EP0553373A1 - Vacuum tube - Google Patents

Abstract

The invention relates to a vacuum proof electrical feed-through from a first electrically conductive part, via connecting insulation consisting of enamel or glass, to a second electrically conductive part. For vacuum proof, voltage-resistant and sufficiently robust connecting insulation between electrical parts (2, 3, 8, 9), a support body (34) is provided, consisting especially of ceramic or plastic, and having an enamel or glass coating (35). This electrical feed-through can be used particularly advantageously in the case of high-voltage vacuum tubes or in the case of X-ray image intensifiers, as connecting insulation of the electrically conductive parts. <IMAGE>

Description

The invention relates to a vacuum-tight electrical voltage feedthrough from a first electrically conductive part via a connection insulation made of enamel or glass to a second electrically conductive part.

DE-A-39 12 607 discloses a relatively permanent, vacuum-tight glass-metal connection or metal-metal connection by means of glass solder, which is suitable for use in the assembly of glass laser tubes.

From EP-A-0 048 510 a cathode ray tube is known in which voltage feedthroughs are provided for electrically conductive pins, the pins being guided through connection plates and through support plates and being held on the support plates, these insulations also consisting of glass melting bodies which are introduced into openings in the carrier plates. Insulating, sealing glass melting bodies are also known for the mutual insulation and spacing of electrodes.

The European patent application, file no. 91105785.9, relates to an X-ray image intensifier, which is used, for example, in X-ray devices in order to generate a visible image from an X-ray silhouette. Such X-ray image intensifiers have an approximately cylindrical vacuum vessel, on the one end of which there is an input fluorescent screen and on the other end of which an output fluorescent screen is arranged. Electrodes are provided in the interior of the vacuum vessel and are held in the vacuum vessel by means of holding elements. For focusing when X-rays are incident Electrons generated on the input fluorescent screen are applied to the output fluorescent screen to the electrodes, which can be supplied to them via contact pins which are guided through the vacuum vessel in a vacuum-tight manner. It is known to connect the electrodes to one another via an insulating material, so that there is a stable electrode arrangement in the vacuum vessel.

In X-ray image intensifiers, it is known to carry out contact or holding pins through a vacuum vessel - if the piston of the vacuum vessel is made of glass - with melted-in metal pins, e.g. made of Vacon or another material that can be connected to glass. However, if the vacuum vessel is made of metal, a component is soldered or welded into an opening in the metal jacket of the vacuum vessel. Known components of this type consist of an insulation body (e.g. made of aluminum oxide Al₂O₃), in which a metal pin is soldered, and a welding flange attached to the insulation body for connection to the metal jacket. Such connections are prone to leaks due to the soldering and welding points.

In order to avoid these disadvantages of the known soldered and welded connections, bonding by glass or enamel is provided according to European patent application No. 91105785.9. A coating of enamel or glass is then applied to at least one electrically conductive part, the gluing of the electrically conductive parts being carried out by supplying heat, then melting and then cooling the coating. According to this proposal, enamel or glass is used as an insulation separation layer in an adhesive bond in order to make connections or bushings vacuum-tight and stable. When a contact pin connected to a voltage is held in an electrically conductive support component by means of an enamel or glass melt, this does indeed result compared to known ceramic feedthroughs an improvement in vacuum tightness and mechanical stability, but such feedthroughs by means of enamel or glass melts have limits for a certain size of the parts to be connected and in the dielectric strength. If you want to enlarge the parts to be glued by glass or enamel in order to increase the electrical voltage resistance, stability problems arise when enamelling or when connecting with glass or glass solder.

Accordingly, the present invention has for its object to provide an improved voltage implementation of the type mentioned, which is particularly characterized by simple manufacture, high stability, high dielectric strength and relatively little effort.

This object is achieved by a voltage implementation according to claim 1. Advantageous embodiments of the invention are specified in claims 2 to 16.

The voltage feedthrough according to the invention enables the use of a support body which is simple and inexpensive to produce, for example made of ceramic, plastic or the like, depending on the size and shape. This insulating piece can therefore consist of relatively inexpensive material and, depending on requirements, can be provided in whole or in part with a coating of enamel or glass, so that the desired vacuum tightness can be achieved. Advantageously, this places only minor demands on the support or base body with regard to porosity, surface properties and vacuum tightness. The support body should only be enamelled or be provided with a glass coating, should be sufficiently temperature-resistant for enamelling (enamel firing) or glass coating and should have the required strength for the task as a voltage feedthrough.

• Figur 1 zeigt einen Röntgenbildverstärker in prinzipieller Darstellung, bei dem erfindungsgemäße Spannungsdurchführungen vorgesehen sind,
• Figur 2 zeigt ein erstes Ausführungsbeispiel einer erfindungsgemäßen Spannungsdurchführung, mit einem ringförmigen Stützkörper, der Adapterflansche trägt und zwischen den Adapterflanschen und durch seine Ringöffnung eine Beschichtung aus Email oder Glas aufweist,
• Figur 3 zeigt eine erfindungsgemäße Spannungsdurchführung, deren Stützkörper endseitig Adapterflansche aufweist, die durch eine Wendel aus Widerstandsdraht od.dgl. verbunden sind, wobei die Wendel zwischen den Adapterflanschen eine Email- oder Glasbeschichtung trägt,
• Figur 4 zeigt eine erfindungsgemäße Spannungsdurchführung, deren Stützkörper zwischen Adaptermitteln eine Spiralfeder aufweist,
• Figur 5 zeigt eine erfindungsgemäße Spannungsdurchführung, angeordnet in einem elektrisch leitenden Trägerteil, das eine Durchführung für ein elektrisch leitendes zweites Teil, z.B. für einen Stift, aufweist,
• Figur 6 zeigt eine Ausführung einer erfindungsgemäßen Isolierung 6 der elektrisch leitenden Teile 2, 3 bzw. 8, 9 gemäß Figur 1,
• Figur 7 zeigt eine Spannungsisolation 33 mit Stützkörper 34 zwischen elektrisch leitenden Teilen 2, 3 sowie mit Adapterflanschen 38 und einer Halbleiterschicht 37 auf einer Email- oder Glasschicht 35,
• Figur 8 zeigt eine Spannungsdurchführung 15 gemäß Figur 1, bei der der Stützkörper 34 aus einem rohrförmigen, in Email oder Glas eingebetteten Isolationskörper besteht.

Further advantages and features of the invention result from the following description of exemplary embodiments and from the drawing. Corresponding reference numbers are used in the description of the drawing for corresponding parts.

• FIG. 1 shows a basic illustration of an X-ray image intensifier in which voltage bushings according to the invention are provided,
• FIG. 2 shows a first exemplary embodiment of a voltage feedthrough according to the invention, with an annular support body which carries adapter flanges and has a coating of enamel or glass between the adapter flanges and through its ring opening,
• FIG. 3 shows a voltage feedthrough according to the invention, the support body of which has adapter flanges at the end, which are or the like by means of a helix made of resistance wire. are connected, the coil between the adapter flanges having an enamel or glass coating,
• FIG. 4 shows a voltage feedthrough according to the invention, the support body of which has a spiral spring between adapter means,
• FIG. 5 shows a voltage bushing according to the invention, arranged in an electrically conductive carrier part which has a bushing for an electrically conductive second part, for example for a pin,
• FIG. 6 shows an embodiment of an insulation 6 according to the invention of the electrically conductive parts 2, 3 or 8, 9 according to FIG. 1,
• FIG. 7 shows a voltage insulation 33 with a support body 34 between electrically conductive parts 2, 3 and with adapter flanges 38 and a semiconductor layer 37 on an enamel or glass layer 35,
• FIG. 8 shows a voltage bushing 15 according to FIG. 1, in which the support body 34 consists of a tubular insulation body embedded in enamel or glass.

A section of an X-ray image intensifier 1 is shown in FIG. For orientation, the input screen and the output screen on the right of the X-ray image intensifier 1 would follow. As shown in this illustration, the housing of the X-ray image intensifier 1 is formed by a first and a second electrically conductive part 2, 3, which are shaped as cylinders from a sheet metal strip. In region 4, one end 5 of the first housing part 2 is connected to one end 7 of the second housing part 3 via a voltage feedthrough 6 according to the invention.

A first and a second cylindrical electrode 8, 9 are arranged in the X-ray image intensifier 1 and are connected to one another in a region 10 via voltage insulation 6.

For the electrical contacting of the electrodes 8, 9, an electrically conductive pin 11 or 12 is passed through a bushing 13 or 14 in the housing parts 2, 3, a bushing 13 or 14 according to the invention being provided in the bushings 13, 14. These pins 11, 12 can also serve to hold the electrodes 8, 9 in the X-ray image intensifier 1. For this purpose, further pins 17, 18 can also be provided, which are connected to the electrodes 8, 9 and the housing parts 2, 3 via further voltage feedthroughs 19, 20.

The x-ray image intensifier 1 finally comprises a further electrode 21 with a connection 22 to a high voltage source and with a ground connection 23, a voltage feedthrough 24 being provided between the ground connection 23 and the electrode, the support body 25 coated with enamel or glass or the like having a winding 26 made of resistance wire. contains and has adapter means 27, 28 connected to the resistance wire, which on the one hand makes contact with the electrode 21 or, on the other hand, are electrically conductively connected to the ground connection 23. The electrode connections 22, 23 are insulated by means of voltage feedthroughs 29 and 30 through the cylindrical housing part 3 and are led to the outside in a vacuum-tight manner.

In the voltage feedthrough 33 shown in section in FIG. 2, the support body 34 consists of a e.g. annular insulation piece made of ceramic or plastic. In order to increase the dielectric strength and possibly stability of the voltage feedthrough, the support body can be designed as an insulation component in the desired or required size and shape. The desired vacuum tightness of the insulation part is achieved by a complete coating or a necessary coating 35 made of enamel or glass. While in the case of bonds in accordance with European patent application No. 91105785.9, the enamel technology or the glass coating sets limits for the dielectric strength and the stability of the connection, and the use of an enamel tube or glass tube as connection insulation for two electrically conductive parts would not be a problem-free solution the use of the support body 34 in connection with the enamel or glass cover 35 a solution can be specified that fully meets the task.

The voltage feedthrough 33 according to FIG. 2 can, for example, be inserted into a feedthrough (eg bore) 13, 14 of a first electrically conductive part 2 or 3 and it can be inserted through the Ring opening 36, for example a pin 11, 12, can be guided as a second electrically conductive part. The pin 11, 12 can be melted into the ring opening 36 by means of a glass or enamel melt layer 35, so that after subsequent cooling, the pin 11, 12 is rigidly connected to the support body 34. The support body 34 can in turn be melted into the leadthrough 13, 14 of a supporting part 2 or 3 by an enamel or glass layer. The glass or enamel coating 35 also serves for the insulating, vacuum-tight arrangement between the parts 2, 3 or 11, 12 and the support body 34.

In the case of voltage feedthroughs, which are particularly affected by high voltages, a certain permissible current flow through the voltage insulation is often assumed. Particularly with vacuum-tight high-voltage bushings, 100% insulation is often not desirable, since complete insulation could lead to charging and high-voltage flashovers.

In an embodiment of the invention according to Figure 7 it is therefore provided that the support body 34 on its enamel or glass coating 35 has a semiconducting coating 37, e.g. made of chromium oxide, in order to achieve a certain conductivity via the insulation between the parts 2, 3 through the coating 37.

As is also shown schematically in FIG. 2, adapter means 38, e.g. Adapter pins, adapter flanges, adapter tongues or the like, inserted, let in, soldered in, sintered in, enameled or melted in by means of glass solder.

3, a winding, spring 39 or the like forms in the support body 34. made of electrically conductive material, an electrical resistance, at the end of the support body provided adapter means 38, for example

Adapter flanges are connectable. In the embodiment, the adapter flanges 38 designed in the desired shape are connected to one another with the spring 39 made of resistance wire. The resistance wire is wound with a small pitch in order to avoid the individual turns from resting against one another. The spring thus produced is contacted with the adapter flanges. In addition, the support body 34 formed by the spring is coated with an enamel or glass 35 by an application process, immersion process, spray process, by floating or the like. Mistake. Because of the spring inserted into the support body, an insulation part with a relatively high strength results on the one hand, on the other hand insulation bodies with a defined current flow or electrical resistance value can be produced. The spring material used, the wire thickness, the spring diameter and the number of turns can determine the resistance value. The electrical voltage difference occurring between the individual turns of the spring 39 can be kept relatively small, so that with a low enamel or. Glass pad 35 a good insulation effect can be achieved. Taking into account the expansion coefficients of the coating material and the desired conductivity of the voltage feedthrough, a coordination between the selected coating material (enamel, glass), resistance wire, flange material and size of the support body is possible. For carrying out the voltage, the support body 34 forms a hollow cylinder with the adapter means 38, through which e.g. a contact pin can be inserted.

Figure 4 shows a voltage feedthrough 31, in which the support body 34 consists of a spiral spring 40 wound at short intervals in turns of resistance wire, which has an enamel or glass coating 35 and the ends of the spiral spring 40 are contacted on adapter means, for example adapter flanges 38 . This version is particularly suitable if the diameter of the voltage feedthrough is to be increased if the electrical resistance of the voltage feedthrough via the coil spring is to be increased and / or if the strength or stability of the voltage feedthrough or the support body 34 is to be improved.

In the embodiments according to FIGS. 3 and 4, the turns of the resistance wire of the spring 39 or the spiral spring 40 are wound separately from one another at least at a small distance in order to avoid electrical bridges. The ends of the resistance formed by the spring 39 or by the spiral spring 40 can be welded to the adapter means or contacted in some other suitable way. The insulation property or the electrical resistance of the voltage feedthrough 31-33 is essentially determined by the structure of the support body, for example by the material of the support body, by the material of the support body spring or support body winding 39, 40, and the length and thickness of the spring wire , the winding diameter, the number of turns and the thickness of the glass or enamel layer 35. This results in the advantage for the voltage feedthrough the possibility of variably adapting the required stability and fine-tuning the overall resistance of the voltage feedthrough or a permissible current flow between the the parts to be connected.

An embodiment of a voltage feedthrough 15 is shown in FIG. 5. A support body 34 made of ceramic or plastic is inserted into a bore 13 of a first electrically conductive part 2. In the embodiment, a pin 11 is guided as a second electrically conductive part through the ring-shaped support body provided with a flange 41. In the area of the bore 13, a coating 35 made of glass or enamel is applied to the electrically conductive part 2, which is used for the insulation and fastening of the contact pin 11 against the support body 34 on the one hand and for insulation and fastening the support body against the electrically conductive part 2 serves on the other hand. As indicated in FIG. 5, the enamel or glass layer 35 is also provided between parts 11 and 34 or parts 2 and 34, 41. If the voltage feedthrough 15 is to have a certain electrical conductivity, a semiconducting coating 37, for example made of chromium oxide, can be applied to the glass or enamel layer 35 between the electrically conductive parts 2 and 11.

In the embodiment according to FIG. 8, a stepped depression is provided in part 2, into which a support body 34 embedded in glass or enamel is inserted in the form of a tube. The voltage guide 15 shown also has a contact pin 11 according to FIG. 1.

With the voltage feedthrough 24 shown in FIG. 1, it is possible, e.g. to form the one adapter means 27 of the support body 25 directly as an electrode 21 or to contact it directly with an electrode. Furthermore, e.g. the second adapter means 28 directly with an electrical part, e.g. an electrical supply line or a contact pin, can be connected as a voltage connection or ground connection.

The voltage bushings 6, which are only indicated schematically in FIG. 1, between the electrical parts 2 and 3 or between the electrodes 8 and 9 can e.g. consist of support body rings made of ceramic or plastic and have enamel or glass coatings at least on the inner ring surface and on the ring jacket (contact and connection surfaces to parts 2, 3 and 8, 9 in regions 4 and 10).

Because of the simple, stable structure, the simple and inexpensive manufacture and because of the good adaptability of the voltage feedthrough to the desired insulation values or

Resistance values are the use of the voltage bushing according to patent claims 1 to 14 - with its connection insulation by a support body and an enamel or glass coating - particularly advantageous in vacuum tubes or X-ray image intensifiers.

Claims (16)

Vacuum-tight electrical voltage feedthrough (6, 15, 16, 19, 20, 24, 29, 30-33) from a first electrically conductive part (2, 8, 11, 17, 21, 22) via a connection insulation made of enamel or glass to a second electrically conductive part (3, 9, 12, 18, 23), the connection insulation having a support body (34) which carries an enamel or glass coating (35). Voltage feedthrough according to claim 1, wherein the support body (34) is completely covered with an enamel or glass layer (35). Voltage feedthrough according to claim 1, wherein the support body (34) is made of an enamelled material which is temperature-resistant for an enamel or glass coating (35) and has sufficient mechanical strength for connecting electrically conductive parts (2, 3, 8, 9, 11, 12, 17, 18 , 21-23). Voltage feedthrough according to claim 3, wherein the support body (34) consists of ceramic. Voltage feedthrough according to claim 3, wherein the support body (34) consists of plastic. Voltage feedthrough according to claim 1, wherein the support body (34) has adapter means (38), such as adapter pins, adapter flanges, adapter cables or the like. A voltage feedthrough according to claim 6, wherein the adapter means (38) are inserted, embedded, soldered, sintered, enamelled or melted in by means of glass solder in the support body (34). Voltage feedthrough according to claim 1, wherein the support body (34) has a semiconducting coating (37) on its enamel or glass coating (35). Voltage feedthrough according to claim 8, wherein the semiconducting coating (37) consists of chromium oxide. Voltage feedthrough according to claim 1, wherein in the support body (34) a winding, spring (39, 40) or the like. forms an electrical resistance from electrically conductive material, to which adapter means (38) can be connected. Voltage feedthrough according to claim 10, wherein the support body (34) consists of a winding (39, 40) made of electrically conductive material, which has an enamel or glass coating (35) for stability and vacuum tightness, and wherein adapter means (38) are provided on the end of the winding are. Voltage feedthrough according to claims 10 and 11, wherein the winding (39, 40) consists of resistance wire. Voltage feedthrough according to claim 10, wherein at least one adapter means (27) is designed as an electrode (21). Voltage feedthrough according to claim 10, wherein at least one adapter means (28) is designed as an electrically conductive pin (23). Voltage bushing according to one of claims 1 to 14, wherein the connection insulation with support body and enamel or glass coating is used in vacuum tubes. Voltage bushing according to one of claims 1 to 14, wherein the connection insulation with support body and enamel or glass coating is used in X-ray image intensifiers.

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