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About Neon
Inventor of the First Neon Lamp
Where did the word “neon” come from? The word neon comes
from the Greek "neos," meaning "the new gas." Neon gas was
discovered by William Ramsey and M. W. Travers in 1898 in
London. Neon is a rare gaseous element present in the
atmosphere to the extent of 1 part in 65,000 of air. It is
obtained by liquefaction of air and separated from the other
gases by fractional distillation.
The French engineer, chemist, and inventor Georges Claude
(b. Sept. 24, 1870, d. May 23, 1960), was the first person
to apply an electrical discharge to a sealed tube of neon
gas (circa 1902) to create a lamp. Georges Claude displayed
the first neon lamp to the public on December 11, 1910, in
Paris.
Georges Claude patented the neon lighting tube on Jan. 19th,
1915 - U.S. Patent 1,125,476.
In 1923, Georges Claude and his French company Claude Neon,
introduced neon gas signs to the United States, by selling
two to a Packard car dealership in Los Angeles. Earle C.
Anthony purchased the two signs reading "Packard" for
$24,000.
Neon lighting quickly became a popular fixture in outdoor
advertising. Visible even in daylight, people would stop and
stare at the first neon signs dubbed "liquid fire."
Hollow glass tubes that are used to make neon lamps for neon
signs come in 4, 5 and 8 ft lengths. To shape the tubes, the
glass is heated by lit gas and forced air. Several
compositions of glass are used depending on the country and
supplier. What is called 'Soft' glass has compositions
including lead glass, soda-lime glass, and barium glass.
"Hard" glass in the borosilicate family is also used. We at
Hope Neon Ltd. use lead glass for most of our neon signs.
Depending on the glass composition, the working range of
glass is from 1600' F to over 2200'F. The temperature of the
air-gas flame depending on the fuel and ratio, is
approximately 3000'F using propane gas.
The tubes are scored (partial cut) with a file and then
snapped apart. Then we create the angle and curve
combinations. When the tubing is finished, the tube must be
processed. The procedure is called "bombarding". The tube is
partial evacuated of air. Next, it is short circuited with
high voltage current until the tube reaches a temperature of
550 F. Then the tube is evacuated again until it reaches a
vacuum of 1 micron. Argon or neon is back filled to a
specific pressure depending on the diameter of the tube and
sealed off. In the case of an argon-filled tube, additional
steps are taken for the injection of mercury. Funny, but a
large percentage of tubes are filled with argon, but they
are still known as “neon” tubes. Not often do people call
them an “argon” tube
Red is the color neon gas produces, neon gas glows with its
characteristic red light even at atmospheric pressure. There
are now more than 150 colors possible; almost every color
other than red is produced using argon, mercury and
phosphor. Neon tubes actually refer to all positive-column
discharge lamps. The colors in order of discovery were blue
(Mercury), white (Co2), gold (Helium), red (Neon), and then
different colors from phosphor-coated tubes. The mercury
spectrum is rich in ultraviolet light which in turn excites
a phosphor coating on the inside of the tube to glow.
Phosphors are available in most any pastel colors.
Manufacturing process
Lead glass tubing in external diameters ranging from about 8
to 15 mm is most commonly used in producing neon tubes for
neon signs. The tube is heated in sections using several
types of burners that are selected according to the amount
of glass to be heated for each bend. These burners include
ribbon, cannon, or cross fires, as well as a variety of
torches that run on a simple combination of natural gas
(butane or propane work better, however natural gas is
cheapest) and air.
A section of the glass is heated until it is malleable; then
it is bent into shape and aligned to a pattern containing
the graphics or lettering that the final product will
ultimately conform to your custom neon sign.
An electrode is melted (or welded) to each end of the tube
as it is finished. The electrodes are also lead glass and
contain a small metal shell with two wires protruding
through the glass to which the sign wiring will later be
attached. All welds and seals must be perfectly leak-proof
before proceeding further. These electrodes are painted with
a special black glass paint that virtually goes unseen and
hidden in your custom neon sign.
The tube is attached to a manifold which is itself attached
to a high-quality vacuum pump. The tube is then evacuated of
air until it reaches near-vacuum. During evacuation, a high
current is forced through the tube via the wires protruding
from each electrode (in a process known as "bombarding").
The current depends on the specific electrodes used and the
diameter of the tube, but is typically in the 500mA to
1000mA range, at an applied voltage usually between 15,000
to 25,000V. The bombarding transformer acts as an adjustable
constant current source, and the voltage produced depends on
the length and pressure of the tube. Typically our operator
will maintain pressure in the tubes as the bombarder bombard
electrons hence heating the tube. This very high power
dissipation in the tube heats the glass to a temperature of
several hundred degrees Celsius, and any dirt and impurities
within are drawn off in the gasified form by the vacuum
pump. The current also heats the electrode metal to over 600
degrees Celsius, which activates a special coating that
scavenges unwanted contaminants in the tube and reduces the
work function of the electrode for cathodic emission. When
completed properly, this process results in a very clean
interior at a high vacuum which is important to producing
your long lasting, high quality neon sign.
While still attached to the manifold, the tube is allowed to
cool while pumping down to the lowest pressure the system
can achieve. It is then filled to a pressure of a few torr
with one of the noble gases, or a mixture of them, and
sometimes a small amount of mercury. The required pressure
depends on the gas used and the diameter of the tube, with
optimal values ranging from 6 torr (for a long 20 mm tube
filled with argon/mercury) to 27 torr (for a short 8 mm
diameter tube filled with pure neon). Neon or argon are the
most common gases used; krypton, xenon, and helium are used
by artists for special purposes but are not used alone in
normal signs. A premixed combination of argon and neon is
often used in lieu of pure argon when a tube is to be
installed in a cold weather climate. Neon glows bright red
or reddish orange when lit. When argon or argon/neon is
used, which is used for certain tubes in your custom neon
sign, a tiny droplet of mercury is added. Argon by itself is
very dim pale lavender when lit, but the droplet of mercury
fills the tube with mercury vapor when sealed, which then
emits ultraviolet light upon electrification. This
ultraviolet emission allows finished argon/mercury tubes to
glow with a variety of bright colors when the tube has been
coated on the interior with ultraviolet-sensitive phosphors
after being bent into shape.
The finished glass pieces are illuminated by either a
transformer or a switching power supply running at voltages
ranging between 3,000 and 15,000 volts and currents between
20 and 60 mA. These custom neon sign power supplies operate
as constant-current sources (a high voltage supply with a
very high internal impedance), since the tube has a negative
characteristic electrical impedance. The most common current
rating is 30mA for general use, with 60mA used for
high-brightness applications like channel letters or
architectural lighting. 120mA sources are occasionally seen
in illuminating applications. Custom neon signs are a type
of cold cathode lighting. Your custom neon sign will have a
30ma transformer.
Making Your Custom Neon Sign
Once you have given us either a picture, faxed sketch, or
just an idea over the phone, we design a layout, then get it
to you for your approval of you custom neon sign. Once you
have approved the layout, we glass bend your neon tubes by
hand, and build a black acrylic box to suit your neon sign,
then we mount the neon to the box. Your neon sign can be
hung. Your neon sign has a 120volt plug with an on/off pull
chain.
The light-emitting tubes form colored lines with which a
text can be written or a picture drawn, including various
decorations. By programming sequences of switching parts on
and off, there are many possibilities for dynamic light
patterns that form animated images in your custom neon sign.
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