US2194547A

US2194547A - Electron discharge tube

Info

Publication number: US2194547A
Application number: US160561A
Authority: US
Inventors: Donald G Haines
Original assignee: RCA Corp
Current assignee: RCA Corp
Priority date: 1937-08-24
Filing date: 1937-08-24
Publication date: 1940-03-26
Anticipated expiration: 1957-03-26

Description

March 26, 1940.

6. HAINES ELECTRON DISCHARGE TUBE Filed Aug. 24, 1937 llq'gni lM/NES R N VA/M ND '0 l. T 4 NW A Patented Mar. 26, 1946 I v l d v UNITED STATES PTENT OFFICE ELECTRON DISGHARGE TUBE Donald G. Haines, Bloomfield, N. J., assignor to Radio Corporation of America, a corporation of Delaware Application August 24; 1937, Serial No. 160,561 2 Claims. (o1. 250-163) This invention relates to an improvement in Referring to the drawing an envelope 5 is electron discharge tubes particularly of the shown for housing the elements of the cathode cathode my type as used for frequency multipliers. ray tube and it is to be understood that this enve- Cathode ray tubes when used as frequency lope may be made of any desirable material such 5. multipliers ordinarily have a relatively small outas glass, metal, a vitreous substance, etc. Within 5 put current and in most cases it is necessary to use the tube is positioned an electron emitter 6 which at least one or more stages of amplification in may be directly or indirectly heated by an elecorder to increase the magnitude of the current of trical heating element or which may be supplied the output frequency to the desired amount. The with heat from any desirable source. This m use of these amplifying tubes is of course obelectron emitter is preferably elongated in shape 10 jectionable in that it entails considerably more and is constructed in a manner, for instance, as electrical apparatus together with the fact that shown and described in the patent to Nicolson some wave form distortion may occur in the #1,459,412 of June 19,1923. f amplifying tubes. Positioned near the emitter is a focusing shield it It is the purpose of the present invention, or electrode l, the purpose of which is to concentherefore, to produce a frequency amplifier tube trate the electrons produced by the emitter into a which will produce sufficient current output to narrow beam. This focusing shield may be obviate or minimize the necessity of amplifying circular in form with a rectangular opening such output. v therein, the edges of the opening being provided A further purpose of the invention is to prowith extensions which project in the direction of 20 duce'a frequency multiplier tube with a cathode the beam. The focusing shield may, however, shield for deflecting substantially all of the ak he form f tw s p rat p at s mounted electrons in a direction toward the focusing and adjacent each other so as to produce the desired deflecting plates of the tube. results. p

A still further purpose of the invention is to A pair of deflecting plates are also provided for 5 produce a multiplier tube having an electrode causing the electron beam to be deflected in a positioned between the electron emitter and the particular manner in order that it may be swept focusing electrodes for accelerating the electrons across the anode structure which is provided in produced by the emitter and for directing the the end of the tube. These deflecting plates so electrons in a particular predetermined path. omprise a portion 3 which extends parallel to the A still further purpose of the present invention direction in w ch t e deve pe e m e is to provide means in a frequency multiplier tube and a portion 9 which extends at right es to for collecting and focusing substantially all of the t direction of travel of the beam! The P electrons produced by the emitter into a beam of D se Of the right angle extension s is to assist in electrons which may be later deflected by suitdeflecting the beam and produce e 35 able deflecting plates. trated electrostatic field at this region in order Another purpose of the present invention is to that an increased movement or deflection of the provide deflecting plates which will be efficient beam will result whereby smaller deflecting voltin operation and. which will produce maximum a ay b pplied to produce the desired beam 40 deflection of the beam through a minimum of deflection. 4o voltage applied to the deflecting plates. In the end of he tube is positioned the anode A still further purpose of the invention is to Structure which Comprises tWO p es 1 elecprovide a frequency multiplier tube-which will trodes, one of which consists of a plurality of produce a stream of electrons which is rectanguparallel conducting portions I l which are elselar in cross-section in order that the current outtrically connected together and the other of 45 put of the tube may be increased. which is a flat plate l2 which is positioned on Still further purposes and objects of the presthe side of the first anode plate ll opposite which cut invention will become apparent to those the electron gun structure is positioned. The skilled in the art from the following specification anode may be of any desired construction for and claims, particularly when considered in coninstance, as shown in the patent to Ferry 50 nection with the drawing, in which: #2,011,920 or the patent to H. J. van der Bijl Figure 1 represents the improved cathode ray #1,614,626. frequency multiplier tube and The anodes may be connected to any desired Figure 2 represents a section through the imelectric circuit so that as the beam is caused to proved tube. 4 sweep across the anode structure, it will contact 5 I shield [3 are attracted toward this electrode l4,

alternately the plates H and ll! of the structure, thereby producing a frequency multiplication over that applied to the deflecting plates of the tube.

In order to utilize amaximum of the electrons which are produced by the emitter, an emitter or cathode shield is is provided which is generally of semi-cylindrical shape and which may be provided with a pair of plane fins as shown in cross-section in Figure 2. l i

This shield is normally maintained at a potential negative with respect to the electron emitter in order that the electrons which are produced by the emitter will be repelled from the shield and projected in the direction of the focusing plates. Since the focusing plate is positive with respect to the emitter, it is obvious that some percentage of the electrons would be absorbed by the focusing plate and would not be projected through the tube as a useful cathode beam. In order to prevent this situation from arising, a grid or electrode member M is provided which is maintained at a potential positive with respect to the emitter. This electrode is positioned opposite the rectangular opening of the focusing shield and between the focusing shield and the emitter as shown in Fig. 2. Due to the positive potential of this electrode, the electrons as produced by the emitter and as reflected by the but, because of their acceleration, the velocity of the electrons is sufficient to permit them to be projected beyond the electrode it and into the field of the focusing plate i. From this point.

the electrons are further accelerated and attracted to the anodes i I and i2 because of the positive potential applied to the anodes.

It has been found desirable to utilize a coiled Wire for the electrode M. However, a single Wire or combination of wires can readily be substi-. tuted for this structure. When a coiled wire is used, the coil may be of .001 inch tungsten wire with approximately turns per inch, having a wound diameter of .005 inch; an electrode so constructed is effectively electron pervious. It is to be understood, however, that these dimensions are merely suggested and that other forms or dimensions which will produce the desired results may well be used.

In the operation of the device, the electrons emitted from the cathode surface or the emitter are repelled from the shield is and are attracted by and accelerated toward the wire grid or electrode it, that surface being at a positive potential with respect to the cathode. A small portion are attracted to the surface of the electrode M, but the majority of the electrons continue past the coiled wire structure toward the slit in the focusing shield 1. This shield also being at a positive potential attracts the electrons in the general direction of the slit which is in line with the grid wire and the cathode or emitter. The resulting electrostatic field produced by the potentials of the focusing shield l and the electrode 14 is of such a nature that the electrons entering this field are directed toward the slit and simultaneously focused into a narrow beam. Some few electrons may be taken from the stream as it passes through the slit but the percentage is relatively low, the majority of the electrons, because of focusing action, being permitted to be projected in a direction of the anodes.

When a deflecting voltage is applied to the deflecting plates, the beam, as produced by the electron gun, is therefore deflected so as to contact alternately-the anodes l-land l2 andth-ereby produce a frequency voltage variation in the output circuit of the tube.

So far as the output circuit of the tube is concerned, any circuit may be used and by way of example a transformer I5 is shown in Fig. 2 and a resistance It is shown in Fig. 1. The positive potential for the anodes is connected to the midpoint of the resistance H5 or to a center, tap of the primary winding of transformerlii as shown in the drawing.

In certain instances the electrode M may be electrically connected to the focusing shield I while in other instances the connection to the that the potential applied to this electrode may be varied as desired. In such an instance it is possible to modulate the beam as produced by.

the electron gun by applying appropriate modulating voltages to the electrode l4.

The elements of the tube may be supported in any desired manner and, asshown in the drawing, for example, the emitter, the emitter shield l3 and the electrode it may be supported by the stem press of the tube. The focusing shield and the deflecting plates, as well as the anodes, may be supported in any desired manner as long as they occupy the desired positionswith reference to the other elements of the tube.

Since the invention is not concerned primarily electrode I4 maybe entirely separate in order Furthermore, the use of cathode ray frequency multiplier tubes is well known to those skilled in the art. 7

Various modifications and alterations may be made in the device'without departing from the spirit of the invention and it is desired that all such modifications be considered as within the purview of the invention except as limited by the hereinafter appended claims.

I claim as my invention:

1. A cathode ray tube comprising apparatus for producinga flat electron beam elongated electron emitter, means provided with an elongated aperture positioned at oneside of l the emitter with the aperture parallel to the emitter and adapted to be maintained at a potential positive with respect to the emitter for attracting and focusing the electrons produced by the emitter, elongated shield means positioned on the other side of the emitter adapted to be maintained at a potential negative with respect to the emitter for repelling the electrons produced thereby, said last named means being substantially semi-cylindrical in form, and an elongated rod-like electrode positioned parallel to the emitter and between and in alignment with said emitter and said aperture of said first named means whereby substantially all of the electrons may be directed through the aperture.

2. A cathode ray tube comprising apparatus for producing a flat electron beam including an elongated electron emitter, an accelerating electrode provided with an elongated aperture positioned adjacent the emitter with the aperture,

including an H 5 the accelerating ter opposite Said accelerating electrode and adapted to be maintained at a, potential negative with respect to the emitter for directing the electrons produced by the emitter in the direction of electrode, and an elongated electron pervious rod-like electrode positioned parallel to the emitter between the emitter and the accelerating electrode and in alignment with the aperture of said accelerating electrode whereby substantially all of the electrons may be directed through the aperture. DONALD G. HAINES.