Note: Descriptions are shown in the official language in which they were submitted.
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SUBWAY MOVIE/ENTERTAINMENT MEDIUM
FIELD OF THE INVENTION
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
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.
The systems disclosed in US patents 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 speed 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. This requires modifications to the vehicle,
which may
prove expensive and undesirable.
US patent 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 system requires modifications to and regular maintenance of the vehicle,
which is
expensive and undesirable.
US patent 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
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to the liquid crystal projectors from an image source such a digital video
player. This
combination is expensive.
US patent 3,951,529 uses 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.
All of the patents referred to above are incorporated herein by reference.
One common problem with all of these patented inventions is the
possibility 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 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.
SUMMARY OF THE INVENTION
The present invention provides of the type described above characterized
in that:
each image has a width Wp and is spaced from the adjacent images by a
spacing W; and the dimensions Wp and W; are related to the vehicle speed by
(Wp + W;) ? V/R
where R is the viewing rate of the images and is greater than or equal to 24
images per
second; and
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.
The images, of minor variation in successive content, give to an observer
the illusion of a motion picture when seen rapidly and illuminated
stroboscopically. The
advantages of the apparatus over the prior art include its moderate cost, the
relatively
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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. The
frequency
of illumination is not synchronized with the vehicle speed or window
positioning. The
frequency is conveniently that of local mains current, usually 50 or 60 Hz.
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
Embodiments of the invention will be described by way of example and
with reference to the drawings in which:
FIG. 1 is a perspective view of an installation of a system according to the
present invention;
FIG. 2 is a perspective view of a panel mounting device:
Fig, 3 is a schematic front view of a section of mounted panels;
Fig. 4 is a schematic side view illustrating a system compensating for
variations in the vehicle to image spacing; and
Fig. 5 is a schematic representation of the illumination system.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to the accompanying drawings, one embodiment of the invention
is illustrated in Fig. 1. A subway train 10 travels along a pathway defined by
track 12.
Along one sides of the vehicle's pathway are placed image panels 14, each of
which
displays one image. In this preferred embodiment, 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 15. Each image panel 14 is Illuminated by a strobe
light 20
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directed towards the image on the front face of the panel. All of the strobe
lights are
operated by a common controller 22.
As illustrated in Figure 5, the controller 22 includes an infrared (1R) 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.
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.
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.
Referring to Figures 3 and 4 of the drawings, each panel has a panel width
Wp and a height Hp. It is spaced from each adjacent panel by a spacing W;. 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 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
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second, this imposes an upper limit on the width Wp of each image panel plus
the
spacing W; 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 >_(Wp + W;) R,
where R is the viewing rate 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.
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.
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
Figure 4,
the size of an image as seen by an observer inside the vehicle is inversely
proportional
25. 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 Wp and height Hp to the distance
from the train
to the wall remain constant The consequent expansion or contraction in image
panel
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size is compensated by a decrease or increase in the separating distance so as
to leave
unperturbed the viewing rate.
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).
As illustrated most particularly in Figure 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'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.
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 with each light is preferably adjustable, using a rotating
light head and
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"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.
Each set of lights is preferably connected to the next set by interlocking
receptacles. This produces modularity, resulting in ease of extension and
maintenance.
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.
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.
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.
