Note: Descriptions are shown in the official language in which they were submitted.
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S P E C I F I C A T I O N
TO WHO~I IT MAY CONCERN:
BE IT KNOWNt that I, Roland Thoms~ a citizen of West
Germany, have invented new and useful improvements in TELEVISION
PICTURE TUBES AND IIOLE TEOEI~lOLOGY, of which the Eollowing is a
specification.
Back round of the Invention
Field of the Invention. This invention relates generally
to hole technology and to television picture tubes and, more speci-
fically, to hole technology useful in television picture tubes
having aperture masks with a plurality of line of sight openings
therein.
Summary of the Invention
BrieEly, one part oE the present invention comE)rises a
method for making a line oE sight opening which may be square,
rectangular or the like and the second part comprises an article
having a line of sight opening which may be square, rectangular or
the like. The article comprises a sheet of material having a line
of sight opening wherein a portion of the edges of the line of
sight opening is partially defined by surface material located on
one side of the article with the remainder of the edges of the line
of sight opening defined by material located on the opp~site side
of the article.
The process involves the selective removal of mate~-ial
from one surface of an article by milling or etching a recess in the
article with at least a portion of the material removed by under-
cutting the surface of the article. After forming a recess, an
opening is formed in the opposite side of the material by milling
or etching an opening from the opposite side into the recess.
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Brief Description oE the Drawing
Fig. 1 is a perspective view of a single line of sight
opening in a television aperture mask;
Fig. 2 is a top view or cone side view oE the line oE
sight opening of Fig. l;
Fig. 3 is a bottom view or grade side view o~ the line
of sight opening of Fig~ l;
Fig. 4 is ~ oross sectional view of a televlsion picture
tube;
Fig. 5 is a partial top sectional view o~ an aperture
mask and television tube,
Fig. 6 is a partial side sectional view of an aperture
mask and television tube; and
Fig. 7 is a front schema-tic view oE an aperture mask
having a plurality of openings therein.
Descrip-tion of_t~!e PreEerred Embodiment
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Re~erring to F:igs. 1, 2 and 3, reEerence numeral 10
generally defines a portion of a television aperture mask having
a cone side surface lOA and a grade side surface lOB. Surface
lOA is referred to as the cone side since the larger opening or
recess 15 is located therein and surface lQB is referred to as
the grade side. In typical use of an aperture mask in a television
picture tube the grade side faces the electron guns while the
cone side faces the television picture tube. This type of position-
ing provides the best pictures for conventional etched masks.
Located in aperture mask 10 is a line of sight opening which has
edges tha~ are defined by the cone side surface lOA and the grade
side surface lOB of aperture mask lO. Located in cone side surface
lOA is a recess 15 which is defined in cone side surface lOA by
pair of side edges 11 and llA and a pair of end edges 14A and 16A
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which are all located in the plane of cone side surface lOA oE
~pertu~e mask 10. Side edges 11 and llA connect to end edges 14A
and 16A to form a closed boundary in the plane o~ cone side surface
lOA. Thus, edges 11, llA and edges 14A and 16~ define the junc-
tion of the side walls of recess 15 w:ith the cone side surface lOA.
The side walls o recess 15 include an undercut sur-Eace
14 and an un~l~rcut surface 16 which respe~tlvely connect to ecl~
14A and edge 16A. Surfaces 14 and 16 are undercut downward from
cone side lOA and radially outward from edges 14A and 16A -toward
grade side lOB.
The thickness of aperture mask 10 is denoted by T which
usually ranges from .004" to .008". The length of undercut is
denoted by A. The undercut angle is denoted by ~ and -the thickness
of the remaining material -that forms the bot-tom oE r~cess 15 is
denoted by Tl with Tl being substan-tially less than the thickn~
T oE aperture mask 10.
Re~erring to Fig. 3 tgracle side), it will be noted that
the bottom view show& th~ outline of an elongated slot in grade
side surface lOB which i9 defined by edge 12A, edge 12, edge 12B
and edge 12C which are all located in the plane of grade side
surface lOB. Edges 12 and 12A are straight whereas edges 12B
and 12C are curved. The portion of the opening to the outside
of lines X-X defines the portion of the opening which con-tains
curved edges 12B and 12C.
The line of sight opening through aperture mask 10 is
formed by edges 12A and 12 which define the longitudinal opening
and edges 14A and 16A which define the transverse portion of the
line of sight openings. Note, in the grade side view (Fig. 3)
edge 12 and edge l2A also define the longitudinal opening; and
edges 14A and 16A define the transverse portion of ~e line of
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sight opening. Although the grade side view of aperture mask 10
is different from -the cone side view of aperture mask 10, the line
of sight opening through aperture mask 10 is the same.
The two lines X-X, which are located on both ends of the
elon~ated slot, deno-te the separation point between the curvatu:re
J~!~; .L:~U .~ tr.l.i-Jl~ t.iOll~; l.!l~ .Irl-l :L~ J~ tll~
embodiment shown, lines X-X are located to the ou-tside of edges
14A and 16A to thereby insure the line of sight opening in aper-
ture mask 10 is comprised of a set of straight edges wi th sub-
stantially square corners. The curved ends are typical of cut-
ting operations such as chemical etching.
Thus, although grade side surface lOB re~eals an elong-
ated opening therein which is substantially longer than the line
of s:ight opening through the article, the surEaces 1~ and 16,
which were produced by undercutting material :Erom edges 1~ and
16A, project out suf.ficiently Ear to prevent the :radiused edges
12B and 12C from ~orming a boundary of the line oE si~ht opening
-through aperture maslc 10.
In forming elongated openings in aperture mask, the
process of etching permits one to etch a recess 15 in aperture mask
10. Typically, -the etching process is continued until it produces
a recess 15 with undercut surface 14 and 16. The size and shape
of undercut surface can be controlled by the amount of etchant and
time of etching and is generally within the skill of those in the
art.
After forming recess 15 in one side, the elongated open-
ing is etched from the opposite side. If desired, the elongated
opening can be formed during the etching o the recess by simul-
taneously spraying etchant on opposite surfaces lOA and lOB.
After etching, the elongated slot appears with radiused corners
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as shown in Fig. 3. In the process of forming the line of sight
opening through the article, -the etching continues Imtil the etch-
ant penetrates throucJh the material of thickness Tl. After pene-
tration, the etchant is removed typically leaving an el.on~ated
opening such as cle~ined by ed~es 12A, 12B, 1~ and 12D. L:ines
X-X denote the radius port.ion of elonya-~e~ openi.ng which re~ults
~rom the etch.ing action.
An inspection of Fig. 3 shows the radius portion 12B
and 12C project onto surfaces 15 and 16. Thus, the radiused
corners 12B and 12C of aperture mask 10 do not form a part of the
line of sight opening in aperture mask 10. While the article and
method have been described w.ith respect to rectangular openings,
it is apparent the process can be used to make other unusually
shaped line of sight openings which are diEficult or impos,s.ible
to make with conventional techniques.
EXAMPL,E 1
To illustrate the improvement in light trans:mission,
a conventional television aperture mask was etched having Plongated
slo~s with parallel sides and rounded ends. The dimensions oE
the slot were as follows:
slot width - 175.2 micrometers
tie bar width - 145 micrometers
slot length - 613 micrometers (maxim~lm dimension)
The measured light transmission through the slot was
measured as 17.7 units.
A second aperture mask was made in accordance wi.th the
present invention in which the outline of the line of sight opening
had a substantially rectangular configuration in accordance with
Figs. 1, 2 and 3. The dimensions of the rectangular line of
sight opening were as follows:
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slot width - 174.8 micrometers
tie bar width - 144 micrometers
slot len~th - 614 micrometers
The transmission through the opening was measured as
18.36 units or an increLIse of approximately ~i percent in licJht
transmisslon. For the second mask, however, since the dimensions
of the two holes were not exactly equal, a compellsation for the
area revealed that the second mask actually had an approximately
6.5 percent grea-ter light transmission capab:ility.
lQ Referring to Fig. 4, reference numeral 30 generally
designates a cross sectional view of a telev:ision picture tube
using the line of sight ape~ture mask of the present invention.
The television pic-~ure tube comprises a glass enclosure 3] having
a base 32 ancl pron~s 33 thereon Eor attachment to the electronics
of the television set. Located on the exterior of tha neck of ~ho
television picture tube is a focusing coil 35 -that focuses the
electron beam so the ~lectron beams converge as they pass through
openinqs 47 in aperture mask 4a. Located adjacent focusing coil
35 is a deilection coil 37 which sweeps the electron beam across
aperture mask 48. ~rhe aperture mask 48 is locaked with a plurality
of elongated openings 47 located therein. Located immediately
behind elong~ted slots 47 is a phosphor strip 40. Although three
phosphor strips are located behind each opening in the cross sec-
tional view only one strip is visible in the cross sectional view.
The phosphor strips comprise the primary colors red, blue and green
which, when excited by the electrons, produce the proper
color on Eace plate 39 of television picture tube 30.
To understand the operation o the present invention in
a television picture tube, reference should be made to Figs. 5
and 6 which respectively show a top view of a portion of the
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television aper-ture mask and a television picture tube and a side
view of a television pic-ture tube. rl'he front glass envelope por-
tion of the television pic-ture tuhe is desiynated by reEerence
numeral 39 with reference numerals 40, 41 and 42 desigrla-ting the
red, blue and green phosphor stripes which extcnd lcngitudinally
parallel to the elongated openings which are located in aperture
mask ~8. ~ig. 7 shows schematically -the slot arrangement of a
typical aperture mask having a series of elongated slots. ocated
between phosphor stripes 40, 41 and 42 is a suitable black light-
absorbing medium that does not emit any color should it be struckby electrons.
Referring to Fig. 5, the aperture mask is deno~ed by
reference numeral 48 and with cone side 45 Eacing the ~l~ctron
gun and tlle grclcle side 46 facing the phosphor ~trip~s whlch are
locatQd on Eace plate 34~ Sinc~ the most metal is removed ~rom
sidc 45 to provicle r~cass ~5~, this side is danot~d as tll~ con~
side and in the en~ocliment showII is located ~acing the elec-tron gun.
~ypical prior art aperture masks the cone side was located facing
the phosphor side. Fig. S re~eals how the grade side edge surfaces
53 and 54 limit the electrons in the lateral direction.
Fig. 6 shows a side view o~ aperture mask 48 with refer-
ence numeral 39 denoting the face plate and reference numeral 40
indicating a phosphor stripe. The aperture masks 4~ has an opening
45A on the cone side 45 and an elongated opening on the opposite
side. The tie bar or bridges as they refer to in the prior art
are located with the narrow end of the bridge or tie bar facing
the phosphor stripe 40 and the tie bar extending from the cone
side 45 to grade side 46. Fig. 6 shows tie bar 50 to comprise a
grade side surface 50B, a cone side surface 50A and an interior
surface 51 on lower tie bar and an upper interior surface 52 on
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upper tie bar 50. The upper and lower boundaries of the line of
sight opening in aperture mask 48 is defined by the junction of
surface 52 with cone side sur-face 44 and junction o~ surface 51
with cone side surface 45.
In practice the plurality of tie bars located in the
spaced relationship provide for accurate deEininy of an opening
for the excitation of the phosphor stripes located along the tele-
vision picture tube.
Note, if the aperture masks have the cone side facing the
electron gwl, one should llave the bottom o the recess region,
which is located adjacent the sides of the line of sight openigns,
sufficien-tly flat or angled so that the electron beams that impinge
on the bottom of the recess region do not deflec-t throutJh -the Line o~
sight openinc3 in the aperture mask. Typically, iE the bottom o~ t~e
recess region is ~arallel to the mask cone sic~e surEace, onc cloe~
not obtain sc~t~ering ~lectron reflections ~hrouyh the linc of
sight openings.
In addi~ion, with the aperture mas~c cone side acing the
electron guns the portion of the rec~ess side walls which do not
2Q define a portion of the line of sight opening should be set suf-
ficiently far ~ack from the line of sight opening in the aper-ture
mask so that the path of the electron beam is not obstructed by the
recess region side walls or the cone side surace of the aperture
mask. In conventional mounting with the grade side toward the elec-
tron gun, these adjustments would not be necessary.
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