Note: Descriptions are shown in the official language in which they were submitted.
This invention relates to a novel and improved
method for adhering a platform to the external surface of a
cathode-ray tube, and to the novel product of this method.
The platform is employed for mounting one or more components
in prescribed positions with respect to the tube.
U. S. patent No. 3,786,185,issued January 15,
1974 to T. M. Shrader,describes a cathode-ray tube having a -
platLorm adhered directly to the external surface of thè
funnel portion of the tube. The platform is used to mount
the deflection yoke in a desired position with respect to
the tube. The patent suggests that the plat~orm
may be adhered to the tube surface with either a solidified
thermoplastic adhesive,such as paraffin or a commercially-
available hot-melt adhesive; or an irreversibly-hardened or
cured adhesive,such-as an e~oxy resin. As used herein a
thermoplastic adhesive is one that is reversibly hardened
by physical action; that is, solidified by cooling and
liquified by heating. ~ cured adhesive is one that is
irreversibly solidified by chemical reaction.
A thermoplastic adhesive has the advantage that
it can be cooled and solidified rapidly,permitting rela-
tively fast rates of assembly. However, a thermoplastic
adhesive has the disadvantage of slight plastic flow over
relatively long periods of tube operation. Also, it is
temperature sensitive,requiring special considerations during
assembly oL the platform to the tube and during subsequent
handling and usage. An irreversibly-hardened or cured
adhesive has the advantages of greater strength and rigidity
after curing and relative temperature insensitivity during
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assembly of the platform to the tube and during subsequent
handling and usage. However, an irreversibly-hardened
adhesive takes a relatively long time to cure, requiring
considerable s~orage space and handling durinq assembly.
In accordance with the invention, the novel method
~ollows the prior method except that at least one liquid
thermoplastic mass and at lease one liquid irreversibly-
hardenable mass are applied between the platform and the tube.
The thermoplastic mass is solidified rapidly by cooling,
providing temporary but~adequate adherence and rigidity for
the platform. After the thermoplastic mass has solidified,
components such as the yoke may be mounted on the platform.
After the component has been mounted, the irreversibly-
hardenable mass cures over a relatively long time period,
developing the desired strength, rigidity and temperature
insensitivity.
The novel article is the cathode-ray tube with a
platform adhered to the external surface of the tube by
separate masses of both solidified thermoplastic and
irreversibly-hardened adhesive. In preferred embodiments
an annular platform is adhered to the tube with equal
pluralities of each adhesive type alternately positioned
around the platform.
By using one or more masses of solidified,
thermoplastic adhesive9 the advantages of rapid cooling and
solidification may be reaiized, permitting fast assembly
rates. By using one or more masses of irreversibly-hardened
adhesive, the advantages of temperature insensitivity and
greater rigidity are realized, imparting greater stability
3 to the assembly during subsequent usage.
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In the dxawing:
FIG~RE 1 is an enlarged broken-away view of a
portion of an embodiment of the novel article.
FIGURE 2 is a sectional view of ~he novel article
shown in FIGURE l along section lines 2-2.
FIGURE 3 is a partially-sectional, paxtially-
elevational view of the funnel ring which is adhered to the
funnel in the novel article shown in FIGURES 1 and 2.
The preferred embodiment is described with respect
to FIGURES 1 and 2. Briefly, FI~,URES 1 and 2 show a portion
of the funnel 23 of an operative cathode-ray tube whose
longitudinal axis is designated by the numeral 35. A
platform 51 is positioned against the external surface of
the funnel 23. The left side of FIGURE l shows the structure
with the funnel 23 removed. The platform 51, which is shown
in FIGURES 1, 2 and 3, comprises generally annular ring or
base 53 having four upstanding lugs 62a, 62b, 62c, 62d
extending qenerally parallel to the tube axis 35 when
assembled. The platform 51 is preferably of a plastic,
such as Noryl No. SEO-225 or S~-l mar~eted by General
*trademark
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1 Electric Com~any, Schenectady, N. Y.
The annular ring or base 53 includes two annular
- forward inner surfaces 52a and 52b generally contoured to
conform substantially to thc contour of the outer surface of
the funnel 23. The ring 53 is positioned on the funnel 23
in a position generally concen~ric with the neck. The
ring 53 has an annular recess 54 between the two inner
surfaces. The recess 54 is about 25.4 mm tl.00 inch) wide
and varies in depth but is mostly about 1.59 mm (0.063 inch)
deep. When ~ositioned on the funnel 23, the recess 54 and
the funnel surface form a chamber 60 for liquid adhesive.
The annular inner surfaces 52a and 52b contact the ~unnel
surface forming ring seals for containing the adhesive.
The four lugs 62a-d are substantially equally
spaced apart from each other on the ring 53. The lengths of
the lugs are tailored to the particular application. In
one embodiment, each lug is about 8.71 mm tO.343 inch) in
diameter and about 18.72 mm (0.737 inch) long. A passageway
59 about 5.08 mm (0.200 inch) in diameter extends through
each lug 62a-d into the recess 54. Between each adjacent
pair of lugs 62a-d are two weep holes 71 dividing the
distance therebetween into three about-equal parts. The
weep holes 71 extend through the wall of the ring into the
recess 54.
The platform 51 is positioned against the funnel
with the lug 62a in the 12 o'clock position and the lug 62c
in the 6 o'clock position; that is, these lugs correspond
to the center of the upper and lower margins of the viewing
screen. The recess 54 forms a chamber 60 between the funnel
2`3 and ring 53. Masses 73a and 73c of a first irreversibly-
I hardened or cured adhesive fill the passageways 59a and 59cof the 12 o'clock and 6 o'clock lugs 62a and 62c and the
chamber 60 adjacent thereto out to just beyond the closest
weep holes 71. Masses 73b and 73d of a second solidified
thermoplastic adhesive fill the passageways 59b and 59d of
the 3 o'clock and 9 o'clock lugs 62b and 62d and the chamber
60 adjacent thereto ou~ to just beyond the closest weep
holes 71.
The platform 51 may be adhered to the funnel 23 in
several simple steps. The inner surfaces 52a and 52b of the
ring 53 of the platform 51 are pressed against the surface
of the funnel 23 with the ring 53 about concentric with the
neck. The lugs 62b, 62c, 62d and 62a are opposite the
3, 6, 9 and 12 o'clock positions of the viewing screen of the
tube. This -forms the chamber 60 for the adhe5ive.
- With the platform held in position, irreversibly-
hardenable (uncured) adhesive in liquid form is injected
through the passageways 59a and 59c of the 12 o'clock and
6 o'clock lugs 62a and 62c filling the chamber 60 adjacent
thereto with masses 73a and 73c. The injection is continued
until a small amount of adhesive is seen protruding from the
two weep holes 71 nearest the lug. Curing of the masses 73a
and 73c starts immediately and continues for periods of up
to 10 days or more.
With the platform still held in position, thermo-
plastic adhesive in liquid form is injected through the
passageways 59b and 59d of the 3 o'clock and 9 o'clock lugs
62b and 62d filling the chamber 60 adjacent thereto with
masses 73b and 73d. The injection is continued until a
small amount of adhesive is seen protruding from the two
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1 weep holes 71 nearest the lug. The thermoplastic masses 73band 73d are permitted to cool and solidify spontaneously
and/or they may be stimulated to cool and solidify faster
as by blowing cool air against the ring 53 or by other
methods.
When the thermoplastic masses 73b and 73d have
solidified, which may be of the order of 0.5 to 5.0 minutes,
the tube with the platform adhered thereto may be advanced
to the next step in manufacture. For example, a yoke may
be assembled to the platform by methods and with structures
known in the prior art.
One example of a yoke assembly mounted on the
pla~form is shown in FIGURES 1 and 2. A yoke 31 is mounted
in a housing 63 to form a yoke assembly 64. The housing
63 comprises a ring-shaped member which includes four
retainers (not shown) which conform to a portion of the
exterior surface of the yoke 31. The yoke 31 is temporarily
maintained against the retainers in a fixed position in the
housing 63 by ~lexible hooks 66. The yoke 31 is permanently
fixed in position in the housing by adhesive material 69
between the lugs 62a-d and the housing 63.
The housing 63 also includes indentations or
troughs 67a-d which engage over each of the lugs 62a-d
respectively. Trough passageways 68 open into the bottom
of each of the troughs 67a-d. The troughs 67a-d are larger
than each of their corresponding lugs 62a-d to permit
adjustment of the position of the housing 63 with respect
to ~he platform 51 prior to injecting a third liquid
adhesive material 69 into the troughs 67a-d through trough
passageways 68. It is preferred that each of the troughs
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1 67a-d be sufficiently lar~cr than the lugs 62a-d to permit
movement of about 3.18 mm ~0.125 inch) in each direction.
The inner surface of the troughs 67 is formed by the outer
surface of the yoke 31.
~ third hardened adhesive material 69 substanti-
ally fills the troughs 67a-d around each of the lugs 62a-d
and also contacts ~he outer surface of the yoke 31 at the
inner side of the troughs 67a-d thereby rigidly fixing the
yoke 31 in the housing 63.
One advan~age of the novel method is that the
platform can be adhered to the funnel in a relatively short
period of time, developing sufficient strength from the
solidified thermoplastic masses to permit accurate mounting
of components thereon. This permits rapid mass-production
methods to be used in the assembly. While the yoke-tube
assemblies ~ass through further assembly steps up to the
time they are placed into television receivers or other
chassis, the irreversibly-hardenable masses continue to
cure, developing great strength and rigidity. By the time
the yoke-tube assembly is placed in a chassis, the yoke
is no longer subject to displacement with respect to the
tube due to plastic flow of adhesive.
The selection of the two adhesives is important
to the novel method~ The thermoplastic adhesive may be
any of, or similar to~ the thermoplastic adhesives mentioned
in the above-cited United States patent. It is preferred to
use hot-melt adhesives which melt above 125C and can be
dispensed or injected into the platform at about 190 to 215C.
Preferred hot-melt adhesives are Versalon 1138 and TPX 833
trademark
.
.
7~
1 polyamide thermoplastics marketed by General Mills
Chemicals, Inc., Minneapolis, Minn.
The irreversibly-hardenable or curable adhesive
may be selected from the large number of known adhesives of
this type. Since this adhesive after curing is both strong
and rigid, it is desirable to select those adhesives whose
dimensional changes so match those of the platform and the
funnel that no delamination, or spalling or loss of adher-
ence occurs as a result of the curing step. Silicone adhe-
sives are preferred. Some preferred silicone adhesives arethe following commercially-available RTV adhesive sealants:
Silastic 732, Silastic 891, and Silastic 3145 each marketed
by Dow Corning Corp., Midland, Mich.; and RTV-108 marketed
by Silicone Products Dept., General Electric Co., Waterford,
N.Y.
~ The irreversibly-hardenable adhesive may be
squeezed from a tube in which it is packaged directly into
the lug of the platform. Or the adhesive may be mixed and
then injected with a syringe or a dispensing nozzle. It may
also be applied into the recess of the ring just before the
ring is positioned on the funnel. In another embodiment
using the platform shown in FIGURE 3, four masses of a very
viscous form of irreversibly-hardenable adhesive are applied
in the recess 54 between the two weep holes 71 between each .
pair of lugs. The platform 51 is then pressed into position
aga~nst the external surface of the funnel. With the plat-
form 51 held in this position, liquid thermoplastic adhesive
is injected through the passageways 59a-d of each of the
four lugs to form four masses of thermoplastic adhesive in
~0
the chamber 60. The thermoplastic adhesive is solidified
*trademark g
1 giving temporary but ade~uate strength and rigidity so tha,t
subsequent manufacturing operations can be carried out while
the irreversibly-hardenable adhesive cures to strong, rigid,
adhesive masses.
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