May 24, 1938.
C. J_ LE BEL
2,118,452
ELECTRIC LAMP
Original Filed Aug. 14, 1929
INVENTQOR
_
. CLARENCE J £5551. ‘.
Br
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Arrow/5r
2,118,452
Patented May 24, 1938
UNITED“ STATES ‘PATENT OFFICE
2,118,452
ELECTRIC LAMP
Clarence J. Le Bel, New York, N. Y., assignor to
Raytheon Manufacturing Company, Newton,
Masa, a corporation of Delaware
Original application August 14, 1929, Serial No. _
385,707. Divided and this application January
28, 1935, Serial No. 3,689
5 Claims. (Cl. 176-424)
This invention relates to electric lamps and
particularly to a lamp which will radiate a sub
stantial portion of its energy in a predetermined
portion of the spectrum. The lamp of this inven
5 tion is characterized by an extraordinary high
case of mercury of about 2537 Angstrom units.
By varying the pressure of the mercury within
narrow limits, this percentage may be reduced
somewhat as the energy goes into other wave -
lengths. v Apparently some obscure resonance
phenomenon is involved in which rare gas par-V
output of energy lying in the ultra-violet portion
ticles freely interact with mercury particles to
of the spectrum.
transfer substantially all energy to the latter, and
cause it to emit as described. It is possible that
,
A lamp of this character has great utility in
many ?elds. Thus for sterilizing and antiseptic
purposes, such a lamp is very eiiicient. Further
more, many chemical reactions, especially obscure
organic reactions such as are involved in the tan
ning of leather, treating of foods and the like, are
greatly accelerated by ultra-violet light.
For
purposes such as these it has been found that only
a comparatively narrow portion of the spectrum
in the ultra-violet region is useful, and any of
the radiant energy outside of this spectrum is
therefore wasted. While devices such as mercury
arcs in quartz containers are generators of sub
stantially powerful ultra-violet rays, their radi
ant energy is nevertheless distributed over a con
siderable spectrum in this region with a resultant
loss of e?iciency.
some unstable compound of mercury and rare 10
gas is formed which emits its characteristic
radiation. The radiation emitted will in general
be one of the prominent lines of the substance
having the lower ionization potential, in this in
15
stance mercury.
By varying the mercury pressure over the wider
limits, as from 1 to 20 microns, it is possible to
ionize both the gas and the vapor, and change
the color of the resulting light. In fact it is pos
sible to go from the pure color of the gas to the 20
pure color of mercury through the combination
of the two colors by properly adjusting the mer
cury vapor pressure. In this latter case, however,
the lamp does not emit as great a portion of its
energy in the narrow region of the ultra-violet
An object of this invention is to devise a lamp ' spectrum as is true when the mercury pressure
in which radiant energy in a certain portion of
the ultra-violet spectrum is generated in a much
more efficient manner than has previously been
the case.
A further object is to devise a lamp
30 which will be simple and cheap.
.
I have discovered that a metal vaporasuch as
mercury, and an inert gas,‘ such as argon or neon,
at certain pressures when carrying a discharge,
exhibit a remarkable phenomenon. Under oper
35 ating conditions the pressure of either one of the
rare gases may be between 1 and 8 mm. while the
pressure of the mercury must be between 1 and 8
microns. The pressure of the rare gas is not
very critical, and may be varied over substantially
wide limits. It is, however, necessary to main
tain the mercury pressure within critical limits.
This may be done by either having the neces
sary amount of cooling surface in the tube or by
arti?cially cooling the tube so that the desired
pressure is maintained.
Sodium or other easily vaporizable metals may
also be used instead of mercury, while a compara
tively inert gas like nitrogen may be used instead
of neon. In general the gas should have a high
ionization potential.
When a lamp with such a mixture of gas is
energized so that the gas therein becomes ionized,
Irhave discovered that as much as 65% of the
total radiant energy is emitted in the form of
55 ultra-violet light having a wave length'in the
is maintained within smaller limits.
Referring to the drawing, the ?gure shows an
induction lamp drawn to full size. '
In the ?gure is shown in true’ form, at sub 30
stantially full size, an electrodeless induction
lamp comprising a tubular portion Hi and bulb
H2. Either or both may be made of material
transparent to the ultra-violet rays generated. A
coil H3 energized by a suitable source of high 35
frequency, such as an oscillator H4, encircles
bulb H2 and energizes the lamp.
After the tube has thus been constructed, it is
treated in the customary manner to remove all
occluded gases, and exhausted to a high vacuum. 40
A small drop of mercury vapor, indicated by M,
may be introduced within the container. In
addition, a quantity of argon or neon may be in
troduced so that at the operating temperature of
the tube, the pressure will preferably be within
the limits previously speci?ed. When the tube is
?rst started, much of the discharge is carried by
the rare gas. The discharge, however, warms the
mercury so that its pressure becomes su?lcient
for it to partake of the discharge. Within a very 50
short space of time the lamp begins to function
as a generator of ultra-violet rays.
For example, in a lamp embodying my invention
and containing neon at about 4 mm. and mercury
‘ at about 2 microns, a discharge resulted in a very 55
2
2,118,452
powerful emission of ultra-violet in a region of
the spectrum below 2900 Angstrom units. A
major portion of this energy was concentrated
in the 2537 line. During the operation of this
ture, a container having a gas and a vaporizable
material located therein, a coil surrounding the
major portion of said container, said coil being
lamp, the current and pressure within the lamp
sage of an electric current through the same, to
could be adjusted so that practically the greatest
portion of the energy was concentrated in the
2537 line.
This application is a division of my co-pending
application, Serial No. 385,707 ?led August 14,
1929.
-
'
What is claimed is:
1. As a new and improved article of manufac
ture, a container, an induction coil passing
15 around a major portion of the wall of said con
tainer, a medium located within said container
and adapted to become excited into luminescence
by the passage of an alternating current through
said induction coil, so as to produce an arc of
20 predetermined dimensions within said container,
a minor portion of the wall of said container be
ing suf?ciently spaced from said arc so that the
temperature of said spaced part of the wall re
mains sufficiently low to prevent the pressure
25 within said container from exceeding a predeter
_ mined. limit.
2. As a new and improved article of manufac
ture, a container having therein a gas and mer
cury, said container having a spherical portion
30 of relatively large volume, and a coil substantially
surrounding said spherical portion so that said
spherical portion is directly with the ?eld of said
coil, said spherical portion having an integral
extension which is beyond the ?eld of said coil
35 and which has a smaller volume than said spheri
cal portion.
-
3. As a new and improved article of manufac
adapted, when 'the same is energized by the pas~
vaporize said material and to cause said gas and
said vaporized material to emit light, said con
tainer having a minor portion oi.’ the wall thereof
spaced from the zone of direct luminescence.
4. As a new and improved article of manufac 10
ture, a container having a gas and a vaporizable
material located therein, a coil surrounding the
major portion of said container, said coil being
adapted, when the same is energized by the pas~
sage of an electric current through the same, to 15
vaporize said material and to cause saidgas and
said vaporized material to emit light, said con~
tainer having a condensing chamber integral
therewith and sharply de?ned from that portion
‘of the container which is surrounded by said 20
coil, said condensing chamber being beyond the
zone of direct luminescence.
5. A method of’ producing light which consists
in exciting into luminescence a gas which is lo
cated within an enclosed chamber and also ex
citing into luminescence a vapor which is located
within said enclosed chamber, so as to produce a
de?nite zone of direct luminescence, and allowing
a part of said container which is beyond said ‘zone
to remain relatively cool in order to form a con
densing chamber for said vapor, the volume of
said condensing chamber being smaller than the
volume of said zone, said gas and vapor being ex
cited into luminescence by an electro-magnetic
?eld which is produced external to said con
tainer.
.
CLARENCE J. LE BEL.