US2880348A

US2880348A - Gettering units for electron tubes

Info

Publication number: US2880348A
Application number: US483501A
Authority: US
Inventors: Charles R Gray
Original assignee: Philco Ford Corp
Current assignee: Space Systems Loral LLC
Priority date: 1955-01-24
Filing date: 1955-01-24
Publication date: 1959-03-31
Anticipated expiration: 1976-03-31
Also published as: GB833215A

Description

March 31, 1959 c. R. GRAY 4 GETTERING UNITS FOR ELECTRON TUBES Filed Jan. 24, 1955 IN V EN TOR. CHAEL 55 ,6 62A Y United States Patent GE'I'IERING UNITS FOR ELECTRON TUBES CharlesR. Gray, Lansdale, Pa., assignor to Philco Corporation, Philadelphia, Pa., a corporation of Pennsylvama Application January 24, 1955, Serial No. 483,501

4 Claims. (Cl. 313--176) This invention relates to getters and more particularly it refers to novel gettering units for electron tubes and the like.

A principal object of the invention is to provide a more eflicient and accurately controllable gettering arralngement for cleaning up residual gases in electron tu es.

Another object is to provide a novel gettering unit for more accurately controlling the gettering trajectory of the flashed getter.

Another object is to provide a novel gettering unit whereby a plurality of spaced getter bars can be flashed with substantially equal getter flashing energy, even though the flashing or bombarding coil is not symmetrically located with respect to both bars at the instant of flashing.

A feature of the invention relates to a double getter bar unit whereby both bars are always energized by the same amount of induced flashing current, and whereby positive flashing of both getter bars simultaneously is always assured.

Another feature relates to a novel double getter bar unit whereby both bars can be flashed simultaneously without relative movement of the bombarding coil from the region of one getter bar to the other.

. A further feature relates to a double getter bar unit whereby larger deposition areas of the flashed getter can be obtained while insuring simultaneity of flashing of both bars.

A still further feature relates to the novel organization, arrangement, and relative interconnection of parts which enable a more efficient and uniform getter flashing operation to be achieved.

Other features and advantages not particularly enumerated will be apparent after a consideration of the following detailed descriptions and the appended claims.

In the drawing,

.Fig. 1 shows one known arrangement of a plurality of gettering units;

- Fig. 1A is a schematic representation of the flashed trajectories from the two units of Fig. 1;

Fig. 2 shows another known arrangement of two getter units; 1

Fig. 2A is a schematic representation of the flashed trajectories of the units of Fig. 2;

Fig. 3 is a view of the novel gettering unit according to the invention;

Fig. 4 is a perspective view of a typical electron tube, such as a cathode-ray tube, embodying a plurality of getter units according to the invention. I

In certain kinds of electron tubes, especially in cath ode-ray tubes, it is desirable to be able to produce a deposited flashed getter material over a substantially large area on the inner surface of the tube envelope. This involves the utilization of a number of individual gettering units which are distributed so as to produce the desired large area of deposited material. One known arrangement which attempts to solve this problem is 2,880,348 Patented Mar. 31, 1959 2 illustrated in Fig. I, wherein two similar getter units designated 10 and 11 are shown. Each of these units consists for example of longitudinally slitted tubular metal members 12, 13 (see Fig. 1A), having a narrow slit 14, 15. The

tubular members

12 and 13 are loaded or packed with any well known flashable gettering ma terial indicated by the

numerals

16, 17, facing that portion of the wall 18 of the enclosing bulb or envelope on which the flashed getter material is to be deposited. The conventional manner of flashing these getters is to locate a so-called bombarding coil in inductive relation with each getter unit. For various reasons it is desirable to have this coil of relatively small dimensional configuration. Consequently, where two relatively widely spaced gettering units such as units 10 and 11 (Figs. 1 and 1A) are employed, it is usually necessary to locate the bombarding coil schematically indicated by the numeral 19 in inductive alignment with one gettering unit 10, and then it may be necessary manually to move this bombarding coil into inductive registry with the other gettering unit 11. Since in the meanwhile the unit 10 has been flashed, the material may be deposited on the,

envelope wall 18 in such a position as to render the visibility of the other unit 11 not clear. When it is remembered that the movement of the bombarding coil in such devices may be effected by an attendant op'er ator, it may happen that the flashing of the first getter unit visually obscures the second gettering unit. Thus, the operator is unable to position the bombarding coil 19 in the most eflicient relation with respect to the second unit. Furthermore, if the units 10 and 11 are slit ficiently widely spaced so as to prevent this visual 'ob' scuring, the trajectories of the flashed getter may not overlap. Thus, as shown in Fig. 1A, the trajectories of the flashed getters deposited on the wall 18 will leave a substantial uncoated area which for certain purposes may be undesirable.

In an attempt to overcome this objection, it has been proposed heretofore to locate the getter units with their

bars

12, 13, closely spaced. Thus, as shown in Figs. 2 and 2A, the units 10 and 11 are reversed with respect to'their relation shown in Fig. 1, thus bringing the

bars

12 and 13 closer together. While this may solve the problem of non-overlapping of the flashed material, it introduces other difiiculties which it is the object of the present invention to overcome.

Each of the conventional gettering units illustrated in Fig. 1 and Fig. 2 consists of a slitted tubular bar 12 containing the well known getter material, in order to provide a complete inductive loop for each getter bar, a

metal wire

20, 21 is bridged across the ends of each bar.

It is quite clear, therefore, that with such an arrangement the amount of electromagnetic energy or flashing current that is induced into each unit loop is a function ofthe location of the bombarding coil with respect to that loop. Unless therefore the operator accurately positions the bombarding coil in the same inductive relation to each separate loop, there is always the likelihood that at some time one loop may receive a greater or less amount of induced flashing current than the other loop. In some instances the coil may be located in such a position as to induce insuflicient current into one of the loops to enableit to be flashed. If, therefore, the second getter unit is obscured visually by the deposited material from the first loop, the attendant has no way of determining whether the second loop actually has been flashed. This difliculty exists not only with the widely spaced getter bars in the known arrangement of Fig. 1, but also in the known are rangement of Fig. 2. In fact, it is present in any case;

in which each getter bar forms a part of a respective and separate getter loop.

In accordance with the present invention the above noted diflieulties' are overcome by using two separate getter bars which, however, are assembled'ina single loop. Thus, as shown in Fig. 3, the-

getter bars

22 and 23 which may be similar to the

bars

12 and 13 of Figs. 1 and 2, namely each in the form of a longitudinally slitted metal tube containing the getter material 24, are arranged substantially parallel to each other and united at opposite ends'by two

wires

26, 27. Thus, both getter bars form parts of the same closed inductive loop which is located in a single plane substantially parallel to the axis of the neck 29, and the magnetic axis of the bombarding coil 19 is substantially normal to that axis as shown in Figs. 3a and 4. Consequently, the induced current flowing in one getter bar by the bombarding coil 19 is the same induced current flowing in the other bar, thus the bombarding currents in both bars will always be the same magnitude, regardless of the position of the bombarding coil with respect to the double bar unit. Furthermore, with such an arrangement it is not necessary for the'attendant operator to move the bombarding coil to effect complete flashing of both getter bars. The only requirement is that the bombarding coil be moved to a position in substantial registry with the double bar unit. The operator is given a satisfactory indication of the proper position immediately that the visible flashing takes place because when one bar is thus flashed it is an assurance that the other bar is also flashed. Furthermore, it is possible by this arrangement to space the

bars

22 and 23 apart so that the deposited flashed material slightly overlap and thus cover the desired large area on the wall 18 of the tube.

it will be understood, of course, that the invention is not limited to the use of only one double bar getter loop, as shown in Fig. 3. For example, Fig. 4- shows in diagrammatic form a typical cathode-ray tube comprising the usual evacuated bulb or envelope 28 in the neck portion 29 on which is mounted the usual electron gun 30. Suitably supported within the neck 29 are four double bar getter units according to the invention and designated 31, 32, 33, 34. Each of these units may be identical with the unit shown in Fig. 3. The bombarding coil may be formed in two sections located on opposite sides of the neck 29 so that by moving it into substantial registry with the

units

31 and 32, the complete flashing of both these units can always be achieved. The bombarding coils can then be moved into registry with the next set of

units

33 and 34 so as to effect flashing thereof. Alternately, the bombarding coils may be stationary during the flashing, and the tube 28 may be moved longitudinally to bring the

units

33 and 34 into registry with the bombarding-coils. If desired, the bombarding coil may be designed so as to induce the flashing current simultaneously into all four units 31-34.

As a result of the above described double bar individual inductive loop units, it is possible to obtain equal flashing of both getter bars since the position of the getter material in the bombarding field is not critical. In actual manufacture of tubes using the invention, it has been found that less'time is required for the flashing operation and the flashing is not dependent upon the visibility of both getters. Furthermore, the spacing between

the'bars

22, 23 of each unit is not critical, with the result that there is a substantial reduction in the cost of manufacturing electron tubes and a smaller percentage of rejects which tends to result from incomplete or improper getter flashing. It will be understood, of course, that the invention is not limited to the particular construction of getter bar or getter holder shown in the drawing. It will be understood that this bar may take the form of a solid wire 'or flat strip of getter material.

Various changesand-modifications may be made in the-disclosedembodiments without departing from the spirit and scope 015- the invention.

What is claimed is: I

1. A multiple getter unitfor an electron discharge device, comprising at least two discrete elongated spaced getter holders each containing a flashable getter, wire means joining the adjacent ends of the holders to maintain them in spaced relation and forming therewith a single closed inductive loop to be raised to getter flashing temperature by a flashing coil having its magnetic axis directed transversely to the plane of said loop and arranged to be moved to a single setting wherein the same induced current flows through both getters whereby the simultaneous flashing of both getters is insured in said single setting. 7

2. A multiple getter unit for an electron discharge device, comprising atleast two discrete elongated getter holders each containing respective flashable getter material, wire means joining the adjacent ends of the holders to maintain them in spaced relation and forming therewith asingle closed inductive loop to be raised to getter flashing temperature by an induction heating device arranged to be moved to a single setting wherein the same induced current flows through the getter materials in both holders to insure simultaneous flashing of both materials and to produce respective overlapping getter deposits on an adjacent receiving surface within the device.

3. A multiple getter unit for an electron discharge dc: vicehavingan elongated cylindrical envelope, said getter unit comprising at least two discrete, elongated getter holders disposedapproximately equidistant from said envelope, said two getter holders occupying substantially the same longitudinal position in said envelope, conductive means joining adjacent ends of said getter holders to maintain them in spaced relation and forming therewith a closed inductive loop with said getter holders on opposite sides of said loop, said loop lying in a plane which is substantially parallel to the longitudinal axis of said cylindrical envelope, each of said getter holder portions of said loop being adapted to be raised to getter flashing temperature by current induced in said loop by a relatively small'flashing coil having its axis directed transversely to the axis of said envelope and transversely to the plane defined by said loop.

4. A multiple getter unit for an electron discharge device having an elongated'cylindrical envelope, said getter unit comprising at least two discrete, elongated, substantially straight getter holders disposed parallel to the longitudinal axis of said cylindrical envelope and approximately equidistant from said envelope, said two getter holders occupying substantially the same longitudinal position in said' envelope, conductive means joining adjacent ends of said getter holders to maintain them in spaced relation and forming therewith a closed inductive loop with said getter holders on opposite sides of said loop, each of said getter holder portions of said loop being adapted to be raised to getter flashing temperatureby current'induced in said loop by a relatively small flashing coil having its axis directed transversely to the axis of said envelope and transversely to the plane defined by said getter holders.

References Cited in the file of this patent UNITED STATES PATENTS 1,689,297 Rentschler Oct/30, 1923" 1,699,112 MacRae Jan. 15, 1929 1,883,174 Von Wedel Oct. 18, 1932 2,126,686 Malloy Aug. 9, 1938 2,263,164 Dailey Nov. 18, 1941 2,341,941 Mouromtseif et al. Feb. 15, 1944 2,474,335 Skellett June 28, 1949 2,503,806. Diggle Apr. 11., 1950. 2,638,559 Giacchetti May 12. 1953