US1716153A

US1716153A - House electric

Info

Publication number: US1716153A
Authority: US
Publication date: 1929-06-04
Anticipated expiration: 1946-06-04

Description

June 4, 1929. K. ROTTGARDT VACUUM TUBE FOR AMPLIFICATION AND OSGILLATION GENERATION Filed Sept. 2, 1921 d v r .E R6 N W N0 1 E T VP A N Il/ Patented June 4, 1929.

UNITED STATES 1,716,153 PATENT OFFICE.

KARL ROTTGARDT, OF DAIEILEBL BERLIN, GERMANY, ASSIGNOR TO WESTING- HOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYL VANIA.

VACUUM TUBE FOR AMPLIFIGATION AND OSCILLATION GENERATION.

Application filed September 2, 1921, Serial No. 497,946, and in Germany March 8, 1917.

(GRANTED UNDER THE PROVISIONS} GF THE ACT OF MARCH 3, 1921, 41 STAT. L, 1313.)

This invention relates to tlnee-electrode vacuum tubes and nu a particularly to the arrangement of the electrodes within the lube.

It is an ol'iject of this invention to provide a. supporting means for the several electrodes which will. space them more closely than has heretofore been possible. 'llhis object oi the invention relates more particularly to the spacing between the cathoifle and. the grid although it is entirely possible, by "following the teachings of this invention, to also locate the anode close to the other electrodes.

it is a further object of this invention to arrai'i ie the grid or control electrode so that he maximum i-silect oi" the field of this leclrod-e upon the eleetrtni stream will be secured. it is well known that the field o'l'i a charged body is more intense near the eorners than at other points. The invention makes use ext this principle to accomplish this object.

Other objects ot the invention will. be

A apparent hour the :liollowing detailed desci ;ion and the illustrations on the accompanying: drawings, wherein .l igr. .l is a view, in pm'speotive, of one tl orrn o't mounting for the electrodes in a vacuum tube embodying my inveiuuion.

Fig.1. it is a similar View showing; another form, the lower portions of the supports "iavingg' been omitted.

21 is a similar view :torm.

l igs. 4 and 5 illustrate another form of niouilzinojl or the electrodes, Fig. i: being a section upon the line 41- of Fig. 5 and. Fig. 5 beir a section upon the line 5-5, o t Fig. 4.

showing another cathode ill and. anode The difference of potential between the anode and the cathode causes a space current to tlow. This current is controlled by changing the potential of the grid. Iii this grid is close to the oathod 1., smaller clninges in the potential of the grid will be necessary to produce the desired changes in the space current. F or this reason, it is desirable to mount the electrodes so that the grid is as close as possible to the cathode. In l, the cathmle 11, the grid 12 and the anode lilare each mounted upon a pair of e antic supports. The supports 15 at the left in this figure and the supports 16 at the right are (.zaused, by their elasticity, to move away from one another, they thus put a ten sion upon the electrodes ll, 12 and 13. "ii hen these eleitrodes are heated and expand, this resilient action of the si'ipports keeps the el.eetro .les from sagging, so that there is no substantial. change in their distance apart and no danger of their coming into contact with one another. In order to accomplish this, the supports must be rigidly held at their lower ends. This is done by pas-ling them througl'i a glass press 17 which is part of the material. of the evacuated tube.

In Fig. 2 a similar construction is illustrated except that the cathode 21, the grid. 22 and the anode 23 are shown as ribbons instead. of Wires. In order to properly support these ribbons the resilient sumyorts 25 and .26 are also of considerable Width. Their lower ends are secured in place in the same way as the lower ends of the supports 1:") and 16, illustrated in Fig. l.

l ig. 3 shows a modification in which the 33 and their supports are like the correspoiuling parts in Fig. 2. The grid 32 in this figure stands at an angle with the plane oi? the anode and the cathode. For convenience in illiiistration, this is shown as it it were a right angle but it is obvious that any angle is possible. It the angle between the grid 32 and the plane of the other electrodes is near 90 degrees, the grid may be supported. by wiredilce support-s and 36, although the other electrodes are sup-- ported by rihbon-like supports, as described in connection with Fig. 2.

The mounting illustrated in Figs. 4 and 5 has a ring-shaped cathode ell. Preferably,

this is not a complete ring but instead is made in the form of a loop which nearly completes a circumference and the ends of which form the leads by which the heating current for the cathode is conducted. The anode, in this form, consists of a conducting tube which goes through the plane of the ring a l. The grid i3 is in the form of a ring surrounding the anode &5 and con tained within the ring ll. The material of this ring-shaped grid is preferably rectangular in cross section so that the grid ali'ords sharp edges, or corners, where its end surfaces join its cylindrical surface. The grid is separated from the tubular anode by a layer of insulation as: and from the ring-shaped cathode by a layer of insulation 42. The leads d6, which form the ends of the cathode, may also serve as the support for the whole system of electrodes, or, if desired, any other supporting means may be employed. a

The mounting illustrated in Figs. 6 and 7 also has a ring-shaped cathode 51. ends of this cathode may serve as supports, as described in connection with Fig. 5 or any other desired form of support for leading the heating current to this cathode, may be employed. The grid in this form of the device is a ring 52, the radial section of which is preferably U-shaped, so that the two flanges of the ring extend beyond the circumference of the cathode 51, while the cylindrical part of the grid is within the cathode. The cathode 51 and the grid 52 are separated by insulation 53, preferably this insulation does not extend out as far as the edges of the flanges on the grid 52. The anode 5G is similar in shape to the grid. The tubular part of the anode is within the tubular part of the grid and the flanges of the anode do not extend outward as far as the flanges of the rid. rates the anode from the grid. 52. Preferably, this insulation does not extend to the edges of the flanges on the anode and,

even if it should do that, it ought not to extend to the edge of the flanges on the grid.

Tn the operation of the tube, the electron stream from the cathode to the anode, must go by the grid. in the form shown in Fig. 1, the grid 12 being very close to the cathode 11, enables it to have a strong influence upon the electron stream. In the form shown in Fig. 2, the grid 22 extends for considerable distance parallel to the electron stream and so readily exerts a considerable influence thereon. In the form shown in Fig. 3, the grid 32. being oblique to the plane of the other electrodes, the electron stream must pass around the edges of the grid. The charge upon the grid produces a stronger iield at the edges than elsewhere. The electron stream, therefore, is obliged to pass through the strongest part of the field of The Insulation 5 L sepa- H the grid and so is readily influenced. In the form shown in Figs. a and 5, the electron stream between the filament ll and the anode 45 is obliged to pass by the corners of the grid 43 and so is subjected to the ac ion of the strongest part of the hold of the grid. In the form shown in Figs. (3 and. 7, the electron stream from the cathode 5i and the anode is obliged. to go around the edges of the flange 52 and there is acted upon by the strongest part of the field of the grid.

It has been found by experiment that tubes may be made in the way described herein, so that the distance between the cathode and the grid is not more than a few tenths of a millimeter, and, with such tubes, a change in the potential of the grid amounting only to a fraction of a volt is sullicient to control the electron stream even when the plate potential is large.

The electrodes used may be wire or strips of platinum or tantahun. lVhen strips of foil are used it is necessary that considerable care be employed in cutting out the strips, in order that they may be mounted at the small distance apart, illustrated in Fig. 2. ()rdinary foil may be used for all three electrodes or, if desired, the grid may be perforateC, as illustrated in Fig.

For the forms illustrated in Figs. 4- and (5, the tubular anode may be made 01? any suitable metal, such as tantalum, platinum, nickel, copper, etc. The insulation used may be either mica or any of the usual. oxides.

Although I have illustrated a limited number of forms of supports embodying my invention, it is obvious that many other forms will come within the spirit of the invention, and I, therefore, do not desire the patent granted to be limited except as necessitated by the prior art .or indicated by the claims.

I claim as my invent-ion:

1. ln a thermionic device, an anode, a control ele :trode, a cathode and solid insulating means separiiiting said electrodes and in intimate contact with each, whereby relative movement of the electrodes is positively prevented and the device is rendered nonmicrophonic.

2. A thern'iionic device including a tubular anode, a ring-shaped cathode and spoolshaped grid between them, the flanges of the grid projecting beyond the circumference of the other electrodes.

3. in a thermionic device, three concentric ring-shaped electrodes and solid insulation separating said electrodes, the thickness of said insulation. being approximately the same as the thickness of the material of the electrodes.

In testimony whereof I afiix my signature.

D11. KARL ROTTGARDT.