US2093876A - Braun tube - Google Patents

Description

Sept. 21, 1937. M. voN ARDENNE BRAUN TUBE Filed NOV. 17, 1934 Patented Sept. 2l, 1937 PATENT FFICE BRAU NTUBEA Manfred von Ardenne, Berlin-Lichterfelde 0st, Germany ApplicatonNovember 17, 1934, Serial No. 753,481 In Germany November 30, 1933 s claims.

It has hitherto been usual to support the various electrodes which are necessary for ray generation and for ray deection in Braun tubes, by means of a glass frame by direct lateral leads or by more or less rigid conducting Wires. This method of mounting is rather complicated, since in addition to the various connecting leads a large number of struts are required to support the various electrodes. Conditions are particularly difficult when it is required that theva rious electrodes shall be exactly adjusted in their position with respect to the axis of the system, and also shall remain exactly adjusted after undergoing substantial temperature variations, such as for example occur during the heating process when evacuating the bulb.

Difficulties of this kind are avoided by the present invention one embodiment of which is shown in the accompanying drawing. The sin gie figure oi the drawing shows a longitudinal section of a tube constructed in accordance with my invention with parts broken away to simplify the showing.

The main feature of the invention consists in the fact that the electrodes, and particularly the electrodes of the'ray generation system are supported by a tubular and preferably cylindrical body A of insulating material, which is mounted in the evacuated vessel B. Ceramic materials which have recently found application in the high frequency art are particularly suitable for the tubular bodies A. These materials in addition to their very good insulating properties have a very low temperature co-emcient and give o no gas in vacuum.

In the ray generating system of a Braun tube, the electrodes are usually circular discs or bodies of rotation, the centre points or axes of which are intended to coincide with the axisof the whole structure. A substantial improvement in the electrical and mechanical symmetry of the tube structure results if not only the electrodes but also the member constituting the electrode support are formed as bodies of rotation, the electrode supporting member being so positioned that its axis coincides with the axis of the who-le structure or system. The supporting member A, on account of its circular cross section, has the ad-4 vantage that electrodes of the shape now generally used can be retained. It is, however, within the scope of the invention to give the member A a cross-section other than circular, for example octagonal, and to give the electrodes C a corresponding shape.

The new arrangement, moreover, has the ad- (Cl. Z50-27 .5)

vantage that the electrical symmetry is improved since the conducting leads may be carried to the various electrodes from outside the tubular member A. When the leads are brought together in a common socket, they must to a great extent be carried parallel to the electrode system, whereby, unless special steps are taken, the eld is distorted. If however, there is arranged between the conducting leads D and the actual electrode system, an insulating member or better still, a metallic screen, then the symmetry is improved. Even if an insulating member alone be employed, a noticeable improvement still results. This is due to the fact that wall charges are formed, the inuence of which is greater on the electrodes than that of the leads situated outside. The conditions are particularly good, if the member A is metallized on the outside or on the inside, for example over a zone E. and the metallization connected to points oi suitable constant potential P. If it is not desired to use metallization, in `order-for instance that the manufacture be as simple as possible, then the desired screening effect can also be produced by turning over the edges of the electrodes in such manner that a more or less cylindrical or conical extension 2 is formed. This shaping is particularly suitable if the extension 2' is provided with slits 3 to render it resilient, and if the member A is formed inside with stepped annular recessed portions. In this manner it is possible to support the various essential electrodes C of the ray generating system in an extremely simple, stable, well-adjusted manner. The current supply to the electrodesC is preferably eiected by providing at suitable points in. the wall of the tubular member A, apertures through which project tags 5 bent around or welded onto the respective electrodes. 1 The ray generation system of a Braun tube has the purpose of supplying to the deecting system an electron ray possibly adapted to be modified in its intensity, and usually of circular cross section. As a rule it contains the following components:

1. A cathode, 2. An electrode for intensity modulation, 3. An electrode for accelerating the electrons and 4. Finally in accordance with recent practice an electrostatic converging lens. All these electrodes are shown in the drawing which also shows the great simplicity of the mounting of these numerous electrodes and the extreme precision of their adjustment. With the mounting of the cathode Cx only a slight dimculty arises, since contrary to the other electrodes, the cathode must not be carriedV directly by its supporting disc C, for with an indirectly -heated cathode this would cause too great a heat leakage from the cathode. For this reason special precautions are necessary in the support of the oxide carrier of the cathode. One suitable method of supporting the cathode is shown in the drawing. The cathode C' here rests in a mica disc 6 supported on two insulating rings 1 and another mica disc 8, the parts 6, 1, 8 being secured to the cathode supporting ring C by a pair of clamping members 9.

The member A can, at least partly, be carried by the rigid conductors D, secured in the glass pinch F. It may also be secured to glass rods, glass tubes or metal rods G, which like the leads D and H are squashed in well known manner, in the glass pinch F. A rigid supporting structure may also be secured to a clamping band 4adapted to encircle the lower portion of the glass pinchlF.

The tubular member A is not only advantageous in supporting the electrodes of the ray generating and concentrating systems, but it may also be used to carry the deflecting system. This, in the embodiment shown consists of two plates K of the usual type, which are positioned in the member A in the manner shm In the region adjacent which the plates K are carried the member A may depart from the cylindrical shape. For example it may be so formed that the deecting electrodes which in the drawing are constituted by the plates K, are formed on the member A itself, for example by electrolytic metallization.

In the aperture in the member A opposite the screen L an additional electrode M may be provided which has a larger surface than the electrodes C and serves to pick up secondary electrodes coming from the screen L. This electrode, which is preferably brought to a potential that coincides with the mean speed of the electrons in the deecting system, may at the same time serve to hold the member A centrally in the vessel B, as shown in the drawing.

What is claimed is:

1. A Braun tube comprising an evacuated vessel containing a plurality of electrodes adapted aoa'asvs to generate a narrow ray of electrons and a tubular insulating member in which all of saidraygenerating electrodes are supported in spaced relation, the relative spacing of said electrodes being determined by said tubular insulating member independently of the wall of said member.

2. A Braun tube comprising an evacuated vessel containing a plurality of electrodes adapted to generate, concentrate, control and deflect a narrow ray of electrons, and a tubular insulating member in which all of said electrodes for generating, concentrating, controlling and deecting said ray of electrons are supported in spaced relation, the relative spacing of said electrodes being vdetermined. by said tubular insulating member independently of the wall of said member.

3. A Braun tube according to claim 1, in which the said tubular insulating member is formed of ceramic material and is of circular cross section.

4. AV Braun tube comprising an evacuated vessel containing a plurality of electrodes and a tubu lar insulating member in which said electrodes are mounted in spaced relation independently o! the wall of said vessel, said electrodes being provided with resilient edges bearing against the inner wall of said member and said member being provided with metal screening coatings adapted to be maintained at a constant potential.

5. A Braun tube according to claim 4, further comprising leads for said electrodes which extend through the wall of the said member thence extending along the outside of said member to a common press seal.

6. A Braun tube according to claim 1, wherein said electrodes form part of a ray generating system, further comprising other electrodes which form part of a cooperating deflecting system, said defiecting system electrodes being mounted within and supported by the said member.

1. A Braun tube according to claim l, wherein the inner wall of, the said member is stepped to provide for the :Scorrect positioning of the said electrodes.

8. A Braun tube according to claim 1, wherein the electrodes are provided with resilient edges bearing against the inner wall of the said member.

MANFRED voN ARDENNE.

Images