US2835841A - Getter support structure - Google Patents

Description

May 20, 1958 H. DODSON GETTER SUPPORT STRUCTURE Filed Sept. 8, 1955 FIG.2.

FIG.I.

FIG.3.

III III INVENTOR HAROLD L. DODSOlN,

HI TTOR EY.

.envelope.

United States Patent GETTER SUPPORT STRUCTURE Harold L. Dodson, Owensboro, Ky., assignor to General Electric Company, a corporation of New York Application September 8, 1955, Serial No. 533,055

9 Claims. (Cl. 313-181) My invention relates to electric discharge devices and pertains more particularly to a new and improved getter support structure for use therein.

In the manufacture of some electric discharge devices such as electronic tubes, it is customary to introduce into the tube envelopes a getter material or a material which is adapted for being flashed or vaporized in the tubes after evacuation thereof, to absorb any gases which have been left by the evacuating means.

In producing certain tube types it is desirable that the gettering operation or flashing of the getter material be accomplished by radio-frequency inductive heating and as the tubes pass through a getter flashing station on automatic tube manufacturing equipment. Additionally, in such tubes the getter material is often supported on a disk of material which is adapted for being inductively heated to a point where it. eflects flashing of the getter material supported thereby. This type of support is generally referred to in the art as a flag getter support and heretofore has een mounted in the tube atop a mount structure or electrode support assembly by means of a single tab formed off the disk and welded to a portion of the mount structure. The flag is generally tilted at an oblique angle relative to the longitudinal axis of the tube so that, when the tube is passed in a predetermined oriented manner through the radio-frequency field at the flashing station, the flag will extend transverse a substantial quantity of flux lines and thereby facilitate induction of circulating currents in the flag for increasing the temperature thereof and flashing the getter material supported thereby. It has been found that for a given field strength the flag should be tilted at a predetermined angle since a lesser angle will tend to result in insuiflcient heating to effect flashing and a greater angle will cause excessive flashing with undesirable splashing or spraying of loose getter material particles as well as getter flash, or the silvery conductive deposit resulting from flashing, on the elements of the tube mount.

As indicated above, heretofore the flag was supported by a single tab atop the tube mount. The tilt of the flag was accomplished by an operator who bent it to the desired angle before inserting the tube mount in an Unfortunately, in tubes thus constructed and assembled the flags at flashing did not always extend at precisely the same angle, due to handling, human errors, and heat distortion resulting during processing. As a result the tubes were not always uniformly flashed and some failed to flash on the automatic manufacturing equipment.

Additionally, the tube mount structures on which the getter supports are mounted generally comprise a plurality of electrode elements supported between and spaced and insulated from each other by insulative members such as mica disks. These mount structures tend to be affected by getter flash in that the flash deposits on the insulative members and provides undesirable short circuiting electrical paths between the electrode elements. In order to avoid this, shield structures have been utilized between the getter and mount structures. These, however, are generally undesirable in that they add to the 7 cost and effort of tube manufacturing.

Accordingly, the primary object of my invention is to provide a new and improved getter support structure.

Another object of my invention is to provide new and improved means for insuring predetermined uniform flashing of the getter material in successively processed electric discharge devices.

Another object of my invention is to provide a new and improved means for minimizing the adverse effects of getter flashing on tube mount elements.

Another object of my invention is to provide a new and improved getter support structure adapted for facilitating satisfactory getter flashing and shielding the tube mount structure from the getter flash.

Another object of my invention is to provide a getter support and mount shielding structure adapted for minimizing cost and effort in tube manufacture.

Further objects and advantages of my invention will become apparent as the following description proceeds and the features of novelty which characterize my invention will be pointed out With particularity in the claims annexed to and forming part of this specification.

In carrying out the objects of my invention I have provided a getter support structure or member including a flag or base portion adapted for supporting a quantity of getter material to be flashed by inductive heating. A plurality of leg portions extend from the base portion at a predetermined oblique angle whereby the base portion is mountable in a tube envelope in a predetermined oriented position. The legs may be formed for embracing portions of a tube mount in the envelope. Additionally,

the base portion is shaped for extending substantially completely across the interior of the envelope.

For a better understanding of my invention reference may be had to the accompanying drawing in which:

Fig. l is an enlarged fragmentary partially sectionalized view of an electric discharge device incorporating a preferred embodiment of my invention;

Fig. 2 is a somewhat enlarged fragmentary schematic illustration of the manner in which the getter material is flashed through the use of my invention;

Fig. 3 is a sectional view taken along the line 3-3 in Fig. 1 and looking in the direction of the arrows;

Fig. 4 is a fragmentary enlarged perspective view of the getter support structure illustrated in Figs. 1 and 3 and shows an alternative manner of supporting same; and

Fig. 5 is an enlarged fragmentary perspective illustration of a modified form of my invention.

Referring to Fig. 1 there is partially shown an electric discharge device or electronic tube generally designated 1 and comprising an evacuated envelope 2 containing a tube mount structure or electrode support assembly 3. The envelope 2 is shown as being cylindrical and of a circular cross section. However, as will be seen hereinafter my invention is not limited to envelope structures of this particular configuration. The mount structure 3 includes a pair of spaced insulative members 4 which may be mica disks and only one of which is shown. Supported between the members 4 as by having end portions extending therethrough is a plurality of electrode elements which may include a cathode (not shown), a grid 5 which may comprise a helically wound wire on a pair of parallel spaced support rods 6, and an anode or plate 7 which may be sleeve-like in construction.

The mount 3 is suitably positioned in the envelope 2 and is maintained in substantially coaxial alignment with the longitudinal axis of the envelope 1 by engagement of the insulative members 4 with the side walls of the on velope in the manner shown in Fig. 1.

In the tube structure illustrated in Fig. 1 a support Patented May 20, 1958 frame 10 is provided which is secured atop the mount 3 by means of a plurality of tabs 11 which extend through and are bent under the upper one of the insulative mem bers 4. The frame It includes a pair of diametrically opposed upright tabs 12. The tabs 12 provide convenient means for securing my improved getter support member or structure generally designated 13 to the top of the mount structure 3 and between the mount structure and the upper end of the envelope 2.

The getter support member 13 is formed of a material adapted for being headed inductively and comprises a substantially planar flag or base portion 14 from the sides of which extend a pair of diametrically opposed leg portions 15. The leg portions 15 extend from the base portion 14 at a predetermined oblique angle such that when the leg portions 15 are secured to the mount structure 3, as by welding to the tabs 12 of the support frame 10, the flag or base portion 14 of the getter support extends at a predetermined oblique angle relative to the longitudinal axis of the envelope 2. The predetermined positioning of the flag is fixed or inherent in the structure and the mounting of the flag by a plurality of legs reinforces it against unintended alterations of the predetermined position of the flag. The purpose for this feature of my invention will be brought out in detail subsequently in description of the getter flashing operation.

Formed in the base portion 13 and extending inwardly toward the mount structure is a depression 16 adapted for receiving a predetermined quantity of any suitable getter material illustrated in outline in Figs. 1 and 3 and designated 17. Secured across the upper surface of the flag portion 14 so as to cover the depression 16 and retain the getter material 17 therein is a perforated plate 18.

Now, the tube structure illustrated in Fig. l is one in which the getter has already been flashed and which has already been tipped-d or sealed after having been evacuated. The customary flash, or silvery deposit resulting from flashing of the getter material, is shown on the end wall portions of the envelope as stippling designated 19. When the getter 17 is flashed the tube is not yet tipped-off but instead, and as illustrated in Fig. 2, it is held in an inverted position by a tubulation portion thereof in one of a plurality of exhaust heads 29 of the tube manufacturing equipment by which devices of the illustrated type are processed automatically. Additionally, at a predetermined operating station on the equipment there is provided suitable radio-frequency coils schematically illus trated and generally designated 21. By control means not shown, these coils set up a radio-frequency field of a predetermined strength and are arranged for having tubes pass through the field in the oriented vertical position illustrated.

When the tubes pass through the field of the coils 21 in the just-described manner, the flag 14 traverses or cuts across flux lines indicated by the arrows designated 22 in Fig. 2. This causes current circulation in the flag portion and thereby increases the temperature thereof, the resultant temperature being dependent both on the tilt of the flag portion, which determines the quantity of fiux lines traversed by or concentrated in the flag, and the field strength. Now, in my improved getter support structure 13 the quantity of flux lines to be traversed by the flag may be fixedly predetermined. That is, by predetermining the oblique angle at which the legs 15 extend relative to the flag portion 14 and securing the support structure 13 to the mount structure in the manner illustrated in the drawing, the flag portion will extend at a fixed predetermined oblique angle relative to the axis of the tube envelope 2. Thus, when the tube is moved through the field in a predetermined oriented position, such as that illustrated in Fig. 2, the flag will traverse the flux lines in a predetermined angular position relative thereto and a predetermined quantity of flux lines will be concentrated in the flag. This will have a predetermined heating effect on the flag. By knowing such effect an operator can preset the field strength of the coils 21 and the dwell period of successively processed tubes in the field and thereby insure that the getter material in successfully processed tubes incorporating my improved getter support 13 will be substantially uniformly flashed and at a predetermined substantially uniform flashing temperature. Additionally, by building the predetermined oblique angle into the support structure the success of the flashing operation of individual tubes is not in reliance upon human judgment as regards the positioning of the individual flags, nor are the flags likely to be bent out of their desired positions as a result of handling or by the effects of heat during processing. Still further, the predetermined fixed angular position of my flag, which enables a predetermined setting of the radio-frequency coils, enables the temperature of the flag 14 to be so controlled as not only to insure uniform flashing of all tubes passing through the radio-frequency field, as pointed out above, but additionally avoids over-heating and undesirable resultant excessive flashing which would tend to spray loose getter material particles as well as getter flash onto the tube mount structure.

In order further to minimize the effects of getter flash on the tube mount, and as seen in Figs. 1 and 3-5 I have formed my flag 14 elliptically. Thus, in a tube envelope of circular cross section, such as that illustrated in the drawing, the flag 14 extends substantially completely across the interior of the envelope or, in other words, substantially conforms to a transverse section of the envelope corresponding to the oblique angle of the flag portion, Consequently, when the getter material 17 is flashed the resultant flash or silvery conductive deposit is confined or restricted to an end portion of the envelope 2 which is substantially remote from the mount structure 3, with the result that the mount structure 3 is substantially shielded from the getter flash. Thus, any substantial deposit of getter flash on the mount insulative members 4 which would tend to provide undesirable short circuiting electrical paths between the electrode elements supported by the members 4 is avoided.

Additionally, by utilizing the flag portion of my getter support as a flash shield, manufacturing costs are reduced due to the facts that no other mount shielding device such as a mica shield is required and less time and effort is required in assembling the tube mount.

It is to be understood that while I have shown my flag portion shaped elliptically, it may assume any configuration required for it to conform substantially to an internal section of the envelope. For example, if the envelope were rectangular in cross section the flag portion of my getter support would be rectangular in shape.

In Figs. 1 and 3 I have shown my getter support structure 13 mounted atop the mount structure 3 by means of the upright tabs 12 formed 013? the frame support 10. However, as seen in Fig. 4, alternatively the leg portions 15 of my getter support structure may be suitably secured, as by welding, to extensions of the grid support rods 6. Additionally, if for any reason it is undesirable to mount the getter support on the grid support rods 6, separate stakes or the like may be provided in the tube mount structure for having the legs 15 secured thereto.

As seen in Fig. 5, the leg portions 15 may be formed Withlongitudinal flutes or channels designated 23. Thus, the leg portions 15 may be adapted for embracing and being secured, again as by welding, to the grid support rods 6 or other elements such as stakes provided in the mount structure. The fluted construction of the legs 15 enables an assembler to position the getter support 13 precisely before and during the securing operation simply by nesting or positioning the rods in the flutes 23. This insures precise angular disposition of the flag 14 when the leg portions 15 are secured in place on the tube mount.

It will be seen further that this last-described form of my invention not only insures predetermined precise positioning of the flag 14 but provides reinforced mounting of the flag whereby unintended changes of the angular position thereof due to handling and the effects of processing are minimized.

Thus, it will be seen that I have provided a new and improved getter support structure which automatically insures predetermined uniform flashing of the getter material in successively processed electric discharge devices and minimizes the adverse effects of getter flashing on tube mount structures. Additionally, it will be seen that my structure facilitates satisfactory getter flashing and minimizes both the cost and effort involved in tube manufacture.

While I have shown specific embodiments of my invention, I do not desire my invention to be limited to the particular form shown and described, and I intend by the appended claims to cover all modifications within the spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In an electric discharge device, a cylindrical envelope, a quantity of getter material in said envelope, a member in said envelope directly supporting said quantity of getter material and comprising material adapted for being inductively heated to eflect flashing of said getter material, said member extending at a predetermined oblique angle relative to the longitudinal axis of said envelope to facilitate inductive heating thereof and said member extending substantially completely across the interior of said envelope in a region spaced from the op posite ends of said envelope for confining the flash of said getter material to one end of said envelope.

2. In an electric discharge device, an envelope having a circular cross section, and a member in said envelope adapted for supporting a quantity of getter material and for being heated to eflect flashing of said material, said member being elliptical in configuration and positioned in said envelope at a predetermined angular position to facilitate inductive heating and to confine the flash of said getter material to a particular portion of said envelope.

3. In an electric discharge device, an envelope including a longitudinal axis, a mount structure in said envelope, a quantity of getter material in said envelope adapted for being flashed by inductive heating, a metal member in said envelope supporting said quantity of getter material, and said member including a plurality of legs fixedly supporting said member on said mount at a predetermined oblique angle relative to said axis of said envelope, whereby said inductive heating is facilitated.

4. In an electric discharge device, an envelope, a mount structure in said envelope, a quantity of getter material in said envelope adapted for being flashed by inductive heating, a member in said envelope directly supporting said quantity of getter material, said member including a plurality of legs formed off the opposite lateral edges thereof and fixedly supporting said member on said mount at a predetermined integral oblique angle in said envelope, whereby said inductive heating is facilitated, and said member extending substantially completely across the interior of said envelope in a region spaced from the ends of said envelope and said mount structure and conforming substantially to an oblique cross-section of said envelope for confining the flash of said getter material to a portion of said envelope remote from said mount.

5. In an electric discharge device, an envelope including a longitudinal axis, a quantity of getter material in said envelope adapted for being flashed by inductive heating, a mount structure in said envelope including a plurality of longitudinally protruding support elements, a member in said envelope supporting said quantity of getter material, and said member including a plurality of longitudinally extending legs embracing said support elements and fixedly supporting said member on said mount at a predetermined oblique angle relative to said axis of said envelope, whereby said inductive heating is facilitated.

6. In an electric discharge device, an envelope including a longitudinal axis. a quantity or" getter material in said envelope adapted for being flashed by inductive heating, a mount structure in said envelope including a plurality of longitudinally extending support rods ex tending from one end thereof, a member in said envelope supporting said quantity of getter material, said member including a plurality of legs extending at a predetermined oblique angle relative to said member, and said legs being longitudinally fluted for receiving and having said support rods secured therein, whereby said member is fixedly supported on said mount at a predetermined oblique angle relative to said axis of said envelope for facilitating said inductive heating.

7. In an electric discharge device, an envelope including a longitudinal axis, a quantity of getter material adapted for being flashed by inductive heating, a mount structure in said envelope including a plurality of support rods extending longitudinally from one end thereof, a member in said envelope supporting said. quantity of getter material, said member including a plurality of legs extending at a predetermined angle relative to said memher, said legs being longitudinally fluted for receiving and having said support rods secured therein, whereby said member is fixedly supported on said mount at a predetermined oblique angle relative to the longitudinal axis of said envelope, whereby said inductive heating is facilitated, and said member substantially conforming to an oblique cross section of said envelope and extending across the interior of said envelope in a region spaced from the ends of said envelope and said mount structure for confining the flashing of said getter material to a portion of said envelope remote from said mount.

8. A getter assembly comprising, a metal base portion including a depression opening on the upper side thereof, a quantity of getter material in said depression, and a plurality of legs extending downwardly from said base portion at a predetermined oblique angle whereby said support structure is mountable for fixed predetermined angular disposition.

9. A getter assembly comprising, a metal base portion including a depression opening on the upper side thereof, a quantity of getter material in said depression, a plurality of legs extending downwardly from said portion at a predetermined oblique angle, and said legs including longitudinal flutes whereby said support structure is mountable for fixed predetermined angular disposition.

References Cited in the file of this patent UNITED STATES PATENTS

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