US2131563A

US2131563A - Cathode ray tube

Info

Publication number: US2131563A
Application number: US738435A
Authority: US
Inventors: Knoll Max
Original assignee: Telefunken AG
Current assignee: Telefunken AG
Priority date: 1933-08-01
Filing date: 1934-08-04
Publication date: 1938-09-27
Anticipated expiration: 1955-09-27

Description

Sept. 27, 1938. M. KNOLL CATHODE RAY TUBE Filed Aug. 4, 1934 .A Mw B the attached schematic drawing.

Patented Sept. 27, 1938 VCATHODE RAY TUBE" Knoll, Berlin, Germany, assignor to Telefunken Gesellschaft fiir Drahtlose Telegraphic m. b. H., Berlin, Germany a Germany, a corporation of Application August 4, 1934, Serial No. 738.435

' In Germany August 1," 1933 i I 5 Claims.

Cathode-rays" which, for instance, are produced in a Braun tube which is to be adapted to the reception of television pictures, in order that a highly luminous picture may be created, must be as dense or numerous as feasible, while they should have as little hardness as possible in order that the necessary deflection potentials may not be unduly high. 1 I

To fulfill these two'requirements, according to the invention, the cathode-rays'are accelerated after their emergence from the cathode by the agency of electrodes whose diameter is large in contrast with the cross-section of the cathode-ray pencil, whereupon they are retarded in which state of low velocity they are subjected to deflection, whereupon they are again accelerated. Unless the focussing or concentration of the cathode-rays is accomplished simultaneously by the same electrodes which serve to insure the first acceleration or the retardation, also the focussing is to be efiected by additional electrodes of large diameter.

One exemplified embodiment of the invention shall be described in what follows by reference to Referring to the drawing, I0 denotes the cathode, II a disk serving to homogenize the first accelerator field which, for instance, may be in conductive relationship with the cathode. l2, l3, and I4 denote annular electrodes to which is applied a potential that is positive in reference to the cathode Ill, to be more precise, the potential applied to electrode [3 is more positive than that at electrode I2. The

potential of the electrode I4 is negative relative to that of electrode l3 so that the cathode-rays which travel through the middle of electrode l3 at a fairly high rate of velocity, experience a decrease in speed. Between the electrodes 14 and I5, of which the last-named one surrounds the deflector plates of the Braun tube, is applied the voltage of an auxiliary battery l6 whereby the electrode I5 is maintained at a negative potential relative to the electrode l4 and the next electrode l'l located below the deflector plates. As they enter electrode. l5 the cathode-rays are caused to pass through the equipotential surfaces indicated by the broken lines, said surfaces acting in the sense of increased convergence of the cathoderay pencil. The cathode-rays which in this stage have a still lower speed than at the time they emerged from electrode M, will be deflected in the deflector plates even by the action of small fields. On leaving electrode IS the cathode-rays are passed again through curbed equipotential surfaces which are likewise shown in the drawing by dotted lines and which, similarly as in the case of f the equipotential surfaces traversed upon the exit from theelectrode l 5, tend toact in the sense of increased convergence of the pencil of"c'athode= rays. -Impressed upon the electrodes'l8-2l in the lower end of the tube being of truncated con'e shape are increasingly more positive potentials so that'thepotential of electrode [8 is more positive than that of electrode ll, thepotential at electrode 19 more positive than that-of electrode l8, and so on. The potentials acting at electrodes ll 2l are so graduated that the equipotential surfaces are practically spherical, with the center of the curvature being located between the pairs of deflector plates. Hence, the equipotential surfaces are traversed by the pencil of cathode-rays almost at right angles so that an increase in luminosity, but no additional deflection of the spot upon the screen of the tube will be caused.

It will thus be evident that in a tube of the kind here disclosed cathode-rays in copious quantitles will be produced because of the positive potential prevailing at the electrodes l2 and I3; furthermore, that these rays, on the one hand, because of the negative potential of electrode M in reference to electrode l3, and, on the other hand, because of the negative potential of the electrode [5 in reference to electrode 14, will have between the deflecting plates but a moderate hardness so that they are readily deflectible, and that, finally, the spot upon the screen of the tube will turn out very bright for reason of the increasing positive potential between the electrodes, I1 and 2 I.

Instead of distinct electrodes "-2 l also a spiral made from resistor material through which an auxiliary current is conducted, could be employed.

Similarly, electrodes l2l3 could be replacedby r a resistor spiral traversed by an auxiliary current.

In the said spirals each individual turn or the fall of potential occurring along an individual turn can be compared with the voltage between two consecutive electrodes. A spiral with n. many turns would then correspond to n many electrodes. In other words, the requisite fields are producible in just as fine a graduation by the use,

rescent screens of the kind used in connection with the recording of sound-films and the like for the photographic recording of acoustic actions, Roentgen-ray tubes, electron tubes used for amplification, rectification, and wavegeneration, and finally ion-ray tubes for the generation of high potential by kinetic ways and means where similar problems are involved which are solvable by a similar application of the invention.

I claim:

1. An electronic device comprising a fluorescent screen structure, an electron emitting surface for producing an electron beam, a plane apertured shielding electrode lying in the plane of the electron emitting surface, a plurality of beam deflecting electrodes, and a plurality of hollow cylindrical electrodes positioned intermediate the deflecting electrodes and the electron emitting surface, and a second plurality of hollow cylindrical electrodes positioned intermediate the deflecting electrodes and the fluorescent screen.

2. An electrode system for a cathode ray tube which comprises a plurality-of similar annular cylindrical electrodes, a shielding cylindrical annular electrode in register with the plurality of similar electrodes, a plurality of deflecting electrodes positioned within the shielding electrode, and a plurality of annular conical electrodes in register with the shielding electrode.

3. An electrode system for a cathode ray tube comprising a source of electrons, a shield electrode in register with said source of electrons, a plurality of similar annular electrodes in register with said source of electrons, a plurality of hollow surface-of-revolution electrodes in register with said first plurality of electrodes, a hollow shielding electrode intermediate the first and second plurality of electrodes, and deflecting electrodes positioned within the shielding 'electrode.

4. A cathode ray' .tube comprising an envelope having an end wall, a fluorescent screen on said end-wall, a source of electrons positioned remotely from the end wall, a shield electrode in register with said source of electrons, a plurality of I similar annular electrodes in register with said source of electrons, a plurality of hollow surface-of-revolution electrodes in register with said first plurality of electrodes, a hollow shielding electrode intermediate the first and second plurality of electrodes, and deflecting electrodes positioned within the shielding electrode.

5. 'A cathode ray tube comprising an envelope having an end-wall, a fluorescent screen on said end-wall, a source of electrons positioned re-- motely from the end Wall, a shieldelectrodedn register with said source of electrons, a plurality of similar annular electrodes in register'with said source of electrons, a plurality of dissimilar hollow conical electrodes, a hollow shielding electrode intermediate the first and second plurality of electrodes, and deflecting electrodes positioned within the shielding electrode.

7 MAX KNOLL.