Note: Descriptions are shown in the official language in which they were submitted.
79~
TELEVISION' TUBE WITH OPTIONAL SHADOW MASK AND
METHOD OF MANUFACTU~E
'Backgrouhd 'o'f''khe''In~e'n'tion
- The in~ention relates to a TV picture tube components
and their method of manufacture. More par~icularly, there is
provided a color TV picture tube panel having a black matrix
and color phosphors printed thereon, and an optional mask
produced by a printing technique. Preferably, a collector
silicone process is utilized for applying a target comprising
color phosphor compounds and a black matrix onto the inner
face of the cur~ed TV panel. The shadow mask is produced using
a new process wherein acid resist is applied by an offset
printing technique.
In a conventional color TV bulb, the black matrix
background and color phosphors of the target are separately
applied to ~he panel in a succession of relati~ely complex
process steps. The process requires the use of a mask
having apertures formed therein by a photo-etch process. The
mask is thereafter stamped into shape. The mask and panel
are mated and become a unique combination for the particular
TV bulb.
In the preferred process of the present invention, a
resist ink pattern is printed on both sides of the mask after
it has been formed into the desired spherical or cylindrical
shape. The mask may be thereafter etched. Because forming
takes place be~ore etching, the structure is not subjected
to significant deformations after the apertures are in place.
Thus, the possibility exists that masks can be construct2d
which are interchangeable with various panels of similar
manufacture.
~222 ~9~
In the present invention, the application of the target
onto the panel is reduced to a single step. The color
phosphors and background inks are printed onto a silicone
collector in the pattern of the target. Thereafter, the
target may be printed from the collector onto the panel. A
major advantage of the collector process is that registration
is accomplished on the collector independently of the panel.
The process herein described is compatible with conven-
tional TV tubes having a shadow mask and more recently devel-
oped TV tubes of the beam-indexing type (i.e. maskless picture
tubes).
_mmary of the Invention
A color TV panel and method of manufacture is disclosed
wherein a collector printing process is utilized for printing
the target, comprising color phosphors and black matrix inks,
onto the TV panel.
A preformed shadow mask is printed on both sides with a
coating of an acid resist ink in a selected pattern. The
mask is then acid treated. Portions of the mask not coated
with the ink dissol~e, thereby producing an aperture array
in the mask corresponding to the selected patterns.
The inks are specially formulated thermoplastic pressure
æensitive media. Masks and panels produced in accordance with
the present invention are interchangeable.
Thus the present inven~ion provides, in a color TV
bulb, a panel comprising: a screen and an array of background
ma~rix and color phosphors in a selected pattern. The pattern
is deposited on an interior surface of the screen simultaneously
as a cohesive film of pressure-sensi~ive, thermoplastic inks,
one for each color phosphor and the background matrix. The inks
have organic and inorganic components ana are combined in the
selected pattern prior to deposition onto the screen. The inks
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~222J~
are hereafter fired to volatilize the organic components
and to fix the inorganic components to the screen of the
panel.
In another aspect the present invention provides a
method of producing a color TV bulb having a panel and
funnel fused together in a conventional manner in which the
panel has a composite of a black matrix pattern and respective
red, blue and green color phosphor patterns deposited thereonu
The method comprises the s~eps of formulating separate
thermoplastic ink compositions for each of the black matri~
and color phosphors, said inks exhibiting cohesive strength
and pressure sensitivity at near room temperaturei forming
each composition into a corresponding separate pattern;
establishing the black matrix and respective color phosphors
in separate ink patterns on separate carriers from the separ-
ate inks; comple~ely transferring and registrably combining
the separate patterns into the composite onto at least one
collector; and completely transferring the composite from the
collector to the panel.
In another aspect the present invention provides an
interchangeable aperture mask for a color TV panel and
having apertures formed therein by acid etching. rrhe mask
includes a mask portion having front and back sides bound by
a peripheral margin and being formed into a desired shape.
The front and back sides of the mask portion are registrably
printed with a respective pattern, each pattern being formed
of an acid resistant hot-melt material for coating selected
portions of the mask portion. The registrably printed pattern
for each of the front and ~ack mask portion in the same
relative position front to back, such that, upon etching
the apertures are formed in the mask portion in the uncoated
areas as through holes; the aperture mask having the acid
resistant material and acid removed after etching.
- 2a -
~27~)
n ~ nother aspect the present invention provides
~ me.:hod of p~oducing a target for a color TV panel formed
of separate pat~erns corresponding to a background matrix
and respective color phosphors comprising the steps of:
establishing separate patterns of each of the background matrix
and color phosphors onto separate surfaces, collecting the
separate patterns in registration on~o a common surface as
a composite pattern; and transferring the entire composite
pattern onto the panel by intimate contact of the common
surface and the panel in a single pass for forming the target
on the panel.
In still a further aspect the present invention provides
a color TV panel comprising a screen and a target formed of an
array of background matrix and color phosphors affixed thereto
in a selected pattern. The pattern is deposited on an interior
surface of the screen portion as a cohesive film of
pressure-sensitive, hot melt inks, one ink for each color
phosphor and the background matrix. The inks have organic
and inorganic components and are combined in the selected
pattern prior to deposi~ion onto said screen and thereafter
are fired to thereby volatilize the organic components and
~ix the target onto the screen.
In a broad method aspect the present invention provides
a method of making a cathode-ray tube which comprises a
panel and a screen within an array of background matrix and
color phosphors in a selected pattern, and a target, comprising
the steps of depositing said screen pattern on the interior
surface of said screen simultaneously as a cohesive film of
pressure-sensitive, thermoplastic inks, one for each color
phosphor and the background matrix, the inks having organic
and inorganic components and being combined in the selected
- 2b -
9~
pattern prior to deposition on said screen, and then firing
the inks to volatilize the organic components and to fix
the inorganic components to the screen of said panel.
Descript.ion of the Drawings
FIG. 1 is a schematic representation oE a collector
printing process adapted for use in the present invention.
FIGS. 2a, 2b, and 2c are sequential drawings showing
printing from a flexible membrane to the inside of a color
TV panel.
FIG. 3 is a schematic plan view of the panel with an
exemplary few triads of color dots and a portion of the
black matrix illustrated.
FIG. 4 is a fragmented schematic representation in
side section of a printing apparatus and a preformed and
framed shadow mask.
FIG. 5 shows an alternate method of printing opposite
sides of a shadow mask using flexible membrane printing.
FIG. 6 is a schematic representation of the shadow
mask aftr printing.
FIG. 7 shows the shadow mask of FIG. 6 after etching
and cleaning.
FIG. 8 is a fragmented front view of the shadow mask
of the pxesent invention before and after etching.
FIG. 9 schematically illustrates a TV picture tube
produced from components manufactured in accordance with
the techniques described herein.
Description of the Preferred Embodiment
.
Panel Manufacture
The present invention uses separately formulated inks
to print the target of a TV panel. The inks comprise a
heat-processable, thermoplastic, pressure-sensitive, hot-
~22~9~
melt medium mixed with a selected pigment. The preferred
medla melt when heated above room temperature forms cohes,-~e,
pressure-sensitive, tacky films when cooled to near room
temperature. The pigments are conventional materials used
in the TV industry, namelyo green, red, and blue phosphors
for the colors and a black graphite for the black matrix or
background.
-, A preferred printing device is a gravure printer
including collector; transfer surfaces; and corresponding
heated gravure surfaces, which receive melted thermoplastic,
pressure-sensitive ink from separate heated supplies.
Each gravure surface has a different recessed gravure
pattern etched therein for receiving a corresponding ink
from its separate supply. Because the gravure surface is
heated, the inks remain melted when in contact therewith.
The corresponding transfer surface is formed of an elasto-
meric silicone material and contacts the hot fluid ink in
the recessed gravure pattern. The ink splits almost evenly
between the two surfaces, leaving an impression of the
pattern on the transfer surface. The ink immediately cools
upon contact with the transfer surface and forms a cohesive,
pressure-sensitive, tacky film. The transfer surface,
carrying the tacky film, is intimately contacted with the
collector formed of an elastomeric silicone material. The
ink transfers completely from the transfer surface to the
collector.
The separate patterns developed by the separate gravure
surfaces are printed on the collector in registration. This
means that each separate ink pattern is printed on the col-
lector in a specific geometric relation with each of theother ink patterns. Registration is accomplished by align-
ment of the components. When all of the inks are printed on
~Z~7~
the collector in the proper relation, the target is estab-
lished. Once established, the target may be completely
transferred to the panel by intimate contact of the collector
with said panel.
The complete and successive transfer of the separate
inks occurs for a number of reasons. The inks are tacky.
They tend to stick to almost anything they come in contact
with~ The respective transfer surface, the collector and
the panel are formulated so that they each have increasing
affinity for the inks. The inks form cohesive films when
cool. Thus, when transfer occurs, it is complete because
the film holds together. The films neither split nor tear.
FIG. 1 is a schematic drawing exemplary of a printing
device 10. The present invention utilizes at least four
printing stations I-IV, one for each color phosphor and one
for the black matrix. Each printing station I-IV includes:
a heated ink trough 18; a heated gravure roll 12 and a transfer
roll 14 mounted in pairs 13 on base plate 11 by means not shown;
and a doctor blade 22. A turret 19, mounted for rotation
about a central axis C, carries collectors 16 in holders 20.
Each collector 16 includes a flexible silicone membrane 26
secured in a frame 28. Each ink trough 18 carries a separate
ink formulation for deposition onto a gravure roll 12 (e.g.,
M-black matrix, R-red, G-green, and B-blue)O
Each gravure roll 12 has a selected pattern etched
therein. For example, at station I gravure roll 12 has a
pattern P-M corrsponding to the desired configuration of
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~2227~3
the black matrix. The hlack ink M carried in heated trough
18 is a melted, graphite filled, thermoplastic fluid. The
ink ~l, deposited on gravure roll 12 a~ station I, is doctored
in a conventional manner by blade 22. Ink M in pattern P-M
on gravurs roll 12 is carried into intimate contact with
transfer roll 14, whereupon the ink M is split between such
rolls. The ink M, deposited onto cool transfer roll 14,
forms a tacky cohesive film 24M wherein the pattern P-M is
reproduced on transfer roll 14. The film 24M is brought
into intimate contact with collector 16. In this instance,
the ink M forming the film 24M does not split, but completely
transfers from the transfer roll 14 to the collector 16.
The pattern P-~, generated on gravure roll 12, is thereby
formed on collector 16 as film 24M'.
The above process is repeated at stations II, III and
IV for the remaining inks R, G, and B. Respective patterns
P-R, P-G and P-B are reproduced in the corresponding collector
16 as films 2gR', 24G' and 24B' and deposited in registration
onto the collector 16 as a composite film 24. There is no
print back from any collector 16 to any of the transfer
rolls 14. The collector has a higher affinity for the ink
than the transfer rolls 14.
The collector 16, carrying the composite film 24, is
removed from holder 20 and is locked in position within a TV
panel 30 by means not shown (see FIG. 2a). Flexible plunger
32 engages a re~r side 34 of membrane 26, urging the membrane
26 and film 24 carried thereby against an inside surface 38
of panel 30 (see Fig. 2b). The film 24 preferentially
adheres to the inside surface 38 of panel 30. The plunger
32 is thereafter withdrawn. The membrane 26 relaxes and
279i[1
peels away from the film 24 which forms target 24' (see FIG.
2c).
In FIG. 3 an illustrative portion of target 24' is
shown. The target 24' comprises black matrix 40 and triads
41 formed of a green dot 42G, a red dot 42R and a blue dot
42B. The black matrix 40 corresponds to the pattern P-M
generated by gravure roll 12 at station I using ink M. The
dots 42R, 42G and 42B correspond respectively to the patterns
P-R, P-G, and P-B generated at stations II-IV.
The target 24' is finished with an organic sealant 46
and sputtered aluminum reflective conductive coating 48.
The panel 30 is fired, and the organic materials forming the
various ink media are burned off. The inorganic pigments
forming the target ~4', and the aluminum coating 18 are fixed to
the panel 30.
In another embodiment, the collector 16 may be a ~iber-
glass reinforced silicone blanket ~not shown). Also transfer
of the film 24 to the panel 30 may be effected by applying
pressure with a cut roll (not shown~ on the opposite side of
the membrane 34 on the blanket.
Aperture Mask Manufacture
FIGS. 4-8 illustrate aperture mask printing and manu-
facture. Resist inks are deposited on the mask after it is
ormed in the required shape. Resist inks utilized may be
pressure-sensitive hot-melt inks which exhibït sufficient
adhesion and acid resistance to serve as satisfactory acid
resists in their cooled ambient state. The inks may be
pressure-sensitive hot-melt inks which are capable of cross-
linking or curing to enhance their acid resistance. Latent
30catalysts may be added to the inks, which catalysts are
~:2279()
selected not to induce curing at temperatures below about
300F. Once curing occurs, the inks may be referred to as
thermoset materials. Waxes may also be employed as suitable
resist inks.
A member that prints the resist ink onto the mask may
be a roll, blanket, membrane, or pad, havîng a silicone
working surface. Gravure or flexographic techniques may be
useful. The mask receives the resist in]c directly from a
heated metal inking surface, or through an intermediate
offset or transfer roll. Transfer of the ink to the mask is
effected by causing intimate mechanical contact between the
mask and the transfer member carrying the ink. Intimate
contact may be accomplished by urging the transfer member
against the metal surface of the mask.
In FIG. 5, there is illustrated a fragmented side view
of an aperture mask 110 having a preformed cylindrical or
spherical shadow mask portion 112 and peripherally attached
frame 11~. The frame 114 may be an internally formed bead,
as shown, or a separately welded ring. The shadow mask
portion 112 has respective front and back sides 113 and 115,
each of which receives a printed coating as hereafter described.
In the present invention an offset gravure printing
apparatus 120 is disclosed for printing the respective front
and back sides 113 and 115 of the mask 110. The printing
apparatus 120 requires similar elements for printing the
respective front and back sides 113 and 115 of the mask 110.
Such similar elements, hereinafter described, will be
referred to by the same descriptive name but with the
reerence numerals in the elements used to print the back
side 115 of mask 110 being primed counterparts of the
elements used for printing the front slde 113 thereof.
The printing apparatus 120 includes heated gravure
rolls 122-122', heated troughs 124-124', melted thermo-
plastic ink 126 ~the same material for both sides~ in
heated troughs 124~124', doctor blades 128-128' and silicone
elastomeric offset rolls 130-130'. A surface 132-132' of
each gravure roll 122-122' is etched or engraved with a
pattern PG-PG'. The ink 126 is deposited on each gravure
lC roll 122-122' and any excess is removed in a known manner by
corresponding doctor blade 128-128'. The ink 126 remaining
on each roll 122-122' forms a film 134-134' in a pattern
corresponding to the etchings PG-PG' in each respective
gravure roll 122-122'.
Although exaggerated ;n thickness and the dimensions,
each film 134-134' has respective solid portions 138-138'
and aperture portions 140-140'. Each offset roll 130-130'
contacts the corresponding gravure roll 122-122' as shown,
and picks up the film 134-134' hy split.ting action (see
reference numerals 135-135'). Each oEfset roll 130-130' is
preferably cool. The film 134-134', freezes upon contact
with the offset roll 130-130' thereby forming a xespective
patterned cohesive film 136-136' thereon.
The ink 126 forming cohesive films 136-136 7 iS tacky
at near room temperature. Each cohesive film 136-136' is
transferred completely from the corresponding offse~ roll
130-130' to the respective front and back side 113 and 115
of aperture mask 110 upon intimate contac-t (see reference
numerals 137-137'~. The offset rolls 130-130' act as mutual
~22Z79~
backing members as mask 110 is passed therebetween during
the printing operation.
The offset roll 130', used for printing the back side
115 of mask 110, has a cut 141' formed thereinO Cut 141'
allows the offset 130' to clear the frame 114. Also the
offset roll 130' may be oriented so that a leading edge 143'
of the cut 141' engages the back side 115 of mask 110 near
where the frame 114 and mask portion 112 meet at inside
corner 145'.
In another preferred embodiment, plain inking rolls may
be substituted for gravure rolls 122-122', and raised patterned
flexographic rolls may be substituted for offset rolls 130-
130'.
In FigO 5 the aperture mask 110 may be printed using
flexible blankets or membranes as collectors 150-150'.
Respective cohesive films 136-136' may first be deposited
into collectors 150-150' by a gravure process. Each cohesive
film 135-136' may thereafter be deposited on the respective
front and back sides 113 and 115 of mask by urging the
collectors 150-150' and the respective cohesive films 136-
136' into intimate contact with opposite front and back
sides 113 and 115 of the mask 110. Opposed rolls 154-154'
urge the respective collectors 150-150' against the mask
110. The rolls 150-150' act as complimentary backing members
for each other. The roll 154' may have cut 151' for allowing
it to clear frame 114. The cohesive films 136-136' have a
greater affinity for the mask 110 than respective collectors
150-150' and thus transfer to the mask 110 as integral
cohesive films.
--10--
~;~227~)
In FIG.6 the cohesive films 138-138' are shown after
deposition onto the opposite sides 113 and 115 of the mask
110. The cohesive films 136-136' are printed onto the
shadow mask portion 112 so that solid portions 138-138' from
coated areas 159-159' and aperture portions 140-140' leave
uncoated areas 160-160'. The respective aperture portions
140-140' and solid portions 138-138' are in alignment or
registration. The respective unsoated portions 160-160' of
the mask 110 are aligned in registration, one opposite the
other, on the respective front and back sides 113 and 115 of
the mask 110. Thus, the exposed portions 160-160' are subjected
to acid etching whereby through holes 170 may be made (see
FIG. 7)O
In FIG. 8 the aperture mask 110 is shown in two frag-
mented parts of a fron~ elevation. In the upper part of the
drawing, prior to acid etching, the cohesive film 138 is
shown deposited onto the front side 113 of the aperture mask
110 with exposed portions 160 of the same shown as darkened
circles. In the lower portion of the drawing, after acid
etching, the exposed portions 160 of the aperture mask 110
- have been dissolved, creating holes or apertures 170 therein,
shown as open circlesO It should be understood that the
etching takes place from both sides of the aperture mask
110. Once etching is complete, the aperture mask 110 is
thoroughly cleaned and rinsed for removing acid and ink
therefrom (see FIG. 7)O The interchangeable aperture mask
110 of the present invention is thus complete~.
~L2;2~7~{1
A preferred ink 126 is disclosed in the following
example.
Material Parts/Wt.
EPON 1001 (Shell) 60
FC 431 (3M)
Z6040 (Dow-Corning) 2
Dicyandiamide
Dibutyl Phthalate 25
K745 Black (Ferro) 25
Print at between 125-175F
Cure for 1/2 hour at 300-500Fo
In the example, the ink 126 is a heat processable hot
melt, thermoplastic (thermosetting above 300F), pressure-
sensitive material. The ink reversably melts with heat and
solidifies upon cooling. It cures and becomes thermosetting
once cross-linking occurs above 300F. The ink 126 may be
formulated to become tacky at near room temperature so that
a pressure-sensitive cohesive film may be produced. The ink
126 may also be formulated to preferentially stick to one
surface over another. Thus, in the present invention, ink
- 126 preferentially sticks to the mask 110 and releases from
the offset rolls 130 130'. Similarly if intermediate surface
carriers are used, for example, collectors 150-150', the
surfaces against which the ink 126 preferentially adheres
are formulated to provide adherence in a specific order~
Picture Tube Manufacture
In FIG. 9 a picture tube 100 is shown schematically in
side section. The tube 100 includes the panel 30 with
target 24' printed thereon, ma~k 110 with an aperture pattern
106 manufactured as hereinbefore described, and a conventional
-12-
o
funnel 102 and gun 103. If a tube 100 is manufactured
using a beam indexing gun, the mask 110 is not used. Thus,
the mask 110 becomes an optional feature.
Conventional means, not shown, may be used to fix the
panel 30 and mask 110 in a desired spatial relation~ Each
panel 30 is interchangeable with any other mask 110 of the
same model tube. That is, the respective target 24' and
aperture pattern 106 are desiged to work together in a
particular picture tube arrangement.
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