US2462813A - Getter structure - Google Patents

Description

Feb. 22, 1949.

L.RHNER GETTER STRUCTURE Filed June 18, .1946

INVENTOR LEOPOLD RUNER ATTORNEY Patented Feb. 22, 1949 GETTER STRUCTURE Leopold Reiner, Orange, N. J., assignor'to United Electronics Company, Newark, N. J., a corporation of New Jersey Application June 18, 1946, Serial No. 677,461

8 Claims. 1

The object of this invention is to provide an improved getter structure for a vacuum tube which will result in an improved tube.

In the drawings, Fig. l is a front view of a vacuum tube employing my invention which is cut away so that the getter structure may be seen;

Fig. 2 is a cross section of the getter structure on the lines 2-2 of Fig. 1; and

Fig. 3 is an end View of the getter structure looking from the right of Fig. 1.

In the drawings the vacuum tube I has therein rods 2 and 3 mounted in the press which rods may be used to support the filament at its lower end. Secured to one or both of the rods 2 or 3 in any suitable manner, as by a rod 4, is a yoke 5 which supports the getter structure of my invention. Secured to the yoke 5 by welding or other suitable means are two nickel shields 6 and l and a molybdenum flag, support, or partition 8, to which is attached a getter cup 9 within which may be placed any suitable getter such as that sold commercially as barium-aluminum pellets. Held in position by the shields 5 and l is a glass tube In which surrounds the getter capsule and flag.

The shields 6 and I may be made by stamping out a tab as seen most clearly in Figs. 2 and 3, the tab ll being secured as by welding to one end of the yoke 5 and flag 8 and the tab !'2 being similarly secured to the other end of the yoke 5 and flag 8. These tabs II and I2 leave openings in the shields 6 and I which serve as vents for the getter material. The flag 8 shields the getter capsule from direct access to the vent openings to reduce the pressure at these vents.

The getter may be vaporized by high frequency induction heating and the glass tube lil permits a visual examination of the amount of getter in the trap during vaporization, which permits control of the heat used so that too high a temperature may be avoided.

The getter trap thus described serves to confine the getter deposit within the getter trap structure. The vent or vents serve to minimize pressure of residual gases which might force getter material from the trap to be deposited on the inside of the bulb and tube parts. The result is that the tube remains clear, with no visible getter deposit at the time of flashing getter or later durme use of the tube, and also there is no contamination of the internal tube parts and electrodes with getter material.

The advantages of a clear glass bulb may be listed briefly as follows:

1. Radio-frequency losses resulting from conductive getter deposit on the bulb are reduced to a minimum. This leads to: ((1.) increased power output; (12) increased tube eficiency (both power output and tube efficiency increase with higher operating frequencies); (c) local overheating of the glass bulb and stem which might result in bulb puncture and electrolysis of the stem press is, in the main, avoided since there is no getter deposit to absorb radio frequency energy.

2. Decreased values of inter-electrode capacitances result from the absence of conductive getter deposit on the bulb. This permits tube operation at higher frequencies at full tube ratings, or, alternatively, allows increased ratings for a given operating frequency.

3. More stable inter-electrode capacitance values are attained. In conventional transmitting tubes the amount of conductive getter deposit on the'bulb varies with the tube operating temperature; hence, the stability of the inter-electrode capacitances is varied. The results of greater inter-electrode capacitance stability are increased frequency stability and more constant tube characteristics.

The advantages resulting from non-contamination of internal tube parts and electrodes include the following:

1. Decrease in primary emission from active getter particles deposited on plate and grid.

2. Decrease in secondary emission which may be caused by pollution of plate and grid surfaces.

In addition to the foregoing, in the isolated getter trap of my invention the getter material is kept at a lower temperature than in conventional tubes Where getter is deposited on the bulb; hence the keeper effect of the getter persists for a longer time.

The foregoing advantages exist for both metal and carbon anode electronic tubes.

It has heretofore not been practicable to use graphite anodes in very high frequency transmitting tubes because the metallic deposit from the conventional getter structure causes a Waste of radio frequency power. My isolated getter trap, however, eliminates this disadvantage and permits the use of graphite anodes in high frequency tubes.

My invention is particularly adapted for high voltage, high vacuum tubes such as rectifier, oscillator and. modulator tubes in radio transmitters, for example. With my new getter structure I have observed by actual test gains in power output of oscillator tubes of 20 per cent at 30 megacycles over conventonal tubes with the same input.

This getter has made possible the use of thoriated-tungsten filaments instead of tungsten filaments in high voltage rectifier tubes with consequent gain in filament emission. My getter structure has been effective in reducing gas which leads to the emission poisoning of thoriatedtungsten electron tubes.

The 3'71--B transmitting tube is an example of a tube type whose maximum life .without my getter structure was considered by the Signal.

Corps, U. S. Army, as exceptionally good if it lasted 250 hours. With my getter structure, life records of several thousand hours are common.

One tube in which I have tested my new getter structure is the I-IV18 type. Tubes of this type were life tested with both conventional getter structure and with getter structures of the present invention with 800 watts input, which is a very high input for this type of tube. Under this test, tubes with conventional getter structures exhibited a life of a few minutes before the bulbs collapsed or other defects appeared. The same tubes with my new getter structure gave a satisfactory life for about 500 hours and then failed because of a cracked grid bead, a defect which was not a result of the getter structure.

It will be obvious to those skilled in the art that my invention is capable of various modifications and I do not therefore wish to be restricted to the particular details shown and described but only .within the scope of the appended claims:

What I claim is:

1. A getter structure for an electronic tube comprising a getter, a flat plate supporting said getter intermediate the ends of said plate, a transparent tube surrounding said getter and plate, and end members fixed to said plate at either end thereof and holding said tube, each of said end members being apertured to provide vents.

2. A getter structure for an electronic tube comprising a getter capsule, a plate supporting said capsule, a getter trap which completely encloses said capsule and plate except for a small vent in each end of the enclosing trap, said plate being connected to said enclosing trap at each end thereof.

3. A getter structure for an electronic tube comprising a transparent tube surrounding the getter, said transparent tube being enclosed at its ends except for venting openings, and a supporting plate for said getter extending within and along substantially the entire length of said tube.

4. A getter structure for an electronic tube comprising a partition, a getter capsule mounted on said partition, an enclosure surrounding said partition and capsule, said enclosure having a vent opening, said partition shielding said capsule from said opening.

5. A getter structure for an electronic tube comprising a molybdenum partition, a getter secured to said partition, a glass tube surrounding said partition and getter, a nickel shield at each end of said glass tube, each of said shields having a vent opening, said openings being on the opposite side of said partition from said getter.

6. A getter structure comprising a molybdenum support, a getter capsule secured to said support, a tube surrounding said support and capsule, a nickel shield at each end of said tube, each of said shields having a vent opening, said support shielding said capsule from said vent openings. I

'7. A getter structure for an electronic tube comprising a support, a getter capsule attached thereto, a glass tube surrounding said support and capsule, a shield at each end of said glass tube, each of said shields having a vent opening, said capsule being shielded from said vent openings by said support,

8. A getter structure for an electronic tube comprising a support, a getter supported thereby, a tube surrounding said getter and support, an enclosure at each end of said tube, each enclosure having an opening, said support shielding said getter from said openings.

LEOPOLD REINER.

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

UNITED STATES- PATENTS Varian June 1, 1937

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