U.S. patent number 3,700,949 [Application Number 05/108,366] was granted by the patent office on 1972-10-24 for color television picture tube.
This patent grant is currently assigned to Nippon Electric Co., Ltd.. Invention is credited to Yuzi Saito, Takeshi Watanabe.
United States Patent |
3,700,949 |
Watanabe , et al. |
October 24, 1972 |
COLOR TELEVISION PICTURE TUBE
Abstract
A color television picture tube comprises an integrally formed
shadow mask unit including electron beam passing apertures, and
skirt, and flange portions. The unitary mask construction is
secured to a bulb housing via studs, and bimetal is employed for
temperature compensation. The structure obviates welding and
welding associated nonuniformity and expense, and also permits
accurate registration of the mask structure within the tube.
Inventors: |
Watanabe; Takeshi (Tokyo,
JA), Saito; Yuzi (Tokyo, JA) |
Assignee: |
Nippon Electric Co., Ltd.
(Tokyo, JA)
|
Family
ID: |
22321798 |
Appl.
No.: |
05/108,366 |
Filed: |
January 21, 1971 |
Current U.S.
Class: |
313/405 |
Current CPC
Class: |
H01J
29/073 (20130101); H01J 2229/0772 (20130101) |
Current International
Class: |
H01J
29/07 (20060101); H01j 029/46 (); H01j
029/56 () |
Field of
Search: |
;313/85,85S,92B |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Saalbach; Herman Karl
Assistant Examiner: Chatmon, Jr.; Saxfield
Claims
What is claimed is:
1. A color television picture tube comprising a bulb having a front
panel including portions for producing a plurality of colors
responsive to electron bombardment and formed of a substantially
transparent material, said bulb including a peripheral side wall
portion adjacent to the edge of said front panel, an aperture mask
unit having plural apertures for permitting passage of electron
beams therethrough corresponding to said front panel portions for
producing a plurality of colors, and means for securely supporting
said aperture mask unit wherein said aperture mask unit is formed
of a plate integrally comprising an aperture plate portion, a
cylindrical aperture plate skirt portion, and a flange portion bent
inward nearly perpendicular to the surface of said skirt portion
and then bent outward extending toward the inner wall of said
peripheral side wall portion.
2. A color television picture tube as in claim 1, in which a part
of said supporting means is inserted into the space formed between
the reversely bent flange portion of said aperture mask unit.
3. A color television picture tube as in claim 2, in which said
supporting means comprises an L-shaped stud one end of which is
sealed into the inner wall of said peripheral side wall portion,
the other end of said stud being engaged with an aperture mask unit
support hole bored in the vicinity of the edge portion of said
flange portion of said aperture mask unit.
4. A color television picture tube as in claim 2, in which said
support means part comprises a piece of bimetal.
Description
This invention relates to a color television picture tube of shadow
mask type and, more particularly, to an improved color television
picture tube having a shadow mask secured within the glass
bulb.
Prior art color television picture tubes comprise a bulb having a
front panel which is made of a substantially transparent material,
and includes portions for emitting a plurality of colors responsive
to electron bombardment. Further, a peripheral side wall portion is
fitted along the edge of the front panel. An aperture mask or a
shadow mask assembly includes many apertures which pass only the
electron beam directed to the color display tube portion; a frame
for holding the shadow mask in its requisite shape, and support
metal associated with the bulb to support the frame, wherein the
shadow mask is welded to the frame.
However, such a picture tube has several drawbacks. For example,
the shadow mask structure, assembled by welding individual
components together, is made nonuniform during welding and suffers
assembly accuracies; the composite structure is heavy; and the
welded parts often become loose by reason of vibration or impact.
In addition, a complicated assembly process is required to
construct every picture tube unit, resulting in high production
costs.
In view of the above, it is an object of the present invention to
provide a color television picture tube having a light-weight,
vibration and impact-resistant shadow mask unit of integral
structure, realized without depending upon a conventional assembly
process.
Another object of the present invention is to provide a color
television picture tube having a shadow mask support provision
permitting easy insertion of the shadow mask into position with
high accuracy, and rendering efficient temperature compensation
possible.
The color television picture tube of the present invention is
provided with a shadow mask unit integrally constructed of a piece
of metallic plate comprising: a plate-shaped shadow mask portion
including plural apertures; a cylindrical skirt portion supporting
the mask portion; and a flange portion about one end of the skirt
portion and bent inside nearly perpendicular to the surface of the
skirt and then bent in a reverse direction, the flange thereafter
extending outward beyond the surface of the skirt. The extended
part of the flange portion is provided with several mounting holes
which engage the ends of L-shaped studs which are sealed into the
side wall of the panel skirt. A temperature compensating bimetal is
employed in conjunction with these mounting holes and to the
studs.
A complete understanding of the present invention, and of the above
and other objects, features and advantages thereof, will be gained
from a consideration of the following detailed description of an
illustrative embodiment thereof, presented hereinbelow in
conjunction with the accompanying drawings, in which:
FIG. 1 is a sectional diagram showing a portion of conventional
color television picture tube,
FIG. 2 is a sectional diagram showing a portion of color television
picture tube embodying the principles of the present invention,
and
FIG. 3 is an enlarged sectional diagram showing a part of the color
television picture tube of FIG. 2.
Referring now to FIG. 1, there is shown a color television picture
tube of the shadow mask type, wherein a phosphor screen 3 is
disposed about the inner wall of a front panel 2 of a glass bulb 1.
A shadow mask 4, made of a thin plate having many apertures and
supported by a frame 5 by welding thereto, is mounted inside the
front panel 2. An elastic support 8, welded to the frame 5 by way
of a bimetal 6, is used to attach the shadow mask 4 to the panel.
In particular, the support 8 engages a stud 9 sealed into a side
wall 7 of the glass bulb 1. The purpose of the bimetal 6 is to
compensate for the deformation of the shadow mask 4 due to
temperature rise and the resultant thermal expansion occurring when
electrons hit the mask surface, and thus to prevent deterioration
in color purity. An electron shield 10 is welded to the frame 5 to
prevent emissions from the phosphor screen 3 when the electron beam
hits the inner surface of the side wall of the panel. The electron
shield 10 is made of a thin metallic plate disposed so as to hinder
electron propagation between the frame 5 and the side wall 7 of the
glass bulb 1.
In the color television picture tube arranged as above, the elastic
support 8 must have a strong elastic characteristic to prevent the
shadow mask from being moved by vibration or impact. Also, the
frame 5 must be thick enough to maintain the shape of the shadow
mask. Thus the elastic support 8 is required to sustain a fairly
heavy weight. In the prior art, therefore, the welded components
often cause deformation or separation due to vibration or impact
giving rise to degradation in color purity.
In the process wherein the bimetal 6 is welded to the frame 5 and
the elastic support 8 welded to the bimetal 6, the distance between
the shadow mask 4 and the phosphor screen on the front panel 2 can
scarcely be maintained constant because welding is not uniform. To
compensate for such nonuniformity in welding, the welded portion of
the elastic support 8 must be adjusted for every assembly by using
a measuring tool or instrument.
Furthermore, the prior art procedures and construction requires a
considerable number of welding processes for assembly, such as
welding between the shadow mask 4 and frame 5; between the frame 5
and bimetal 6; between the bimetal 6 and the elastic support 8; and
between frame 5 and the electron shield 10. This causes increased
costs in the production of color television picture tubes.
Referring now to FIG. 2, there is shown a part of a color
television picture tube embodying the principles of the present
invention, wherein the shadow mask, frame, elastic supporter,
electron shield, and the like, which have heretofore been set into
a unit by a welded assembly, are integrally constructed into one
unit. The integral unit comprises a piece of metallic plate forming
a shadow mask portion 11 having plural apertures; a skirt portion
12 which supports the shadow mask 11; a flange portion 13 which
corresponds to the conventional electron shield, the flange being
contiguous to one end of the skirt, bent inwardly nearly
perpendicular to the surface of the skirt and thereafter bent
outwardly; extended outward with respect to the surface of the
skirt; and a raised portion 14, which is contiguous to one end of
the flange 13, being bent perpendicular to the flange 13. In this
structure, the skirt portion 12 may be embossed for reinforcement
purpose. The flange portion 13 is bent inside the skirt 12 to serve
as a shield for preventing the occurrence of fog caused by stray
secondary electrons produced by electron bombardment at the inner
surface of the skirt.
To maintain efficient temperature compensation, one end portion of
a bimetal 6 is inserted into the space formed by the reversely bent
segments of the flange portion 13 so that the top and bottom sides
of the bimetal is brought into full contact with the surface of the
bent flange portion 13. Such a composite shadow mask structure can
readily be formed by a plurality of reducing processes through the
use of a press with a hydraulic die cushion or hydraulic press
machine.
FIG. 3 is a partly enlarged diagram showing the structure by which
the shadow mask unit is affixed to the glass bulb. A hold 15 is
bored in the flange 13, and engages each of a plurality of studs 9
which are sealed into the side wall 7 of the panel. The bimetal 6
is provided for each of the studs 9. A hold 16 is bored in the
bimetal 6, which hole 16 is coincident with the hole 15 of the
flange 13.
The bimetal 6 is inserted into the space formed by the bent flange
portion 13 with its low expansion side in contact with the skirt
portion 12. The purpose for such an arrangement of the bimetal is
to compensate an aperture position with respect to the electron
beam. More specifically, the shadow mask 11, when heated by the
electron bombardment, expands in its radial direction due to the
thermal constraints and, accordingly, the aperture moves toward the
radial direction. Thus the position at which the electron beam will
arrive, after passing through the aperture, is deviated outside of
the position where the electron beam should reach. However, the
bimetal 6 is attached to the flange portion is bent inward on the
low expansion side due to the temperature rise and, as a result,
the shadow mask unit is pushed forward on the part thereof attached
to the bulb, and the aperture moves forward accordingly. In other
words, the electron beam, after its passing through the aperture,
is compensated to reach the same position as that obtaining before
the temperature rise brought about by the electron bombardment.
The studs 9 are L-shaped, one end of each stud being sealed into
the side wall 7 of the glass bulb 1. The other end of each stud
extends in the direction away from the phosphor screen 3. A hold 18
is provided at a position near the tip of the interior end of the
stud 19. The bimetal 6 and flange portion 13 are engaged by the
stud 9 by way of holes 15 and 16 and secured together by a pin 17.
The reference surface 19 of the stud 9 is positioned so as to
determine the distance between the surface of the phosphor screen 3
and the shadow mask 11 as in FIG. 2. Thus the distance between the
two is kept constant in the state where the surface of the bimetal
6 is pressed to the reference surface as in FIG. 3.
The shadow mask unit according to this invention, as has been
described above, requires no welding operation. It is therefore
impossible for this shadow mask to undergo deformation or
separation in a welded part as in the prior art. Thus degradation
in color purity due to deformation or separation in a welded
portion is entirely eliminated. According to this invention, there
is no assembly error due to a welding process and, hence, the
shadow mask and the glass panel can be set at an accurate design
distance. Further, temperature compensation can be efficiently
accomplished. Also, the number of assembly processes can be
markedly reduced in comparison with prior art procedures. In
addition, the invention makes it possible to omit the use of a
conventional frame, elastic support and electron shield, and to
thereby realize a considerable reduction in production costs.
While the principles of the invention have been described above in
connection with a specific embodiment, it is to be clearly
understood that this description is made only by way of example and
not limitation as to the scope of the present invention.
* * * * *