EP1686556A2 - Anzeigevorrichtung mit animiert erscheinenden Standbildern für sich bewegende Betrachter - Google Patents

Anzeigevorrichtung mit animiert erscheinenden Standbildern für sich bewegende Betrachter Download PDF

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Publication number
EP1686556A2
EP1686556A2 EP06007605A EP06007605A EP1686556A2 EP 1686556 A2 EP1686556 A2 EP 1686556A2 EP 06007605 A EP06007605 A EP 06007605A EP 06007605 A EP06007605 A EP 06007605A EP 1686556 A2 EP1686556 A2 EP 1686556A2
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EP
European Patent Office
Prior art keywords
backboard
viewer
slitboard
images
image
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP06007605A
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English (en)
French (fr)
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EP1686556A3 (de
Inventor
Joshua D. Spodek
Matthew H. Gross
Brian Mills
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Submedia LLC
Original Assignee
Submedia LLC
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Filing date
Publication date
Application filed by Submedia LLC filed Critical Submedia LLC
Priority claimed from EP01948640A external-priority patent/EP1295280B1/de
Publication of EP1686556A2 publication Critical patent/EP1686556A2/de
Publication of EP1686556A3 publication Critical patent/EP1686556A3/de
Withdrawn legal-status Critical Current

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    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09F—DISPLAYING; ADVERTISING; SIGNS; LABELS OR NAME-PLATES; SEALS
    • G09F19/00—Advertising or display means not otherwise provided for
    • G09F19/22—Advertising or display means on roads, walls or similar surfaces, e.g. illuminated

Definitions

  • This invention relates to the display of still images that appear animated to a viewer in motion relative to those images. More particularly, this invention relates to the display of still images that can be other than planar and perpendicular to a viewer's line of sight.
  • Display devices that display still images appearing to be animated to a viewer in motion are known. These devices include a series of graduated images (i.e., adjacent images that' differ slightly and progressively from one to the next). The images are arranged in the direction of motion of a viewer (e.g., along a railroad) such that the images are viewed consecutively. As a viewer moves past these images, they appear animated. The effect is similar to that of a flip-book.
  • a flip-book has an image on each page that differs slightly from the one before it and the one after it such that when the pages are flipped, a viewer perceives animation.
  • Each of the known arrangements provides for the presentation of a series of graduated images, or "frames," to the viewer/rider so that consecutive frames are viewed one after the other.
  • the simple presentation of a series of still images to a moving viewer is perceived as nothing more than a blur if displayed too close to the viewer at a fast rate.
  • the viewer sees a series of individual images with no animation.
  • known arrangements have introduced methods of displaying each image for extremely short periods of time. With display times of sufficiently short duration, the relative motion between viewer and image is effectively arrested, and blurring is negligible. Methods for arresting the motion have been based on stroboscopic illumination of the images. These methods require precise synchronization between the viewer and the installation in order that each image is illuminated at the same position relative to the viewer, even as the viewer moves at high speed.
  • a stroboscopic device The requirements of a stroboscopic device are numerous: the flash must be extremely brief for a fast moving viewer, and therefore correspondingly bright in order that enough light reach the viewer. This requirement, in turn, requires extremely precisely timed flashes. This precision requires extremely consistent motion on the part of the viewer, with little or no change in speed. All of the aforementioned requirements result in a high level of mechanical or electrical complexity and cost, or greater consistency in train motion than exists.
  • Other known arrangements have overcome the need for high temporal precision by providing a transponder of some sort on the viewer's vehicle and a receiver on the installation to determine the viewer's position. These arrangements involve considerable mechanical and electrical complexity and cost.
  • the aforementioned known arrangements generally require the viewer to be in a vehicle. This requirement may be imposed because the vehicle carries equipment for timing, lighting, or signaling; or because of the need to maintain high consistency in speed; or to increase the viewer's speed, for example.
  • the use of a vehicle requires a high level of complexity of the design because of the number of mechanical elements and because one frequently is dealing with existing systems, requiring modification of existing equipment.
  • the harsh environment of being mounted on a moving subway car may limit the mechanical or electrical precision attainable in any unit that requires it, or it may require frequent maintenance for a part where high precision has been attained..
  • a vehicle also imposes constraints. At the most basic level, it limits the range of possible applications to those where viewers are on vehicles. More specifically, considerations of the vehicle's physical dimensions constrain a stroboscopic device's applicability. The design must take into account such information as the vehicle's height and width, its window size and spacing, and the positions of viewers within the vehicle. For example, close spacing of windows on a high speed train requires that stroboscopic discharges preferably be of high frequency and number in order that the display be visible to all occupants of a train.
  • the dimensions of the environment such as the physical space available for hardware installation in the subway tunnel and the distances available over which to project images, impose further constraints on the size of elements of any device as well as on the quality and durability of its various parts.
  • a stroboscopic device can work for slowly moving viewers, simply by spacing the projectors more closely, in practice it is difficult. First, closer spacing increases cost and complexity. Also, once the device is installed with a fixed projector-to-projector distance, a minimum speed is imposed on the viewer.
  • the zootrope is a simple hollow cylindrical device that produces animation by way of the geometrical arrangement of slits cut in the cylinder walls and a series of graduated images placed on the inside of the cylinder, one per slit. When the cylinder is spun on its axis, the animation is visible through the (now quickly moving) slits.
  • the zootrope is, however, fixed in nearly all its proportions because its cross section must be circular. Since the animation requires a minimum frame rate, and the frame rate depends on the rotational speed, only a very short animation can be viewed using a zootrope. Although there is relative motion between the viewer and the apparatus, in practice the viewer cannot comfortably move in a circle around the zootrope. Therefore only one configuration is practicable with a zootrope: that in which a stationary viewer observes a short animation through a rotating cylinder.
  • At least one known system displays images along an outdoor railroad track in an arrangement that might be referred to as a "linear zootrope" in which the images are mounted behind a wall in which slits are provided. That outdoor environment is essentially unconstrained.
  • apparatus that displays still images.
  • the still images form an animated display to a viewer moving substantially at a known velocity relative to the images substantially along a known trajectory substantially parallel to the images.
  • the apparatus includes a backboard having a backboard length along the trajectory.
  • the images are mounted on a surface of the backboard.
  • Each still image has an actual image width and an image center. Image centers are separated by a frame-to-frame distance.
  • a slitboard is positioned substantially parallel to the backboard facing the surface upon which the images are mounted and is separated therefrom by a board-to-board distance.
  • the slitboard is mounted at a viewing distance from the trajectory.
  • the board-to-board distance and the viewing distance total a backboard distance.
  • the slitboard has a slitboard length along the trajectory and has a plurality of slits substantially perpendicular to the slitboard length. Each slit corresponds to a respective image and has a slit width measured along the slitboard length and a slit center. Respective slit centers of adjacent slits are preferably separated by the frame-to-frame distance.
  • the side profiles of the slitboard and backboard (viewable either cross-sectionally or elevationally in the same direction as the trajectory) can be preferably as follows:
  • the apparatus advantageously allows the apparatus to be constructed such that its side profile can be conformed to fit better within a spatially-constrained environment, such as, for example, a subway tunnel.
  • the present invention preferably produces simple apparatus operating on principles of simple geometric optics that displays animation to a viewer in motion relative to it.
  • the apparatus requires substantially only that the viewer move in a substantially predictable path at a substantially predictable speed.
  • riders on subway trains including, but not limited to, riders on subway trains, pedestrian on walkways or sidewalks, passengers on surface trains, passengers in motor vehicles, passengers in elevators, and so on.
  • riders on subway trains including, but not limited to, riders on subway trains, pedestrian on walkways or sidewalks, passengers on surface trains, passengers in motor vehicles, passengers in elevators, and so on.
  • rider on subway trains including, but not limited to, riders on subway trains, pedestrian on walkways or sidewalks, passengers on surface trains, passengers in motor vehicles, passengers in elevators, and so on.
  • a particular exemplary application an installation in a subway system, viewable by riders on a subway train -- but the present invention is not limited to such an application.
  • Benefits of the present invention include the following:
  • the apparatus preferably includes a series of graduated pictures ("images" or “frames”) spaced at preferably regular intervals and, preferably between the pictures and the viewer, an optical arrangement that preferably restricts the viewer's view to a thin strip of each picture.
  • This optical arrangement preferably is an opaque material with a series of thin, transparent slits in it, oriented with the long dimension of the slit perpendicular to the direction of the viewer's motion.
  • the series of pictures will generally be called a "backboard” and the preferred optical arrangement will generally be called a "slitboard.”
  • the illumination can back-light the pictures or can be placed between the slitboard and backboard to front-light the pictures substantially without illuminating the viewer's environment.
  • lighting it preferably should be constant in brightness. Natural or ambient light can be used. If ambient light is sufficient, the apparatus can be operated without any built-in source of illumination.
  • the slitboard need not necessarily be dark or nonreflective.
  • the viewer face of the slitboard could have a conventional billboard placed on it with slits cut at the desired positions. This configuration is particularly useful in places where some viewers are moving relative to the device and others are stationary. This may occur, for example, at a subway station where an express train passes through without stopping, but passengers waiting for a local train stand on the platform.
  • the moving viewers preferably will see the animation through the imperceptible blur of the conventional billboard on the slitboard front.
  • the stationary viewers preferably will see only the conventional billboard.
  • apparatus 10 is essentially a rectangular solid formed by housing 20 and lid 21.
  • the front and rear of apparatus 10 preferably are formed by slitboard 22 and backboard 23, which are described in more detail below.
  • Slitboard 22 and backboard 23 preferably fit into slots 24 in housing 20 which are provided for that purpose.
  • Lightframe 25 preferably is interposed between housing 20 and lid 21 and preferably encloses light source 26, which preferably includes two fluorescent tubes 27, to light images, or "frames" 230, on backboard 23.
  • Slitboard 22 preferably includes a plurality of slits 220 as described in more detail below.
  • each slit 220 is covered by a light-transmissive, preferably transparent cover 221 (only one shown).
  • each slit 220 may be covered by a semicylindrical lens 222 (only one shown), which also improves the resolution of viewed images.
  • the focal length of the lens is approximately equal to the distance between slitboard 22 and backboard 23, the resolution of the image may be increased. This improvement of the resolution is effected by narrowing the width of the sliver of the actual image visible at a given instant by the viewer.
  • the use of lenses may allow the slit width to be increased without lowering resolution.
  • housing 201 is similar to housing 20, except that it includes light-transmissive, preferably transparent, front and rear walls 202, 203 respectively, forming a completely enclosed structure. At least one of walls 202, 203 (as shown, it is wall 202) preferably is hinged as at 204 to form a maintenance door 205 which may be opened, e.g., to replace backboard 23 (to change the images 230 thereon) or to change light bulbs 27).
  • light bulbs 27 are provided in a backlight unit 206 instead of lightframe 25, necessitating that backboard 23 and images 230 be light-transmissive.
  • embodiment 200 could be used with lightframe 25 instead of backlight unit 206.
  • apparatus 10 could be provided with backlight unit 206 instead of lightframe 25, in which case backboard 23 and images 230 would be light-transmissive.
  • FIG. 3 is a schematic plan view of a portion of apparatus 10 being observed by a viewer 30 moving at a substantially constant velocity V w along a track 31 substantially parallel to apparatus 10.
  • Track 31 is drawn as a schematic representation of a railroad track, but may be any known trajectory such as a highway, or a walkway or sidewalk, on which viewers move substantially at a known substantially constant velocity.
  • FIG. 3A An alternative geometry is shown in FIG. 3A, where track 31' is curved, and slitboard 22' and backboard 23' are correspondingly curved, so that all three are substantially "parallel" to one another.
  • the other parameters are the same as in FIG. 3, except that, depending on the degree of curvature, there may be some adjustment in the amount of stretching or enlargement of the image as discussed below.
  • the apparatus relies on the well known effect of persistence of vision, whereby a viewer perceives a continuous moving image when shown a series of discrete images.
  • persistence of vision uses two distinct, but simultaneous, manifestations of persistence of vision. The first occurs in the eye reconstructing a full coherent image, apparently entirely visible at once, when actually shown a small sliver of the image that sweeps over the whole image. The second is the usual effect of the flip-book, whereby a series of graduated images is perceived to be a continuous animation.
  • FIG. 4 illustrates the first persistence of vision effect. It shows the position of viewer 30 relative to one image at successive points (FIGS. 4A, 4B, 4C) in time.
  • double-ended arrow 40 represents the total actual image width, D i
  • distance 41 represents the portion of the image visible at a given time.
  • This diagram shows that viewer 30, over a short period of time, gets to see each part of the image. However, at any given instant only a thin sliver of the picture, of width 41, is visible.
  • FIG. 4 the representation of movement of the viewer's eye is purely illustrative. In practice the viewer's gaze is fixed at a screen that is perceived to be stationary, and the entirety of the frame can be seen through peripheral vision, as with a conventional billboard.
  • FIG. 5 illustrates the second persistence of vision effect. It shows viewer 30 looking in a fixed direction at three successive points in time.
  • a thin sliver of a first image n is in the direct line of the viewer's gaze through slit 221.
  • the viewer's direct gaze falls on a blocking part of slitboard 22.
  • the viewer continues to perceive the sliver of image n just seen through slit 221.
  • the direct line of the viewer's gaze falls on slit 222, adjacent to slit 221, and viewer 30 sees a sliver of adjacent image n+1.
  • each slit 221, 222 preferably is substantially perfectly aligned with its respective image
  • the slivers visible at a given angle in the two separate slots preferably correspond substantially precisely. That is, at a position, say, three inches from the left edge of the picture, the sliver three inches from the left edge of the picture is viewable from one frame to the next, and never a sliver from any other part of the image. In this way, the alignment between the slit and the image prevents the confusion and blur perceived by the viewer that otherwise would be caused by the fast motion of the images. Because successive frames differ slightly as with successive images in conventional animations, the viewer perceives animation.
  • FIG. 6 illustrates the geometrical considerations explaining this stretching effect.
  • Labeled "Position 1" and “Position 2" are the two positions of a given frame 230 where the opposite edges of frame 230 are visible. Because the positions of frame 230 and slit 220 are fixed relative to each other, they precisely determine the angle at which viewer 30 must look in order that slit 220 be aligned with an edge of the image 230.
  • the left edge of image 230 is aligned with slit 220 and the viewer's eye.
  • the right edge of image 230 is aligned with slit 220 and the viewer's eye. In fact, the two positions occur at different times, but, as explained above, this is not observed by the viewer 30. Only one full image is observed.
  • the perceived width of the image, D i ' is 2x.
  • the perceived width of the image, D i ' is increased over the actual width of the image by a factor of the ratio of the viewer-slitboard distance to the slitboard-backboard distance.
  • FIG. 6A shows the magnification effect when the backboard 23' is not substantially parallel to the viewer's trajectory.
  • the magnification is found by defining a formula f(x), where x is the distance along the viewer's trajectory, for the shape of the backboard -- that is, the distance of the backboard from the axis defined by the viewer's trajectory -- around each slit (for example, FIG. 7 shows a backboard 71 on which each image 730 forms a semicircle around its respective slit 220).
  • x axis along the direction of the viewer's motion and a y axis perpendicular to the x axis and choose the origin at the position of the viewer 30.
  • FIG. 6A a section of the true backboard 23' is shown between slitboard 22 and the projected backboard 23".
  • a length PR of the backboard 23' defines a picture element 230'. This section 230' will appear to viewer 30 as if on projected flat backboard 23", as indicated.
  • the section of backboard 23' shown is a straight line segment, but this linearity is not required.
  • Viewer 30, at position A sees the left edge P of picture element 230' when slit 220 is at Q. Because the positions of picture element 230' and slit 220 are fixed relative to each other, they precisely determine the angle at which viewer 30 must look in order that slit 220 be aligned with an edge of the element 230'. Therefore, the right edge R of this picture element 236' will be visible when the device has moved relative to viewer 30 to a position where a line parallel to QR passes through A.
  • the left edge of picture element 230' will appear on projected backboard 23" at position B, a distance ⁇ x from the y axis.
  • the right edge of picture element 230' will appear on projected backboard 23" at position C.
  • the apparent width of the image, D i ', is the distance BC.
  • Point P is the intersection of backboard 23' with the line through A and B.
  • Point Q is the intersection of slitboard 22 with the line through A and B.
  • Point R is the intersection of backboard 23' with the line through Q and R.
  • the distance D i is the distance from P to R.
  • D i ( ( R x ⁇ P x ) 2 + ( R y ⁇ P y ) 2 ) 0.5 , where the variables on the right hand side can all be found in terms of dimensions of the apparatus and ⁇ x.
  • each element can be preshrunk and placed at the appropriate location on the backboard.
  • the images may be shrunk in the direction of motion before being mounted on the backboard in order that when projected they are stretched to their proper proportions, allowing a large image to be presented in a relatively smaller space.
  • Curved or inclined surfaces on the backboard can be used to augment the effect. That is, as a nonplanar backboard approaches the slitboard, the magnification increases greatly. However, for simplicity, the discussion that follows will assume a planar backboard unless otherwise indicated.
  • the stretching effect when adjusted through the relevant variable parameters of apparatus 10, can be very useful.
  • the relation between the perceived image size, D i ', and the viewer distance, D vs is linear -- the image gets bigger as the viewer moves farther away. This can be a useful effect in the right environment.
  • multiple instances of a single frame can be displayed, in a manner similar to that used in commercial motion picture projection.
  • the effect can also result in confusion or blur perceived by viewer 30. In practice this confusion is barely noticeable, however, and can be reduced through a higher frame rate or a slower varying subject of animation.
  • Another possibly useful effect occurs when the image of one frame 230 is visible through the slit 220 corresponding to an adjacent frame 230.
  • multiple side-by-side animations may be visible to the viewer.
  • These "second-order" images can be used for graphic effect, if desired. Or, if not desired, they may be removed by increasing slitboard thickness D sb or the ratio D ff /D i , by introducing a light baffle 32 between slitboard 22 and backboard 23, or by altering the geometry of backboard 23. All of these techniques are described below.
  • Still another possibly useful effect arises from the fact that the stretching effect distorts the proportions of image 230.
  • V w the viewer's speed
  • D bs the backboard-to-slitboard distance
  • D vs the distance from viewer to slitboard
  • D i ' the perceived image width
  • D ff can be as great as about 2 feet (about 67 cm).
  • the minimum V w is determined by the minimum D ff allowable by the image, which is constrained by the fact that D ff can be no smaller than D i .
  • the stretching effect theoretically allows D i to be lowered arbitrarily without lowering D i ', because D bs can, in principle, be lowered arbitrarily.
  • D bs cannot be lowered arbitrarily, because very small values result in very different perceived image widths for each viewer 30 at a different D vs . That is, at too small a D bs , viewers on opposite sides of a train could see too markedly differently proportioned images.
  • small D bs resulting in high magnification, requires correspondingly high image quality or printing resolution.
  • the closest ones (those with the smallest D vs ) generally determine the limits on D bs .
  • D i D ff and one can view second order images, they will appear to abut the first order image, slightly out of synchronization. The resulting appearance will be like that of multiple television sets next to each other and starting their programs at slightly different times. This effect may be used for graphic intent, or, if not desired, three variations in parameters can remove it.
  • slitboard thickness D sb so that second order images are obscured by the cutoff angle. That is, for any non-zero thickness of slitboard 22, there will be an angle through which if one looks one will not be able to see through the slits. As the thickness of slitboard 22 increases, this angle gets smaller, and can be seen to follow the relation D s b / D s ⁇ D b s / ( D i / 2 ) This relation may alternatively be written D s b / D s ⁇ D v s / ( D ′ i / 2 ) by substitution for D i ' from Relation 1. This shows the limit on D sb imposed by the desired perceived image width.
  • backboard 71 bears curved images 730 so that second order images are not observed.
  • the change in backboard shape will result in a slightly altered stretching effect. As before, this stretching effect can be undone by preshrinking the image in the direction of motion.
  • the embodiment illustrated in FIG. 7 has the potentially useful property not only of showing no second order images, but also of an arbitrarily wide first order image. This effect is related to, but distinct from, the stretching effect described above, which assumes a flat backboard geometry.
  • the final observed width of the image is limited by the vignetting of the slitboard -- the exact relation can be found by solving Relation 5 for D i '. It can be observed from FIG. 7 that as the viewing angle becomes large, the viewer continues to observe through each given slit 220 only the image 730 corresponding to that slit 220.
  • the leftmost sliver of the image is viewable when the viewer looks 90° to the left and the rightmost sliver is viewable when the viewer looks 90' to the right.
  • the slivers in between are continuously viewable between these extreme angles.
  • each image is observed as infinitely wide.
  • the curved image 730 does not quite reach the slitboard 22, in order to illustrate the maximum viewing angle allowed by the vignetting of a non-zero width slitboard. In principle, the curve of image 730 may reach the slitboard.
  • the slit width must vary inversely with the light brightness -- i.e., D s ⁇ 1/B.
  • the device has higher resolution and less blur the smaller the slit width (analogously to how a pinhole camera has higher resolution with a smaller pinhole). Since smaller slits transmit less light, the brightness must increase with decreasing slit width in order that the same total amount bf light reach viewer 30.
  • the width of slit 220 relative to the image width determines the amount of blur perceived by viewer 30 in the direction of motion. More specifically, the size of slit 220, projected from viewer 30 onto backboard 23, determines the scale over which the present device does not reduce blur. This length is set because the sliver of the image that can be seen through slit 220 at any given moment is in motion, and therefore blurred in the viewer's perception.
  • the size of slit 220 relative to the image width should thus be as small as practicable if the highest resolution possible is desired. In the parameter ranges of the two examples below, slit widths would likely be under about 0.03125 inch (under about 0.8 mm).
  • the achievable brightness and resolution, and their relationship, can be quantified.
  • L ambient describes the luminance of a typical object within the field of view of the viewer while looking at the image projected by the apparatus.
  • This typical object should be representative of the general brightness of the viewer's environment and should characterize the background light level. For example, in a subway or train it might be the wall of the car adjacent to the window through which the apparatus is viewable.
  • B ambient is the brightness of that object as seen by the viewer
  • B ambient L ambient / 4 ⁇ D ambient 2
  • D ambient is the distance between the viewer and the ambient object. It is sometimes difficult to select a particular object as representative of the ambient.
  • the ambient object could be the wall of the subway car adjacent the window, in which case D ambient is the distance from the viewer to the wall. For ease of calculation, this may be approximated as D vs because the additional distance from the window to the apparatus is relatively small.
  • R the image resolution
  • This quantity is called the resolution because the image tends to blur in the direction of motion on the scale of the width of the slit. Because the eye can see the whole area of the image contained within the slit width at the same time, and the image moves in the time it is visible, the eye cannot discern detail in the image much finer than the projected slit width.
  • D s effectively defines the pixel size of the image in the direction of motion.
  • the image effectively has ten pixels in the direction of motion.
  • the eye resolves the image to slightly better than R, but R determines the scale.
  • c is the contrast between the apparatus image and the ambient environment at the position of the viewer. In order that the image be viewable in the environment of the viewer, the apparatus brightness must be above a minimum brightness B device ⁇ B ambient ⁇ c .
  • c defines a minimum device brightness that depends on the properties of the human eye: if the device's image is too dim relative to its environment it will be invisible.
  • the brightness of the device may always be brighter than the minimum defined by c. Practically speaking, c ought to be at least about 0.1. For many applications, such as commercial advertising, it may be desirable that c be greater than 1.
  • the following parameters comprise the smallest set of parameters (which may be referred to as "independent” parameters) that fully describe the apparatus according to the invention -- D vs , D bs , V w , L ambient , D ambient , c, L device , D i , D s , and D ff .
  • D ′ i D i ⁇ D v s / D b s
  • D v b D v s + D b s
  • R D i / D s F
  • D s / D ff B ambient L ambient / 4 ⁇ D ambient 2
  • B device ( L device / 4 ⁇ D vb 2 ) ⁇ T F
  • the first five are substantially determined by the environment in which the apparatus is installed.
  • these five parameters are determined by the cross sections of the tunnel and train, the train speed, and the lighting in the train.
  • these parameters are determined by the dimensions of the walkway or hallway, pedestrian foot speed, and the ambient lighting conditions.
  • D i ' is constrained either by the environment (the width of a subway window, for example) or by the requirements of the image to be displayed by the apparatus (such as aesthetic considerations) or both.
  • the remaining dependent parameters are determined by the independent parameters.
  • the inequality between the far left and far right sides of the relation forces a minimum luminance for the apparatus, L device . That is, if the luminance of the apparatus is below a minimum threshold, the apparatus image will be too dim to see in the brightness of the viewer's environment.
  • the inequalities between D s and the far left and far right of the relation determine the allowable slit width range.
  • a smaller slit width gives higher resolution but less brightness and a greater slit width gives brightness at the expense of resolution.
  • a higher luminance of the apparatus extends the lower end of the allowable slit width range.
  • apparatus 10 requires no included light source for its operation if ambient light is sufficient, such as outdoors (lid 21 or backboard 23 would have to be light-transmissive), in practice the use of very thin slits does impose such a requirement. That is, when operated under conditions of low ambient light and desiring moderate resolution, bright interior illumination is preferable.
  • the designation "interior” indicates the volume of the apparatus 10 between backboard 23 and slitboard 22, as opposed to the "exterior,” which is every place else.
  • the interior contains the viewable images 230, but otherwise may be empty or contain support structure, illumination sources, optical baffles, etc. as described above in connection with FIGS. 1, 2 and 2A.
  • this illumination preferably should not illuminate the exterior of the device, or illuminate the viewer's environment or reach the viewer directly, because greater contrast between the dark exterior and bright interior improves the appearance of the final image.
  • This lighting requirement is less cumbersome than that for stroboscopic devices -- in a subway tunnel environment, this illumination need not be brighter than achievable with ordinary residential/commercial type lighting, such as fluorescent tubes.
  • the lighting preferably should be constant, so no timing complications arise.
  • the interior of apparatus 10 should be physically sealed as well as possible from the exterior subway tunnel environment as discussed above, preferably while permitting dissipation of heat from the light source, if necessary.
  • the enclosure may also be used to aid the illumination of the interior by reflecting light which would otherwise not be directed towards viewable images 230.
  • the first example illustrates how all constraints tend to relax as V w increases.
  • V w 30 mph (train speed)
  • D bs ⁇ 6 inches (space between train and wall)
  • D vs ⁇ 6 feet half the width of a train, for the average location of a viewer 30 within the car
  • D i ' ⁇ 3 feet (width of train window)
  • the second example illustrates how the constraints tighten when near the minimal frame rate.
  • frame rate ⁇ 20 frames / sec D bs ⁇ 6 inch D vs ⁇ 6 feet D i ′ ⁇ 2 feet .
  • D ff D i
  • FIG. 8 illustrates another exemplary embodiment 80 altering the optimal viewing angle of the animation.
  • backboard 83 bears images 830 that are inclined at an acute angle to backboard 83, varying the viewing angle from a right angle to that acute angle.
  • This alteration permits more natural viewing for a pedestrian, for example, by not requiring turning of the pedestrian's head far away from the direction of motion.
  • This embodiment may also eliminate second order images.
  • FIG. 9 illustrates a further exemplary embodiment 90 similar to apparatus 80, but in which slitboard 92 is also angled.
  • This refinement again provides a more natural viewing position for a pedestrian.
  • the asymmetric triangular design permits natural viewing for viewers moving from left to right.
  • a symmetric design (not shown), in which the plan of the slitboard might more resemble, for example, a series of isosceles triangles, could accommodate viewers moving in both directions.
  • FIG. 10 illustrates a technique of using one slitboard 101 as the backboard of a different slitboard 102, while simultaneously using that slitboard 102 as the backboard of the original slitboard 101.
  • This configuration permits the back-to-back installation of two devices in the space of one.
  • This apparatus 100 may be improved by offsetting one set of slits from the other by D i /2, or some fraction of D i .
  • FIG. 11 shows a simple schematic plan view of apparatus 100.
  • Slits 220 of one slitboard 101 are centered between slits 220 of the opposite slitboard 102, which is acting as the former slitboard's backboard. That is, between slits 220 of one slitboard are images 230 viewable through the other slitboard, and vice-versa. Because the slits are very thin, their presence in the backboard creates negligible distraction.
  • FIG. 12 shows another embodiment 120 similar to apparatus 100, but having a set of curved images 1230 (as in FIG. 7) facing slits 220 of opposite slitboards/ backboards 101, 102.
  • Apparatus 120 thus has characteristics, and advantages, of both apparatus 70 and apparatus 100.
  • FIG. 13 illustrates a roller type of image display mechanism 130 that may be placed at the position of the backboard.
  • the rollers may contain a plurality of sets of images that can be changed by simply rolling from one set of images to another.
  • Such a mechanism allows the changing of images to be greatly simplified.
  • In order to change from one animation to another instead of manually changing each image, one may roll such rollers to a different set of images. This change could be performed manually or automatically, for instance by a timer.
  • mechanism 130 can be used in apparatus 100 or apparatus 120.
  • FIGS. 14 and 15 Yet another exemplary embodiment 140 is shown in FIGS. 14 and 15.
  • "backboard" 141 With its images 142, is placed between viewer 30 and a series of mirrors 143.
  • Each mirror 143 preferably is substantially the same size and orientation as any slits that would have been used in the aforementioned embodiments.
  • Mirrors 143 preferably are mounted on a board 144 that takes the place of the slitboard, but mirrors 143 could be mounted individually or on any other suitable mounting.
  • the principles of operation of apparatus 140 are substantially the same as those for the aforementioned embodiments. However, because “backboard” 141 would obscure the sight of mirrors 143 by viewer 30, “backboard” 141 may be placed above or below the line of sight of viewer 30. As shown in FIGS.
  • backboard 141 is above the line of sight of viewer 30. As drawn in FIGS. 14 and 15, moreover, both “backboard” 141 and “mirrorboard” 144 are inclined. However, with proper placement, inclination of boards 141, 144 may not be necessary. As in the case of a'slitboard, "mirrorboard” 144 will work best when its non-mirror portions are dark, to increase the contrast with the images.
  • a complete animation displayed using the apparatus of the present invention for use in a subway system may be a sizable fraction of a mile (or more) in length.
  • such an animation can be implemented by breaking the backboard carrying the images for such an animation into smaller units, providing multiple apparatus according to the invention to match the local design of the subway tunnel structure where feasible.
  • Many subway systems have repeating support structure along the length of a tunnel to which such modular devices may be attached in a mechanically simplified way.
  • the New York City subway system has throughout its tunnel network regularly spaced columns of support I-beams between many pairs of tracks. Installation of apparatus according to the present invention may be greatly facilitated by taking advantage of these I-beams, their regular spacing, and the certainty of their placement just alongside, but out of, the path of the trains.
  • this single example should not be construed as restricting the applicability to just one subway system.
  • the modularization technique has many other advantages. It has the potential to facilitate construction and maintenance, by taking advantage of structures explicitly designed with the engineering of the subway tunnels in mind.
  • the I-beam structure is sturdy and guaranteed not to encroach on track space.
  • the constant size of the I-beams consistently regulates D bs , easing design considerations. Additionally, cost and engineering difficulties are reduced insofar as the apparatus may be easily attached to the exterior of the supports without drilling or possibly destructive alterations to existing structure.
  • FIG. 16 schematically illustrates an example of the modularization possible for the two-sided apparatus of FIGS. 10 and 11.
  • construction of the whole length of two slitboards which could be a half mile or more in length, is reduced to constructing many identical slitboards 160, each about as long as the distance between adjacent I-beam columns 161 (e.g., about five feet).
  • Each of the slitboards is then attached to a pair of the existing support I-beams, along with the other parts of the apparatus as described above.
  • FIG. 17 schematically illustrates the side profile of display apparatus 1700, which includes slitboard 1722 and backboard 1723.
  • Slitboard 1722 and backboard 1723 are parallel to each other, planar, and perpendicular to a viewer's line of sight 1701.
  • viewer-to-backboard distance, D vb and backboard-to-slitboard distance, D bs .
  • D vb and D bs are well defined for any viewer's horizontal line of sight and, accordingly, so is the magnification factor.
  • D vb and D bs both increase by a factor of 1/cos ⁇ (where ⁇ is measured from the horizontal), so the magnification factor remains the same.
  • This cancellation allows display apparatus with a vertical slitboard and a vertical backboard to project images whose magnification is constant in the vertical direction.
  • FIG. 18 shows a subway tunnel 1802 in which display apparatus 1700 is mounted on each side of the tunnel wall.
  • Walkway 1804 and subway car 1806, with windows 1808, are also shown.
  • Walkway 1804 is an access catwalk used by maintenance personnel and is typically only wide enough for one person (walkway 1804 is not a subway station platform used by subway passengers).
  • subway tunnels are built to accommodate subway trains and not necessarily display apparatus, some subway tunnels have very limited space for installation of such display apparatus.
  • display apparatuses 1700 leave little clearance for either subway car 1806 or a person on walkway 1804, as shown in FIG. 18. Therefore, a less spatially protrusive display apparatus would improve the safety of passing trains 1806 and maintenance personnel on walkway 1804. Moreover, such apparatus would likely be easier to install and maintain.
  • Display apparatus 1900 is shown in FIG. 19 mounted in subway tunnel 1802. Both slitboard 1922 and backboard 1923 are slanted outward to conform better to the available space in tunnel 1802. Display apparatus 1900 accordingly provides increased clearance, and thus safety, for both subway car 1806 and persons walking on walkway 1804.
  • determination of the various display apparatus parameters discussed above are advantageously the same for apparatus 1900 as they are, for example, for display apparatus 1700, which has a slitboard and backboard perpendicular to a viewer's horizontal line of sight.
  • the determination is the same because the magnification effect of slanted display apparatus 1900 is also constant in the vertical direction provided both the slitboard and backboard are slanted by the same angle. In other words, the magnification factor is constant with respect to viewing angle.
  • display apparatus 1700 can be advantageously installed by simply tilting apparatus 1700 inward.
  • FIG. 22 shows an embodiment of a curved display apparatus 2200 constructed in accordance with the invention mounted in subway tunnel 1802. Both slitboard 2222 and backboard 2223 are curved outward to conform even better than display apparatus 1900 to the available space in tunnel 1802. This embodiment, therefore, provides even more clearance and safety than apparatus 1900.
  • FIG. 23 shows an embodiment of nonplanar display apparatus 2300 in accordance with the invention.
  • - Apparatus 2300 includes nonplanar slitboard 2322 and nonplanar backboard 2323, which are non-vertical and have the same profile (i.e., they are parallel).
  • FIG. 24 shows another embodiment of nonplanar display apparatus 2400 in accordance with the present invention.
  • Apparatus 2400 includes nonplanar slitboard 2422 and nonplanar backboard 2423, which are non-vertical and do not have the same profile (i.e., they are not parallel). Neither slitboard 2322 and backboard 2323 nor slitboard 2422 and backboard 2423 are perpendicular to a viewer's respective lines of sight 2301 and 2401. Note that the slitboard and backboard profiles shown in FIGS. 23 and 24 are merely illustrative and should in no way limit the invention.
  • display apparatus that provides a constant magnification for more than one viewer position (e.g., the optimal position) is possible for only a few geometries. Viewers at other positions will observe images whose magnification varies up and down the backboard, resulting in a warped looking image -- overly magnified at some positions and under-magnified at others. In practice, however, the amount of warping is often within acceptable limits for viewing positions close to the optimal viewing position.
  • magnification factor which varies with position along the backboard.
  • the magnification factor depends on viewer position, which determines both D vb and D bs .
  • magnification factor, m can be found for each position on the backboard, designated by coordinates (x b ,y b ). That is, m is a function of x v , y v , x b , and y b .
  • images of a display apparatus are visible from a range of viewer positions.
  • the display apparatus is substantially parallel to the viewer's direction of motion (which for FIGS. 19-24 is into and out of the page, or in the z direction).
  • reference to a viewer's position, or position along a slitboard or backboard refers to position in the cross-sectional or side-elevational plane (e.g., with respect to FIGS. 23 and 24, the x-direction is horizontal and the y-direction is vertical).
  • FIG. 25 is a flow diagram of an exemplary process 2500 for determining whether a display apparatus with arbitrary slitboard and backboard geometries results in acceptable animation in accordance with the invention.
  • side profiles of a slitboard and a backboard are selected. This selection is preferably in accordance with available installation space. These profiles are preferably smooth with no jumps or sharp corners. Preferably, they monotonically rise, meaning that any horizontal line crossing the profile crosses in at most one point. Should the profiles not meet these preferences, appropriate modifications to process 2500 may be necessary, although much of the process will remain unchanged.
  • each board profile is represented by a mathematical function (e.g., f backboard(x,y) and f slithoard(x,y) ), which can be an approximation.
  • a mathematical function e.g., f backboard(x,y) and f slithoard(x,y)
  • an optimal viewer position (x v,OPT ,y v,OPT ) is selected. This selection should be made in accordance with the available installation space and most likely or average position of a viewer. For example, in a subway tunnel, this position might be in the center of a subway car at the average height of a person. On a pedestrian walkway, this position might be in the middle of the walkway also at the average height of a person.
  • a worst case viewer position (x w ,y w ) is selected in order to determine whether the chosen profiles will yield acceptable images for viewers away from the optimal position. For example, a worst case position for the subway tunnel installation may be at the seat closest to the window. The worst case position should be the one that results in the most warped observed image. Typically, a worst case position is the farthest from (x v,OPT ,y v,OPT ), but not necessarily.
  • a worst case magnification delta or limit, ML is selected.
  • Limit ML represents the largest acceptable difference between magnification as observed from the optimal position and magnification as observed from the worst case position. For example, an ML of ⁇ 10% may be set as the largest acceptable magnification difference between the two magnifications (i.e., the difference between the worst case position magnification and the optimal position magnification should be no more than ⁇ 10%).
  • the selection of ML can be arbitrary and can depend on the degree of tolerable image warpage for a particular display apparatus application.
  • the magnification factor is preferably determined as a function of position along the height of the backboard (i.e., the y-direction as defined above). Assuming the preferences above, the position on the backboard is referred to as y b , which can vary from the bottom of the backboard, y b,LOW , to the top of the backboard, y b,HI , and for which each y b , there is a unique x b .
  • f LOS (x,y),that is, the line joining (x v,OPT ,y v,OPT ) and (x b ,y b ) -- is now uniquely determined at 2512.
  • m OPT (y b ) and m w (y b ) are compared in view of limit ML. If the difference between the two magnifications is less than or equal to ML, as calculated below:
  • ⁇ M L the selected profiles for the slitboard and backboard will result in acceptable observed images.
  • Process 2500 then moves to 2518, where images are preshrunk as described above in accordance with m OPT (y b ).
  • process 2500 returns to 2502 where the process repeats with new selected profiles for the slitboard and backboard.
  • process 2500 can also be used to design display apparatus having curved slitboard and backboard profiles such as display apparatus 2200.

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EP06007605A 2000-06-23 2001-06-22 Anzeigevorrichtung mit animiert erscheinenden Standbildern für sich bewegende Betrachter Withdrawn EP1686556A3 (de)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2009060253A1 (en) * 2007-11-09 2009-05-14 Innovative Media Solutions Lighted subway signage

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1051712A (fr) * 1952-02-19 1954-01-19 Perfectionnements aux dispositifs cinématographiques à images fixes pour observateur mobile
GB2230104A (en) * 1989-03-28 1990-10-10 Paul Warren Walsh A system for creating the effect of a stationary or moving image
WO2000007059A1 (en) * 1998-07-29 2000-02-10 Spodek Joshua D Apparatus for displaying images to viewers in motion
DE29820186U1 (de) * 1998-11-11 2000-03-16 Kemper, Lutz, 44799 Bochum Installation zur Wahrnehmung bewegter Bilder

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1051712A (fr) * 1952-02-19 1954-01-19 Perfectionnements aux dispositifs cinématographiques à images fixes pour observateur mobile
GB2230104A (en) * 1989-03-28 1990-10-10 Paul Warren Walsh A system for creating the effect of a stationary or moving image
WO2000007059A1 (en) * 1998-07-29 2000-02-10 Spodek Joshua D Apparatus for displaying images to viewers in motion
DE29820186U1 (de) * 1998-11-11 2000-03-16 Kemper, Lutz, 44799 Bochum Installation zur Wahrnehmung bewegter Bilder

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2009060253A1 (en) * 2007-11-09 2009-05-14 Innovative Media Solutions Lighted subway signage

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