US1906048A - Thermionic tube - Google Patents

Description

April 25, 1933. c. L. DAVIS 1,906,048

THERMIONIC TUBE Filed Jan. 29, 1929 /0; INVENTOR.

- (960M224 YvfDcwX/a,

BY Q6 d 'ATTORN Y Patented Apr. 25, 1933 EUN EDf PATENT"OFFICE? I! cnEs'rEn L. navrsor wasnmeron. 151m or comma, AS-SIGNQB 'ro wrann,

1 mm, me, or new yoax, N. Y., A coaroaarron or DELAWARE 'rnnamronic TUBE I U r v Application filed January 2 9, 1929. Serial No; 335,866.

Myinvention relates to thermionic tubes in general and more specifically to thermionic tubes of the type employed in signaling systems.

An object of my'invention is to provide at thermionic tube wherein the anode space charge is reduced and the efliciency of the from the specification following and from the accompanying drawing, wherein:

Figure 1 is an illustration showing one form of the anode employed in the thermionic tube of my invention; Fig. 2 is an illustration showin a form of the anode employed in the t ermionic tube of my invention and Fig. 3 is an illustration showing schematically the thermionic tube of my invention.

In Fig. 1, the anode 1 consists of a metallic plate of nickel or other suitable metal or alloy thereof. A screen 2 is spacially related to the anode 1 and extends substantially .parallel thereto. Screen 2 may be of any suitable metal such as nickel or the like and may be in the form of a grid instead of the screen as shown. The word screen hereinafter referred to is interpreted according to I its operation which is to screen or shield o and it is to be understood that the same may be in the form of a grid. Screen 2 is rigidly positioned and spacially related to anode l by means of members 3, 4, 5 and 6. Mem- . bers 3, 4, 5 and 6 may be of suitable material or composition depending upon the type and size of tube. The resistance of members 3, 4, 5 and 6 are such as to supply the proper potential to screen 2, when the rated potential is supplied toanodel. This potential 4 should be lower than that supplied anode 1 vacuum,

which'drop of potential is eifectedby the composition of the'members 3, 4, 5 and-6. Suitable resistance materials include carbon orgraphite which inaterialsmay be com"-" bined with other elements or materials whereby the resistance-will be of proper value for the particular type of tube em ployed. Many variables enter into the design of such tubes including the degree of the electronic emission of the cathode, the spacial relationof electrodes and the area of the electrodes. The composi' tion of members 3, 4, -5 and 6 as .well as the design of screen 2'as'to number of wires and area depend upon these variables which must be considered in the design of the tube for maximum efliciency. I 4

Fig. 2 of the accompanying drawing shows amodified form of my invention. In the modification illustrated in this drawing, resistance member 7 serves a purpose similar to that of members 3, 4, 5 and 6. Inthismodification the screen is not supported from anode, as was the case in Fig. 1.-

Screen 12 is supported from stem 8 which also supports anode 14, cathode 9 and control electrode or grid 10. The conducting wires 14a, 9a and 10w lead through base 11 and are connected to prongs 146, 9b and 1012; Resistance element 7 may take the form of an impregnated material in which case theimpregnation may be that of carbon, a metal; allow of metals or oxide thereof. Resistance" element 7 may be a wire'wound resistance if desired. A'metallic band encircles the stem -8*and provides a mechanical sup-g port foranode 14.; Member 700 extends lat of electrical energy is connected between terminals 9?) and 141) a potential difference exists between electrodes 9 and 1 4. If the positive polarity of the source is connected to anode 14 and the negative polarity er the source connected to cathode 9' the electronic stream from cathode 9 to anode 1 will be increased. In operation however it is true that a number of these electrons never reach the anode 14. Should these electrons reach anode 14 the electronic stream would be increased and hence the resistance of the tube considerably decreased. Screen 12 is positioned adjacent anode 1 in such manner as to cause these electrons to be further attracted to anode 14, This action of screen 12 is due to the positive polarity of the screen 12 with respect to the polarity of cathode 9. The potential difference between screen 12 and cathode 9 is less than the potential difference between anode 14 and cathode 9. Screen 12 directly associated with anode 14 may be considered as an integral part of anode 14 increasing its efficiency. It is obvious that a low potential is necessary for the operation of the thermionic tube of my invention as compared to the usual type of triode tube. The number of lead in wires to the elements are, however, the same as the triode. This feature makes the wiring less complicated. The lead from such an electrode as screen 12 if insulated from anode 14 and carried through the base of the tube, must be carefully shielded from stray fields.

The thermionic tube of my invention may beemployed as an oscillator or amplifier in high frequency signaling systems. Water cooled tubes may be constructed wherein the anode is provided with a screen electrode according to my invention. The capacity of the tube is much less than that where a separate wire leads-through the base for supplying the screen electrode potential.

I realize that many modifications of my invention are possible without departing from the spirit of my invention audit is to be understood that my invention is not limited by the foregoing specification or by the accompanying drawing but that modifications ma be made within the scope of the appende claims without departing from the spirit of my invention.

" What I claim as new and by Letters Patent of follows: g

1. An electron tube comprising an enclosing envelope, a cathode, a control grid and an anode mounted therein, a resistance element carried by said anode and ashield grid supported by said resistance element in desire to secure the United States is as Said resistance element.

2. An electron tube comprising an enclosing envelope, a cathode, acontrol grid and an anode mounted therein, a plurality of resistance elements carried by said anode and a shield grid bridged between said resistance elements in a position spacially related to said anode and disposed between said anode and control grid, said resistance elements forming a conductive path for impressing an electrical potential on said shield grid in proportion to the dropalong said resistance elements from the potential of said anode.

3. An electron tube comprising an enclosing envelope, a cathode, a control grid and an anode mounted therein, said anode including a pair of side plate portions extending substantially parallel to each other, a plurality of laterally extending resistance members separating said pair of side plate portions, and a shield grid supported by said resistance members in spacial relation to said anode and control grid for receiving a charge from said anode in proportion to the electrical drop along said resistance members from said anode.

In testimony whereof I affix my signature.

, CHESTER L. DAVIS.

Images