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Патент USA US3026173

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March 20, 1962
3,026, 1 63
C. L. DAY
METHOD AND APPARATUS FOR ASSEMBLING PHOTO TUBES
Filed June 25, 1959
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United States Patent Oiiice
1
2
3,026,163
NEYI'HOD AND APPARATUS FOR ASSEMBLING
PHOTO TUBES
3,026,163
Patented Mar. 20, 1952
0
Cyril L. Day, Huntington, Ind., assignor to International
Telephone and Telegraph Corporation
Filed .lune 25, 1959, Ser. No. 822,833
7 Claims. (Cl. 316--21)
This invention relates generally to photo tubes and
photocathode is then deposited on the inner surface of
the faceplate and activated in its compartment and is then
transferred to the other compartment where it is posi
tioned so as to close the body portion and with its flange
engaging the ñange ofthe body portion. The two flanges
are then joined, preferably by a cold pressure weld, after
which the vacuum is released and the completed tube
removed. The improved apparatus of my invention com
prises a bell jar having two compartments joined by a
more particularly to a method and apparatus for form
passage for supporting the faceplate portion for movement
ing and sensitizing a photocathode on the face plate por
tion of the tube prior to its assembly on the body portion
and for thereafter joining the two portions.
between a first position closing one compartment with
the inner surface thereof exposed thereto and a second
position in the opening of the other compartment.
Means are provided for evacuating both compartments
ventionally comprising an evacuated envelope or body 15 and the passage of the bell jar, and means are positioned
having a photocathode formed at one end and a phosphor
in the one compartment for forming and activating the
viewing screen formed at the other end. In the past,
photocathode on the inner surface of the faceplate por
the photocathode of such tubes has conventionally been
tion when it is in its first position. A ñrst annular die
formed and sensitized or activated after assembly and
member is provided positioned in the other compartment
evacuation of the tube; this has required that the evapo 20 and proportioned to support the llange of the body por
rator which deposits metal, typically silver, on the face
tion and having a cavity formed therein for accommodat
plate together with the source of activating vapor, typi
ing the `body portion so that the faceplate portion in its
second position closes the body portion with the flanges
cally cesium, be located in the tube itself. Since the
cesium vapor conventionally employed for activating the
being respectively in engagement. A second annular die
photocathode will contaminate the phosphor screen and 25 member is provided positioned in the other compartment
other tube elements which may be provided between the
and proportioned to engage the llange of the faceplate
phosphor screen and the photocathode, it has, in the past,
portion in its second position, the die members being
relatively movable and respectively cooperating to join the
been necessary to isolate the source of cesium vapor from
An image tube is a common form of photo tube, con
the phosphor screen and other tube elements, and numer
flanges of the faceplate and body portions.
ous mechanically complex shutter arrangements have 30
The above mentioned and other features and objects
of this invention and the manner of attaining them will
been provided for this purpose. ln addition, in such
become more apparent and the invention itself will be
prior photo tube constructions, it is obvious that the
photocathode forming and activating source remains in
best understood by reference to the following description
of an embodiment of the invention taken in conjunction
the finished tube, that external terminals are required on
the tube body for making the necessary electrical con 35 with the accompanying drawings, wherein:
nections to the photocathode forming and activating
FIG. l is a cross-sectional view illustrating the im
proved apparatus and method of my invention;
sources, and finally that the conventional exhaust tubu
lation must be provided on the tube body.
FIG. 2 is a top view of a bottom section of the bell
jar assembly of the apparatus of FIG. l; and
It has in the past been proposed to provide a photo
FiG. 3 is a cross-sectional View of a completed photo
tube construction in which the photocathode is formed 40
tube assembled in the apparatus of and in accordance
on the faceplate and activated prior to assembly of the
with the method of my invention.
faceplate portion on the body portion of the tube, thus
permitting elimination of shutter arrangements for iso
Referring now to the figures of the drawing, the appa
lating the source of cesium vapor from the phosphor
ratus of my invention, generally identified at 10 com
prises a bell jar assembly 11 having a body portion
screen and other elements of the tube and also permitting
formed of mating top and bottom sections 12 and 13.
elimination of the external terminals previously required
for making connections to the photocathode forming and
Top and bottom sections 12 and 13, which are preferably
formed of steel, have mating elongated channels 14 and
activating sources. However, to the best of the present
applicant’s knowledge, no satisfactory apparatus or
15 formed therein which define an elongated passage 16
method for thus assembling a photo tube has been pro 50 having a generally flat bottom surface when top and
posed.
bottom sections l2 and 13 are assembled as shown in
FIG. l. Bell jar 11 is provided with two containers or
lt is accordingly an object of my invention to provide
compartments 17 and 18 respectively communicating with
an improved apparatus for assembling a photo tube.
passage 16 adjacent its ends 19 and 21, as shown. It
Another object of my linvention is to provide an im~
will be seen that the opening 22 communicating between
proved method for assembling a photo tube.
55
end 19 of passage 16 and the compartment 17 is smaller
A further object of my invention is to provide an im
than the inside diameter of compartment 17. Top and
proved apparatus for assembling a photo tube in which
bottom sections 12 and 13 of bell jar 11 are secured to
the photocathode is formed on the faceplate portion of
gether by means of suitable threaded fasteners 23, with
the tube and activated prior to assembly of the faceplate
a vacuum-tight seal being provided in any suitable man
portion on the body portion of the tube.
60 ner, such as by an annular copper ring 24, as shown.
A still further object of my invention is to provide an
Compartment 17 is the photocathode forming com
improved method for assembling a photo tube in which
partment, and has a suitable window 25 formed in its
the photocathode is formed on the faceplate portion of
bottom facing opening 22 to assist in the photocathode
the tube and activated prior to assembly of the faceplate
formation. An evaporator cup 26 is positioned in com
portion on the body portion of the tube.
55 partment 17, being suspended from and removably
In accordance with the broader aspects of my inven
tion, a photo tube is constructed with separate faceplate
secured to opening 22 in the bottom surface of channel
and body portions joined by mating metal flanges. In
1S, as shown. Evaporator cup 26 has an opening 27 in
accordance with the improved method of my invention,
its bottom end defined by an annular ñange 28, opening
the faceplate portion and body portion of the tube are
27 being in alignment with the window 25 and the open
initially positioned in separate but communicating con 70 ing 22. A pair of spaced apart metal rings 29 and 31 are
tainers or compartments which are then evacuated. The
provided in the evaporator cup 26, the bottom ring 29
3,026,163
3
cathode-forming position, as shown in FIG. l. 1n order
to release the clamping action of tubular member 52
evaporator 33 is supported on the uppei` surface of the
ring 31 facing the opening 22, as shown. One or more
so as to transfer the faceplate portion 42 to the other
compartment 18, as will be hereinafter described, studs
63 are provided extending upwardly from the top section
12 of bell jar 11 and threadingly engaging openings 64
vapor producing channels 34 is provided having its
bottom end connected to the bottom ring 29 and its
top end connected to a ribbon electrical lead 35 extend
in the top plate 55. Thus, studs 63 can be utilized to
lift top plate 55 and thus in turn tubular member 52
in through the top ring 31 and insulated therefrom by
a suitable insulator 36.
4
62 engages inner section 53 of annular ñange 4S, thereby
tightly clamping the faceplate portion 42 in its photo
being supported on the annular flange 2S and the upper
ring 31 being secured to the bottom ring 29 by means
of a plurality of stand-off insulators 32. An annular
The ribbon electrical lead 35
from Vthe vapor producing channel 34 and ribbon elec
away from annular ñange 48 of faceplate portion 42
trical lead 37 from evaporator 33 are carried out of
against the vacuum in compartments 17 and 18 and in
passage 16.
evaporator cup 26 by means of suitable insulators 38
and through insulators 39, attached to the inner wall of
compartment 17, and in turn through the wall of com
partment 17 by means of insulators 41. lt will be Yreadily
Compartment 18 has an annular pinch-off die 65 posi
tioned therein and removably secured thereto, as by
threaded connection 66. The working surface 67 of
stationary die part 65 is arranged to support the outer
seen that when the top section 12 of bell jar 11 is re
periphery 68 of annular ilange 49 of body portion 43,
with body portion 43 being accommodated in cavity 69
moved from the bottom section 13, the evaporator assem
bly may be removed for cleaning and replacement of the
formed in the fixed annular die part 65. It will be
observed that the working surface 67 of annular die
leads 35 and 37 which permits the leads to be pushed
65 is disposed slightly below the bottom surface of
through insulators 3S thus permitting removal of evapo
channel 15 of bottom section 13 of bell jar assembly
rator cup 25 through opening 22. ln order to replace
l1 so that the outer surface 68 of annular ñange 49 is
the evaporator cup 25 in compartment 17, new ribbon
generally Hush with the bottom surface of channel 15.
leads can be welded to the portions extending out of
Movable annular pinch-off die part 71 is positioned in
insulators 39 and fed through the insulators 38.
opening 72 in top section 12 of bell jar assembly 11,
The particular photo tube adapted to be assembled in
opening 72 being in alignment with compartment 18.
the apparatus of FIG. 1 is shown in FlG. 3, and com
Movable die part 71 is secured to an upper part 73 by a
prises a faceplate portion 42 and an envelope or body
portion 43. Faceplate portion 42 includes a transparent 30 suitable threaded fastening 74, upper part 73 being sealed
to the top section 12 of bell jar assembly 11 in vacuum
faceplate 44 having a photocathode formed on its inner
tight relationship by another suitable collapsible bellows
surface 45, while body portion 43 has a phosphor screen
75 which thus accommodates movement of the movable
46 formed in the inner surface of its end wall 47; con
die member 71. In order to retain the movable die
ventional focusing electrodes (not shown) are also pro
member 71 out of cooperative engagement with the fixed
vided. Faceplate portion 42 and body portion 43 are
die member 65, a suitable bracket 76 may be provided
joined together by mating annular metal flanges 48 and
SGCHrêd t0 the upper die part '73 by a suitable threaded
49 respectively secured to faceplate 44 and body por
fastener 77, as shown.
tion 43, as shown. Annular metal flanges 48 and 49,
In accordance with the method of my invention, the
which preferably are formed of copper, are preferably
generally cup-shaped with flange 4S facing away from the 40 top section 12 of bell jar 11 and the elements connected
thereto is removed from bottom section 13 with faceplate
inner surface 45 of faceplate 44 and flange 49 facing
portion 42 initially being positioned in passage 15 closing
away from the open end of the body portion 43, as
photocathode formation materials by clipping the ribbon
opening 22, as shown, and with body portion 43 being
positioned in compartment 1S with flange 49 supported
shown.
Referring back to FIG. l, it will be observed that the
on working surface 67 of die 65, as shown. Top sec
tion 12 of bell jar assembly 11 is then assembled on bot
tom section 13 and sealed thereto. Exhaust tubulations
58 and 59 of compartments 17 and 18 are then connected
faceplate portion 42 of photo tube 40 is initially posi
tioned in passage 16 at end 19 with flange 48 resting on
the bottom surface `'of channel 15 so-that faceplate 44
closes opening 22 communicating with compartment 17
to a suitable vacuum pumping system which evacuates
and with inner surface 45 of faceplate 44 being in
alignment with window 25 of compartment 17 and the
evaporator cup 26 and window 56.
ln order to clamp faceplate portion 42 in the position
shown in FIG. l in order to segregate the photocathode
both compartments and passage 16; it will be observed
Y that since each compartment of the compartments 17 and
13 has its own exhaust tubulation 58 and 59 respectively,
the two compartments 17 and 18 can be isolated by plac
ing a cold trap between them during pumping as is well
activating vapor, such as cesium, from the rest of the bell
known to those skilled in the art.
jar, an opening 51 is provided in the top section 12 of
bell vjar 11 in alignment with opening 22 in bottom sec
tion 13. A tubular member 52 is positioned in opening
Studs 63 may then be
manipulated permitting tubular member 52 to move down
wardly in the direction shown by the arrow 61 under the
influence of the vacuum in passage 16 so that its lower
51 extending upwardly therefrom, tubular member 52
end 62 ñrmly engages inner portion 53 of annular ñange
having a diameter proportioned so that tubular member
52 can be seated -on the radially inner portion 53 of 60 4S of faceplate portion 42. After the desired vacuum has
been obtained, the assembly, which may have been located
annular flange 48, thus clamping the same tightly against
in an oven, may be run through an appropriate baking
the bottom suiface of channel 15. The upper end 54 of
cycle as required for the particular tube. The assembly
tubular member 52 is attached to a top plate 55 which
is then cooled and the photocathc-de formation carried
has another window 56 formed therein in alignment with
on in the usual way. Evaporator 33 is connected to a
and facing the faceplate 44, window 56 also assisting in
suitable source of power, thereby to evaporate the de
the photocathode formation. Top plate 55 is sealed to
sired metal, such as silver, on the inner surface 45 of
top section 12 of bell jar 11 in vacuum-tight relationship
faceplate 44 following which the Vapor producing chan
by a suitable collapsible bellows 57 which thus accom
nel 44 is connected to a suitable source 0f potential there
modates the movement of the tubular member 52.
Compartments 17 and 18 are respectively provided with
70
exhaust tubulations 58 and 59 as shown, and it will
thus be readily comprehended that when the two com
partments and the connecting passage 16 are evacuated,
tubular member 52 will be moved downwardly in the
direction shown by the arrow 61 so that its lower end 75
by to produce the desired vapor, typically cesium, which
is deposited on the silver coating formed on the inner sur
face 45 of faceplate 44 thereby activating the same. lt
will thereby be readily understood that the particular
photocathode and its method of activation does not form
a part of my .present invention, and therefore that other
3,026,163
5
6
or additional vapor producing channels may be provided.
After formation and activation of the photocathode has
been completed, the vacuum tubulations 58 and 59 of
compartments 17 and 18 are sealed oñ and the bell jar
11 is removed from the pumping system, with the vacuum,
however, being maintained in the compartments 17 and 18
and passage 16. Bellows 57 are then expanded by manip
way of example and not as a limitation to the scope of
my invention.
What is claimed is:
l. The method of assembling a photo tube of the type
having separate faceplate and body portions respectively
having mating annular metal flanges joining said portions _
and with the inner surface of the faceplate portion having
ulating studs 63 to raise top plate 55 thereby freeing face
a photocathode formed thereon comprising the steps of:
plate portion 42. Faceplate portion 42 is then transferred
initially positioning said faceplate portion in a iirst com
to compartment 18 by slightly tilting the bell jar assembly 10 partment; initially positioning said body portion in a
11; it will be understood that the bottom surface of the
second compartment which communicates with the first
channel 15 in bottom section 13 of bell jar assembly 11
compartment; simultaneously evacuating both of said com
is relatively ñat, thus in essence forming a track, permit
partments; forming a photocathode on said inner surface
ting faceplate portion 42 to slide from a first position clos
0f said face plate while the same is in said ñrst compart
ing opening 22 to compartment 17 to a second position 15 ment; transferring said faceplate portion to said second
closing body portion 43 as will now be described. lt will
compartment and positioning the same to close said body
now be observed that when faceplate portion 42 has been
portion with said flanges respectively in engagement; join
transferred to end 21 of passage 16, ñange 48 will drop
ing said ñanges while said faceplate and body portions are
into and nest with ñange 49 as shown in FIG. 3. Threaded
in said second compartment in vacuum by cold pressure
fastener 77 is then removed permitting bellows 75 to col
welding; and releasing the vacuum and removing the as
lapse under the influence of the vacuum in compartment
sembled tube from said second compartment.
.
18 and passage 16, thus firmly pressing working surface
2. The method of assembling a photo tube of the type
78 of movable die 71 against outer portion 79 of flange
having separate faceplate and body portions respectively
48 and in turn pressing flange 48 of the faceplate portion
having mating annular metal ñanges joining said portions
42 firmly into engagement with flange 49 of body por
and with the inner surface of the faceplate portion having
tion 43.
a. photocathode formed thereon comprising the steps of:
Bracket 76 is then removed and extensions 81 and 82
initially positioning said faceplate portion in a ii-rst com
on pinch-off die members 65 and 71 are then placed in
partment of a bell jar; initially positioning said body
a suitable hydraulic press. Suitable pressure to join outer
portion in a second compartment of said bell jar; evacuat
portions 68 and 79 of ñanges 48 and 49 by cold pressure 30 ing said bell jar; forming a photocathode on said inner
welding, such as from ten to fifty tous of pressure, is then
surface of said faceplate while the same is in said first
applied by the press. As will be seen in FIG. 3, outer por
compartment; transferring said faceplate portion to said
tions 79(a) and 6801) of flanges 48 and 49 may respec
second compartment and positioning said faceplate por
tively spread outwardly deíining a “V” as the result of the
tion to close said body portion with their franges respec
cold pressure welding o eration or, alternatively, dies 65
tively engaging; joining said ñanges in said second com
and 71 may completely pinch-off the end portions 79 and
partment; and releasing the vacuum and opening said bell
68 as indicated by the dashed lines 83 in FIG. 3. It will
jar.
be seen that the provision of the -mating cup-shaped ñanges
3. The method of assembling a photo tube of the type
48 and 49 not only permits accurate centering of faceplate
having separate faceplate and body portions respectively
portion 42 on body portion 43, but also tends to prevent 40 having mating annular metal flanges joining said portions
outward buckling when the pressure is applied to the die
and with the inner surface of the faceplate portion having
parts, as is encountered with flat flanges. It will also be
a photocathode formed thereon comprising the steps of:`
seen that the flanges serve as a radiator for the photo
initially positioning said faceplate portion to close a first
cathode..
compartment of a bell jar with said inner surface exposed
Exhaust tubulations 58 and 59 are then opened breaking
thereto; initially positioning said body portion in a second
the vacuum in the bell jar 11, threaded fasteners 23 are
compartment of Said bell jar with the flange of said body
removed and the top section 12 is then removed from
portion being seated on a ñrst die member; evacuating
the bottom section 13 of bell jar assembly 11, with the
said bell jar; forming a photocathode on the inner surface
resulting sealed tube 40 then being removed from the
of said »faceplate while the same closes said ñrst compart
compartment 18. After cleaning the evaporating cup 26 50 ment; shifting said faceplate portion to said second com
and renewing the photocathode forming materials and
partment and positioning said faceplate portion to close
tubulations, the bell jar assembly 11 is then again ready
said body portion with their ñanges respectively engaging;
for use.
relatively moving said ñrst die member and a second die
member so that said second die member is in engagement
lt will now be readily observed that the tube 40 pro
duced with my apparatus and in accordance with my 55 with the flange of said faceplate portion; applying pres
method completely eliminates the gates and shutter de
sure on said die members to join said flanges with a cold
vices previously required to isolate the photocathode form
pressure weld; and releasing the vacuum and opening the
ing sources from the phosphor display screen. Further
more, it will be observed that since the photocathode was
bell jar.
4. The method of assembling a photo tube of the type
formed prior to assembly of the faceplate portion 42 and 60 having separate faceplate and body portions respectively
the body portion 43, the external electrical terminals in
having mating annular metal ñanges joining said portions
the body portion 43 formerly needed to make connection
and with the inner surface of the faceplate portion having
to the photocathode forming devices and for other tube
a photocathode formed thereon comprising the steps of:
processing are no longer necessary, and it will further be
positioning said faceplate portion in a passage in a bell
observed that since the faceplate portion 42 is assembled 65 jar with its ñange supported by said passage and with said
on the body portion 43 in a vacuum, the resulting tube
faceplate portion closing a first compartment which com
is already evacuated, thereby eliminating the requirement
municates with said passage and having said inner surface
for a conventional exhaust tubulation in the body por
exposed to said first compartment; positioning said body
tion 43. 1n addition, free cesium is completely eliminated
portion in a second compartment of said bell jar which
in the finished tube and thus cold emission is reduced, the
communicates with said passage with the flange of said
tube can be operated at higher voltages, and screen edici
body portion being seated on a iìrst die member; evacuat
ency is increased.
ing said bell jar and tightly clamping the ñange of said
While I have described above the principles of my in
faceplate portion against the wall of said passage with
vention in connection with specific apparatus, it is to be
which said ñrst compartment communicates; evaporating
clearly understood that this description is made only by 75 a photocathode on the inner surface of said lfaceplate and
3,026,163
8
7
plate while the same is in said ñrst compartment; trans
sensitizing the same from a source in said first compart
ment; releasing said clamping; terminating said evacuating
ferring said faceplate portion to said second compart
and maintaining ~the vacuum; shifting said faceplate por
tion through said passage to said second compartment» to
close said body portion and with said flanges respectively
engaging; relatively moving said first die member and a
ment and positioning the same to close said body por
tion; sealing said faceplate portion to said body portion;
and releasing the vacuum and removing the assembled
tube from said second compartment.
'
7. The method of assembling a photo tube of the type
second die member so that said second die member is in
engagement with the flange of said faceplate portion;
having separate faceplate and body portions respectively
Yopening the bell jar.
a photocathode formed thereon comprising the steps of:
positioning said faceplate portion in a passage in a bell
having mating annular metal flanges joining said portions
applying pressure on said die members to join said ñanges
With a cold pressure weld; and releasing the vacuum and 10 and with the inner surface of the faceplate portion having
5. The method of assemblin" a photo tube comprising
the steps of: providing a faceplate portion which is to have
jar with its ñange supported by said passage and with
said faceplate portion closing a first compartment which
a photocathode formed on one surface thereof and which
is secured to a `first generally cup-shaped annular metal 15 communicates with said passage and having said inner
surface exposed to said first compartment; positioning said
body portion in a second compartment of said bell jar
which communicates with said passage with the ñange of
said body portion being seated on a first die member;
generally cup-shaped annular metal flange which faces
away from said open end and which mates with said first 20 evacuating said bell jar and tightly clamping the ñange of
said faceplate portion against the wall of said passage
flange; positioning said faceplate portion in a iirst con
with which said first compartment communicates; evapo
tainer with said one surface facing the same and isolating
ñange which faces away from said one surface; providing
a body portion to which said faceplate portion is to be
joined and which has its open end secured to a second
rating a photocathode on the inner surface of said face
said faceplate portion from a second container which com
plate and sensitizing the same from a source in said ñrst
municates with said first container; positioning said body
portion in said second container with said open end and 25 compartment; releasing said clamping; shifting said face
plate portion through said passage to said second com
second ñange facing the opening thereof; evacuating both
partme-nt to close said body portion and with said ñanges
of said containers; depositing and activating a photo
respectively engaging; relatively moving said first die
cathode on said one surface of said faceplate portion
member and a second die member so that said second die
from a source located in said lirst container; transferring
said faceplate portion from said iirst container to said 30 member is in engagement with the flange of said face
plate portion; applying pressure on said die members to
second container and positioning the same to close said
join said ñanges with a cold pressure weld; and releasing
body portions with said first ñange nesting in said second
the vacuum and opening the bell jar`
ñange; joining the outer peripheral extremities of said
flanges with a cold pressure Weld; and releasing the vacuum
References Cited in the file of this patent
and removing the assembled photo tube.
6. The method of assembling a photo tube of the type
UNITED STATES PATENTS
having separate faceplate and body portions with the inner
surface of the faceplate portion having a photocathode
formed thereon comprising the steps of: initially position
ing said faceplate portion in a ñrst compartment; initially
positioning said body portion in a second compartment
which communicates with the first compartment; simul
taneously evacuating both the said compartments; form
ing a photocathode on said inner surface of said face
40
1,651,386
Gustin _______________ __ Dec. 6, 1927
2,162,209
Trutner _____________ __ June 13, 1939
2,561,404
Nordquist ____________ __ July 24, 1951
2,721,108
Lewin ______________ __ Oct. 18, 1955
2,807,517 '
2,837,396
Marschka et al. ______ __ Sept. 24, 1957
Warren _____________ __ June 3, 1958
Ryan _______________ __ Feb. 24, 1959
2,874,523
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