Sealed effusive structure for use in a cathode ray tube

The invention provides a sealed effusive material structure for angular orientation within a cathode ray tube. The effusive material, which is disposed in an annular channelized container, is protectively sealed by a metallic covering that melts at a temperature above that encountered during panel-funnel sealing, and below that used for activation of the effusive material. Receptacle means integral with the container is provided to collect and retain the gravity flow of the melted covering material.

TECHNICAL FIELD 
This invention relates to effusive material structures for use in cathode 
ray tubes and more particularly to a sealed effusive material structure 
for utilization therein. 
CROSS REFERENCE TO RELATED APPLICATION 
This application contains matter disclosed but not claimed in a related 
United States patent application filed concurrently herewith and assigned 
to the assignee of the present invention. The related application is Ser. 
No. 962,637, filed Dec. 22, 1978. 
BACKGROUND ART 
The term "effusive material" encompasses sufficient breadth to include any 
vaporizable or effusive material that may be desirably diffused within 
environment of a cathode ray tube, such as gettering or gas adsorbing 
substances, selected gases, and discrete metallic deposits. Such effusive 
material structures have been positioned at various locations within the 
tube to achieve maximum accomplishment of the desired results. 
For example, in color cathode ray tubes, gettering structures have been 
affixed to the forward end of the electron gun assembly and projected by 
support means to position adjacent to the coated interior surface of the 
funnel. During tube processing activation of getters so positoned, the 
effusive material emanating therefrom is usually deposited over an 
expansive area of the funnel-disposed conductive coating. 
In certain types of tube constructions, two or more diverse 
electrically-related coatings are adjacently disposed on discrete interior 
areas of the funnel portion. In such instances, the dispersal of a broad 
area of gettering material thereover becomes a deleterious factor in that 
it may effect electrical leakage between the coated areas. While diffusion 
directive means have been fashioned and incorporated with the getter 
containers to control the effusion of material emanating therefrom, there 
are times when adequate and consistent control is difficult to achieve, 
especially when the effusive structure is positioned proximal to the 
diversely coated areas. To minimize the above problem, the effusive 
structure, such as a gettering means, has been mounted in the forward 
region of the tube envelope on a screen related member, such as the color 
tube shadow mask structure, prior to sealing the face panel to the funnel 
portion of the envelope. This prior-to-sealing positioning of the 
exemplary gettering means evidences disadvantages in that the ambient 
atmosphere in conjunction with the heat required for sealing of the panel 
to the funnel produces a temperature-related environment which adversely 
affects the subsequent quality of the effusive material. 
DISCLOSURE OF INVENTION 
The present invention obviates and reduces the aforementioned disadvantages 
of the prior art. In one aspect of the invention, the advantages achieved 
are realized by the provision of a sealed effusive structure formed 
substantially as an annular V-shaped channel member having an effusive 
material disposed within the channel. An annular metallic covering is 
fitted into the channel and secured therein in a manner to provide a seal 
over the effusive material. The covering material has a melting point 
within the range of substantially 500.degree.-700.degree., which is higher 
than the processing temperatures encountered during panel-funnel sealing. 
Receptacle means is formed integral to the channel to receive and retain 
the melted covering material which is removed in a subsequent processing 
procedure immediately prior to the release of the effusive material. The 
sealed structure provided by the invention protects the effusive material 
therein from heat and associated atmospheric deterioration during 
panel-funnel sealing. Thus, the desired benefits of the effusive material 
are fully available to achieve the most advantageous results at the proper 
time in the tube processing procedure.

BEST MODE FOR CARRYING OUT THE INVENTION 
For a better understanding of the present invention, together with other 
and further advantages and capabilities thereof, reference is made to the 
following specification and appended claims in connection with the 
aforedescribed drawings. 
With reference to the drawings, FIG. 1 illustrates a partially sectioned 
view of an exemplary color cathode ray tube 11 whereof the face panel 
portion 13 is joined to the funnel portion of the envelope 15 by a 
peripheral seal of a frit material 17 therebetween. In this instance, the 
panel member has a patterned cathodoluminescent screen 19 disposed on the 
inner surface thereof. Spatially oriented within the confines of the panel 
13, and adjacent to the screen, is a screen-related discretely apertured 
member 21, as for example a shadow-mask or open-patterned electrode 
structure. Usually such screen-related members are comprised of a 
supportive framing means 23 to which the apertured element 25 is affixed. 
The positioning of this screen-related structure within the panel is 
effected by conventional means not shown. 
The effusive material structure of the invention 27 is affixed to the mask 
framing means 23 by suitable attachment means, such as the spring clip 29 
and an associated wand or longitudinal supporting member 31. Terminally 
oriented upon the supporting member is an annular container means 33, 
which as further delineated in FIGS. 2 and 3, is substantially structured 
as an open continuous U-shaped channel wherein the effusive material is 
contained. A conventional sled or rest member 35 may be employed if deemed 
necessary to prevent the container from contacting the coating 37 disposed 
upon the inner surface of the funnel. 
In greater detail, the U-shaped channel container 33, having a curved 
center-line 39 therearound, is formed to have a bottom portion 41 
wherefrom inner and outer upstanding walls 43 and 45 separately extend as 
spatially-related concentric formations. Containers of this type are 
usually fabricated of stainless steel, such as 305 material, which has a 
melting point much higher than any temperatures encountered during CRT 
manufacture. 
An effusive material 47 is uniformly disposed within the confines of the 
channel. As previously stated, the effusive material is chosen for the 
intended functional requirement, and may be one or a combination of 
substances of which the activated diffusion provides gas adsorption, a 
selected gaseous atmosphere or a thin metallic film. For purposes of 
example, a gettering structure will be described henceforth herein. The 
gettering material may be either endothermic or exothermic. Conventional 
getter alloys are those of substantially barium and aluminum and sometimes 
nickel. Depending upon the formulation, the flashing or vaporization 
temperatures of such materials are substantially within the range of about 
750.degree. to 1100.degree. C. 
An annular metallic covering 49 is fitted into the channel container 33 
atop the getter material 47 and secured therein in a manner to form a 
substantially hermetic contiguous seal over the effusive material. This 
covering 49 is formed of a material having a melting temperature higher 
than any of the sealing and processing temperatures to which it may be 
subjected during tube processing prior to that encountered for getter 
activation. The highest prior temperature ambient to the getter location 
occurs during the panel-funnel sealing operation, and may be in the order 
of 450.degree. C. A suitable covering material is one such as aluminum, 
which has a melting point of 660.degree. C. The preferred thickness of the 
covering is in the order of 2 to 5 mils (0.051-0.127 mm.) to assure 
adequate protection. 
One means for securing the covering 49 within the container 33 is to form 
the covering material as a substantially planar annular member, whereof 
the width dimension is substantially greater than the internal width 
dimension "d" of the channel at the surface of the disposed getter 
material 47. The circumferential edges 51 and 53 of the covering material 
49 are rolled inwardly around a pair of Alpha "A" and Beta "B" metallic 
rings of suitable differing circumferences, formed of material similar to 
that of the container. This provides a substantially unitized covering 
structure 55 which is securely press-fitted within the channel, the 
center-line of the covering 56 being substantially perpendicularly 
coincidental with the container center-line 39. Thus, the "A" ring portion 
is contiguous with the upper portion 57 of the inner channel wall 43, and 
the "B" ring portion contiguous with the upper portion 59 of the outer 
channel wall 45. Since the coefficients of thermal expansion of the rings 
and the container are similar, a substantially hermetic seal is achieved. 
As shown in FIG. 2, greater rigidity can be imparted to the unitized 
covering structure 55 by providing at least three traverse support members 
61 between the "A" and "B" cover-securing rings. As shown in FIGS. 3 and 
4, the cross-sectional configurations of these rings may be round, square 
or L-shaped, or variations thereof. 
Integrally associated with the container 33 is a receptacle means 63 which 
is formed to receive and retain the melted covering material that is 
liquified immediately prior to vaporization of the getter material. Since 
the getter container 33 is oriented in an angular position within the 
tube, the receptacle means 63 is located on the container in a manner to 
collect the gravity flow of the melted covering material. As illustrated 
in FIGS. 2 and 3, the exemplary receptacle is an added member 63 affixed 
to the container as by welding, the two materials being substantially 
similar. The receptacle incorporates formed retention means, such as a 
partially inwardly rolled formation of the lip portion 65, to secure the 
solidified covering material collected therein. It is to be noted that the 
outer wall 45 of the container has a depressed area 67 to allow the melted 
covering material to enter the receptacle. 
In referring to FIG. 4, there is shown another embodiment of the receptacle 
means wherein a receptacle 69 is achieved by a deformation of the channel 
structure particularly relating to a portion of the outer container 
sidewall 45. This deformation is localized to substantially the upper 
portion of the sidewall. In this instance, the retention means for 
securing the solidified covering material is in the form of at least one 
internally oriented projection 71, extending from the interior surface 
thereof, such as a small configuration of wire welded thereto. 
While there has been shown and described what are presently considered the 
preferred embodiments of the invention, it will be obvious to those 
skilled in the art that various changes and modifications may be made 
therein without departing from the scope of the invention as defined by 
the appended claims. 
INDUSTRIAL-APPLICABILITY 
The aforedescribed sealed effusive structure has advantageous utilization 
in CRT manufacture, particularly in the area of color tubes. The sealed 
getter is attached to the mask frame before the panel and the funnel are 
assembled at the entrance of the frit sealing lehr. Since the getter is 
sealed by a metal not affected by the heat encountered at panel-funnel 
sealing, protection is provided to the getter material preventing 
oxidation or otherwise deterioration thereof during the frit-lehr 
temperature cycle. The sealed panel-funnel assembly then moves to gun 
sealing and on to exhaust. Shortly into the exhaust cycle, the sealed 
getter is RF heated to about 660.degree. C., or slightly higher, whereupon 
the getter seal melts and by gravity flow is collected and retained in the 
channel-related receptacle. Thus, the getter material is exposed to the 
vacuum environment within the tube. Upon completion of exhaust, the tube 
is sealed and the getter RF flashed as in conventional practice. 
The invention provides several advantages not heretofore achieved. 
Installation of the sealed getter on the mask frame assembly is easily and 
securely accomplished prior to panel-funnel sealing. Thus, there is no 
scraping of loose particles of coating as was often prevalent when 
subsequently introducing the getter structure through the neck of the 
sealed panel-funnel assembly. More accurate positioning of the getter can 
be accomplished thereby insuring optimum flashing. Since the getter 
material is protected during panel-funnel sealing and a major portion of 
the exhaust cycle, the ensuing getter deposition within the envelope 
provides a finished tube of enhanced quality.