U.S. patent number 3,728,573 [Application Number 05/277,617] was granted by the patent office on 1973-04-17 for leakage inhibiting shield.
This patent grant is currently assigned to GTE Sylvania Incorporated. Invention is credited to Henry W. Roeber.
United States Patent |
3,728,573 |
Roeber |
April 17, 1973 |
LEAKAGE INHIBITING SHIELD
Abstract
An improved shielding means, for inhibiting the formation of
electrical leakage between the stem leads of an electron discharge
device, is a substantially infundibular shaped member formed for
umbrella-fashion-attachment to an individual lead to effect better
shielding of the bead area surrounding the lead. A hollow conic
section, extending below a tube-like attachment portion, has an
annular basal-oriented projecting portion with a peripheral
downturned portion therearound. The integral shaping of the
downturned portion with the projection provides beneficial
structural reinforcement and rigidity to the structure and effects
improved shielding characteristics.
Inventors: |
Roeber; Henry W. (Waterloo,
NY) |
Assignee: |
GTE Sylvania Incorporated
(N/A)
|
Family
ID: |
23061649 |
Appl.
No.: |
05/277,617 |
Filed: |
August 3, 1972 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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216111 |
Jan 7, 1972 |
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Current U.S.
Class: |
313/313;
174/50.59; 313/239; 313/242; 313/356; 313/335; 313/626 |
Current CPC
Class: |
H01J
19/50 (20130101); H01J 19/40 (20130101); H01J
2893/0008 (20130101) |
Current International
Class: |
H01J
19/50 (20060101); H01J 19/40 (20060101); H01J
19/00 (20060101); H01j 001/52 (); H01j
061/04 () |
Field of
Search: |
;313/219,239,242,313,331,333,335,356 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Wibert; Ronald L.
Assistant Examiner: Sacher; Paul A.
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATION
This application is a continuation-in-part of application Ser. No.
216,111, filed Jan. 7, 1972. Filed concurrently with this
application, and assigned to the assignee of the present invention,
is a related application Ser. No. 277,616, filed Aug. 3, 1972 also
pertaining to the art of leakage inhibiting shields.
Claims
What is claimed is:
1. Metallic shielding means for inhibiting leakage between the stem
leads of an electron discharge device employing a wafer closure
member wherethrough a plurality of supportive and electrical
connective leads are hermetically disposed in a spaced array, said
shielding means being a substantially infundibular shaped member
formed for separate attachment to individual leads of said wafer
and comprising:
a hollow conic section having a conical wall portion, an open apex,
an opposed basal perimeter and a longitudinal axis extending
therethrough;
an integral terminal section extended from said open apex to
provide a lead attachment provision;
an annular projecting portion extending substantially outward from
said basal perimeter, said projecting portion having a defined
outer periphery; and
a downward turned portion integrally extending from the outer
periphery of said annular projection, said projection and said
downward turned portion being of an integral shaping extending
longitudinally beyond said basal perimeter to provide structural
reinforcement and rigidity, and improved shielding.
2. Improved shielding means according to claim 1 wherein said
annular projecting portion is formed as a planar ledge extending in
a manner substantially normal to said axis.
3. Improved shielding means according to claim 2 wherein said
downward turned portion is formed as a skirt downstanding from said
periphery in a manner substantially normal to the plane of said
annular projecting ledge.
4. Improved shielding means according to claim 2 wherein said
downward turned portion is formed from the periphery of said planar
projecting portion as an inwardly turned annular roll.
5. Improved shielding means according to claim 1 wherein said
annular projecting portion is shaped as a substantially continuous
concentric depression formed intermediate said basal perimeter and
said projection outer periphery.
6. Improved shielding means according to claim 5 wherein said
downward turned portion is formed as a closed skirt downstanding
from the periphery of said annular projecting portion.
7. Improved shielding means according to claim 5 wherein said
downward turned portion is formed from the periphery of said
annular projecting portion as an inwardly turned annular roll.
8. In a cathode ray tube having a wafer closure member wherethrough
a plurality of electrical connective and supportive leads are
arranged to accommodate an electron gun, said leads being
hermetically disposed in spaced array whereof each of said leads
has an encircling bead of glass therearound integral to the
interior surface of said closure member; a plurality of
substantially infundibular shaped metallic shielding members
individually attached to separate leads proximal to said beads for
inhibiting electrical leakage between said leads, each of said
shielding members comprising:
a hollow conic section having a conical wall portion, an open apex,
an opposed basal perimeter and a longitudinal axis extending
therethrough;
an integral terminal section extended from said open apex to
provide a channel for accommodating a respective lead whereat
attachment is effected;
an annular projecting portion extending substantially outward from
said basal perimeter, said projecting portion having an outer
periphery; and
a downward turned portion integrally extending from the outer
periphery of said annular projection, said projection and said
downward turned portion being of an integral shaping extending
longitudinally beyond said basal perimeter to provide beneficial
structural reinforcement and rigidity,
and improved leakage inhibition by effecting increased shielding of
the bead area.
Description
BACKGROUND OF THE INVENTION
This invention relates to shielding means for an electron discharge
device and more particularly to improved means for reducing
electrical leakage therein.
A problem commonly associated with electron discharge devices, and
with electron tubes in particular, is that of electrical leakage
paths developing on the enclosure surface between the supportive
and connective leads of the device during fabrication processing
and subsequent operation.
In general, a conventional form of an electron tube comprises an
evacuated envelope wherein an electron source with elements for
generating and controlling electrons is usually supported by a
plurality of leads hermetically sealed in a wafer closure member
and extended therethrough to provide electrical connections to
associated external circuitry. The supportive and connective leads
are conventionally spaced in close vertical array and extend
through the closure member in a manner to conserve space, thereby
keeping the physical magnitude of the tube structure to a desirable
minimal size. Such compactness often creates a problem in achieving
desired electrical isolation of the leads which individually
conduct electrical potentials of different levels.
During the manufacture and subsequent operation of electron
discharge devices, there is a tendency for conductive materials to
spuriously sublimate from the heated electron generating structure
and deposit or collect on the adjacent closure surface. Continued
sublimation results in the forming of an electrically conductive
film on the surface of the closure bridging the interlead spacings
thereby producing a detrimental electrical leakage condition which
markedly interferes with the intended operation of the device. To
insure and maintain a satisfactory level of operational
performance, this electrical leakage film must be eliminated or
made discontinuous between the individual leads in the closure
member.
In certain types of electron tubes, such as for example, in cathode
ray tubes, it is conventional practice to form beads at discrete
areas on the interior surface of the closure member where the
hermetically encompassed leads protrude therethrough. A lead-bead
formation of this nature provides additional material and enhances
the reliability of the hermetic bonding of the leads within the
closure member, but usually the bead itself has no properties to
inhibit the formation of a sublimed leakage film thereover. To
deter the forming of a continuous sublimation film, a metallic
shielding member or "eyelet", fashioned as a hollow substantially
infundibular shaped article, is fitted on each of the several leads
and attached thereto at a position proximal to the bead. The
umbrella effect of the shielding means is intended to prevent the
formation of a continuous leakage path between leads. The eyelet
shielding means of the prior art is of funnel-like construction
having an annular ledge outstanding from the perimeter of the
funnel. In bonding the shield to the lead, the cylindrical
tube-like portion of the funnel is pressured against the lead and
often deformed by the attaching procedure. Degrees of this
reshaping pressure are transferred to the cone portion causing
deformation thereof and a resultant bowing of the annular ledge.
Such deformation of the shielding means reduces the protective
efficiency thereof; as an elliptical shaping of the conic section
and resultant upward bowing of the ledge diminishes the amount of
desired shielding, thereby lessening the inhibition of leakage path
formation.
OBJECTS AND SUMMARY OF THE INVENTION
It is an object of the invention to reduce the aforementioned
disadvantages and to provide an improved shielding means for
inhibiting leakage between the stem leads of an electron discharge
device thereby promoting greater reliability of operation.
Another object of this invention is to provide an improved
shielding means embodying reinforcement and structural rigidity
characteristics that are retained in the completed device to
accomplish the intended protectional results.
The foregoing objects are achieved in one embodiment of the
invention by the provision of an improved shielding means that is a
substantially infundibular shaped metallic structure formed to be
attached in umbrella-fashion on each of several leads to effect
shielding of the bead area surrounding the lead. The hollow conic
section, extending below the tube-like attachment portion, has an
annular projection outstanding from its basal perimeter. From the
outer periphery of the projection, an integral downturned portion
extends in a discretely shaped relationship to effect beneficial
structural reinforcement and rigidity, and provide improved uniform
shielding, thereby inhibiting the formation of deleterious
electrical leakage paths between leads.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a fragmentary sectional view showing a prior art
shielding means oriented for utilization on the lead of an electron
discharge device;
FIG. 2 is a sectional view illustrating an embodiment of the
improved shielding means of the invention;
FIG. 3 is a plan view of the shielding means taken along the line
3--3 of FIG. 2;
FIG. 4 is a partial sectional view illustrating utilization of the
above-cited embodiment of the invention in an electron discharge
device; and
FIGS. 5 and 6 are sectional views showing additional embodiments of
the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
For a better understanding of the present invention, together with
other and further objects, advantages and capabilities thereof,
reference is made to the following specification and appended
claims in connection with the aforedescribed drawings.
With reference to the drawings, there is shown in FIG. 1 a
sectional view of a prior art funnel-like shielding member 11
oriented on a stem lead 13 adjacent to the bead area 15 surrounding
the lead. During attachment to the lead, the encompassing
cylindrical tube-like attachment portion 17 of the shielding member
11 was pressured against the lead 13 and somewhat deformed by the
bonding procedure. In many cases, sufficient pressure from this
deformation was transferred to cone portion 19 causing a
substantially elliptical reshaping thereof and effecting a
resultant upward bowing of the annular ledge 21. Such reshaping and
bowing decreased effective shielding protection.
To overcome the structural deficiencies and shielding inadequacies
evidenced in the above-described prior art shielding member 11, an
improved shielding means was produced to better inhibit the
development of deleterious electrical leakage paths between the
stem leads of an electron discharge device.
In FIGS. 2 and 3, there is shown an embodiment of the improved
shielding means 23, which has a longitudinal axis 24 therethrough,
is comprised of a hollow conic section 25 having a conical wall
portion 27 with an open apex 29 and an opposed basal perimeter 31.
Integral with the open apex 29 and extending longitudinally upward
therefrom is a terminal cylindrical tube-like section 33 through
which a stem lead is inserted for attachment. The tube-like section
has an inner diameter A which is sufficiently larger than the
diameter of the stem lead to facilitate insertion thereon.
Outstanding from the aforementioned basal perimeter 31 is a
projecting portion 32. In this embodiment the projection is in the
form of a planar annular ledge 34 which extends in a manner
substantially normal to the axis 24, as defined by .angle..alpha..
The projecting ledge has a defined outer periphery 35 from which a
downward turned portion 37 extends longitudinally beyond the plane
of the basal perimeter 31. In the embodiment shown in FIGS. 2 and
3, the downward turned portion is formed as a closed skirt portion
integral with the outer periphery of the annular ledge 34 extending
therefrom in a substantially downstanding manner to preferably
effect a substantially right angle relationship with the plane of
the annular ledge, such being denoted by .angle..beta.. This
angular relationship between the skirt 37 and the ledge 34 provides
beneficial structural reinforcement and rigidity.
In referring to FIG. 4, a partial sectional portion of a
representative electron discharge device 41 is shown, which may be
the basal end of a cathode ray tube though not necessarily limited
to such. The envelope portion 43 is hermetically sealed to a
substantially disc-shaped stem 45 which comprises a wafer member 47
having an interior surface 49 and an exterior surface 51. The wafer
enclosure member 47 includes a concentrically located sealed
exhaust tubulation 53 about which a plurality of spaced electrical
conductors or leads 55 are vertically disposed in substantially
circular array and hermetically sealed in the wafer member 47 in
parallel alignment to extend through both surfaces 49 and 51
thereof. Also, forming an integral part of the wafer's interior
surface 49 are a plurality of formed beads 57, each hermetically
encompassing a section of each individual lead 55. As previously
mentioned, a function of the beads is to provide increased
glass-to-metal seal area and also give support and impart rigidity
to the leads 55. As shown, the aforedescribed improved shielding
means 23 are attached, as by welds or swages 56, to the leads 55 in
umbrella-fashion at a position thereon adjacent to the beads to
provide adequate shielding protection to the bead areas 57. The
interior terminal ends 59 of the leads 55 are suitably disposed for
attachment to the mount structure or electron gun assembly, not
shown, from whence sublimation emanates during device operation, a
portion of which is directed toward the beads 57 and the interior
surface 49 of the stem 45. It is evident that unless some
protection is afforded, a sublimation film of conductive material
spuriously emanating from the electron gun or emission source will
result in the formation of electrical leakage paths on the interior
surface 49 between the several leads 55 disposed therethrough.
The improved shielding means 23 is advantageously formed to retain
its intended shaping. In the afore-described embodiment, the
angular relationship between the annular ledge 34 and the
downstanding closed skirt portion effects positive structural
reinforcement and rigidity which minimizes distortion of the
conical wall portion 27 and prevents bowing of the ledge 34.
Another embodiment of the invention 63 is shown in FIG. 5 wherein
the annular projecting portion 38, extending substantially outward
from the basal perimeter 31 of the conical wall portion 27', is
shaped as a substantially continuous concentric depression 65
formed intermediate the basal perimeter and the outer periphery 67.
The downward turned portion 37' integrally extending beyond the
plane of the basal perimeter 31' is a closed skirt formation 69
projecting in a downstanding manner substantially parallel with the
longitudinal axis 24.
An additional embodiment 71 is illustrated in FIG. 6 wherein the
annular projecting portion 39 outstanding from the basal perimeter
31 is formed as a substantially planar projection or annular ledge
34'. The downward turned portion 40, extending from the periphery
73 of the planar portion, is formed as an inwardly turned annular
roll 75.
In referring to the embodiments 63 and 71 referenced in FIGS. 5 and
6, it is within the scope of the invention to incorporate the
inwardly turned annular roll 75 of embodiment 71 as an alternate
formation for the downward turned portion 37' in the second
embodiment 63.
In considering the several embodiments disclosed, there is provided
in each instance improved rigidity and structural reinforcement
that is not evidenced in the prior art. Additionally, the several
forms of the downward turned portion each provides increased
shielding of the beads.
Thus, there is provided a markedly improved shielding means for
more positively inhibiting the formation of sublimation induced
electrical leakage paths between the several stem beads in an
electron discharge device, thereby assuring greater reliability of
operation.
While there has been shown and described what is at present
considered the preferred embodiment of the invention, it will be
obvious to those skilled in the art that various changes and
modifications may be made therein without departing from the scope
of the invention as defined by the appended claims.
* * * * *