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Патент USA US2118002

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May 17, 1938-
Filed April 8, 1937
Patented May 17, 1938
2,1 l8,002
Richard G. Bennett, Emporium, Pa., assignor to
Hygrade Sylvania C orporation, Salem, Mass,
a corporation of Massachusetts
Application April 8, 1937, Serial No. 135,642
11 Claims. (01. 250—-2'7.5)
This invention relates to electron discharge
tubes and more particularly to shielding means
for such tubes.
A principal object of the invention is to pro
5 vide an improved form of getter shield for ra
dio tubes and the like.
A feature of the invention relates to an im
proved means for securing a shielding member,
for example a getter shield, in position within
a radio tube or similar device.
A further feature relates to a radio tube of the
metal envelope type wherein a getter shield of
ceramic or other insulating material is employed
in conjunction with a novel form of fastening
means to hold the shield in place.
Another feature relates to an improved form
of metal clip for fastening an insulator member,
for example, a getter shield, within a radio tube
or the like.
A still further feature relates to the novel or
ganization, arrangement and relative location of
parts which go to make up an improved radio
tube of the metal envelope type.
Other features and advantages not speci?cal
25 ly enumerated will be apparent after a considera
under the trade name “Kovar” or of an alloy
sold under the trade name “Fernico”. These al
loys may be composed substantially of 18% co
balt, 28% nickel and 54% iron and the glass beads
may be of any suitable boro-silicate glass such
for example one having the following approxi
mate composition: 65% silica, 23% boric oxide,
7% sodium oxide and 5% aluminum. oxide. It
will be understood of course that the invention
is not limited to these particular materials so
long as the glass beads can be sealed in a vacuum
tight manner to the header.
Merely for purposes of illustration the inven
tion is shown as embodied in a tube of the triode
type comprising any well-known form of indi
rectly heated cathode I3, a ?ne wire grid I4, and
a tubular metal plate I5. The grid side rods I6,
tion of the following detailed descriptions and
the appended claims.
ii are welded or otherwise fastened at their low
er ends to the wires 6, 8 while the plate is elec
While the invention will be illustrated as em
trically connected to the lead-in wire 1. Wire ‘I
is provided with an upwardly extending offset
portion I8 which passes through a bore in the
shield member 26 described hereinbelow, the up
per end of wire l8 being connectedto the plate
I 5. The heater ?lament 26 has its ends connected
to the wires 4, 5 and the cathode sleeve I3 is
connected to the wire 9. Preferably there are
provided upper and lower insulator discs or spac
ers 2|, 22 in the form of mica sheets perforated
to receive the ends of the cathode sleeve and the
various side rods. If desired a flexible extension
bodied in a radio tube of the metal envelope type,
30 it will be understood that certainaspects of the
invention are not necessarily limited to this type
of tube and can be equally well embodied in a
wide variety of tubes and similar devices. Ac
cordingly in the drawing,
port wires 4 to I0 inclusive, for the electrodes of
the mount._ Preferably, these wires are insulated
from the header by glass beads I I which are her
meticaliy sealed into the upper ends of the asso
ciated metal eyelets I2, each of these eyelets be
ing in registry with a corresponding perforation
in the header and preferably welded thereto.
Preferably also the eyelets are of an alloy sold
Fig. 1 is a vertical sectional view of a metal
radio tube embodying features of the invention
and taken along the line I—I of Fig. 2.
Fig. 2 is a sectional view of Fig. 1 taken along
the line 2-2 thereof.
Fig. 3 is a side elevational view of the tube
mount of Fig. 1, with the envelope removed.
Fig. 4 is a detailed sectional view of part of
Fig. 1, showing the shield clip in its normal posi
Referring to Figs. 1 to 3 the numeral I repre
sents a base or header of suitable metal such
for example as steel, iron, nickel or similar metal.
Preferably, although not necessarily, the header
I is ‘formed with a downwardly depending rim
50 2, and a centrally located exhaust tubulation 3
through which the device may be evacuated in
known manner. The header I is provided with
a series of perforations, preferably although not
necessarily, circularly arranged, through which
55 insulatingly pass the various lead-in and sup
or extensions may be attached to the disc 2| to
engage the inner'face of the metal bulb 23 for
the purpose of steadying the upper end of the
As shown in the drawing, the bulb 23 is in the
form of a metal cylinder of iron, steel, nickel or
similar metal having a flattened top 24 and provided at its lower end ‘with a peripheral flange 25
which may be welded or otherwise fastened in a
vacuum-tight manner to the member I. As is
well-known in the radio tube art it is necessary 50
for various reasons to employ during part of the
evacuation process a getter or clean-up agent
which can be readily ?ashed or vaporized at the
appropriate time so as to clean-up the residual
gases or vapors that remain after the main evac
uation takes place. However in flashing this get
ter it is highly important that it be prevented
from depositing to any substantial extent on the
glass beads H and thus reducing the insulation
of the lead-in wires from the metal header i.
For this purpose, there is provided a cylindrical
shield 26 preferably, although not necessarily, of
ceramic or similar insulating material which is
adapted to surround the various lead-in wires.
The shield 26 is provided at its upper end with a
shoulder 2'! on which is seated the lower end of
the plate electrode as shown clearly in Figs. 1
rial 34 attached thereto is then assembled over
the mount and forced downwardly causing the
upper free ends of the clips 29 to enter the corre
sponding slots 32. The ?ange 23 is then welded
to header I, and the completed tube is evacuated
through tubulation 3 and heat treated and other
wise subjected to the customary pumping sched
ule. At the appropriate interval of the said.
schedule the flame of a small torch is applied
instantaneously against the bulb 23 adjacent the 10
getter 34 causing the latter to be ?ashed. Be
cause of the shield 26, the vaporized getter ma
and 4. Preferably the shield is also provided with
terial is substantially prevented from depositing
a series of recesses 28 to accommodate the glass
on the glass beads II, or on the micas 2|, 22.
After the tube has been completely evacuated and
processed, the tubulation 3 is sealed off and any
well-known form of prong or contact base is at
tached to the header l.
While certain speci?c materials and arrange
15 beads H. Since the shield is of insulating mate
rial and the header l is of metal, ordinary meth
ods of fastening the shield in place as for example
welding, cementing,‘etc., are not feasible. There
fore in accordance with the present invention
20 the shield is held in place by one or more sub;
stantially L-shaped metal clips such as clip 29
the bottom 30 of which is welded or otherwise
fastened to the header i. In order to accommo
date the clips, the shield 26 is provided with
notches 3i and in vertical alignment with the
25 notches the wall of shield 26 is provided with
slots or grooves 32.
As shown in Figs. 1 and 4, each clip 29 is bent
to form' a shoulder 33 which is adapted to en
gage the bottom of the slot 32 to prevent verti
cal displacement of the shield. In order to hold
the said shield ?rmly in place the end of clip
23 is bent to a V-shape so that when the tube 23
is ?tted over the mount the upper end of the
35 clip is forced inwardly from its normal position
as shown in Fig. 4 to the position shown in Fig. l
where it lies in the slot 32. The getter material
in the form'of a small strip or sheet welded to
the inner face of the tube 23 is indicated by the
dotted rectangle 34, Fig. 3, and in order to en
able the tube 25 to be assembled over the shield
without disturbing the getter strip, the shield is
provided with a ?at 35.
It will be understood of course that the get
ter instead of being in the form of a ?at metal
ment of parts have been disclosed herein, it 2.0
will be understood that various changes and
modi?cations may be made without departing
from the spirit and scope of the invention.
What I claim is:
1. An electric discharge tube comprising an 2.5
envelope consisting of a tubular member her
metically sealed to a base member, a tube mount
carried by said base member, leadj-in wires for
said mount and sealed into said base member,
getter material carried on the inner face of said .
tubular member, and an insulating shield within
the envelope for protecting said lead-in wires
and seals from the vaporized getter material.
2. An electric discharge tube comprising an en
velope consisting of a tubular member hermeti- :
cally sealed to a base member, a tube mount
carried by said base member, lead-in wires for
said mount insulatingly sealed into said base
member, a cylindrical shield of ceramic insulat
ing material within the envelope surrounding 40
said lead-in wires, and means flexibly latching
with said shield to fasten said shield to said base
3. In a device of the character described the
combination of a tube mount, a metal base mem 45
strip or tab, may be in the form of a pellet en
closed in a suitable getter cup or capsule which
ber supporting said mount, lead-in wires insulat
is welded to the inside face of bulb 23. Similarly
the getter may be in the form. of a powder com-4
shield of insulating material for protecting said
lead-in wires and seals from vaporized getter‘
material, and a flexible metal, clip carried by 50
pressed into a suitable pocket or depression on
the inner face of the bulb as, is well-known in the
art; In order to flash or vaporize the getter, heat
is applied locally, as for example by a small
torch, to the exterior of bulb 23 adjacent the 10
, cation of the getter, and if desired a suitable
mark or indentation may be employed to indi
cate, from the exterior of the bulb, the getter
The assembly of the various elements of the
tube is believed to be obvious from the fore
going and is in general as follows. The cathode
and grid electrodes are assembled on the mica
members 2!, 22 which are held in place on the
grid side rods by suitable metal eyelets or the
The grid side rods are welded to the cor
responding lead-in wires 6, 8; the heater ?lament
is connected to its lead-in wires 4, 5; and the
cathode is connected to its lead-in wire 9. The
shield 26 is then assembled in place and forced
70 downwardly to cause the shoulders 33 of clips 29
to latch in the corresponding recesses 32. The
plate 15 is then assembled in the end of shield
26 and rests on the shoulder 21 being held against
upward movement by wire l8 which is fastened
75 to the plate. The bulb 23 with the getter mate
ingly sealed into said base member, a curved
said base member and latching with said shield.
4. In a device of the character described the
combination of a tube mount, a metal base mem
ber supporting said mount, lead-in wires insu
latingly sealed into said base member, a ceramic
getter shield surrounding said lead-in wires, a
metal clip fastened at its lower end to said base
member, a shoulder formed on the wall of said
shield, said clip being bent intermediate its ends
to form a shoulder arranged to latch over the 60
shoulder on the shield.
5. In a device of the character described the
combination of a tube mount, a metal base mem
ber supporting said mount, lead-in wires insulat
ingly sealed into said base member, a ceramic get
ter shield for said lead-in wires and their seals,
a slot in the wall of said shield, a flexible metal
clip having an offset portion lying in said slot
and engaging said shoulder to hold said shield
?rmly against said base member.
6. A device according to claim 5 in which the
said shield is cylindrical and supports a tubular
plate electrode at its upper end.
'7. In a device of the character described the
combination of a metal base member, a tube
‘mount carried by said base member, a curved
‘ getter shield of insulating material disposed
around the vertical axis of the mount, a shoulder
formed on said shield, a tubular bulb sealed to
said base member, and at least one metal clip
having a pair of oiisets one engaging said shoul
der to prevent vertical movement of said shield
and the other engaging the inside of said tubular
bulb to space said shield from said bulb.
8. In a device of the character described the
combination of a metal header, a plurality of
glass beads sealed to- said header, a wire sealed
through each bead, a tube mount carried by said
header and having its electrodes connected to
15 said wires, a metal bulb enclosing said mount and
hermetically sealed to said header, an insulating
getter shield surrounding said wires, a plurality
of recesses in said shield into which said beads
partially extend, a plurality 01’ slots in the
shield wall, a corresponding plurality of ?exible
wire clips each fastened to said header, each clip
having a substantially V-shaped end with the
apex of the V engaging the inner face of the
bulb to force the end of the clip into a corre
sponding slot in said shield.
9. A device according to claim 8 in which the
shield is of ceramic material spaced from the
wall of the bulb, and a quantity of getter mate
rial is located between the bulb wall and the 10
10. A getter shield for a metal envelope radio
tube comprising a tubular ceramic- member hav-.
ing at least one slot in its outer faceto receive a
wire clip.
11. A getter shield according to claim 10 in
which the upper end of the ceramic member is
shouldered to receive a tubular electrode.
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