US2332876A

US2332876A - Braun tube

Info

Publication number: US2332876A
Application number: US261726A
Authority: US
Inventors: Uhlmann Wolfram
Original assignee: Individual
Current assignee: Individual
Priority date: 1938-04-04
Filing date: 1939-03-14
Publication date: 1943-10-26
Anticipated expiration: 1960-10-26
Also published as: BE433386A; CH208840A; FR851959A

Description

Oct. 26,1943. w, UHLMANN 2,332,876

' BRAUN TUBE nFiled March 14, 1939 fnvenfar:

Wolfram 0/71/7701? y mm? Psremea Oct. 26, 1943 BRAUN TUBE Wolfram Uhlmann, Berlin, Germany; the Alien Property Custodian vested in ApplicationMarch 14, 1939, Serial No. 261,726 In Germany April 4, 1938 This invention relates to new and useful im- 3 Claims.

provements in cathode ray or Braun tubes.

A cathode ray emitted from the electron sun of a cathode ray or Braumtube as employed for metering purposes or in television receiver equipments is subjected to a predetermined deflection along two coordinates of the coordinate system on its way toward the fluorescent screen of such tube in order to scan the screen and thus perform image reproduction on this screen. This cathode ray deflection has heretofore been effected by means of homogeneous electrostatic or electromagnetic flelds, or even by suitably combining these two possibilities.

My invention consists in specific features of novelty which will be readily understood from the following description and be pointed out in the appended claims. reference being had to the accompanying drawing, in which Figs. 1 and 2 schematically show alternate aspects of putting this invention into effect.

In contradiction to the heretofore known methods of cathode ray deflection mentioned above. that is. the scanning deflection along coordinates by electrostatic or electromagnetic fields, it is proposed according to the main feature of this invention to effect such deflection by means of an electron mirror or mirrors. With an electron mirror, the electric potential i varied to change the effective shape of the reflecting surface thereby to change the reflecting angle of the mirror. Thus, by impressing a fluctuating potential on the mirror, the cathode ray is caused to scan the screen, such a potential is referred to as a scanning potential. This facility in the first instance involves the essential feature that on account of a considerable bend imparted to the cathode ray when reflected at the electron mirror, also the vessel of the cathode ray tub may be fundamentally changed from its prior straight form and be accommodated to the bend of the cathode ray, in other words, the vessel ma assume a shap which corresponds to the letter L, or even to the letter V. This is of particular importance when it is desirable to increase the diameter of the fluorescent screen, since such increase would inevitably require a proportional elongation of the heretofore known straight cathode ray tube, while a vacuum vessel of the new shape as a result of my invention is compact even in connection with'a fluorescent screen of larger diameter. Moreover, also the throat portion may cathode ray tubes may be partially or entirely omitted by employing an electron mirror or mirrors for deflecting the cathode ray to scan and screen With reference to the drawing which illustrates the invention in a purely schematic manner, G is a V-shaped evacuated vessel of a cathode ray or of a Braun tube according to my invention. The cathode of this tube is shown at K, while the cathode ray concentrating, accelerating and intensity control means are indicated by dashes, since these means form no part of this invention. The-cathode ray T of lumped cross'sectional area emitted from'the cathode K is projected onto the electron mirror S. from where it is reflected toward the fluorescent screen L as shown by either with any predetermined law. My invention makes use of the known fact that it is-possible by varying the potential of the control electrode 2 of the be considerably reduced because of the fact that the electrostatic o'r electromagnetic deflecting means located in this portion of the conventional electron mirror S to, gradually change the reflective action of this mirror from that of a divergent reflector, to that of a convergent or concentrating reflector via the state of a plane mirror, or vice versa. This effect of reflective action variability is involved on account of a change of the electron reflecting equipotential surfaces from con-s vexity via planeness to concavity, or vice versa, in response to a variable potential applied to the electrode 2 controlling said equipotential surfaces. The electron reflecting properties of an electron mirror are thus utilized according to my invention for reflecting the cathode ray onto the fluorescent screen L and for gradually defleeting this ray on the screen in either direction along one of the coordinates of the coordinate system, that is, for the line scanning or for the scanning along the other coordinate.

The deflection along the other of the coordinates may be achieved in a similar manner by means of a second electron mirror as above described. but it is alsopossible to apply any of the heretofore known methods for effecting this deflection without departing from the scope of my invention.

What is claimed is:

1. A cathode ray tube including an evacuated vessel, an electron gun for emitting a cathode ray, a fluorescent screen at one end of said vessel, defleeting means for causing said ray to scan said screen, said, deflecting means including an electron mirror located in thepath of said cathode I my control means for varying the eflective shape of the reflecting surface of said electron mirror, and means for applying a scanning potential to said control means, whereby said cathode ray scans the surface or said screen in: accordance with variation in the scanning potential applied to said control means.

2. A cathode ray tube according to claim 1, in which said electron mirror include electrode means for producing an equi-potential surface in the path of said cathode. ray to reflect said ray at an angle onto said fluorescent scream said mirror including further electrode means for changing the shape or said equi-potential surface.

i 3. A cathode ray tube including an evacuated vessel having a throat portion and a flared n n tion, an electron gun in said throat portion for producing a cathode ray, a fluorescent screen at the end or said flared portion, deflecting means for causing said my to scan said screen, said deflecting means including a first virtual electron mirror in the path of said cathode ray, said electron mirror including means for varying the shape or the reflecting surface of said mirror, and a second virtual electron mirror in the range of said cathode ray for continually reproducing said ray on said fluorescent screen along parallel lines perpendicular to those caused by said first-mentioned electron mirror, and means for applying scanning potentials 'to said shape varying means and said second virtual mirror, whereby said cathode ray scans said fluorescent screen along perpendicular coordinates.