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Патент USA US2108519

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Feb. 15, 1938.
Fil‘pd Sept. 50, 1936
A T Tm N
Patented Feb. 15, 1938
Paul Weigt, Berlin-Reinickendorf, Germany, as
signor to Allgemeine Elektricitats Gesellschaft,
Berlin, Germany, a corporation of Germany
Application September 30, 1936, Serial No. 103,226
In Germany October 10, 1935
3 Claims. (C1. 250-—27.5)
common to pass the exhaust tube of
vacuum vessels, such as amplifier tubes, electric
bulbs, and the like, through the tubular portion
of a reentrant stem. Not only the lead-in wires,
5 but aiso the exhaust tube is thus enclosed within
the glass of the stem tube. There is, however,
danger that when the stem tube is pinched to
form the press the exhaust tube maybe closed.
In accordance with the invention, a small ring
10 or tube of ceramic material is inserted in the‘
exhaust tube to avoid the danger of closing the
inner end of the exhaust tube where it is heated
and joins the stem.
An upstanding arm or ex
tension may conveniently be formed on the ring
1;, to serve as an electrode support.
Figures 1 and 2 illustrate the parts of the stem
in assembled relation before heating and com
pressing the glass around the lead wires and
ceramic cylinder; Figure 3 is a sectional view
20 of an envelope bulb with a reentrant stem and
exhaust tube assembly embodying this inven
tion; Figure 4 is a stem and exhaust tube as
sembly embodying thisinvention, and Figures 5,
6 and 7 are end views of the devices shown in
25 Figures 2, 3 and 4, respectively.
In Figure 1 cylinder 1, which is preferably of
ceramic material and somewhat longer than the
press, is introduced in the end of exhaust tube 2
and is supported upon mounting or jig means 4
30 on the center line of the stem or stem leg 3.
Lead-in wires 5 are held in holes in the jig in
an upright position in the annular space between
the exhaust tube 2 and stem 3. When heated
the stem leg and the glass of the exhaust tube
fuse together and onto the cylinder I. When
the glass becomes su?iciently heated it is squeezed
between the jaws of a vice or anvil to force the
glass into gas tight contact with the lead-in wires
to form a so-called press. The ceramic tubing
40 is enclosed with two layers of glass with the
spaced current lead-in wires sealed between the
concentric rings of glass.
In Figure 2 the diameter of the ceramic tubing
6 is shown considerably larger to accommodate
a greater number of current lead-in wires 5 along
the periphery of the annular seal. The ceramic
cylinder 6 is reduced in diameter as shown at 6'
and extended beyond the seal to function as a
carrier for electrodes to relieve the lead-in wires
of mechanical strain from the electrodes.
In Figure 3, the lead-ins 5 are disposed in
the cylindrical junction between the stem and
exhaust tube which is of such an internal diam
eter as to receive in a snug ?t ceramic cylinder
Exhaust tube II, the wires 5 and the stem
tube l2 are arranged in exactly the same manner
as in the ?rst example, but here the ceramic
cylinder is joined to the glass by continuously
turning the glass in a ?ame until the glass is
wetted to the ceramic to obtain an intimate con
nection between the glass and metal and the
ceramic. The ?are l2’ of the stem is then joined
in the usual manner to the rim of an envelope 1O
bulb, the bulb is exhausted, and the exhaust tube
H sealed oii. On the inner end of the ceramic
cylinder may conveniently be provided rods H4
or eyes l5 for supporting metal parts of the
electrode assembly.
As shown in Figure 4, the ceramic cylinder
may be extended at l6 and joined by glass 18 to
metal strips H, which conveniently provide a
strong and rugged support for electrodes in the
discharge device.
The coei?cient of expansion of the ceramic ma~
terial should approximately correspond to that
of the glass, although vacuum tightness is not
I claim:
1. An electron discharge device comprising a
tubular glass stem, a concentric exhaust tube
joined at one end to said stem along an annular
sealing junction, a tubing inserted in and at—
tached to said exhaust tube at the junction of
the tube and the stem whose material has a CA F)
coefficient of expansion similar to that of glass,
and a melting point substantially higher than
that of glass, the exhaust tube being fused to
said tubing, and a circular series of spaced lead- .3,
in conductors sealed gas tight in said annular '
2. An electron discharge device according to
claim 1, characterized in that the tubing consists
of ceramic material.
3. A sealed glass envelope comprising a bulb
portion, a tubular stem extending inwardly from
one end thereof, an exhaust tube joined inte
grally to said stem portion at the inner end
thereof and open at its inner end to form an 45
annular Wire anchoring portion, a circular series
of spaced lead-in Wires sealed in said annular
wire anchoring portion, and a ceramic cylinder in
the end of said exhaust tube in registry with
said annular anchoring portion to preform said 50
annular portion and maintain the exhaust tube
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