Display apparatus

A display apparatus includes a mechanism for storing images on a plurality of partially transparent sheets. Each sheet includes several rows of graphic material separated by rows of transparent areas. The sheets are relatively stiff so that they do not wrinkle or buckle under their own weight and are supported on upper and lower edges by tabs. A drive mechanism brings one sheet into viewing position as another sheet simultaneously withdraws in the same direction to produce a smooth dissolve of the projected image. Silk screened stripes of material on the sheets prevent the sheets from rubbing against each other and harming the graphic information and otherwise prevent mechanical interference between the sheets. By contouring the surface of the screen, it is possible to create a three dimensional image by illuminating the rear surface with a television screen or other image storage or producing means. It is further possible to transform a black and white television into a digitized color display by placing color filter areas behind each of the cells of the digitizing screen and then selectively illuminating combinations of the color filter areas with the TV raster scan. The digitizing screen can also be used as an image conversion tool by illuminating original art work on the rear face of the digitizing screen and tracing the digitized image thereof from the front face of the screen.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The invention relates to a digitizing screen apparatus which may employ a 
mechanism for storing a plurality of graphic images in sheet form. 
2. Description of the Related Art 
The patent literature discloses several attempts to produce a series of 
stored graphic images. One early technique was to drive a patterned 
backdrop with respect to a plurality of small apertures. Schemes such as 
the foregoing are described in U.S. Pat. Nos. 1,114,267 and 1,172,360, 
among others. 
A more recent technique is to project an image onto a patterned lens 
screen. U.S. Patent references discussing this type of technique include, 
but are not necessarily limited to, U.S. Pat. Nos. 2,432,896; 2,507,975 
and 3,742,631. 
Other U.S. Patents of possible interest include U.S. Pat. Nos. 1,832,894; 
3,335,457; 3,237,331; 3,314,179; 3,329,475; 3,568,346; 3,686,781; 
3,783,539 and 3,987,558. 
In addition to the foregoing, other efforts have been made to produce 
digital-like displays. For example, digitized screens can be found in 
places such as Time Square, New York City. According to one embodiment, a 
field of light bulbs is controlled by an array of photocells, each 
actuating a single bulb on the display screen through an amplifier 
circuit. Movies of shadow graphs and in some cases real shadows, are cast 
upon the screen from a control romm behind the sign. The images projected 
on the photocells appear in lights on the display screen over the street. 
Other, less costly efforts have been made to digitize images on a more 
modest scale. One device marketed under the name Channel 2000 incorporates 
a plurality of lenses. Another device known as Channel 1 used a single 
diffusing sheet and an egg crate separator. 
It is also known in the prior art to produce a three dimensional image by 
projecting a moving picture on the front surface of a contoured screen. 
A useful discussion of the design of light concentrators may be found in 
the book entitled THE OPTICS OF NONIMAGING CONCENTRATORS: Light and Solar 
Energy by W. T. Welford and R. Winston published in 1978 by Acadamic 
Press. 
During the prosecution of my copending application, Ser. No. 630,832 the 
following patent references were also cited: U.S. Pat. Nos. 2,956,359; 
3,918,185; 3,159,936 and 3,629,965. 
SUMMARY OF THE INVENTION 
Briefly described the invention comprises a storage mechanism for storing a 
plurality of images that may be used separately or in conjunction with an 
image element expansion and homogenizing screen which is referred to 
herein and in my copending application as a digitizing means. The storage 
means preferably comprises a plurality of relatively stiff sheets, each 
including several rows of graphic visual material seaprated by rows of 
transparent areas. The sheets are relatively stiff so that they do not 
buckle or wrinkle under their own weight when supported on upper and lower 
edges by tabs. Each pair of upper and lower tabs is offset from the tabs 
of the next adjacent sheet. A drive mechanism is attached to each of the 
sheets by the tabs thereon and is employed to take individual sheets out 
of registration with the other sheets and into viewing position so that 
the rows of graphic material thereon can be viewed. The drive mechanism 
preferably brings one sheet into viewing position as another sheet 
simultaneously withdraws in the same direction in order to produce a 
smooth dissolve of the viewed image. An image element expansion and 
homogenizing means is located in front of the storage means. Image 
elements from the storage means are expanded and homogenized by the 
digitizing screen so that the output image is a digitized mosaic of colors 
representative of the visual information on the sheets. 
In order to prevent mechanical interference between adjacent sheets and to 
prevent abrasion of graphic material on the sheets and to reduce friction, 
vertical separator ribs of material are deposited thereon. The vertical 
separator ribs may be silk screened stripes of ink, or paint, or similar 
durable material. 
The image element expansion screen has several novel applications. For 
example, a filter sheet including cells having several color filter areas 
therein can be placed between the digitizing screen and a TV screen or 
computer monitor. The raster scan of the black and white TV can then be 
used to selectively illuminate specific color filter areas thereby 
producing on the face of the digitizing screen a pattern of colors. A 
tracing device can be constructed by placing the digitizing screen over a 
sheet of original art work and then back lighting the art work so as to 
form a digitized representation of the art work on the face of the 
digitizing screen. Pegs, pins, or other holders, can be used to hold 
tracing paper and the like on the face of the digitizing screen so that 
the image can be traced in color or shades of gray. Lastly, it is possible 
to contour the viewed surface of the digitizing screen so that the image 
has a three dimensional appearance. For example, the contour of a face may 
be incorporated into the viewing surface of the digitizing screen while 
the back portion of the digitizing screen is attached to a television set. 
The planar two dimensional face on the television screen is then converted 
into a digitized three dimensional face on the front of the screen. 
Artifical hair, glasses and the like can be added to the face contour to 
enhance the effectiveness of its appearance. If the TV screen produces eye 
movements or lip movements, the face will appear life-like. These and 
other features of the invention will be more further understood by 
reference to the following drawings.

DETAILED DESCRIPTION OF THE INVENTION 
During the course of this description like numbers will be employed to 
identify like elements according to the different views which illustrate 
the invention. 
The invention essentially comprises a multiple sheet storage device and a 
digitizing screen both of which can be used independently or in 
conjunction with one another. FIG. 1 illustrates a storage device 10 which 
produces an image 12. Storage device 10 is illustrated without a 
digitizing screen in front of it. Cabinet 14 supports and surrounds the 
mechanism of the storage device 10. FIG. 2 illustrates the drive mechanism 
18 employed to cause the graphic partially transparent sheets 16 to move 
up and down and which is described in detail in my copending application. 
A mask 15 printed on a transparent plate and similar in structure to the 
one described in my copending application, preferably with the addition of 
vertical stripes to mask areas previously hidden by vertical ribs of the 
digitizing screen, is located in front of sheets 16 and a retainer 17 
keeps the sheets 16 from curling. 
The important characteristics of sheets 16 are shown in detail in FIG. 3. 
Each sheet 16 includes an upper pull tab 20 located directly opposite a 
lower pull tab 22. Each pull tab 20 and 22 is displaced sideways with 
respect to the pull tabs 20 and 22 on adjacent sheets 16. This permits the 
sheets 16 to be stacked in a relatively compact grouping while leaving 
separated attachment points for support and driving. Sheets 16 are 
preferably formed from a moderately stiff plastic material such as 0.007 
inch thick Mylar.RTM.. The characteristics of the plastic material are 
that the sheets 16 will not wrinkle or buckle under their own weight. Rows 
of graphic information 24 are located horizontally on the sheet 16 and 
ordinarily part of a continuous graphic image covering said sheet. 
Relatively clear transparent rows 26 preferably formed from a plurality of 
apertures 28 are alternately positioned between adjacent graphic 
information rows 24. The storage system 10 described thus far is 
essentially the same as set forth in my copending U.S. application Ser. 
No. 630,832 filed on July 13, 1984 the entire substance of which is 
incorporated herein by reference. An improved sheet separator technique is 
illustrated in horizontal cross-sectional detail in FIG. 4. The 
cross-sectional view of FIG. 4 is taken through the clear apertures 28. A 
plurality of separator ribs 30 are used to space adjacent sheets 16 from 
each other. As shown in FIG. 3, the separator ribs 30 are disposed as 
vertical columns on each sheet 16 at right angles to the horizontal 
graphic rows 24 and relatively clear rows 26. Separator ribs 30 are 
integrated with each sheet 16. Separator ribs 30 are preferably silk 
screened on each sheet 16 using a relatively wear resistant material such 
as enamel which can stand up to substantial frictional abuse. Separator 
ribs 30 may be printed as a single thick coating or built up in several 
layers. The wear surface of the next adjacent slide 16 is a non-image 
bearing area. Accordingly, separator ribs 30 may be located on either face 
of slide 16. It is not necessary for the ribs 30 to be continuous. They 
can be discontinuous provided that they produce the necessary separation. 
It is also possible that other patterns may be used rather than parallel 
lines. Furthermore, the patterns could be formed of materials other than 
ink or paint, such as tape or rivets or possibly by the deformation of the 
slide material itself. In some cases it may be desirable to apply the 
pattern 30 to both faces of every second slide 16. Complementary patterns 
on opposed faces may also be used to act as guides or limits to slide 
motion. 
A light concentrator embodiment 32 is illustrated in detail in FIGS. 5 and 
6. The use of light concentrators is discussed in my copending 
application, Ser. No. 630,832 filed July 13, 1984. The application of 
light concentrators can be moderately broad and may include lenses. In 
FIG. 5 a plurality of light concentrator elements 34 are located behind a 
sheet 38 including a plurality of liquid crystal elements 36 and 
associated circuitry. A digitizing screen 41 comprising a back diffuser 
40, a grid 42 and a front diffuser 44 are located on the opposite sides of 
the liquid crystal sheet 38 from the light concentrators 34. Light 
presented to each concentrator 34 is concentrated at LCD element 36. LCD 
element 36 can be electronically modulated to control the passage of the 
light through the digitizing screen 41. Therefore, a digitized 
television-like image can be produced on front diffuser 44 by modulating 
the light concentrated by concentrator 34 with LCD elements 36. The use of 
light concentrators 34 substantially increases the efficiency of the image 
producing system as a whole. The concentrators 34 collect light from 
behind the grip and prevent light from being lost. It is possible to 
capture much of the light that is available on the back side of the grid 
through the use of concentrators. Moreover, by concentrating the light 
through modulatable elements such as liquid crystals, it is possible to 
achieve a relatively efficient image forming system wherein only a small 
portion of the screen area need be modulatable elements. 
A tracing toy embodiment 50 of the invention is illustrated in detail in 
FIGS. 7 and 8. Tracing toy 50 is illuminated from behind by light source 
52. Lined tracing paper 54 is held in position by four guide pegs or posts 
56. The four guide posts 56 engage four holes 62 located respectively in 
each corner of the lined tracing paper 54. Tracings 61 of the image are 
created by using a pencil or crayon or similar writing instrument 58 on 
the surface of tracing paper 54. A stand or cabinet 60 supports the 
elements of the tracing apparatus 50. The inside walls of the cabinet 60 
are mirrored so as to reflect light from source 52 toward elements 72, 70, 
68, 66, 64 and 54 respectively. Light source 52 can be a conventional 
table lamp or might be built into the game 50 itself. 
The art work frame 72 and digitizing screen 65 are illustrated in an 
exploded overlapping view in FIG. 8. A clear plastic frame 72 is located 
on the bottom under the digitizing screen assembly 65 and is adapted to 
receive and align a transparent, translucent, or at least partially 
transparent graphic original 70. The frame 72 includes a plurality of push 
out slots 71 that permit the user to force the art work 70 out of the 
frame 72 with a wire if the art work 70 becomes stuck. Sidewalls 73 help 
to align the art work with respect to the rest of the elements. A 
digitizing screen section 65 comprising a front translucent diffuser 64, a 
grid 66 and a rear translucent diffuser 68 is located between graphic art 
work 70 and tracing paper 54. Guide posts 56 are preferably integrally 
connected to the corners of the front diffuser plate 64. 
Frame 72 stabilizes cabinet 60 by which it is supported and holds original 
art work sheet 70. A cut-out on the top edge allows the original art work 
sheet 70 to be removed. Frame 72 is preferably formed from transparent or 
translucent material, such as acrylic, or is perforated to allow for the 
passage of light. The sidewalls 73 of frame 72 guide and align the 
origignal drawing sheet 70 and serve to separate the rear diffuser 68 and 
frame 72 an appropriate distance to receive art work sheet 70. Tracing 
sheet 54 must be either transparent or translucent and preferably 
comprises relatively inexpensive tracing paper. Sheet 54 should also be of 
sufficient weight so that drawing on it will not tend to wrinkle or tear 
it. The tracing sheet 54 is punched at locations 62 to receive index guide 
posts 56. A grid pattern printed on sheet 54 aligns directly over top of 
the cell separations of the grid 66. The cellular pattern is of sufficient 
width to allow the user to color within the lines in order to avoid 
unwanted overflow of color into adjacent cells. The lines are preferably 
black, therfore allowing the sheet 54 to appear tidy from either side, 
however, any opaque line color may be used where the coloring sheet 54 is 
of sufficient light transmissability to allow viewing the reverse (i.e. 
uncolored) side under direct light. If the reverse side is to be the 
viewing side, then the printed pattern should be face down before coloring 
and the original drawing should also be face down. A coloring medium, such 
as crayon 58, is preferably provided in a variety of colors sufficient to 
meet the user's taste and needs. Original art work 74 may be pre-printed 
or may be made by the user using a transparent or translucent medium (i.e. 
such as crayons 58) on a transparent or translucent drawing sheet 70 (such 
as tracing paper). The original art work sheet 70 is slipped into the 
frame formed by the sides 73 of the frame 72. Light source 52 is then 
directed into the mirrored bottom of the cabinet 60 thereby illuminating 
the backside of plate 72. The user then notes the color of each cell on 
tracing sheet 54, selects an appropriate crayon 58 or other coloring 
medium as close as possible to the color of the image projected, and then 
colors that cell at an appropriate density or saturation to match the 
projected color. When all cells have been colored in this manner, the user 
will have created art work 61 which has a pleasing mosaic-like quality and 
which may be based on the user's own, possibly crude, original drawing 74. 
A more experienced user might vary the colors and densities in order to 
make individualized art work 61. 
The digitizing screen assembly associated with the toy 50 might be 
supplemented or modified in several ways. The receiving back plate 
sidewalls 73 should be of sufficient thickness to accept both the original 
art work 70 and a supplemental sheet or sheets. A typical supplemental 
sheet might carry a pattern of circles varying in density or a series of 
rainbow colored bands. One partial modification might allow the original 
drawing 70 to act as the rear diffuser 68. In addition, it is possible for 
the digitizing screen assembly to be replaced by a color filter so that 
simple color separations might be prepared by hand. Lastly, special 
processors might be fabricated for use with specific original art work in 
specific formats. For example, a network of optical fibers might 
unscramble pictures which, in scrambled form have been colored by the 
user. 
One unique characteristic of the invention is the ability of the digitizing 
screen assembly to average the brightness of colors and light applied to 
the rear diffuser. It is possible to take advantage of this characteristic 
of the invention in order to produce a digitized color image from a black 
and white original. A selective color screen embodiment 80 is illustrated 
in FIG. 9. A black and white television 82 is shown creating a raster 84. 
A segment of the raster 84 is enlarged and expanded in FIG. 9. A color 
filter sheet 86 is located between the TV screen raster 84 and digitizing 
screen 98. Color filter sheet 86 preferably comprises a plurality of 
orthogonally oriented cells 88, each of which includes three cell areas 
90, 92 and 94. According tot he preferred embodiment cell areas 90, 92 and 
94 are red, green and blue filter area segments respectively. However, 
there could be more or less than three filter cell elements and it is not 
necessary that the filter segments be red, blue or green. Each cell 88 is 
separated by a division line 96 from its neighbors. Digitizing screen 98 
is located on the opposite side of color filter sheet 86 from raster 84 
and comprises a rear diffuser 100, a grid 102 and a front diffuser 104 
structured in the manner described with regard to previous digitizing 
screen assemblies. An image 106 is formed on the front diffuser 104. The 
color of the sections of image 106 are controlled by the selective 
illumination of the cell areas 90, 92 and 94 by television raster 84. It 
is readily apparent that the color of a cell in the viewable image 106 is 
dependent upon the position and the brightness of the illumination behind 
filter areas 90, 92 and 94. For clarity FIG. 9 does not show any cell 
being illuminated through more than one color filter area. However, it is 
not intended that such limitation be inferred. Such a filter might also be 
arranged to provide different brightness levels over different sections of 
the cell. The filter then might be used to produce a variable brightness 
image from a directable light source which may be difficult otherwise to 
vary in intensity. A laser is an example of such a source. 
There are cases where there are specific advantages to digitizing screens 
which are not flat and/or do not have parallel faces. 
A contoured digitizing screen embodiment 110 is shown in FIGS. 10 and 11. 
Television tube 112 supports the three dimensional contour digitizing 
screen 114. Contour screen 114 includes a rear diffuser 116, an interior 
grid portion 118 and a front diffuser 120. The front diffuser 120 is shown 
shaped in a three dimensional likeness of a human head and may be blank or 
may be dressed up with such additions as hair 122, eyeglasses 124, 
eyebrows, or clothing, etc. A small gap 128 may be formed behind the front 
diffuser 120 in order to eliminate cell wall definition. The facial 
features are preferably left uncolored and only loosely defined in the 
shape of the face. Temporary adhesive may be employed to hold the face 110 
in position on the surface of TV tube 112. Grid section 118 preferably 
extends almost the entire distance between front diffuser 120 and rear 
diffuser 116. The cells of grip 118 are preferably uniform but may be of 
different cross section. However, the length of each cell is essentially 
the distance from the front diffuser 120 to the rear diffuser 116 as 
measured perpendicular to the face of the screen of TV tube 112. Gap 128 
may be maintained by occasional spacers at the cell junctions and/or by 
joining the front diffuser 120 and rear diffuser 116 only at the edges. 
Rear diffuser 116 may be included between grid 118 and the screen of TV 
tube 112, however, this may not be necessary where the cells are 
sufficiently long in relation to their cross-section thereby emulating the 
function of the rear diffuser 116. A special video program (either 
broadcast, prerecorded, or computer generated) typically presents an image 
of a human face on the screen of TV tube 112. The facial image 126 matches 
the size and position of the modeled facial assembly 110. Light from each 
portion of the image is carried through its associated cell in grid 118 to 
illuminate the associated portion of front diffuser 120. Thus the 
contoured front diffuser 120 appears to be an articulated human face 126. 
This effect may be enhanced by the use of cell mirroring or tapering as 
previously discussed. A specific enhancement that might be useful is to 
provide a graded filter at the rear diffuser 116 to balance the brightness 
of the image thereby providing greater brightness in portions of the 
facial image where the front diffuser 120 is least parallel to the TV 
screen. This is necessary as the output ends of the cells in those areas 
will be substantially larger than the input ends. Additional balancing may 
also be necessary to account for differing cell lengths where there is 
significant loss of light over a long individual cell. The preferred 
method of light balancing is by appropriately patterning a filter placed 
between the rear diffuser 116 and the face of TV tube 112. The use of such 
a filter would avoid the need for brightness balancing by other methods. 
Such a filter could also be used to introduce graded color to the modeled 
front diffuser 120 so that it might be used more effectively with black 
and white television. Although some color could be introduced by other 
means, such as coloring the front diffuser 120, it is believed to be more 
economical to color a flat surface. The technique illustrated in FIGS. 10 
and 11 could also be employed as a selective color screen located over a 
black and white television such as described with reference to the 
technique illustrated in FIG. 9. The contoured surface of the front 
diffuser 120 need not necessarily be in the shape of a face, but could, 
for example, be a terrain model or a geometric solid, for example a 
hemisphere could produce the illusion of a rotating earth. Moreover, the 
image producing system need not include a television, but could, for 
example, be the image storage or production system of the invention such 
as illustrated in FIGS. 1, 2, 3, 4, 5 and 6. 
A useful variation of the contoured digitizing screen concept would be to 
distort the screen to accomodate a specific input format. For example, the 
grid 118 and diffusers 116 and 120 could be formed into nested cylinders 
with a light bulb in the center so that art work on or inside the interior 
of the rear diffuser 116 could be rotated by a heat motor. Mask and art 
work configurations could be varied to provide a different effect. The 
rear diffuser 116 and the rear face grid 118 might also be shaped to fit a 
portion of a cylinder so that a screen which appears flat to the viewer 
could contain art work and a drive system such as just described. Likewise 
the rear diffuser 116 might comprise the rotating cylinder that carries 
the art work. 
FIGS. 12A and 12B disclose an embodiment 140 of the digitizing screen and 
storage means which increases the resolution of the invention by a factor 
of four without requiring additional mechanical precision or complexity. 
According to embodiment 140 the normal grid cells 142 shown on the left 
side of FIG. 12A are replaced by grid cells 146 having one-half the 
dimensions of grid cells 142 and therefore one-quarter the area. Grid 
cells 146, also referred to as minicells 146, are positioned so that every 
second cell wall 148 coincides with the previous position of each wall of 
a larger cell 142. A mask 144 is located in the conventional location with 
transparent bands now crossing alternate cell walls 148 of minicells 146. 
With this arrangement the graphic information carried on one graphic 
storage element of a slide 16 behind the assembly 140 will be presented to 
a position at the intersection of four minicells 146. Each quadrant of 
that graphic element will then be expanded to cover one minicell 146. 
Accordingly, the images on the front face of the digitizing screen will 
have a greater and sometimes more desirable resolution. The embodiment 140 
may be achieved either by making a grid entirely or partially out of 
minicells 146. 
While the invention has been described with reference to the preferred 
embodiment thereof it will be appreciated by those of ordinary skill in 
the art that modifications can be made to the various embodiments and the 
parts thereof without departing from the spirit and scope of the invention 
as a whole.