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Патент USA US2404057

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July W, 1946.
D- s. GUSTIN ETAL
2,404,057
END-CAP ELECTRODE FOR DISCHARGE LAMP
Filed March 24, 1943
-
INVENTORS
.D. a GUJr/A/
?. L. hIEEMIq/V
BY
mu m
ATTORNEY
Patented July 16, 1946
2,404,057
UNITED STATES PATENT OFFICE
2,404,057
END-CAP ELECTRODE FOR DISCHARGE
LAMPS
Daniel S. Gustin, Bloom?eld, and Alva L. Herman,
East Orange, N. J., assignors to Westinghouse
Electric Corporation, East Pittsburgh, -Pa., a
corporation of Pennsylvania
7
Application March 24, 1943, Serial No. 480,304
4 Claims.
(Cl. 176—126)
This invention relates to discharge lamps and
particularly to such lamps for the generation of
ultra-violet radiations and wherein the ultra
violet is transmitted directly for use exteriorly of
the envelope or utilized to excite a ?uorescent
2
lamp 5 comprises a vitreous envelope 6 which is
permeable to ultra-violet radiations if the latter
are desired exteriorly of the envelope, or the en
velope may be of ordinary glass provided with a
coating 1 on the interior thereof which is excited
coating and convert the invisible ultra-violet into
by the invisible short-wave ultra-violet and ?uo
visible radiations.
resces to produce visible light.
'
'
An ionizable
It is recognized that the ultra-violet output of
medium which may comprise an inert gas, such
lamps of this type is largely dependent on the
as neon, argon or a mixture thereof at about 15 to
area of the envelope through which the ultra 10 20 millimeters pressure, together with a' small
violet is transmitted on the coated area when the
quantity of mercury II, is disposed interiorly of
ultra-violet is converted into visible light. Here
the envelope for the purpose of initiating and
tofore, the electrodes have extended into the glass
supporting a discharge in the customary manner.
envelope and since the ensuing discharge is be
At each end of the envelope 6 an electrode 8 is
tween the electrodes, this has resulted in an ap 16 provided and since both are substantially identi
preciable area at each end of the lamp from which
cal, a detailed description of one should su?ice.
no ultra-violet or converted visible radiations
emanate, thus decreasing the ef?ciency of output
These electrodes are formed of a metal having a
coe?lcient of expansion simulating that, of the
for a given length of envelope.
envelope such, for example, as the alloy commer
It is accordingly an object of the present in 20 cially known as “Kovar.” As shown, such elec
vention to provide a discharge lamp for the gen
trodes are sealed directly to virtually the extrem
eration of ultra-violet radiations wherein the
ity of the envelope 6 with just sufficient of its
e?iciency thereof for a given length of envelope is
peripheral edge overlapping the electrode ‘8 to
form an hermetic seal, thus effectively position
Another object of the present invention is the 25 ing the electrodes substantially beyond the ex
provision of an ultra-violet lamp wherein the
tremity of the envelope so that radiations ema
electrodes are so positioned as to in. no way im
nate throughout the entire length of the latter.
pair the emanation of radiations from substan
Such electrodes are of substantially cylindrical
tially the entire envelope of the lamp.
con?guration with a curved closed end having a
Another object of the present invention is the
recess 9 therein, to enable the lamp 5 to be readily
provision of a lamp for generating ultra-violet
inserted in appropriate sockets. One of these
radiations wherein the electrodes for the lamp
electrodes 8 is provided with an opening ID in the
constitute a seal for each end of the lamp as well
end wall of the recess, which thus communicates
as socket terminals, thus effectively positioning
with the interior of the envelope after the elec
the electrodes at the absolute extremity of the 35 trodes are sealed thereto. During fabrication of
envelope, thereby increasing the area of the lat
the lamp?, a glass exhaust tube L2 is sealed in the
ter through which radiations are transmitted.
recess 9 through which the lamp is exhausted
Still further objects of the present invention
and ?lled with the ionizable medium. Upon com
will become obvious to those skilled in the art
pletion the lamp 6 is sealed off by fusion of this
by reference to the accompanying drawing 40 exhaust tube until the latter forms a vitreous
wherein:
'
button l3'?lling the recess 9.
Fig. 1 is a plan view partly in section of an
In the form of the electrodes shown in Figs. 1
ultra-violet lamp constructed in accordance with
to 4, a short angularly disposed rod l4 of nickel
increased.
the present invention;
_
.
.
.
‘
Fig. 2 is a sectional View taken on the line
II-—II of Fig. 1;
Fig. 3 is a sectional view taken on the line
III-III of Fig. 1;
Fig. 4 is a fragmentary view of one form which
a portion of the electrodes as shown in Fig. 1 may
take, and
Fig. 5 is a fragmentary view similar to Fig. 4
or nickel-plated iron is welded at one end to the
interior of the end wall of the electrode, and its >
other end is bent upon itself to form a clamp for
holding a small piece of electron-emitting mate
rial such as thorium [5 substantially concentric
'
with the electrode 8. During the seasoning proc
50 ess, thorium is sputtered from the small piece [5
onto the interior surface of the electrodes, which
thus forms an electron-emitting surface [6 that
is constantly replenished as need be during the
and showing a modi?cation which a portion of
the electrodes may take.
life of the lamp. Moreover, since the thorium I5
Referring now to the drawing in detail, the 65 is recessed well within the hollow electrode 8, sub
2,404,057
4
stantially no sputtering of electron-emitting ma
terial onto the wall of the envelope -6 occurs during
operation of the lamp, thus eliminating end black
ening with decrease in radiation e?iciency as has
heretofore occurred in such lamps.
In Fig. 5 a slight modi?cation, is shown which
differs from that previously described merely in
the provision of a metallic strip I‘! for the rod M
limits of said envelope to substantially prevent
sputtering of the electrode material onto the en
velope wall and to increase the effective area of
the envelope through which radiations are emit
ted for a given size envelope, and said electrodes
forming a terminal readily engageable with a
socket with at least one of said electrodes having
a recess therein, and an exhaust stem hermeti
cally sealed to the surface of said electrode both
of the preceding modi?cation, with the free end
of this strip being crimped around the thorium 10 within and outside of said recess and fused there
to to substantially close said recess.
piece 18. This modi?cation functions in the
.2. A discharge lamp comprising an envelope
identical manner as that previously described,
containing
an ionizable medium, and a pair of
and in all other respects the complete electrode
electrodes provided with an electron emissive
‘
_ _
7
Upon the application of a suitable potential to 15 coating and between which a discharge occurs
upon the application of a potential therebetween,
the electrodes‘, a discharge occurs therebetween
is identical to Figs. 1 to 4.
and since the ionizable medium is at a low pres
each said electrode being disposed at an extrem
ity of said envelope and forming an hermetic
sure, such discharge substantially ?lls the interior
seal therewith‘ and constituting terminals for en
of the envelope as distinguished from the pencil
discharge attendant high‘ pressure. Moreover, 20 gagement in a socket, a support projecting up
wardly from a surface of said electrode, and an
since the electrodes 6 are positioned at the very
electron emissive material carried by said sup
ends’ of the ' envelope, the discharge occurs
port entirely within the con?nes of said electrode
throughout the entire length of the latter with ‘
and forming a reservoir for replenishment of the
no portion of the envelope being obstructed.
This accordingly enables the radiations generated 25 electron emissive coating on said electrodes dur
ing operation of said discharge lamp.
by the discharge to emanate from the entire area
3. A discharge lamp comprising an envelope
. of the envelope, whether such radiations be ultra
containing an ionizable medium, and a pair of
violet or visible caused by excitation of a coating
electrodes provided with'an electron emissive
on the interior surface of the lamp 5.
'It thus becomes obvious to those skilled in the ,
coating and between which a discharge occurs
upon the application of a potential th‘erebetween,
art that‘a discharge lamp is herein provided
each said electrode being disposed at an extrem
which has a greater e?iciency for a given length
ity of said enevelope and forming an hermetic
lamp than lamps of similar length heretofore
seal therewith and constituting terminals for en
known to the art. In other Words, the lamp of
the present invention can be readily installed in 35 gagement in a socket, a support projecting up
wardly from a surface of said electrode, and a
existing ?xtures having a ?xed spacing between
piece of thorium metal carried by said support
its sockets and for the same wattage input, a
within the con?nes of said electrode and disposed
substantial increase in ef?ciency is obtained.
substantially concentric therewith and constitut
Moreover, the electrodes themselves are employed
as seals for the envelope and as the socket ter 40 ing a reservoir for replenishment of the electron
emissive coating on said electrodes during opera
minals, thus decreasing the amount of metal
tion of said discharge lamp.
formerly employed and at the same. time such
4. A discharge lamp comprising an envelope
electrodes contribute to the construction of a
containing an ionizable medium, and a pair of
more e?icient lamp.
electrodes provided with an electron emissive
Although several embodiments of the present
coating and between which a discharge occurs
invention have been shown and described, it is to
upon the application of a potential therebetween,
be understood that still further embodiments
and at least one of said electrodes including a
thereof may be made without departing from the
support projecting from the wall of said elec—
spirit and scope of the appended claims.
trode and a piece of thorium metal carried by
' We claim:
said support entirely within the con?nes of said
1.‘ A discharge lamp comprising an envelope
electrode and substantially concentric therewith
containing an ionizable medium, a pair of elec- ‘
and constituting a reservoir for replenishment
trodes between which a, discharge occurs upon the
of the electron emissive coating on said electrodes
application of a potential therebetween, said elec
trodes being hermetically sealed to the periph 65 during operation of said discharge lamp.
DANIEL S. GUSTIN.
eral edge of the extremities of said envelope to
ALVA L. HERMAN.
dispose them entirely beyond the longitudinal
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