred to are incorporated herein by reference.  
         [0069]     The control layer permits individual charges applied to the micro particles to be varied for varying the orientation of the particles and thus effectively varying the image being displayed at the viewable surface  60 .  
         [0070]     In a first mode of operation of the system according to  FIGS. 7 and 8 , the viewing rate R is selected as a rate at which the images being displayed are themselves cycled on the viewable surface. The charges on the control layer  62  are cycled rapidly at a fixed frequency viewing rate greater or equal to the required 24 Hz according to the relationship V≦(W p +W i )R for smoothly viewing the images by passengers of the vehicle.  
         [0071]     Cycling of the image being displayed occurs by controlling the charges on the control layer  62  to be cycled between an active state in which a selected static image is displayed and an inactive state in which a blank image is displayed. The blank image is either black or darker than the static image to permit the light source  20  to remain steadily illuminated. An intense light source capable of steady illumination, such as light emitting diodes, is advantageous in this application. The light sources  20  are required as the viewable surface  60  only reflects light and does not emit any light itself. The lights should remain steadily illuminated while the images are cycled on the viewable surfaces of the panels.  
         [0072]     As described above, the digital relays permit the controller to operate activation and deactivation of the banks of images to be cycled on the panels independently of one another in a stepped manner by sequentially turning on or turning off the banks at any programmed time in the vehicle&#39;s transit. When a bank is turned on, the panels are illuminated and the images being displayed are cycled between their active and inactive states simultaneously with any other banks which are also turned on. Alternatively, when a bank is turned off, the illumination is deactivated and the viewable surfaces may be in the inactive state displaying a blank image.  
         [0073]     Plural different active states maybe used each corresponding to a different image being displayed. To display one particular image, one of the active states/static images is selected for cycling intermittently with the blank image of the inactive state. The controller  22  may then be programmed to periodically change the image being cycled or otherwise displayed. This configuration is particularly advantageous when advertising a particular series of images to be cycled for a set duration after which time a new set of images is displayed on the panels respectively for being cycled intermittently with blank images. The controller  22  is arranged for simultaneously cycling all of the images on the panels  14  between respective active and inactive states so that no complex control of the lighting is required.  
         [0074]     In a further mode of operation of the system according to  FIG. 7  and  8 , the viewable surfaces  60  may be programmed to display a prescribed set of images in a steady manner while the lights are cycled in the manner described in the first embodiment so that the rate depends upon the speed of the vehicle. The speed is either assumed constant or measured by the speed monitor as described above. The viewable surface  60  permits the images to be instantly changed to a new set of images which are again steadily displayed. The addressable digital relays of the banks  58  in this instance operate the illumination. When a bank is turned on, the cycling of the illumination for viewing the images is cycled simultaneously with any other banks which are also turned on. When a bank is turned off, the illumination is deactivated for that bank.  
         [0075]     In further embodiments, any viewable surface may be used on the panels  14  which is formed of a material that itself can be cycled between a static image and a blank image at a rate greater than 24 cycles per second to eliminate the need for cycling the illumination system. Though currently cost prohibitive, a liquid crystal display for example could be used for cycling an image, in which the illumination system is incorporated into the panel itself.  
         [0076]     It will be appreciated that the description above relates to the preferred embodiments by way of example only. Many possible variations on the apparatus will be evident to those knowledgeable in the field, and such variations are intended to be within the scope of the invention as described and claimed, whether or not expressly described. Examples of different variations to the features noted above are described in the following: 
        (1) Printed posters may be used with flashing strobelights having a flash rate derived from the mains frequency.     (2) Printed posters may also be used with strobelights operated at a flash rate manually set to a constant train speed and synchronized from a master firing source.     (3) In a further variation, printed posters may be illuminated by synchronously flashing strobelights flashing at a rate automatically set to an approaching train speed by a speed monitor calculating elapsed time between interruption of two cross track IR beams.     (4) In addition to the features of variation (3), the lights may be operable in a series of banks of 10-lights by the use of addressable digital relays in the system junction boxes to permit stepped activation or deactivation of the illumination system in quantums of 10-posters at any programmed time in the vehicle&#39;s transit.     (5) Panels having a display surface programmable to display different images may themselves be cycled at the frequency set by the train velocity sensor while the illumination system provides steady state, zero flash rate, intense light to the panels. The images displayed on the entire series of panels can be changed by inputting a new graphics program to change all animated posters. This variation can make use of banks of 10-posters with addressable digital relays to permit a stepped activation and deactivation of the image cycling on the panels in quantums of 10-posters, at any programmed time in the vehicle&#39;s transit.     (6) Panels having a display surface programmable to display different images themselves may also be operated in a steady non-flashing state. Lighting in this instance must be operated at a flash rate whose frequency has been set by the train speed sensor and which is operable in banks of 10 posters to permit stepped activation and deactivation of the illumination system. Data displayed on entire series of posters can still be changed by inputting a new graphics program to change all animated posters in the sequence.        
 
         [0083]     While the panels of variations (5) and (6) allow changes to the images being displayed throughout the day by keystroke or programming using either flashing illumination with a steady poster image or static illumination with a flashing poster image; in both cases the rate of the flashing must be attunable to the train speed to optimize the quality of animation seen from the transiting vehicle.  
         [0084]     As one example, the vehicle used in the foregoing description is a subway train travelling in an underground subway tunnel. However, this invention is adaptable to be used for outdoor rail systems, monorails, elevators, or any form of transportation where images may be viewed from a moving position and the prevailing lighting conditions are appropriate or are appropriately adjustable.  
         [0085]     The preceding description has described the viewing of a motion picture through the windows on one side of a train. It is to be understood that images may be provided on both sides where appropriate conditions exist. Where used, the images on opposite sides need not be of the same motion picture.