Method and apparatus employing gravity to form a variable message on a sign

A device for forming a changeable sign from either gas bubbles rising within a body of liquid or from drops of liquid moving through the air. When using gas bubbles rising within a body of liquid, the gas bubbles are released sequentially such that a message of the sign is represented as a matrix of bubbles. When using drops of liquid moving through the air, the drops are released sequentially and controllably such that the message of the sign is represented as a matrix of drops of liquid. In one version, air bubbles are released near the bottom of a tank from controllable valves. The valves can be arranged in a single line or in a vertical matrix. As an alternative, a template having a message formed as a dot matrix is applied against a matrix of orifices from which gas escapes, to form the message. In another version, water drops are released from a row of controllable valves on a ballistic trajectory, e.g., a free-fall. As an alternative, the row of valves can be used normally to produce a continuous series of streams of water, but the streams can be interrupted while the message is produced from a dot matrix of drops.

BACKGROUND OF THE INVENTION 
The present invention relates to a display device and method that employ 
gas or liquid to form variable messages therein. More particularly, the 
message is formed from gas bubbles or drops of liquid that represent a 
shape and/or alphanumeric characters depicted by a dot matrix of bubbles 
or drops, respectively. 
Prior art merchandising display devices have the objective of conveying a 
message regarding the merchandiser's product or service. The effectiveness 
of such a message is roughly proportional to the amount of time that a 
viewer spends considering the message. A way to prolong the amount of time 
that a viewer considers a merchandiser's message is to present the message 
in a dynamically developing creative fashion; for example, skywriting. A 
visually arresting sign can greatly enhance the effectiveness of the 
message displayed. 
U.S. Pat. No. 2,308,060 to de Rochefort-Lucay and U.S. Pat. No. 4,122,618 
to Gay show skywriting devices which emit a plurality of individual puffs 
of smoke from a linear array of valved outlets which are programmed to 
open and close so as to produce a predetermined message. The '060 and '618 
patents generally show a combination of a means to control emission of a 
first medium (smoke/vapor), that has a diminishing velocity whose initial 
velocity is non-zero, with another medium (air) to produce a legible 
message or display. The effect of gravity is not used to produce the 
message. 
U.S. Pat. No. 3,640,463 to Kawamura et al. shows a water fountain that 
forms shapes and/or alphanumeric characters out of columns of water. The 
fountains of the '463patent are intended to be viewed from an elevation 
significantly above the fountain, e.g., overhead. FIG. 9 shows an array of 
controllable nozzles for forming shapes and/or alphanumeric characters via 
dot matrix representation, under the control of the control circuit of 
FIG. 10. Each dot in the matrix corresponds to a column of water. The 
message to be displayed is stored on a stencil as in FIG. 11 which is read 
by the reader of FIG. 12. The effect of gravity precludes the '463 
patent's fountains from being legible to an observer from any position 
other than at an elevation significantly above the fountain, e.g., 
overhead. 
U.S. Pat. No. 4,111,363 to Kawamura et al. shows an improvement upon the 
'463 patent. The jets that form the columns of water are tiered so as to 
make the display legible to an observer that is not necessarily elevated 
above the fountain. 
U.S. Pat. No. 1,221,494 to Wiley shows a sign formed by blowing flakes, 
shreds or chips, or other light particles through a vertical stencil in 
continuous streams. The effect of gravity destroys rather than produces 
the message of the sign. 
U.S. Pat. No. 3,973,340 to Khawand shows a set of closely spaced vertical 
tubes. Through those tubes are passed immiscible fluids. Shapes and/or 
alphanumeric characters are formed by selectively alternating the fluids, 
such that a message is formed out of a first fluid contrasted with a 
second background fluid. The effect of gravity is used to produce the 
sign, in conjunction with the necessary fluid confinement within the 
tubes. 
U.S. Pat. No. 3,717,945 to Taylor et al. and U.S. Pat. No. 3,560,641, also 
to Taylor et al. show an arrangement for producing variable 3-dimensional 
displays. It involves an electrostatic system that permits certain drops 
of fluid to fall while other drops are diverted to a collector using 
electrostatic forces. The system employs stroboscopic flash lamps that are 
used to illuminate a pattern of falling drops and essentially "fix" the 
pattern in space insofar as an observer is concerned, due to the phenomena 
of persistence of vision. Whether a falling drop is made visible to an 
observer is determined by whether it is allowed to pass unaffected through 
the deflection electrodes 44 FIG. 1 or is deflected by the deflection 
electrodes into a catcher unit 45 so as to be prevented from falling into 
the viewing area. 
None of these prior art devices take full advantage of the relative motion 
effects of gravity on fluid particles of different respective densities 
and an observer's likely fascination with the phenomenon of air bubbles 
rising within water, or water droplets falling through air. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide a method and apparatus 
for forming a visually arresting sign. 
It is an object of the present invention to provide a method and apparatus 
for using gravity to form a visually arresting sign, for a merchandising 
device, whose message is variable and dynamically formed. 
As a further object of the invention to provide a method and apparatus 
using gravity to form a visually arresting sign whose message is variable 
and is represented by a dot matrix of gas bubbles or drops of liquid, 
respectively, that represent shapes and/or alphanumeric characters. The 
embodiments that employ gas bubbles rising within a liquid take advantage 
of a person's normal fascination with air bubbles rising within water to 
prolong the length of time that an observer concentrates upon the sign. 
The embodiments directed toward forming a sign out of drops of liquid 
moving through the air take advantage of a person's lifelong sensual 
appreciation of dripping water, and to a similar extent, a person's 
fascination with the natural beauty of waterfalls. 
A first embodiment of the present application fulfills objectives of the 
present invention, i.e., forming a changeable message on a sign from gas 
bubbles rising within a body of liquid, by: 
releasing sequentially a plurality of bubble groups within the body of 
liquid; 
each bubble group including at least one gas bubble; 
the message of the sign being represented as a matrix of dots; 
each dot of the matrix being a gas bubble; 
each bubble group corresponding to a row of the dot matrix; 
the gas being less dense than the liquid such that bubbles rise uniformly 
under gravity's effect. 
An exemplary apparatus corresponding to the first embodiment includes: 
a body of liquid; 
a source of the gas; 
a plurality of controllable valves, connected to the source of gas, and 
arranged to release gas into the body of liquid; 
a controller for controlling the valves to selectively open such that the 
gas is released from each selected valve to form a bubble in the liquid, 
thus forming a bubble group; 
the controller releasing sequentially a plurality of bubble groups within 
the body of liquid; 
each bubble group including at least one gas bubble; 
a message of the sign being represented as a matrix of dots; 
each dot of the matrix being a gas bubble; 
each bubble group corresponding to a row of the dot matrix; 
the gas being less dense than the liquid such that the bubbles rise 
uniformly under gravity's effect. 
A second embodiment of the present application satisfies objectives of the 
present invention, i.e., forming a changeable message on a sign from gas 
bubbles rising within a body of liquid, and includes: 
a body of liquid; 
a source of the gas; 
a plurality of controllable valves, each valve having an orifice, the 
orifices being arranged in a matrix, the valves being connected to the 
source of gas, and further arranged to release gas into the body of 
liquid; 
a controller for controlling the valves to selectively open such that the 
gas is released from each selected valve to form a matrix of bubbles in 
the liquid, thus forming a bubble group; 
the message of the sign being represented as a matrix of dots wherein the 
dots are bubbles; 
the orifice matrix being of sufficient dimension such that a bubble group 
can form at least one row of alphanumeric characters; 
the gas being less dense than the liquid such that a row rises uniformly 
under gravity's effect. 
A third embodiment of the present application fulfills the objectives of 
the present invention, i.e., forming a changeable message on a sign from 
gas bubbles rising within a body of liquid, and includes: 
a body of liquid; 
a source of the gas; 
a gas chamber; connected to the source of gas; 
the gas chamber having a first surface with a plurality of apertures 
therein through which the gas escapes, the surface being substantially 
vertical and flat; 
the plurality of apertures being arranged in a matrix; 
a stencil, disposed against the first surface such that the matrix of 
apertures is sealed; 
the stencil having a plurality of apertures therein disposed in a matrix 
such that the stencil's apertures permit gas to escape from the gas 
chamber when aligned with the first surface's apertures; 
the stencil's matrix being arranged to represent alphanumeric characters; 
gas escaping as bubbles from aligned stencil and first surface apertures 
forming a alphanumeric bubble matrix characters of the sign. 
A fourth embodiment of the present application fulfills objectives of the 
present invention, i.e., forming a changeable message on a sign from drops 
of liquid moving through the air, by: 
releasing sequentially and controllably, from controllable valves, a 
plurality of groups of the drops into the air, the drops following a 
ballistic trajectory; 
each group of drops including at least one drop of liquid; 
the message of the sign being represented as a matrix of dots; 
each dot of the matrix being a drop of the liquid; 
each group of drops corresponding to a row of the dot matrix; 
a set of the groups of dots, as a whole, forming at least one alphanumeric 
character discernable by a viewer. 
An exemplary apparatus corresponding to the fourth embodiment, for forming 
a changeable sign from drops of liquid moving through the air, includes: 
a source of the liquid; 
a plurality of controllable valves, connected to the source of liquid, and 
arranged to release the liquid; 
a controller for controlling the valves to selectively open such that the 
liquid is released from each selected valve to form a drop; 
the controller releasing sequentially a plurality of groups of the drops 
into the air, the drops following a ballistic trajectory; 
each group of drops including at least one drop of liquid; 
the message of the sign being represented as a matrix of dots; 
each dot of the matrix being a drop of the liquid; 
each group of drops corresponding to a row of the dot matrix; 
a set of the groups of dots, as a whole, forming at least one alphanumeric 
character discernable by a viewer. 
The foregoing and other objectives of the present invention will become 
more apparent from the detailed description given hereinafter. However, it 
should be understood that the detailed description and specific examples, 
while indicating preferred embodiments of the invention, are given by way 
of illustration only, since various changes and modifications within the 
spirit and scope of the invention will become apparent to those skilled in 
the art from this detailed description.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
A first embodiment of a display device 8 for forming a changeable message 
from gas bubbles rising within a body of liquid, associated with a 
merchandising device, is depicted in FIG. 1. The changeable message 
depicted in FIG. 1 is "DRINK COKE", where the term "COKE " is a registered 
trademark of the Coca-Cola. A tank 10 contains liquid 12. The tank 10 has 
a vent 34 leading to the atmosphere. Bubbles 38 are grouped together as a 
bubble matrix 30. As the bubble matrix 30 rises within the liquid 12 
toward the surface 32 of the liquid, a shape or message of alphanumeric 
characters becomes discernable by an observer. The message incrementally 
dissipates, or disappears as the bubbles reach surface 32. 
A plurality of solenoid valves 14 are connected to the tank by air jets 36. 
In actuality, there would be significantly more solenoid valves than are 
depicted in FIG. 1, FIG. 1 having been simplified for clarity of 
illustration. Each solenoid valve 14 includes a valve 18 and a solenoid 
16. 
A valve 18 is connected to a valve supply line 20 which is connected to a 
main supply line 22 through which gas passes from the gas source 24. A 
controller 26 is connected to the solenoid valves by a plurality of 
solenoid control lines 28. In other words, each solenoid 16 is connected 
to the controller 26 by its own solenoid control signal line 31. 
The gas source 24 may include components that are well-known in the art, 
for example, a gas reservoir connected to a pump driven by an electric 
motor. The depth of the water within the tank is preferably sufficient 
such that an observer can concentrate upon the shape and/or message formed 
for a sufficient amount of time to ensure that the message is visibly 
discernible. 
The controller can take the form of a computer, running a program, 
connected to the solenoid control line 28 via an electrical interface or 
an electro-optical interface connected to a set of electronic drivers. 
Alternatively, the controller can take the form of discrete electronic 
logic components or a combination of discrete electronic logic components 
and opto-electronic components. In particular, the formation of 
alphanumeric characters and shapes is analogous to the techniques used in 
the dot matrix printing art and related ink jet and laser printing arts. 
FIG. 2 depicts the bubble matrix 30 in greater detail. An imaginary grid 46 
is superimposed upon the bubble matrix 30 for purposes of explanation, in 
order to demonstrate the analogy to a dot matrix display field. The 
imaginary grid 46 includes rows 40 and columns 42. The alphanumeric 
character 44 corresponds to the letter "D". 
The operation of the apparatus of FIG. 1 will now be described. The 
controller 26 sequentially releases a plurality of bubbles into the liquid 
12 in the tank 10. Each plurality of bubbles released can be referred to 
as a group, and each such bubble group represents a row 40 in the bubble 
matrix 30. A message is represented in dot matrix form by the bubble 
matrix 30, with each bubble acting as a dot. 
A gas that is less dense than the liquid is chosen so that the bubbles rise 
uniformly under gravity's effect. The upward flow of the bubbles is 
preferably laminar. The gas forming the bubbles 38 is preferably air while 
the liquid 12 is preferably water. Further, the viscosity of the liquid 12 
should be high so that the rate at which the gas bubbles 38 rise is slow. 
The slower the rate at which the gas bubbles 38 rise within the liquid 12, 
the more easily an observer can discern the message represented by the 
bubble matrix 30. In addition, the refractivity and reflectivity of the 
gas and liquid are chosen to maximize a person's ability to distinguish 
visually the bubbles rising within the liquid. 
At least the obverse surface of the tank 10 is transparent. The bubbles are 
preferably released near or at the bottom of the liquid in order to 
maximize the distance that the bubbles can rise. By maximizing this 
distance, the observation time is maximized. 
FIG. 3 depicts an overhead view of an arrangement of the air jets 36 within 
the tank 10. The air jets 36 are arranged in a line parallel to the 
obverse surface 48 of the tank 10. Similarly, FIG. 4 depicts another 
overhead view of an alternative arrangement of the air jets 36 within the 
tank 10. A first line of air jets 36 is arranged parallel to a first 
obverse surface 50 while a second line of air jets 36 is arranged parallel 
to a second obverse surface 52. 
In general, any vertical surface obverse to an observer can have a parallel 
line of jets arranged in relation thereto. One must be careful in 
considering lines of air jets that are parallel to one another, i.e., 
across the tank. An observer on one side of the tank would be able to see 
the bubbles rising on the other side of the tank, which could lesson the 
discernability of the bubble matrix immediately in front of the observer, 
depending upon the distance between the parallel lines of air jets. 
FIG. 5 depicts a second embodiment of an apparatus performing a changeable 
sign from gas bubbles rising within a body of liquid. Only the differences 
between the second embodiment depicted in FIG. 5 and the first embodiment 
depicted in FIG. 1 will be discussed. In FIG. 5, a matrix 56 of orifices 
54 is positioned within the liquid 12 contained within the tank 10. An 
orifice 54 is connected to its own solenoid valve 14 (not shown in FIG. 
5). 
A controller 26 (not shown in FIG. 5) differs from that shown in FIG. 1 by 
having to control a two-dimensional array of solenoid valves rather than a 
single row of solenoid valves. In operation, the embodiment depicted in 
FIG. 5 can produce whole shapes and/or alphanumeric characters at one time 
rather than assembling a shape and/or an alphanumeric character one row at 
a time. 
FIG. 6 depicts a third embodiment for forming a changeable sign from gas 
bubbles rising within a body of liquid. A gas source 24 is connected to a 
solenoid 14 by a main supply line 22. A gas jet 36 connects the solenoid 
14 to gas chamber 58. Gas chamber 58 has a front face 60 (to be discussed 
below in connection with FIG. 7). Against the front face 60 is arranged a 
scrolled stencil 64. The stencil 64 is semi-flexible so as to permit it to 
be scrolled. 
A dot matrix representation of a shape and/or alphanumeric characters is 
formed into the stencil 64 by apertures 66, i.e., and aperture 66 acts as 
a dot in the dot matrix. FIG. 7 depicts the gas chamber 58 in more detail. 
The front surface 60 of the gas chamber 58 has apertures 62 that form a 
matrix of apertures. When the scrolled stencil 64 is positioned against 
the matrix of apertures 60, i.e., the front face, then apertures 62 in the 
front face 60 are selectively uncovered by apertures 66 in the scroll 
stencil 64. 
The stencil 64 can be scrolled horizontally across the front face 60 as 
depicted in FIG. 6, or can be scrolled vertically across the front face 60 
of the gas chamber 58 as depicted in FIG. 8. In the instance in which the 
stencil is scrolled vertically across the front face 60 of the gas chamber 
58, the matrix of apertures in the front face 60 can be a one-dimensional 
row. 
If the size of the front face's 60's matrix of apertures is significant, 
then the size its apertures 62 and/or the apertures 66 in the stencil 64 
should be selected as a function of the aperture's depth in the liquid 
relative to the other apertures such that the gas bubbles appear uniformly 
size while rising. In other words, the lower the depth at which a gas 
bubble is released, the larger the gas bubble should be initially. Such a 
determination is within the ordinary level of skill in the art taking into 
consideration Boyle's Law and the pressure of the liquid as a function of 
depth. Alternatively, instead of adjusting the size of the orifice, the 
duration that the solenoid valve is open could be adjusted as a function 
of depth wherein the longer the valve is opened, the greater the volume of 
gas that will be released. 
An alternative arrangement of the third embodiment involves permanently 
drilling the matrix of holes in the backside of the gas chamber. By 
pulsing the solenoid valve, gas bubbles are emitted to form the shape 
and/or alphanumeric characters which the aggregate of the holes 
represents. 
FIG. 9 depicts a fourth embodiment for forming a changeable sign from drops 
of liquid moving through the air. A source of liquid 76 is connected to 
the main supply line 70. Each of valve supply lines 72 is connected to the 
main supply line 70 as well as to its respective solenoid valve 14. In 
actuality, there would be significantly more solenoid valves than are 
depicted in FIG. 9, FIG. 9 having been simplified for clarity of 
illustration. 
The drops 76 being released from the solenoid valves 14 collectively form a 
drops-of-liquid matrix 78 that displays shapes and/or alphanumeric 
characters. FIG. 9 illustrates the circumstance in which the ballistic 
trajectory of the drops is simply a free-fall from the solenoid valves. 
An alternative embodiment is depicted in FIG. 10. In FIG. 10, the drops are 
released along a ballistic trajectory. 
In operation of the embodiment of FIG. 10, groups of drops are sequentially 
released from the solenoid valves 14 into the air, the drops free-falling 
(a particular example of a ballistic trajectory). As with the path of the 
gas bubbles in the preceding embodiments, the trajectory of the dots in 
this embodiment is preferably laminar. The liquid is preferably water, and 
may be colored to enhance visibility. 
Preferably, the distance that the groups of drops fall, either from the 
apex of the ballistic projectary, or from the solenoid valves in the case 
of a free-fall, should be sufficient such that an observer can concentrate 
his attention on the shape or alphanumeric characters formed by the 
drops-of-liquid matrix for a minimal amount of time. 
The controller 74 for the fourth embodiment is very similar to the 
controller discussed in the preceding embodiments, and, thus, well within 
the level of ordinary skill in the art. In addition to only releasing 
drops such that shapes and/or alphanumeric characters are represented, the 
controller can also operate the solenoid valves to create a conventional 
waterfall. The controller can cause a message and/or shape to appear 
randomly and/or periodically. If the shape and/or message is controlled to 
appear randomly, people will watch the waterfall in anticipation. 
An alternative embodiment of the sign formed by drops of liquid moving 
through the air involves the use of colored oil and water. The colored oil 
is used to deliver the message. Because oil and water do not mix, the oil 
could be separated from the water and reused. 
The invention being thus described, it will be obvious that the same may be 
varied in many ways. Such variations are not to be regarded as a departure 
from the spirit and scope of the invention and all such modifications as 
would be obvious to one skilled in the art are intended to be included 
within the scope of the following claims.