Getter assembly with improved support

A getter assembly is described having an improved support such that the points of contact with the glass wall of a cathode ray tube have as low a temperature as possible. An antenna position mounting can be attached to the lower side of the central disc-shaped form of the getter assembly formed from an upraised portion of the bottom wall of the ring container. Said mounting tab can extend outwardly without touching the internal wall of the container or its bottom wall, in the preferred embodiment there can be attached, for example by means of welding, a support means which has at least one concave surface facing towards the bottom of the container and situated in a plane perpendicular to the outwardly extended portion of the mounting tab. In any case, even if said support is attached to the bottom wall of the container, it has a first portion perpendicular to the tab and approximately parallel to the lower wall, a second portion integral with the first and which forms an angle with it and is at the same time approximately parallel to the lower wall, and a third portion integral with the second, perpendicular to said tab adapted to distance said container from said glass wall.

BACKGROUND TO THE INVENTION 
The present invention relates to a getter assembly with an improved support 
to avoid high temperatures at the points of contact of the supports with 
the wall of the electron tube in which the getter device is located. 
It is known that getter devices are widely used in tubes for the 
representation of visual images such as cathode ray tubes. In use the 
getter assembly is heated to a high temperature usually by means of high 
frequency induction, so that a gettering metal, normally barium, is caused 
to evaporate from the getter assembly. This can be located within the 
cathode ray tube in the "antenna" position or attached to the anode button 
but, whatever its position it is usually in usually in contact with the 
internal surface of the glass envelope of the cathode ray tube. 
Unfortunately the high temperatures, even greater than 1000.degree. C., 
reached by the getter device during evaporation of the gettring metal are 
such as to provoke rupture of the glass envelope. It has therefore become 
the normal practice to provide some tyoe of the thermal insualtion or 
support between the getter material container and the glass wall. Ceramic 
insulators have been used as described in U.S. Pat. No. 3,381,805 or metal 
wire supports as described in U.S. Pat. No. 4,101,247. Another type of 
support is described in Japanese Utility Model Publication No. 50-11453. 
Unfortunately such insulating means or supports are costly or still have 
too high a temperature at the point of contact between the support and the 
glass envelope, especially when the getter device has a small diameter. 
BRIEF OBJECTS OF THE INVENTION 
It is therefore an object of the present invention to provide a means of 
relatively low cost which ensures that the points of contact of the getter 
assembly and the glass wall of a cathode ray tube remain at a sufficiently 
low temperature during evaporation of the getter metal, so that breakage 
of the glass envelope is prevented. 
These and other objects advantages and characteristics of the getter 
assembly with an improved support according to the present invention will 
become more clear from the following detailed description of the preferred 
embodiments described as non-limiting examples with reference to the 
attached drawings in which:

DESCRIPTION OF THE INVENTION 
Referring now to the figures, in which like parts are indicated with the 
same reference number, there is shown in FIGS. 1-3 a getter assembly 10 
which comprises a getter material container 12, which is shown here as a 
ring but which could have any other form, with an external sidewall 14, an 
internal sidewall 16 and a bottom wall 18 which joints said two sidewalls 
defining in such a way an annular channel 20. Annular channel 20 contains 
gettering material 22 in the form of a powder, which generally comprises a 
mixture of an alloy of approximately 50% barium, 50% aluminium together 
with approximately an equal weight of nickel. By the term "getter 
material" as used here in the description and in the claims it is intended 
to means the material both before and after getter material vapour 
release. This term embraces both the materials in the form sold with the 
getter device and in the form in which it is found in an operating tube 
wherein the bulk of the getter metal has been evaporated from the material 
and is in the form of a film on the inside surfaces of the tube. Upper 
edge 24 of the internal sidewall is integrally formed around a disc 
element 26 to provide an upper raised bottom portion 28. 
A mounting tab 30 is attached in a central zone of the disc-shaped element 
26 by means of a horizontal welding zone 32. Horizontal welding zone 32 is 
integrally attached to a downwardly extending zone 34 which is distanced 
from internal sidewall 16 to reduce to a minimum heat transmission towards 
the mounting tab and the support, as will be described later. 
The mounting tab 30 further comprises a zone 36 which extends outwardly and 
is situated in a plane substantially parallel to bottom wall 18, however 
it may have a slight angulation to guide the getter metal vapours in a 
suitable direction. In any case outwardly extending zone 36 does not touch 
bottom wall 18 and is preferably separated from it by at least 0.5 mm. 
This avoids that zone 36 of the mounting tab removes heat from the getter 
container through bottom wall 18 and so prevents formation of a colder 
zone of getter material 22 during the evaporation of getter metal vapours. 
Outwardly extending zone 36 extends to a distance which is greater than 
the radius of external side wall 14. In FIG. 2 there are shown by maens of 
dashed lines, on the right hand side of the drawing, several possible 
configurations of mounting tab 30, or rather of its zone 36, with 
inclinations in either one or the other sense respect ot the horizontal or 
with a discontinuity by means of a joining portion parallel or at least 
complanar with downwardly extending zone 34. 
According to the invention a support means 38 is attached to mounting tab 
30 and has a concave surface 40, facing bottom wall 18 and situated in a 
plane perpendicular to outwardly extending zone 36 of mounting tab 30 
Support means 38, preferably formed from a metal wire, comprises a first 
portion 42 extending perpendicular to mounting tab 30 and approximately 
parallel to bottom wall 18. A second portion 44 integral with said first 
portion extends at an angle of substantially 90.degree. relative to said 
first portion 42 and is approximately parallel to bottom wall 18; 
In FIG. 1 and FIG. 2 there are indicated three different position for 
attaching support means 38 to mounting tab 30, of which the middle one is 
shown in continuous lines and the two at either side with dashed lines. In 
FIG. 2 there is also indicated as detail 44' an alternative variation of 
second portion 44 of the support, shown as a dashed line which has a 
slight inclination with respect to bottom wall 18. Portions 42 and 44 can 
however also be comprised of a single piece without bending. A third 
portion 48 is integrally attached to second portion 44 and extends 
perpendicularly to mounting tab 30 which initially curves downwardly and 
then upwardly thus forming a concave surface 50 (FIG. 3) facing the bottom 
wall 18. 
A part of concave surface 50 may be flattened at 52 (dashed line in FIG. 3) 
to receive a ceramic member 54 if desired which may have the form of a 
wheel or cilinder etc. The third portion of concave surface 50 may be 
comprised of a multiplicity of concave surfaces 60, 60' as shown in FIG. 
5. In this case it is preferable that third portion 48 is longer than when 
there is only one concave surface, for which reason second portion 44 can 
advantageously have the configuration shown in FIG. 4. 
In FIG. 6 there is shown a cross-section view of a getter assembly in which 
supports means 38 is attached, instead of to mounting tab 30, directly to 
the bottom wall 18, from which however second portion 44 is slightly 
distanced to reduce heat transmission. 
Finally FIG. 7 shows a known getter device of the DND type with a capsule 
containing a material able to liberate nitrogen, provided with a 
deflector, in which support means 38 of the present invention is attached 
to this deflector. 
On the other hand support means 38, for some particular types of getter 
which have, in place of mounting tab 30 dixed to the central zone of the 
assembly, a bar mounting tab attached directly to the bottom of the 
getter, support means 38 can be welded by means of first portion 42 to 
said bar. 
It is observed that the position in which support means 38 is attached to 
mounting tab 30 or to bottom wall 18 can be used as a reference point for 
the attachment of the antenna spring. 
Although the invention has been described in detail with reference to 
certain preferred embodiments and uses it is intended that variations 
and/or modifications can be carried out while sill remaining within the 
spirit and scope of the invention.