Method and apparatus for displaying graphic and alphanumeric data

A method and apparatus for displaying the graphic and alphanumeric data of the type utilizing pixel matrix panels with an outside light source. The method comprises reflecting the outside light on a preselected colored surface, rotatably housed within each matrix pixel. Every pixel comprises a cylindrical container (1) having a transparent non-flat cap (3) at one of bases, the other base being missing. The container (1) houses a radiation deflector (5) and a hollow cylinder (7) having two or more reflecting areas (10), differently colored, located on its lateral surface (9). An external light radiation enters the container through the cap (3), is deflected by the deflector (5) and is reflected by one of the reflecting areas to be again deflected and directed to the outside. The hollow cylinder (7) is operated by an electromagnetic control so as to alternatively present to the deflected radiation a preselected colored area.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to an outside light source display for black and 
white and/or colour visualization of graphic or alphanumerical data. The 
display has been particularly designed for an outdoor use utilizing 
sunlight as a light source, but it can work as well with artificial light 
by night and indoor. Also, the invention, utilizing pixel matrix panels, 
has a modular structure, thus covering a wide range of dimensions 
according to each particular need, from the shop to the stadium. 
2. Description of the Prior Art 
As it is known, display apparatuses divide into two main families according 
to where the light source is. Displays with an internal light source can 
be those using a matrix of LEDs or of incandescent lamps, or those 
utilizing a matrix of video monitors each showing a portion of the whole 
image. They both are rather expensive and require a high power consumption 
of many kWatts per square meter. The display apparatuses utilizing an 
outside light source can be represented by the common display used in 
airports and/or stations to give passangers the required information about 
leaving/arriving times etc. The messages are formed by rotation of a 
number of tesseras, each mounted by one of its sides on a support rod as 
sheets in a book. These displays do not require a high power consumption 
and are quite resistant, but they can show only a number of predetermined 
messages and images. Moreover they must be kept free from dust, thus 
limiting their use outside. 
Another apparatus utilizing an outside light source is a matrix based 
display, each matrix comprising a number of plaques or cubes with 
differently coloured faces which are magnetically or mechanically rotated. 
Also this display is affected by dust, even if it has a transparent 
external surface: the dust accumulated on the cube faces has to be cleaned 
away to restore the original colours brightness. Both these two latter 
displays are rather economical and they can preserve the message also 
during a power failure, but their use outdoor is limited by their bad 
resistance to varying weather, they are not flexible enough, and the ratio 
of representative surface versus total surface is too low. Thus the need 
remains of a display apparatus which: utilizes pixels matrix panels, where 
the pixels have dimensions going from about 5 mm to about 50 mm. and can 
have at least 3 colours plus black and white; is weather resistant and 
without openings, so that it can easily be washed; has a representative 
efficiency which is more than 80%; can preserve the message also during a 
power failure; requires a low capacity, of about 50 watts per square 
meter; has a modular structure, where each module is easily replaceable; 
and utilizes an outside light source. 
SUMMARY OF THE INVENTION 
An object of this invention is therefore to provide a method and an 
apparatus for displaying information having the mentioned requirements. 
Accordingly, the invention provides a method for visualizing black and 
white and/or color graphic and/or alphanumerical communications, of the 
type utilizing pixel matrix panels with an outside light source, 
characterized in that, in connection with every pixel, luminous energy is 
drawn from the outside through a transparent surface and is deflected by a 
radiation deflector to hit one of two or more coloured reflecting areas 
belonging to a movable element; the thus reflected radiation is again 
deflected and sent outside through the same transparent surface; said 
movable element being shiftable in such a way that the entering deflected 
radiation hits one of its coloured reflecting areas selected at will. 
The invention also provides an apparatus for visualizing black and white 
and/or colour graphic and/or alphanumeric communications, of the type 
utilizing pixel matrix panels with an outside light source, characterized 
in that every pixel comprises: a container or cell open on one side and 
having one surface made of a transparent material; a radiation deflector; 
a movable element having two or more differently coloured reflecting 
areas, one of which is struck by the deflected light radiation; a drive 
for controlled shifting of said movable element, in order to put one of 
its coloured areas in a reflecting position of the deflected light 
radiation. 
According to another aspect of the present invention, it is also provided a 
process for making a module or submatrix as above stated, characterized in 
that: a module casing is made by injection molding of a transparent 
polymeric material, said casing having a plurality of non-flat caps, and 
having, connected with each cap, a radiation deflector and a cylindrical 
recess closed by said radiation deflector; a plurality of hollow rotatable 
cylinders are separately made, each cylinder having an open base, a number 
of coloured reflecting areas placed on its inner or outer lateral surface, 
and a permanent magnet or a metal sector on its closed base; each hollow 
cylinder is placed in one cylindrical recess; the matrix is closed with a 
plate having electromagnets facing each hollow cylinder base; a vacuum is 
obtained inside the matrix by means of passages connecting said 
cylindrical recess and a port connecting the inside of the matrix with the 
environment; the matrix is nearly completely filled with a dielectric 
fluid; the cited environment connecting port is closed; and the outside of 
the non-flat caps is covered with a multidieletric and/or antiscratch 
material. 
The invention is described in detail in the following passages of the 
specification referring to the accompanying drawings, which however are 
merely illustrative of how the invention might be put into effect. So the 
specific form and arrangement of the invention features shown are not to 
be understood as limiting the invention. 
In the drawings:

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The example pixel as shown in FIG. 1 includes a hollow body 1 which serves 
as a container or cell, has a cylindrical shape and is open on its base 2. 
The closed base is shaped as a non-flat cap 3, spherical or not spherical 
according to end-use requirements and is made of transparent material, 
which in the preferred embodiment is a polymeric transparent material. The 
cap 3 defines the representative surface of the pixel and to this purpose 
is coated with one or more layers 4 of a multidielectric and/or scratch 
resistant material. 
Inside the cell 1, near the inner surface of cap 3 is located a radiation 
deflector 5 which can be made integral with the cell 1. 
In this case the whole cell 1 can be made of injection molded transparent 
polymeric material and the radiation deflector 5 can be any deflecting 
device, but preferably is a mirror or a layer of deflecting material 
placed on the protuding part 6 of cell 1. In the shown preferred 
embodiment the deflector is at 45.degree. with the cell optical axis, but 
it can be placed also at different angles. 
Inside the cell 1 a hollow cylinder 7 is placed having a radius not much 
smaller than that of the cell 1. The cylinder 7 is missing of one of its 
bases, thus being formed by a base 8 and a lateral surface 9 on which 
coloured reflecting areas 10 are located. These areas 10 can be located on 
the inner side or on the outer side of the cylinder lateral surface 9; in 
the latter case the lateral surface 9 should be made of transparent 
material. The cylinder 7 is placed into cell 1 with the radiation 
deflector 5 partially housed within the cylinder 7, with the base 8, 
thereof, partially closing the cell 1. 
The coloured reflecting areas 10 generally consist of a layer of coloured 
reflecting material plated on the inner or outer side of the lateral 
surface 9. In one possible embodiment of the invention, the cylinder 7 has 
a polygonal section comprising a plurality of level areas, as shown in 
FIG. 2, each having its longitudinal axis parallel to the cell optical 
axis, and each plated with a differently coloured reflecting material, 
thus forming the areas 10. In this case, the cylinder 7 and protuding part 
6 are so sized as to allow a free cylinder rotation about its own axis. 
The cell 1 is sealingly closed on its back by a plate 11 which also serves 
as a pivoting support for the cylinder 7 by having on the cylinder 
rotation axis a pinhole 12 mating with a pin 13 located on the base 8 of 
cylinder 7. 
Obviously the pin and pinhole can be arranged vice-versa. When the example 
pixel of FIG. 1 is exposed to a light source (natural or artificial), the 
radiation enters the pixel through the layer 4, the cap 3 and the 
protuding part 6 to be deflected by the radiation deflector 5. In this 
case the light is deflected substantially at 90.degree. and hits that 
reflecting area 10 which is located perpendicularly to the deflected light 
rays, forming on and within said area 10 an elongated focal spot having 
roughly the same area as the transparent cap 3. The thus reflected 
radiation is again deflected by the deflector 5 and sent to the outside 
through the same protruding part 6, cap 3 and layer 4. 
In order to select another reflecting area 10, for changing the colour 
appearing through the cap 3, the cylinder 7 is rotated on its pivoting 
support consisting of the mating pin 13 and pinhole 12. Any convenient 
device may be used to this purpose; in FIGS. 3 and 4 a preferred 
embodiment is shown, consisting in an electromagnetic drive. In the 
embodiment utilizing an electromagnetic drive shown in FIGS. 3 and 4, the 
base 8 of cylinder 7 houses a permanent magnet 14 whose poles are 
symmetrically disposed about the cylinder rotation axis. The closing plate 
11 consists of two separate plates 11' and 11", namely a closing plate 11' 
and a supporting plate 11". The closing plate 11' is located near the base 
8 and houses a pair of magnetizable elements 15 for every couple of 
axially opposed reflecting areas 10. These elements 15 are placed 
symmetrically to the cylinder rotation axis, at the same distance from 
said rotation axis as said poles of permanent magnet 14. 
Outside and near plate 11' is located a plate 11" which removably houses 
one electromagnet 16 for each pair of magnetizable elements 15. The 
electromagnets 16 are aligned with the corresponding pairs of magnetizable 
elements 15 and they can be selectively activated by means of electrodes 
to selectively magnetize one couple of elements 15, thus controlling the 
rotation of magnet 14 and cylinder 7. 
Every pixel is sealingly closed by the closing plate 11 but it is also 
provided with an orifice 19 through which air is driven from the inside of 
the pixels by means of a suction device (not shown) to be replaced by a 
dielectric fluid. This fluid preferably is a silicone oil, and it fills 
nearly completely all the unoccupied spaces inside the pixel so that only 
a small volume of gas, not interfering with the radiation path, is left 
therein, to allow for thermal contractions and expansions. 
The final display apparatus may be made of a number of single pixels, but 
it is preferred to have a matrix panel consisting of two or more modules. 
As shown in FIGS. 5 and 6, each module comprises a casing 20, preferably 
made by injection molding, which has a plurality of caps 3, each connected 
with a hollow sleeve-like cylinder forming a plurality of cells 1. Each 
cell houses the same radiation deflector 5 and hollow cylinder 7 
previously described; also the pivoting support 12, 13 and the 
electromagnetic drive are the same, while only one closing plate 11 is 
used, wide enough for the whole structure. Each pixel communicates with 
the next one through the orifice 19, and only one of them communicates 
with the outside through a last closable orifice 21. The whole module is 
first put under vacuum and then filled with the cited dielectric fluid 
leaving only a small amount of gas housed in a plurality of housings in 
the upper side of the module to allow for thermal expansions and 
contractions. 
As previously cited, electromagnets 16 are energized by means of electrodes 
connected to a computer; in a matrix panel having N pixels per column and 
M pixels per line, the total number of electrodes necessary to control the 
display is 2N+aM, where "a" is the number of coloured reflecting areas 10, 
while the total electrodes in a four colour panel of the present state of 
the art are 6N.times.M. 
It will be clear from the foregoing description that the present invention 
provides an effective economical and resistant display apparatus, which is 
ideally suited for outdoor and daylight use.