US2426247A - Getter apparatus - Google Patents

Description

Patented Aug. 26, 1947 2,426,247 GETTER APPARATUS Benjamin signor to Franklin Steiger,

United Electronics Company, Newark,

Maplewood, N. J as- N. J a corporation of New Jersey Application March 24, 1943, Serial No. 480,283

This invention relates to apparatus for and the method of introducing getter into vacuum tubes.

For many years it has been customary to introduce getter into highly evacuated tubes such as those used for radio transmission and reception, for example, in order to improve the vacuum within such tubes. It has been found, however, that in the case of high frequency and high voltage tubes employing a high vacuum that the introduction of getter, although desirable, presented many difficulties so that it is now the practice not to use any getter in such tubes. The difficulties which have been encountered when a getter has been used in such tubes have been primarily that the getter would deposit on the electrodes or other portions of the tube within the envelope with undesirable results. For example, if any of the getter were deposited on the electrodes within the tube, the electrodes would become primary emitters of electrons so that the tube would either change its characteristics or cease to function. This is particularly true in case any getter becomes deposited on the inside of the plate. The plate begins to emit electrons and the tube either immediately or after an interval ceases to be' useful to perform its desired function. If any getter becomes deposited on the press or stem of the tube or upon the envelope itself, a high voltage puncture is likely to occur particularly in the stem, thus destroying the tube entirely.

I have discovered that a getter may be used in a high voltage, high vacuum tube such as a rectifier tube used in a radio transmitter, for example, with apparatus according to my invention in which the getter is prevented from being deposited upon any of the electrodes of the tube or any portion of the tube itself. With my apparatus, I may confine the getter deposit to the inside of a supplementary open ended tube within the evacuated envelope and thus secure the beneficial effects of using a getter without incurring any of the disadvantages which have heretofore accompanied such use in this type of tube.

In the drawings I have illustrated in Figure l a high vacuum, high voltage rectifier for use in a radio transmitter which has been built in accordance with my invention.

Figure 2 is an enlarged section along the lines 2-2 of Figure 1.

Figure 1 shows an envelope I having mounted therein an anode 2 which surrounds an elongated filamentary cathode maintined taut by the spring 3. Rods 4 and 5 mounted in the press 2 Claims. (01. 206-0.4)

, cuit including the yoke 1 and rod I ll.

support the filament at its lower end. Secured to one or both of the rods 4 and 5 in any suitable manner, as by a rod 6, is the getter structure of myinvention. Secured to the rod 6 is a yoke I which supports a wire mesh 8 which in turn surrounds and supports an open ended tube 9 which is illustrated as a glass tube, but may be of other material, such as metal. Secured to the ends of the yoke 1 is a metal rod H! which has affixed to it a strip of getter material H. The getter strip ll may be of any suitable materials, for example that sold commercially under the trade name Kic Kemit, or it may be of any other suitable material. One very good material to use as a getter, either alone or in combination with other materials, is barium, but barium is a notatable example of the type of getter which, if used in accordance with usual practice in a high vacuum, high voltage tube, is subject to the disadvantages mentioned above. The tube 9 surrounds the strip of getter H throughout the entire length of that strip. After the tube has been thoroughly baked and evacuated in accordance with the usual practice, the getter may be vaporized in any suitable manner, as for example by applying a high frequency coil to the getter structure so as to induce current around the cir- This should be done in such a manner as to avoid flashing the getter, but instead to cause the getter to evaporate. This may be accomplished very simply by simply not applying too strong a field for too long a time, that is, by avoiding too high a degree of heat. As the evaporation from any body occurs in straight lines perpendicular to its surface, the getter which is thus evaporated passes directly to the open ended tube 9 and is deposited thereon. As this tube is open at its ends and as the getter is evaporated gradually there is no building up of pressure within the tube 9 such as would force any of the evaporated getter material out of the ends of this tube so that it is all deposited upon the inner surface of tube 9. Again, as the tube 9 is open at its ends it is, of course, in communication with, indeed a part of, the evacuated space within the bulb and the getter is, therefore, just as effective in cleaning up any residual gas remaining within the tube as it would be if used in accordance with prior practice.

In addition to the other advantages of my new apparatus and method mentioned above, the introduction of getter in this manner prevents any discoloration whatever of the envelope of the bulb so that it remains perfectly clear and transparent for easy viewing of the interior of the tube both in inspection at the time of manufacture and in use.

I have produced tubes in accordance with the method disclosed herein, and having the structure disclosed, and have found such tubes to have all of the advantages Which would be expected from the additiona evacuation effect provided by the getter material, but Without any of the disadvantages that have heretofore inevitably accompanied previous attempts to use a getter in high vacuum, high voltage rectifier What is claimed is:

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,712,370 White May 7, 1929 1,966,226 Sutherlin July 10, 1934 2,043,724 Anderson June 9, 1936 2,154,131 Lederer Apr, 11, 1939 2,183,841 King Dec. 19, 1939 2,093,273 Haslauer Sept. 14, 1937 1,895,867 Sinden s Jan 31, 1933 1,917,044 Loewe 1. 1. July 4, 1933

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