DE2008170A1 - Electron tube for electron-optical image conversion - Google Patents

Description

p. Η »ηβ-Dietrich cell c

Pntentanwalt PHN. 3826

Ar.m- r: NVPhilips'Gloeilampenfabrieken dJo / TMV

File Na IHH- 3826

Registration from: 2Ö.? Ebr.l970 2008170 '

"Electron tube for electron-optical image conversion".

The invention relates to an electron tube for electron-optical image coil, which tube consists of a cylindrical glass jacket closed at both ends, the inner surface of which is covered with a conductive coating and at one end an im essentially spherical ·, al · support of a photo-electric cathode furnished glass window and at the other end has a luminescent screen which is used to collect the emitted by the photocat) ode through an electron-optical set of focused electrons attached between the photocathode and the screen is used.

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-S-

Image tubes of this type are for image conversion

known, e.g. for converting a Höntgen image into a visible image and to increase the brightness of visible images of low light intensity.

The mounted on the cylinder jacket, conductive covering covered dip wall almost completely, and ends at a certain distance from de ¹ * photocathode. Applying a suitable electrical voltage to the substrate results in a larger part of the Photo-P cathode being used than if this coating carries the photocathode potential,

Difficulties of a technical nature in the manufacture of electron picture tubes from glass have led to the window through to connect a metal ring to the cylinder back wall. This ring exists of two equal parts circular cross-section », being at one Edge an outwardly protruding puddle is provided, while the the other hand dee a part by melting it on the cylinder wall and the other hand of the other part in the same way with the window ^ is connected · The two flanges are e.g. welded airtightly connected to each other.

The metal wall covering usually consists of copper or aluminum and covers the flange between the tubes of the latter type the cylinder jacket and the metal ring with which it is electrically connected «

When the most favorable electrical voltage is applied to the covering, which is usually a few hundred volts, it is ensured that the ürÖBce of the photocathode surface, which is shown without disturbing defects, is around 65% of the tube cross-section. I _n general, thus braueht nan a vernaltnianMssig SIZES imager compared turn Format

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of the image to be transferred. ^w

■. The purpose of the invention is to create an improvement in electron-optical picture tubes, which is intended to bring about a further enlargement of the useful KnthodenoTaerf area. This improvement results invented by the fact that the metal covering on the wall of the Cylinder jacket of the tubes deviates from the cylinder jacket at the end running in the direction of the cathode and continues along a surface which is separated from the melting point between the cylinder jacket and the "glass window" by insulating material For this purpose, a ring-shaped glass body can be attached around the inside of the hanteis, which is attached to the wall using a type of glass with a lower melting point, e.g. glass enamel.

The invention is based on the knowledge that the Relatively narrow part of the spherical window along the circumference of the photocathode, which part does not belong to the photocathode, when the photocathode is inevitably somewhat contaminated by a slight deposit of photocathode material, whereby the Insulation resistance is reduced. Venn the wall covering near the

Anechmelzteile or ends on the metal ring, the applied chip- I "." \ - ■ * · '■ -: - ■ "'

voltage due to the reduced resistance of surface conduction lines cause, which have the consequence that near the edge of the Electrons emerging from the photocathode in this case are under the effect the separate, mostly no longer uniform potential distribution find out about anything other than that prescribed for accurate focus Move wards to the fluorescent screen. The glazing sufficiently increases the electrical capacitance between the wall covering and the photocathode, although the part of the insulating material between them does not

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is substantially lost.

It has been shown that when the invention is carried out, the effective photocathode surface is increased to 80 to 85 "fa of the cross-section of the tube.

If the metal ring is to have cathode potential, it is advisable to place the resistance between the wall covering and the Metal ring to be enlarged further. For this purpose, the ring can be placed on the Anachmelzeeite on the coat with an inward and then be provided parallel to the ring surface parallel edge, so that a channel-like space is formed between this edge and the ring will. By covering the bent hand on the inside and outside with glass enamel that extends over the fused edge, the Isolation distance increased considerably.

Another Aueführung "shape, is avoided in a coverage of vitreous insulating material, is that a second metal ring is in the cylinder wall mounted, which is separated by a wall portion of the connecting ring, and Bing that mentioned in the first-W is a metal screen is connected, which extends in the direction of the photocathode past this intermediate wall part, which isolates the two rings from one another, so that the connecting ring can carry the photocathode potential.

The examples mentioned are based on the drawing explained in more detail in the

Fig. 1 in an electron picture tube according to the invention, inter alia the Flg. 2 and 3 each in an · unformed shape of a component.

In the electron picture tube according to FIG. 1, see the

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on the left side of the center line on a completely off Glass-made wall, while dor indicated to the right of the center line Part represents the embodiment in which the cylinder jacket and the Windows are connected by a metal ring. In the trunk are the photocathode 1, the luminescent screen 2, the anode 3 of the electron-optical system and the one in the porin of the wall covering Focusing electrode 4 in a ventilated room. The case this space consists of a cylindrical shell 5 made of glass and a glass window 6. In the left hand side of the figure is the window 6 directly with the cylinder jacket 5 and in the right HSIfte through a metal ring 7 connected. The cylinder jacket 5 is at the other end closed by an end wall 8 which has a protruding sleeve 9, which is connected to an indentation 10 at the edge.

The photocathode 1 is dee on the hollow surface

spherical window 6, in this case a photocathode for direct Exposure appropriate, -as usual in a light amplifier. A luminescent layer is used to reproduce X-ray images in visible light necessary between the wing and the photocathode is provided. .

The anode 3 has a cylindrical edge Ti ″ on the Inversion 10 attached and further provided with a conical part 12 which ends in an almost spherical apex 13 in which a axial opening 14 is provided.

The luminescent screen 2, which is attached to the flat upper side 15 of the indentation 10, is located in the part of the interior space encompassed by the anode 3. A thin metal cap layer 16 _f which is slightly permeable to the electrons and the _f z example made of aluminum, the radiation increases considerably the light generated in the luminescent layer in the viewing direction. 0098 41/1099

The production of the metal ring J with paddles 17 and 18 from the parts facilitates the division of the connection between of the Penater 6 and the cylinder jacket 5. Bieee both parts can each

f
For aioh they can be provided with a metal ring part by annealing , whereupon the flanges are connected airtight, for example by welding.

On the inside of the part 6 there is an annular body 19 made of glass or another heat-sensitive insulating material appropriate. The body 19 can before the assembly of the two tube parts 5 and 6 in the cylinder jacket 5 or on the half metal ring on Cylinderaahtel 5 are fastened by means of vitreous material 20, e.g. glass enamel, the connection material also covering the fused edge between the ring and the wall.

The metallic interior cladding 4 of the wall 5 can be produced in a suitable manner by the deposition of metal particles from the vapor phase, with the entire surface not including xusr.ahr * t "jr ring-shaped surface 21 of the jacket is attached body 1? It is covered, which faces the side of the photocathode 1. During manufacture, it is possible to keep this surface chemically clean, there the formation of the photocathode can take place before the connection of the two tube parts.

The part of a tube with a metal connecting ring shown in Fig. 2 shows that one half of the ring has a U-shaped transverse » has cut, with a leg 21 covered with a glass-like insulating material 20, which also ait the Anaohmelxrand of the ring Rhrine wall covered. The metal cover extends on the inside

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clothing 4 "to the end of this leg 21. The non-conductive lining 20 of this leg in the guttering room 22 forms a high quality insulation between the metal covering 4 and the ring 7 »eggs can be grounded, so that an irregular voltage distribution in the vicinity of the photocathode is avoided entirely.

By attaching a separate metal bushing is inside the R-tube in the manner shown in Pig »3 a part 24 of the cylinder jacket 5 is used as insulation. The metal wall cladding 4 "ends at the one as a result of the attachment of the socket

23 existing metal intermediate piece 25, which is ring-shaped and of * the two cattle by melting together with the cylinder wall are connected. By attaching the socket 23 to the metal Between piece 25, the socket is electrically connected to the conductive cladding 4 and because of the presence of the insulating part

24 of the cylinder jacket 5 it is no longer necessary to use the Vand of the Cover the socket with insulating material.

All other advantages of the types shown can be It can be considered that the metal cladding, which is effective as a focusing electrode in the electron-optical system, can be seen in Extend direction towards the photocathode and can end in a distance that is most favorable for focusing, regardless of the arrangement of the metal ring that forms the window with the cylinder jacket the tube connects.

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Claims (4)

Claims ; Γΐ. ) Electron tube for electron-optical image conversion, which R consist of a cylinder jacket closed at both ends Glass, one end of which has a substantially spherical window is, which serves as a carrier <»iner photo-electric cathode, and which is provided with an electrical coating on the inside, while on another Ünrie a fluorescent screen to collect the between the photocathode and the fluorescent screen from an electron-optical system focused electrons is provided, characterized in that the electrically conductive coating of the cylinder jacket at the end in Direction of the photocathode deviates from the cylinder jacket and continues along a surface that is between the melting edge the cylinder jacket and the glass window is separated by insulating material. 2. Electron tube according to claim 1, characterized in that that all around inside the cylinder jacket an annular body made of glass and with a type of glass with a lower melting point E.g. glass enamel is attached to the tube wall and that the conductive Metal cladding extends over the inner surface of the glass ring. 3 · Electron tube according to claim 1, characterized in that that a metal connecting ring connects the window with the cylinder jacket connects and the connecting ring on the fused-on side with the cylinder jacket has an inwardly directed and then parallel to the annular surface Has bent edge, and that a channel-shaped space is present between the ring and the edge, the edge on the Inside and outside covered with a glass-like insulating material 009841/1099 and the metal wall cladding extends over the inner surface of the Handes extends and is separated from this by the insulating layer. 4. Electron picture tubes according to claim 1, characterized in that a metal connecting ring forms the window with the cylinder head connects and the cylinder jacket by melting second metal ring attached to the wall is interrupted with is connected to a metal sleeve provided in the tube and running towards the photocathode, the conductive cladding ends on the fastening ring, and that this bushing is the covering of the Part of the cylinder wall between the two rings with the conductive lining prevented. 009841/1099 8 * 0 Excerpt ! Electron-to-optical image conversion tube with a photo-electric cathode and a focusing electrode placed on the Rhrenwand is attached, the end facing the photocathode the focusing electrode from the tube wall through insulating material is separated, which increases the insulation resistance between the photocathode and the focusing electrode. 009841/1099