High-voltage connector for filament selection

Abstract

The present invention relates to a connector for selecting an active power drain of an X-ray tube. The connector comprises a first connection unit comprising a plurality of first contact elements, and a second connection unit comprising a plurality of second contact elements, wherein the first connection unit and the second connection unit are configured to be detachably connectable to each other in at least a first orientation and a second orientation, and wherein the first contact elements and the second contact elements are configured to engage with each other when the first connection unit is connected to the second connection unit such that an electrical contact of at least a subset of the first contact elements with a respective one of the second contact elements is established. At least one of the first contact elements is configured to establish the electric contact with a first one of the second contact elements when the first connection unit and the second connection unit are connected in the first orientation, and to establish the electric contact with a second one of the second contact elements when the first connection unit and the second connection unit are connected in the second orientation, wherein the first one of the second contact elements and the second one of the second contact elements are different from each other.

Description

FIELD OF THE INVENTION

[0001] The present invention relates to a connector for selecting an active power drain of an X-ray tube, an X-ray system comprising the connector, and a method for selecting an active power drain of an X-ray tube.BACKGROUND OF THE INVENTION

[0002] Modern X-ray tubes are intended to be designed for long lifetime. Most X-ray tube housing assemblies currently used in the field utilize thermionic emitters for the emission of electrons. However, lifetime is limited by the wear-out of key components like anode plate or filaments, depending on the application. The thermionic emission of electrons leads fundamentally to wear-out of the emitters by material loss through evaporation. Emitter and / or filament wear-out is thus a major limitation of X-ray tube lifetime since other parts of the tube might last longer if the cathode does not fail.

[0003] For a given application, lifetime extension by change of materials and dimensioning of the filament or any other kind of electron emitters is limited due to the needed characteristics of the tube, i.e., emission characteristics and focal spot size. However, the lifetime of the tube may be significantly extended by implementing two, preferably identical, filaments and using them in sequence after the first one is worn out. The mechanical implementation into a cathode cup needs to support a preferably identical position, size, and shape of the focal spot with preferably the same or comparable characteristics of electron emission. Once the lifetime of the first filament comes to its end or if it has already become defective, a mechanism may be installed to switch over to the second filament that has not been used so far.

[0004] Multiple ideas are conceivable to connect a second filament to a power source. Switching between emitters may be done automatically or during service. Different concepts for a switching mechanism are possible. A mechanical solution, e.g., a switch positioned at the tube can be utilized as well as electrical switches that could be activated by the generator or the imaging system.

[0005] However, the switching mechanism to increase tube lifetime needs to be cost effective, easy to service and reliable. In addition, backwards compatibility to reference products may be advantageous.

[0006] The inventors of the present invention have thus found that it would be advantageous to have an improved switching mechanism that provides an efficient way for switching between power drains of an X-ray tube.SUMMARY OF THE INVENTION

[0007] It is an object of the present invention to provide an improved switching mechanism for selecting an active power drain like a filament or e.g. a grid control unit or any other power drain on high-voltage potential inside an X-ray emitter or X-ray source or X-ray tube assembly, that is cost effective, easily accessible for a technician during services and provides backward compatibility to existing systems.

[0008] The present invention is defined by the independent claims, and advantageous embodiments are defined in the dependent claims.

[0009] The described embodiments similarly pertain to the connector for selecting an active power drain of an X-ray tube, the X-ray system comprising the connector, and the method for selecting an active power drain of an X-ray tube. Synergistic effects may arise from different combinations of the embodiments although they might not be described in detail.

[0010] According to a first aspect of the invention, there is provided a connector for selecting an active power drain of an X-ray tube. The connector comprises a first connection unit comprising a plurality of first contact elements, and a second connection unit comprising a plurality of second contact elements, wherein the first connection unit and the second connection unit are configured to be detachably connectable to each other in at least a first orientation and a second orientation, and wherein the first contact elements and the second contact elements are configured to engage with each other when the first connection unit is connected to the second connection unit such that an electrical contact of at least a subset of the first contact elements with a respective one of the second contact elements is established. At least one of the first contact elements is configured to establish the electric contact with a first one of the second contact elements when the first connection unit and the second connection unit are connected in the first orientation, and to establish the electric contact with a second one of the second contact elements when the first connection unit and the second connection unit are connected in the second orientation, wherein the first one of the second contact elements and the second one of the second contact elements are different from each other.

[0011] Thus, a modified plug / receptacle combination is provided that offers a solution to connect power drains of the X-ray tube like the cathode filaments, or power supplies for a grid control unit, sequentially to a power source on high-voltage potential. An extended connector or an additional connector, preferably for high voltage, is disclosed for connecting to the additional filament and switching between the filaments. The connection to the first and the second filament may be located inside the tube housing and on cathode high-voltage level, but outside the evacuated tube vessel.

[0012] The term "X-ray tube" may be used either as the evacuated vessel including the cathode or emitter, or as the X-ray tube housing assembly, which also includes associated environmental parts like housing, lead shield, electronic devices, cooling devices, connectors, etc. Electronics part like a grid control unit may be applied at cathode potential rather than within the evacuated vessel. An X-ray imaging system may include the X-ray tube housing assembly, a generator, a detector, a controller including software, and means for image reconstruction, etc.

[0013] X-ray tubes may comprise two different types of filaments, one to establish a large focal spot and one for a small focal spot. For typical hospital applications, the lifetime of the tube is significantly determined by the lifetime of one of those filaments, typically the one with the small focal spot. In the following, the term "weaker filament" is used for this filament. With a redesign of the tube, three filaments may be implemented: Besides the "strong filament" LF, two "weaker filaments" SF1, SF2 may be implemented in a way that they can produce a preferably identical focal spot. There may be also another tube type with a single filament size and optionally electro-static focusing elements. The proposed concept can also be applied to this type of tube, with a first and a second filament that can be selectively connected via the proposed high-voltage connector. Thus, the lifetime limitation of the tube can be overcome, as the tube lifetime could theoretically be extended by a factor of two.

[0014] For connection of those two weak filaments, one solution is to provide each filament with its own current source, which would mean several copies of all involved components, such as filament inverter, filament current control loops, high-voltage transformers for the filament currents, wires in the HV-cable, HV-connector pins, and feedthrough into the evacuated tube can. This means significant cost and complexity increase. In addition, backwards compatibility to existing systems would not be possible.

[0015] Therefore, a connector is proposed, which may be a high-voltage connector, which provides a link to at least the first and the second "weaker filament" that is located inside the tube housing and on cathode HV-level, but outside the evacuated tube vessel. In general, two overall connector versions are possible. A first version is an extended high voltage connector to connect the tube to power supplying unit and contacting the cathode parts of the X-ray tube. A second version is a separate high voltage connector that may be added to the existing system and that acts as a separate switching device as a selector.

[0016] One of the connection units, preferably a receptacle, includes multiple input elements that are contacted depending on how the other one of the connection units, preferably a plug, is connected. Thus, by changing the orientation of the connection of the plug / receptacle combination by 90 degrees, for example, selection between the different filaments of the tube is carried out.

[0017] In an embodiment of the invention, the first one of the second contact elements is connectable to a first filament of the X-ray tube, and wherein the second one of the second contact elements is connectable to a second filament of the X-ray tube.

[0018] In an embodiment of the invention, the connector is configured for switching between the first filament and the second filament of the X-ray tube as active filament when the connector is moved from one of the first orientation and the second orientation to the other of the first orientation and the second orientation.

[0019] In an embodiment of the invention, the first orientation and the second orientation differ from each other in that one of the first connection unit and the second connection unit is rotated with respect to the other one of the first connection unit and the second connection unit along a connection axis by a predefined angle.

[0020] In an embodiment of the invention, the connection axis is defined by a direction in which the connection between the first connection unit and the second connection unit is established.

[0021] In an embodiment of the invention, one of the first connection unit and the second connection unit is a plug, and the other one of the first connection unit and the second connection unit is a receptacle configured for receiving the plug.

[0022] In an embodiment of the invention, one of the first connection unit and the second connection unit comprises a protrusion, and the other one of the first connection unit and the second connection unit comprises a first recess and a second recess configured for receiving the protrusion, such that when the protrusion is received in the first recess, the first connection unit and the second connection unit are connected in the first orientation, and when the protrusion is received in the second recess, the first connection unit and the second connection unit are connected in the second orientation. For example, pairs of bulges and grooves, optical markings, non-circular shapes etc. can be provided to distinguish between the respective orientations of the first and the second connection unit, respectively. Several variations are exemplified in the following.

[0023] In an embodiment of the invention, the first connection unit comprises a first central contact element, and the second connection unit comprises a second central contact element, and the first central contact element is configured to establish the electric contact with the second central contact element when the first connection unit and the second connection unit are connected in both the first orientation and the second orientation.

[0024] In an embodiment of the invention, the connector is a high-voltage connector configured for connecting the X-ray tube to a set of power sources on high-voltage potential. These can be, for example, high-voltage power supplies, filament current supplies, supplies for other kinds of electron emitters, or grid supplies.

[0025] In an embodiment of the invention, the first connection unit comprises three first contact elements, and the second connection unit comprises five or six second contact elements.

[0026] In an embodiment of the invention, the connector is a dedicated filament selector configured to be attached to the X-ray tube.

[0027] In an embodiment of the invention, the first connection unit comprises two first contact elements, and the second connection unit comprises at least three second contact elements.

[0028] According to another aspect of the invention, there is provided an X-ray system comprising an X-ray tube comprising at least a first filament and a second filament, and a connector for selecting an active filament of the X-ray tube according to any one of the preceding embodiments.

[0029] In an embodiment of the invention, the X-ray tube further comprises a main filament, and the connector is configured for connecting the main filament to a same main filament current source in each of the first orientation and the second orientation, and selectively connecting either the first filament or the second filament to a weak filament current source in the first orientation or in the second orientation, respectively. Preferably, a focal spot of the main filament is larger than a focal spot of each of the first filament and the second filament.

[0030] According to another aspect of the invention, there is provided a method for selecting an active filament of an X-ray tube. The method comprises providing an X-ray system according to any one of the preceding embodiments, disconnecting the first connection unit from the second connection unit in the first orientation, rotating the first connection unit to the second orientation, and connecting the first connection unit to the second connection unit in the second orientation.

[0031] Thus, the benefits provided by any of the above aspects equally apply to all of the other aspects and vice versa.

[0032] In summary, the invention relates to a connector for selecting an active power drain of an X-ray tube. The connector comprises a first connection unit comprising a plurality of first contact elements, and a second connection unit comprising a plurality of second contact elements, wherein the first connection unit and the second connection unit are configured to be detachably connectable to each other in at least a first orientation and a second orientation, and wherein the first contact elements and the second contact elements are configured to engage with each other when the first connection unit is connected to the second connection unit such that an electrical contact of at least a subset of the first contact elements with a respective one of the second contact elements is established. At least one of the first contact elements is configured to establish the electric contact with a first one of the second contact elements when the first connection unit and the second connection unit are connected in the first orientation, and to establish the electric contact with a second one of the second contact elements when the first connection unit and the second connection unit are connected in the second orientation, wherein the first one of the second contact elements and the second one of the second contact elements are different from each other.

[0033] One of the advantages of embodiments of the present invention is that the proposed high-voltage connector provides an efficient solution for selecting an active filament of an X-ray tube, with minimum product costs and easy serviceability. Backwards compatibility to existing configurations used in the field is provided by using an adapter, for example. This increases beneficially the lifetime of an X-ray tube at a given total emission, or can be exchanged in favor of a higher emission or a smaller focal spot size.

[0034] These advantages are non-limiting and other advantages may be envisioned within the context of the present application.

[0035] The above aspects and embodiments will become apparent from and be elucidated with reference to the exemplary embodiments described hereinafter. Exemplary embodiments of the invention will be described in the following with reference to the following drawings:BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Fig. 1 shows a schematic design of a cathode cup for an X-ray tube with two cavities for filaments. Fig. 2 shows a schematic design of a cathode cup for an X-ray tube with three cavities. Figs. 3A and 3B show cross- sectional schematic designs of cathode cups for an X-ray tube with focusing electrodes and one or two emitters, respectively. Fig. 4 shows a typical state-of-the-art shape of a HV-plug and HV-socket connection with a connection scheme of the plug. Figs. 5A and 5B show a connection scheme of circuitry indicating correct contact matching and a cross section view of contacts in both plug and receptacle. Fig. 6 shows a schematic setup of a connector for selecting an active power drain of a cathode cup of an X-ray tube according to an embodiment of the invention. Fig. 7 shows a cross sectional view of the contacts of the first connection element 110 and the second connection element 120 together with optical markings indication the orientation. Fig. 8 shows another schematic setup of a connector for selecting an active power drain of a cathode cup of an X-ray tube according to an embodiment of the invention. Fig. 9 shows another schematic setup of a connector for selecting an active power drain of a cathode cup of an X-ray tube according to an embodiment of the invention. Fig. 10 shows another schematic setup of a connector for selecting an active power drain of a cathode cup of an X-ray tube according to an embodiment of the invention. Fig. 11 shows another schematic setup of a connector for selecting an active power drain of a cathode cup of an X-ray tube according to an embodiment of the invention. Fig. 12 shows another schematic setup of a connector for selecting an active power drain of a cathode cup of an X-ray tube according to an embodiment of the invention. Fig. 13 shows a block diagram of a method for selecting an active power drain of an X-ray tube according to an embodiment of the invention. DETAILED DESCRIPTION OF EMBODIMENTS

[0037] Fig. 1 shows a schematic design of a cathode cup 205 for an X-ray tube 200 with two cavities for filaments. Two filaments 211 and 212 are incorporated in a cathode cup 205 of an X-ray tube 200. This type of tube may use electrostatic focusing of the electron beam and these cathodes can be utilized also in a pulsed imaging mode where a high voltage between emitter and cathode cup can be applied to switch the electron beam on and off. Typical cut-off voltages are in the range of some (single digit) kV. The additional emitter may be incorporated in different ways between the electrodes. This additional emitter can be operated after its predecessor reaches its end-of-life. All parameters such as emitter currents and voltages, the emission, and electron beam cut-off voltages remain unchanged. The lifetime of the X-ray tube can thus be extended as compared to having a single filament.

[0038] Fig. 2 shows a schematic design of a cathode cup 205 for an X-ray tube 200 with three cavities. The additional emitters are incorporated in a symmetric design where the left and right emitters or power drains 210 like filaments are identical and deliver a common focal spot. The central emitter may be a large filament for a larger focal spot compared to the left and right emitters. Both left and right emitters may produce the same focal spot independently of each other. Cut-off voltages may remain unchanged in this setup.

[0039] Figs. 3A and 3B show cross-sectional schematic designs of cathode cups 205 for an X-ray tube 200 with focusing electrodes and one or two emitters, respectively, allowing for deflection of the electron beam. In the case of cathodes that focus via the electrostatic potential of surrounding electrodes, a state-of-the-art typical design is shown in Fig. 3A. A single emitter 210 in central position is focused by two electrodes. Variable focal spot widths and x-deflection can be realized. Introducing an additional emitter in this type of cathode and thus incorporating emitters 211 and 212 in the cathode cup 205 might require additional electrodes to achieve the necessary focusing effect and allow for x-deflection. To enable the additional emitter and switching between emitters, with sustained functionality of the X-ray tube, the cathode cup 205 is also modified with at least one additional filament cavity as shown in Fig. 3B. For tubes with electrostatic electron beam optics, an additional electrode may be added to the cathode cup to achieve the necessary focus effect for each of the emitters.

[0040] Fig. 4 shows a typical state-of-the-art shape of a HV-plug 141 and HV-socket 142 connection with an electric circuit scheme of the cathode cup 205. A first filament 211 and a main filament 215 are included in an X-ray tube 200, each comprising a separate connection SF and LF, respectively, and may share a common connection CM. High voltage connectors may be designed in a cylinder shape or a conical tapered shape. The plug usually builds the terminal of a cable whereas the socket / receptacle is mostly built in a tube housing or an HV unit of an X-ray generator or any other component that needs to be connected by a high voltage cable. On cathode potential, multiple contacts are needed to connect the filaments. Here an example is shown for two filaments that need one contact for the strong filament LF, one for the weak filament SF and one common CM contact to close the current loop. The plug 141 includes a plurality of first contact elements 211, that are connectable to a plurality of second contact elements 121 of the receptacle 142. One of the plug 141 and the receptacle 142 may include a bulge 151 corresponding to a groove 152 at the other one in order to verify an orientation of the connection. The bulge at the connector ensures correct matching of the contacts by a fit into the corresponding groove at the receptacle in this example. Bulge and groove may be allocated vice versa, or other means may be used to indicate the correct geometric assignment of the contacts to each other.

[0041] Fig. 5A shows a connections scheme of circuitry indicating correct contact matching of the first connection element 110 and the second connection element 120 to contact the cathode cup 205 of the X-ray tube 200, and Fig. 5B shows a cross section view of contacts in both the first connection element 110 and the second connection element 120. In this example, the bulge / groove pair is located closely to the LF pin. However, this is not a necessary condition. They may be paired at any position in a way that matching of the according contacts is ensured.

[0042] Fig. 6 shows a schematic setup of a connector 100 for selecting an active power drain 210 a cathode cup 205 of an X-ray tube 200 according to an embodiment of the invention. The purpose is the selection of a desired configuration of downstream circuitry. In general, two versions of selector devices can be distinguished: HV-connectors with a cable that can be plugged at different positions or orientations, or selectors with a dedicated receptacle and a plug-in with an inner connectivity but not with a cable outlet. A HV connector including a first connection element 110, for example a plug, and a second connection element 120, for example a receptacle, is shown. The plug comprises in this example one bulge 151, and the connector jack or receptacle comprises two grooves 152 and 153, or other respective means of indication for appropriate orientation of the plug and the jack to each other. The plug and the receptacle can be changed in their electric configuration or connection orientation in a way that either a first filament 211, which may be a weak filament SF1, or a second filament 212, which may be a weak filament SF2, can be connected to the HV-supply voltage. In this example, a third, stronger, filament 215 is connected to its source in both configurations. This is done by using contacts in such orientations that the plug selects its desired counter contacts by being plugged in at the right positions that are allowed by two different grooves to be matched by the bulge of the plug. The first connection unit 110 comprises a plurality of first contact elements 111, and the second connection unit 120 comprises a plurality of first contact elements 121. A first central contact element 115 may correspond to a second central contact element 125 in both orientations of plug and receptacle, whereas a first one 112 of the first contact elements 111 is connected to a first one 122 of the second contact elements 121 in the first orientation 131, and to a second one 123 of the second contact elements 121 in the second orientation 132. In the example depicted here, this works by a simple arrangement of the contact 112 and the bulge 151 of the plug in one line, and two grooves 152, 153 in line with the respective contacts 122, 123 in the receptacle to select the desired contact of the respective filament 211, 212 by twisting the plug or cable and thus changing the orientation of the plug with respect to the receptacle by 90°. Pairs of bulge and grooves are used to enforce defined orientations of the plug to connect the respective contacts. Other means may be symmetrically shaped sets of connectors with secured indicators or optical markings. These respective markings on the first connection element 110 and the second connection element 120 are indicated in Fig. 7, and with respect to Fig. 7, the reference signs 151, 152 and 153 may simply refer to optical marks to identify the right orientation.

[0043] Thus, after the end-of-life of an emitter, for example the first filament 211, a spare one in the vacuum vessel, for example the second filament 212 which may produce a preferably identical focal spot like its predecessor, can be utilized and increase the lifetime of the whole X-ray tube housing assembly. An advantageous switching mechanism is implemented, which can be operated by a service engineer that takes the new emitter into operation after the original one is worn-out by using the proposed connector 100 for selecting an active power drain of the present invention. However, the increase in lifetime of the tube at a given total emission can also be exchanged in favor of a higher emission or a smaller focal spot size of the filament. The proposed connector can be applied to new products but also as an upgrade to existing ones. Depending on the implementation and the imaging system, the invention can be implemented in existing imaging systems as an upgrade of the tube assembly providing full backwards compatibility with highly increased lifetime. Those could be upgraded and still be compatible with the boundary conditions of their system environment. To overcome the lifetime limitation without altering proven parts and technologies a limited change to the cathode cup is proposed.

[0044] The switching between the two emitters can be done as a service procedure or alternatively automated by the imaging system. For an automated version, a rest-of-life prediction and monitoring must be in place that allows for a switching right before or directly after the end-of-life of the first emitter. If the generator or the imaging system monitors the wear-out of the emitter, it may be possible to implement automated switching, e.g. after a certain increase in emitters resistance.

[0045] The first one of the second contact elements of the second connection element may be connected to a first filament of the X-ray tube, while the second one of the second contact elements may be connected to a second filament of the X-ray tube. Thus, by switching the connector from one to the other orientation, switching between the first filament and the second filament of the X-ray tube as active filament is performed. Switching of the connector may be understood as moving the connector from one orientation to the other orientation, which differ from each other in that the first connection unit and the second connection unit are rotated with respect to the other along a connection axis by a predefined angle. The connection axis may be defined by a direction in which the connection between the first connection unit and the second connection unit is established, i.e., a connection direction of the connector. One of the first connection unit and the second connection unit may be a plug, and the other one may be a receptacle configured for receiving the plug.

[0046] The first and the second orientation may be defined by a protrusion like a bulge at one of the connection elements corresponding to respective recesses like grooves in the other connection element. Thus, when the protrusion is received in a first recess, the connector may be in the first orientation, and when the protrusion is received in the second recess, the connector may be in the second orientation. For example, pairs of bulges and grooves, optical markings, non-circular shapes etc. can be provided to distinguish between the respective orientations of the first and the second connection unit, respectively.

[0047] Fig. 8 shows another schematic setup of a connector 100 for selecting an active power drain 210 of a cathode cup 205 of an X-ray tube 200 according to an embodiment of the invention allowing complete backwards compatibility to the state-of-the-art cables and plugs. This embodiment works with a receptacle that comprises six contacts in a certain order, as can be seen from the electrical circuitry and the example for the mechanical connection in Fig. 8. In both orientations 131 and 132, the CM contact element of the first connection element 110 is connected to a respective CM contact element of the second connection element 120, which are connected to each other. Similarly, the LF contact element of the first connection element 110 is connected to a respective LF contact element of the second connection element 120, which are connected to each other. However, the SF contact element of the first connection element 110 is connected to two different contact elements SF1 and SF2 of the second connection element 120 in the first orientation 131 and the second orientation 132, with the first contact element SF1 and the second contact element SF2 not being connected to each other, but to different filaments 211 and 212 of the X-ray tube 200.

[0048] Fig. 9 shows another schematic setup of a connector 100 for selecting an active power drain 210 of a cathode cup 205 of an X-ray tube 200 according to an embodiment of the invention. This example provides two connecting options for both the LF filaments and the SF filaments. Thus, in the first orientation 131, a first filament 211 is connected to the SF contact element of the first connection element 110, and a first main filament of the X-ray tube 200 is connected to the LF contact of the first connection element 110. In the second orientation 132, a second filament 212 is connected to the SF contact element of the first connection element 110, and a second main filament of the X-ray tube 200 is connected to the LF contact of the first connection element 110. This concept may provide a high-voltage connector with a cable that can be plugged at different positions or orientations to tube. This variant is fully backwards compatible with an existing X-ray tube housing assembly and imaging system. The switch can be also implemented in the generator if an additional electrical connection via feedthroughs and the high-voltage cable is available. In this case the switch would be part of the generator.

[0049] Fig. 10 shows another schematic setup of a connector 100 for selecting an active power drain 210 of a cathode cup 205 of an X-ray tube 200 according to an embodiment of the invention. In this embodiment, a separate pair of connectors like plug and receptacle is provided. The selector plug may be used without any connected cable. The selector plug simply connects two of the pins of the receptacle to select one of the filaments of the X-ray tube. A HV cable may be connected via a standard connection system to a housing of the X-ray tube. The housing may be provided with a second connection element 120, to which a first connection element 110 is connected. By selecting an orientation of the first connection element 110 with respect to the second connection element 120, a respective active filament of the X-ray tube 200 may be selected. Pairs of bulge 151 and grooves 152, 153 may be used to enforce defined orientations 131, 132 of the plug 110 to connect the respective contacts of the receptacle 120. Other means may be symmetrically shaped sets of connectors, like ellipsoidal shape. An oval shape may fulfil the same requirement for two alternative orientations. Thus, this embodiment shows a separate selector with a dedicated receptacle and plug. The selector plug connects pins of the selector receptacle to select the respective filament. Also in this case, the mechanical orientation of the plug with respect to the receptacle may be used to select the active contacts.

[0050] Fig. 11 shows another schematic setup of a connector 100 for selecting an active power drain 210 of a cathode cup 205 of an X-ray tube 200 according to an embodiment of the invention. Such kind of a connector 100 as separate selector may offer the feature to select one out of more than two options or orientations. An example to select one of three possible contacts that are connected to one weak filament terminal each is shown in Fig. 11. Thus, by selecting a respective orientation of the first connection element 110 with respect to the second connection element 120, one of the first filament 211, the second filament 212, and the third filament 213 of the X-ray tube 200 can be selected as active filament. The second connection element 120 may comprise three grooves 152, 153, and 154 corresponding to the bulge 151 of the first connection element 110 in the first orientation 131, the second orientation 132, and the third orientation 133, respectively. This, in each orientation, one of the SF1, SF2, and SF3 contacts of the second contact element 121 of the second connection element 120 is connected via the first contact element 111 of the first connection element 110 to a respective power source. Pins for more than three contacts may be arranged accordingly in the receptacle around a central common input pin. The triangle outer shape of the plug / receptacle pair may avoid the need of grooves and of a corresponding bulge.

[0051] Fig. 12 shows another schematic setup of a connector 100 for selecting an active power drain 210 of a cathode cup 205 of an X-ray tube 200 according to an embodiment of the invention. This embodiment gives an example for a one out of three selector without the use of a central pin. Thus, by selecting a respective orientation of the first connection element 110 with respect to the second connection element 120, one of the first filament 211, the second filament 212, and the third filament 213 of the X-ray tube 200 can be selected as active filament. However, the first connection element 110 comprises a plurality of first contact elements 111, with some of those first contact elements 111 being connected to each other via electrical shorts. Thus, depending on the respective orientation of the first connection element 110 with respect to the second connection element 120, a respective active filament can be selected to be connected to its power source.

[0052] Fig. 13 shows a block diagram of a method for selecting an active power drain 210 of an X-ray tube 200 according to an embodiment of the invention. The method comprises providing S110 an X-ray system comprising an X-ray tube 200 with at least a first filament 211 and a second filament 212, and a connector 100 for selecting an active power drain 210 of the X-ray tube 200. The method comprises further disconnecting S120 the first connection unit 110 from the second connection unit 120 in the first orientation 131, rotating S 130 the first connection unit 110 to the second orientation 132, and connecting S140 the first connection unit 110 to the second connection unit 120 in the second orientation 132.

[0053] While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive. The invention is not limited to the disclosed embodiments. Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing a claimed invention, from a study of the drawings, the disclosure, and the dependent claims.

[0054] In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. Measures recited in mutually different dependent claims can be combined to advantage. Any reference signs in the claims should not be construed as limiting the scope.LIST OF REFERENCE SIGNS:

[0055] 100connector 110first connection unit 111first contact elements 112first one of the first contact elements 115first central contact element 120second connection unit 121second contact elements 122first one of the second contact elements 123second one of the second contact elements 125second central contact element 131first orientation 132second orientation 133third orientation 141plug 142receptacle 151protrusion 152first recess 153second recess 154third recess 200X-ray tube 205cathode cup 210power drain 211first filament 212second filament 213third filament 215main filament LFstrong filament SFweak filament CMcommon

Examples

Embodiment Construction

[0037]Fig. 1 shows a schematic design of a cathode cup 205 for an X-ray tube 200 with two cavities for filaments. Two filaments 211 and 212 are incorporated in a cathode cup 205 of an X-ray tube 200. This type of tube may use electrostatic focusing of the electron beam and these cathodes can be utilized also in a pulsed imaging mode where a high voltage between emitter and cathode cup can be applied to switch the electron beam on and off. Typical cut-off voltages are in the range of some (single digit) kV. The additional emitter may be incorporated in different ways between the electrodes. This additional emitter can be operated after its predecessor reaches its end-of-life. All parameters such as emitter currents and voltages, the emission, and electron beam cut-off voltages remain unchanged. The lifetime of the X-ray tube can thus be extended as compared to having a single filament.

[0038]Fig. 2 shows a schematic design of a cathode cup 205 for an X-ray tube 200 with three cavities...

FIELD OF THE INVENTION

[0001] The present invention relates to a connector for selecting an active power drain of an X-ray tube, an X-ray system comprising the connector, and a method for selecting an active power drain of an X-ray tube.BACKGROUND OF THE INVENTION

[0002] Modern X-ray tubes are intended to be designed for long lifetime. Most X-ray tube housing assemblies currently used in the field utilize thermionic emitters for the emission of electrons. However, lifetime is limited by the wear-out of key components like anode plate or filaments, depending on the application. The thermionic emission of electrons leads fundamentally to wear-out of the emitters by material loss through evaporation. Emitter and / or filament wear-out is thus a major limitation of X-ray tube lifetime since other parts of the tube might last longer if the cathode does not fail.

[0003] For a given application, lifetime extension by change of materials and dimensioning of the filament or any other kind of electron emitters is limited due to the needed characteristics of the tube, i.e., emission characteristics and focal spot size. However, the lifetime of the tube may be significantly extended by implementing two, preferably identical, filaments and using them in sequence after the first one is worn out. The mechanical implementation into a cathode cup needs to support a preferably identical position, size, and shape of the focal spot with preferably the same or comparable characteristics of electron emission. Once the lifetime of the first filament comes to its end or if it has already become defective, a mechanism may be installed to switch over to the second filament that has not been used so far.

[0004] Multiple ideas are conceivable to connect a second filament to a power source. Switching between emitters may be done automatically or during service. Different concepts for a switching mechanism are possible. A mechanical solution, e.g., a switch positioned at the tube can be utilized as well as electrical switches that could be activated by the generator or the imaging system.

[0005] However, the switching mechanism to increase tube lifetime needs to be cost effective, easy to service and reliable. In addition, backwards compatibility to reference products may be advantageous.

[0006] The inventors of the present invention have thus found that it would be advantageous to have an improved switching mechanism that provides an efficient way for switching between power drains of an X-ray tube.SUMMARY OF THE INVENTION

[0007] It is an object of the present invention to provide an improved switching mechanism for selecting an active power drain like a filament or e.g. a grid control unit or any other power drain on high-voltage potential inside an X-ray emitter or X-ray source or X-ray tube assembly, that is cost effective, easily accessible for a technician during services and provides backward compatibility to existing systems.

[0008] The present invention is defined by the independent claims, and advantageous embodiments are defined in the dependent claims.

[0009] The described embodiments similarly pertain to the connector for selecting an active power drain of an X-ray tube, the X-ray system comprising the connector, and the method for selecting an active power drain of an X-ray tube. Synergistic effects may arise from different combinations of the embodiments although they might not be described in detail.

[0010] According to a first aspect of the invention, there is provided a connector for selecting an active power drain of an X-ray tube. The connector comprises a first connection unit comprising a plurality of first contact elements, and a second connection unit comprising a plurality of second contact elements, wherein the first connection unit and the second connection unit are configured to be detachably connectable to each other in at least a first orientation and a second orientation, and wherein the first contact elements and the second contact elements are configured to engage with each other when the first connection unit is connected to the second connection unit such that an electrical contact of at least a subset of the first contact elements with a respective one of the second contact elements is established. At least one of the first contact elements is configured to establish the electric contact with a first one of the second contact elements when the first connection unit and the second connection unit are connected in the first orientation, and to establish the electric contact with a second one of the second contact elements when the first connection unit and the second connection unit are connected in the second orientation, wherein the first one of the second contact elements and the second one of the second contact elements are different from each other.

[0011] Thus, a modified plug / receptacle combination is provided that offers a solution to connect power drains of the X-ray tube like the cathode filaments, or power supplies for a grid control unit, sequentially to a power source on high-voltage potential. An extended connector or an additional connector, preferably for high voltage, is disclosed for connecting to the additional filament and switching between the filaments. The connection to the first and the second filament may be located inside the tube housing and on cathode high-voltage level, but outside the evacuated tube vessel.

[0012] The term "X-ray tube" may be used either as the evacuated vessel including the cathode or emitter, or as the X-ray tube housing assembly, which also includes associated environmental parts like housing, lead shield, electronic devices, cooling devices, connectors, etc. Electronics part like a grid control unit may be applied at cathode potential rather than within the evacuated vessel. An X-ray imaging system may include the X-ray tube housing assembly, a generator, a detector, a controller including software, and means for image reconstruction, etc.

[0013] X-ray tubes may comprise two different types of filaments, one to establish a large focal spot and one for a small focal spot. For typical hospital applications, the lifetime of the tube is significantly determined by the lifetime of one of those filaments, typically the one with the small focal spot. In the following, the term "weaker filament" is used for this filament. With a redesign of the tube, three filaments may be implemented: Besides the "strong filament" LF, two "weaker filaments" SF1, SF2 may be implemented in a way that they can produce a preferably identical focal spot. There may be also another tube type with a single filament size and optionally electro-static focusing elements. The proposed concept can also be applied to this type of tube, with a first and a second filament that can be selectively connected via the proposed high-voltage connector. Thus, the lifetime limitation of the tube can be overcome, as the tube lifetime could theoretically be extended by a factor of two.

[0014] For connection of those two weak filaments, one solution is to provide each filament with its own current source, which would mean several copies of all involved components, such as filament inverter, filament current control loops, high-voltage transformers for the filament currents, wires in the HV-cable, HV-connector pins, and feedthrough into the evacuated tube can. This means significant cost and complexity increase. In addition, backwards compatibility to existing systems would not be possible.

[0015] Therefore, a connector is proposed, which may be a high-voltage connector, which provides a link to at least the first and the second "weaker filament" that is located inside the tube housing and on cathode HV-level, but outside the evacuated tube vessel. In general, two overall connector versions are possible. A first version is an extended high voltage connector to connect the tube to power supplying unit and contacting the cathode parts of the X-ray tube. A second version is a separate high voltage connector that may be added to the existing system and that acts as a separate switching device as a selector.

[0016] One of the connection units, preferably a receptacle, includes multiple input elements that are contacted depending on how the other one of the connection units, preferably a plug, is connected. Thus, by changing the orientation of the connection of the plug / receptacle combination by 90 degrees, for example, selection between the different filaments of the tube is carried out.

[0017] In an embodiment of the invention, the first one of the second contact elements is connectable to a first filament of the X-ray tube, and wherein the second one of the second contact elements is connectable to a second filament of the X-ray tube.

[0018] In an embodiment of the invention, the connector is configured for switching between the first filament and the second filament of the X-ray tube as active filament when the connector is moved from one of the first orientation and the second orientation to the other of the first orientation and the second orientation.

[0019] In an embodiment of the invention, the first orientation and the second orientation differ from each other in that one of the first connection unit and the second connection unit is rotated with respect to the other one of the first connection unit and the second connection unit along a connection axis by a predefined angle.

[0020] In an embodiment of the invention, the connection axis is defined by a direction in which the connection between the first connection unit and the second connection unit is established.

[0021] In an embodiment of the invention, one of the first connection unit and the second connection unit is a plug, and the other one of the first connection unit and the second connection unit is a receptacle configured for receiving the plug.

[0022] In an embodiment of the invention, one of the first connection unit and the second connection unit comprises a protrusion, and the other one of the first connection unit and the second connection unit comprises a first recess and a second recess configured for receiving the protrusion, such that when the protrusion is received in the first recess, the first connection unit and the second connection unit are connected in the first orientation, and when the protrusion is received in the second recess, the first connection unit and the second connection unit are connected in the second orientation. For example, pairs of bulges and grooves, optical markings, non-circular shapes etc. can be provided to distinguish between the respective orientations of the first and the second connection unit, respectively. Several variations are exemplified in the following.

[0023] In an embodiment of the invention, the first connection unit comprises a first central contact element, and the second connection unit comprises a second central contact element, and the first central contact element is configured to establish the electric contact with the second central contact element when the first connection unit and the second connection unit are connected in both the first orientation and the second orientation.

[0024] In an embodiment of the invention, the connector is a high-voltage connector configured for connecting the X-ray tube to a set of power sources on high-voltage potential. These can be, for example, high-voltage power supplies, filament current supplies, supplies for other kinds of electron emitters, or grid supplies.

[0025] In an embodiment of the invention, the first connection unit comprises three first contact elements, and the second connection unit comprises five or six second contact elements.

[0026] In an embodiment of the invention, the connector is a dedicated filament selector configured to be attached to the X-ray tube.

[0027] In an embodiment of the invention, the first connection unit comprises two first contact elements, and the second connection unit comprises at least three second contact elements.

[0028] According to another aspect of the invention, there is provided an X-ray system comprising an X-ray tube comprising at least a first filament and a second filament, and a connector for selecting an active filament of the X-ray tube according to any one of the preceding embodiments.

[0029] In an embodiment of the invention, the X-ray tube further comprises a main filament, and the connector is configured for connecting the main filament to a same main filament current source in each of the first orientation and the second orientation, and selectively connecting either the first filament or the second filament to a weak filament current source in the first orientation or in the second orientation, respectively. Preferably, a focal spot of the main filament is larger than a focal spot of each of the first filament and the second filament.

[0030] According to another aspect of the invention, there is provided a method for selecting an active filament of an X-ray tube. The method comprises providing an X-ray system according to any one of the preceding embodiments, disconnecting the first connection unit from the second connection unit in the first orientation, rotating the first connection unit to the second orientation, and connecting the first connection unit to the second connection unit in the second orientation.

[0031] Thus, the benefits provided by any of the above aspects equally apply to all of the other aspects and vice versa.

[0032] In summary, the invention relates to a connector for selecting an active power drain of an X-ray tube. The connector comprises a first connection unit comprising a plurality of first contact elements, and a second connection unit comprising a plurality of second contact elements, wherein the first connection unit and the second connection unit are configured to be detachably connectable to each other in at least a first orientation and a second orientation, and wherein the first contact elements and the second contact elements are configured to engage with each other when the first connection unit is connected to the second connection unit such that an electrical contact of at least a subset of the first contact elements with a respective one of the second contact elements is established. At least one of the first contact elements is configured to establish the electric contact with a first one of the second contact elements when the first connection unit and the second connection unit are connected in the first orientation, and to establish the electric contact with a second one of the second contact elements when the first connection unit and the second connection unit are connected in the second orientation, wherein the first one of the second contact elements and the second one of the second contact elements are different from each other.

[0033] One of the advantages of embodiments of the present invention is that the proposed high-voltage connector provides an efficient solution for selecting an active filament of an X-ray tube, with minimum product costs and easy serviceability. Backwards compatibility to existing configurations used in the field is provided by using an adapter, for example. This increases beneficially the lifetime of an X-ray tube at a given total emission, or can be exchanged in favor of a higher emission or a smaller focal spot size.

[0034] These advantages are non-limiting and other advantages may be envisioned within the context of the present application.

[0035] The above aspects and embodiments will become apparent from and be elucidated with reference to the exemplary embodiments described hereinafter. Exemplary embodiments of the invention will be described in the following with reference to the following drawings:BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Fig. 1 shows a schematic design of a cathode cup for an X-ray tube with two cavities for filaments. Fig. 2 shows a schematic design of a cathode cup for an X-ray tube with three cavities. Figs. 3A and 3B show cross- sectional schematic designs of cathode cups for an X-ray tube with focusing electrodes and one or two emitters, respectively. Fig. 4 shows a typical state-of-the-art shape of a HV-plug and HV-socket connection with a connection scheme of the plug. Figs. 5A and 5B show a connection scheme of circuitry indicating correct contact matching and a cross section view of contacts in both plug and receptacle. Fig. 6 shows a schematic setup of a connector for selecting an active power drain of a cathode cup of an X-ray tube according to an embodiment of the invention. Fig. 7 shows a cross sectional view of the contacts of the first connection element 110 and the second connection element 120 together with optical markings indication the orientation. Fig. 8 shows another schematic setup of a connector for selecting an active power drain of a cathode cup of an X-ray tube according to an embodiment of the invention. Fig. 9 shows another schematic setup of a connector for selecting an active power drain of a cathode cup of an X-ray tube according to an embodiment of the invention. Fig. 10 shows another schematic setup of a connector for selecting an active power drain of a cathode cup of an X-ray tube according to an embodiment of the invention. Fig. 11 shows another schematic setup of a connector for selecting an active power drain of a cathode cup of an X-ray tube according to an embodiment of the invention. Fig. 12 shows another schematic setup of a connector for selecting an active power drain of a cathode cup of an X-ray tube according to an embodiment of the invention. Fig. 13 shows a block diagram of a method for selecting an active power drain of an X-ray tube according to an embodiment of the invention. DETAILED DESCRIPTION OF EMBODIMENTS

[0037] Fig. 1 shows a schematic design of a cathode cup 205 for an X-ray tube 200 with two cavities for filaments. Two filaments 211 and 212 are incorporated in a cathode cup 205 of an X-ray tube 200. This type of tube may use electrostatic focusing of the electron beam and these cathodes can be utilized also in a pulsed imaging mode where a high voltage between emitter and cathode cup can be applied to switch the electron beam on and off. Typical cut-off voltages are in the range of some (single digit) kV. The additional emitter may be incorporated in different ways between the electrodes. This additional emitter can be operated after its predecessor reaches its end-of-life. All parameters such as emitter currents and voltages, the emission, and electron beam cut-off voltages remain unchanged. The lifetime of the X-ray tube can thus be extended as compared to having a single filament.

[0038] Fig. 2 shows a schematic design of a cathode cup 205 for an X-ray tube 200 with three cavities. The additional emitters are incorporated in a symmetric design where the left and right emitters or power drains 210 like filaments are identical and deliver a common focal spot. The central emitter may be a large filament for a larger focal spot compared to the left and right emitters. Both left and right emitters may produce the same focal spot independently of each other. Cut-off voltages may remain unchanged in this setup.

[0039] Figs. 3A and 3B show cross-sectional schematic designs of cathode cups 205 for an X-ray tube 200 with focusing electrodes and one or two emitters, respectively, allowing for deflection of the electron beam. In the case of cathodes that focus via the electrostatic potential of surrounding electrodes, a state-of-the-art typical design is shown in Fig. 3A. A single emitter 210 in central position is focused by two electrodes. Variable focal spot widths and x-deflection can be realized. Introducing an additional emitter in this type of cathode and thus incorporating emitters 211 and 212 in the cathode cup 205 might require additional electrodes to achieve the necessary focusing effect and allow for x-deflection. To enable the additional emitter and switching between emitters, with sustained functionality of the X-ray tube, the cathode cup 205 is also modified with at least one additional filament cavity as shown in Fig. 3B. For tubes with electrostatic electron beam optics, an additional electrode may be added to the cathode cup to achieve the necessary focus effect for each of the emitters.

[0040] Fig. 4 shows a typical state-of-the-art shape of a HV-plug 141 and HV-socket 142 connection with an electric circuit scheme of the cathode cup 205. A first filament 211 and a main filament 215 are included in an X-ray tube 200, each comprising a separate connection SF and LF, respectively, and may share a common connection CM. High voltage connectors may be designed in a cylinder shape or a conical tapered shape. The plug usually builds the terminal of a cable whereas the socket / receptacle is mostly built in a tube housing or an HV unit of an X-ray generator or any other component that needs to be connected by a high voltage cable. On cathode potential, multiple contacts are needed to connect the filaments. Here an example is shown for two filaments that need one contact for the strong filament LF, one for the weak filament SF and one common CM contact to close the current loop. The plug 141 includes a plurality of first contact elements 211, that are connectable to a plurality of second contact elements 121 of the receptacle 142. One of the plug 141 and the receptacle 142 may include a bulge 151 corresponding to a groove 152 at the other one in order to verify an orientation of the connection. The bulge at the connector ensures correct matching of the contacts by a fit into the corresponding groove at the receptacle in this example. Bulge and groove may be allocated vice versa, or other means may be used to indicate the correct geometric assignment of the contacts to each other.

[0041] Fig. 5A shows a connections scheme of circuitry indicating correct contact matching of the first connection element 110 and the second connection element 120 to contact the cathode cup 205 of the X-ray tube 200, and Fig. 5B shows a cross section view of contacts in both the first connection element 110 and the second connection element 120. In this example, the bulge / groove pair is located closely to the LF pin. However, this is not a necessary condition. They may be paired at any position in a way that matching of the according contacts is ensured.

[0042] Fig. 6 shows a schematic setup of a connector 100 for selecting an active power drain 210 a cathode cup 205 of an X-ray tube 200 according to an embodiment of the invention. The purpose is the selection of a desired configuration of downstream circuitry. In general, two versions of selector devices can be distinguished: HV-connectors with a cable that can be plugged at different positions or orientations, or selectors with a dedicated receptacle and a plug-in with an inner connectivity but not with a cable outlet. A HV connector including a first connection element 110, for example a plug, and a second connection element 120, for example a receptacle, is shown. The plug comprises in this example one bulge 151, and the connector jack or receptacle comprises two grooves 152 and 153, or other respective means of indication for appropriate orientation of the plug and the jack to each other. The plug and the receptacle can be changed in their electric configuration or connection orientation in a way that either a first filament 211, which may be a weak filament SF1, or a second filament 212, which may be a weak filament SF2, can be connected to the HV-supply voltage. In this example, a third, stronger, filament 215 is connected to its source in both configurations. This is done by using contacts in such orientations that the plug selects its desired counter contacts by being plugged in at the right positions that are allowed by two different grooves to be matched by the bulge of the plug. The first connection unit 110 comprises a plurality of first contact elements 111, and the second connection unit 120 comprises a plurality of first contact elements 121. A first central contact element 115 may correspond to a second central contact element 125 in both orientations of plug and receptacle, whereas a first one 112 of the first contact elements 111 is connected to a first one 122 of the second contact elements 121 in the first orientation 131, and to a second one 123 of the second contact elements 121 in the second orientation 132. In the example depicted here, this works by a simple arrangement of the contact 112 and the bulge 151 of the plug in one line, and two grooves 152, 153 in line with the respective contacts 122, 123 in the receptacle to select the desired contact of the respective filament 211, 212 by twisting the plug or cable and thus changing the orientation of the plug with respect to the receptacle by 90°. Pairs of bulge and grooves are used to enforce defined orientations of the plug to connect the respective contacts. Other means may be symmetrically shaped sets of connectors with secured indicators or optical markings. These respective markings on the first connection element 110 and the second connection element 120 are indicated in Fig. 7, and with respect to Fig. 7, the reference signs 151, 152 and 153 may simply refer to optical marks to identify the right orientation.

[0043] Thus, after the end-of-life of an emitter, for example the first filament 211, a spare one in the vacuum vessel, for example the second filament 212 which may produce a preferably identical focal spot like its predecessor, can be utilized and increase the lifetime of the whole X-ray tube housing assembly. An advantageous switching mechanism is implemented, which can be operated by a service engineer that takes the new emitter into operation after the original one is worn-out by using the proposed connector 100 for selecting an active power drain of the present invention. However, the increase in lifetime of the tube at a given total emission can also be exchanged in favor of a higher emission or a smaller focal spot size of the filament. The proposed connector can be applied to new products but also as an upgrade to existing ones. Depending on the implementation and the imaging system, the invention can be implemented in existing imaging systems as an upgrade of the tube assembly providing full backwards compatibility with highly increased lifetime. Those could be upgraded and still be compatible with the boundary conditions of their system environment. To overcome the lifetime limitation without altering proven parts and technologies a limited change to the cathode cup is proposed.

[0044] The switching between the two emitters can be done as a service procedure or alternatively automated by the imaging system. For an automated version, a rest-of-life prediction and monitoring must be in place that allows for a switching right before or directly after the end-of-life of the first emitter. If the generator or the imaging system monitors the wear-out of the emitter, it may be possible to implement automated switching, e.g. after a certain increase in emitters resistance.

[0045] The first one of the second contact elements of the second connection element may be connected to a first filament of the X-ray tube, while the second one of the second contact elements may be connected to a second filament of the X-ray tube. Thus, by switching the connector from one to the other orientation, switching between the first filament and the second filament of the X-ray tube as active filament is performed. Switching of the connector may be understood as moving the connector from one orientation to the other orientation, which differ from each other in that the first connection unit and the second connection unit are rotated with respect to the other along a connection axis by a predefined angle. The connection axis may be defined by a direction in which the connection between the first connection unit and the second connection unit is established, i.e., a connection direction of the connector. One of the first connection unit and the second connection unit may be a plug, and the other one may be a receptacle configured for receiving the plug.

[0046] The first and the second orientation may be defined by a protrusion like a bulge at one of the connection elements corresponding to respective recesses like grooves in the other connection element. Thus, when the protrusion is received in a first recess, the connector may be in the first orientation, and when the protrusion is received in the second recess, the connector may be in the second orientation. For example, pairs of bulges and grooves, optical markings, non-circular shapes etc. can be provided to distinguish between the respective orientations of the first and the second connection unit, respectively.

[0047] Fig. 8 shows another schematic setup of a connector 100 for selecting an active power drain 210 of a cathode cup 205 of an X-ray tube 200 according to an embodiment of the invention allowing complete backwards compatibility to the state-of-the-art cables and plugs. This embodiment works with a receptacle that comprises six contacts in a certain order, as can be seen from the electrical circuitry and the example for the mechanical connection in Fig. 8. In both orientations 131 and 132, the CM contact element of the first connection element 110 is connected to a respective CM contact element of the second connection element 120, which are connected to each other. Similarly, the LF contact element of the first connection element 110 is connected to a respective LF contact element of the second connection element 120, which are connected to each other. However, the SF contact element of the first connection element 110 is connected to two different contact elements SF1 and SF2 of the second connection element 120 in the first orientation 131 and the second orientation 132, with the first contact element SF1 and the second contact element SF2 not being connected to each other, but to different filaments 211 and 212 of the X-ray tube 200.

[0048] Fig. 9 shows another schematic setup of a connector 100 for selecting an active power drain 210 of a cathode cup 205 of an X-ray tube 200 according to an embodiment of the invention. This example provides two connecting options for both the LF filaments and the SF filaments. Thus, in the first orientation 131, a first filament 211 is connected to the SF contact element of the first connection element 110, and a first main filament of the X-ray tube 200 is connected to the LF contact of the first connection element 110. In the second orientation 132, a second filament 212 is connected to the SF contact element of the first connection element 110, and a second main filament of the X-ray tube 200 is connected to the LF contact of the first connection element 110. This concept may provide a high-voltage connector with a cable that can be plugged at different positions or orientations to tube. This variant is fully backwards compatible with an existing X-ray tube housing assembly and imaging system. The switch can be also implemented in the generator if an additional electrical connection via feedthroughs and the high-voltage cable is available. In this case the switch would be part of the generator.

[0049] Fig. 10 shows another schematic setup of a connector 100 for selecting an active power drain 210 of a cathode cup 205 of an X-ray tube 200 according to an embodiment of the invention. In this embodiment, a separate pair of connectors like plug and receptacle is provided. The selector plug may be used without any connected cable. The selector plug simply connects two of the pins of the receptacle to select one of the filaments of the X-ray tube. A HV cable may be connected via a standard connection system to a housing of the X-ray tube. The housing may be provided with a second connection element 120, to which a first connection element 110 is connected. By selecting an orientation of the first connection element 110 with respect to the second connection element 120, a respective active filament of the X-ray tube 200 may be selected. Pairs of bulge 151 and grooves 152, 153 may be used to enforce defined orientations 131, 132 of the plug 110 to connect the respective contacts of the receptacle 120. Other means may be symmetrically shaped sets of connectors, like ellipsoidal shape. An oval shape may fulfil the same requirement for two alternative orientations. Thus, this embodiment shows a separate selector with a dedicated receptacle and plug. The selector plug connects pins of the selector receptacle to select the respective filament. Also in this case, the mechanical orientation of the plug with respect to the receptacle may be used to select the active contacts.

[0050] Fig. 11 shows another schematic setup of a connector 100 for selecting an active power drain 210 of a cathode cup 205 of an X-ray tube 200 according to an embodiment of the invention. Such kind of a connector 100 as separate selector may offer the feature to select one out of more than two options or orientations. An example to select one of three possible contacts that are connected to one weak filament terminal each is shown in Fig. 11. Thus, by selecting a respective orientation of the first connection element 110 with respect to the second connection element 120, one of the first filament 211, the second filament 212, and the third filament 213 of the X-ray tube 200 can be selected as active filament. The second connection element 120 may comprise three grooves 152, 153, and 154 corresponding to the bulge 151 of the first connection element 110 in the first orientation 131, the second orientation 132, and the third orientation 133, respectively. This, in each orientation, one of the SF1, SF2, and SF3 contacts of the second contact element 121 of the second connection element 120 is connected via the first contact element 111 of the first connection element 110 to a respective power source. Pins for more than three contacts may be arranged accordingly in the receptacle around a central common input pin. The triangle outer shape of the plug / receptacle pair may avoid the need of grooves and of a corresponding bulge.

[0051] Fig. 12 shows another schematic setup of a connector 100 for selecting an active power drain 210 of a cathode cup 205 of an X-ray tube 200 according to an embodiment of the invention. This embodiment gives an example for a one out of three selector without the use of a central pin. Thus, by selecting a respective orientation of the first connection element 110 with respect to the second connection element 120, one of the first filament 211, the second filament 212, and the third filament 213 of the X-ray tube 200 can be selected as active filament. However, the first connection element 110 comprises a plurality of first contact elements 111, with some of those first contact elements 111 being connected to each other via electrical shorts. Thus, depending on the respective orientation of the first connection element 110 with respect to the second connection element 120, a respective active filament can be selected to be connected to its power source.

[0052] Fig. 13 shows a block diagram of a method for selecting an active power drain 210 of an X-ray tube 200 according to an embodiment of the invention. The method comprises providing S110 an X-ray system comprising an X-ray tube 200 with at least a first filament 211 and a second filament 212, and a connector 100 for selecting an active power drain 210 of the X-ray tube 200. The method comprises further disconnecting S120 the first connection unit 110 from the second connection unit 120 in the first orientation 131, rotating S 130 the first connection unit 110 to the second orientation 132, and connecting S140 the first connection unit 110 to the second connection unit 120 in the second orientation 132.

[0053] While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive. The invention is not limited to the disclosed embodiments. Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing a claimed invention, from a study of the drawings, the disclosure, and the dependent claims.

[0054] In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. Measures recited in mutually different dependent claims can be combined to advantage. Any reference signs in the claims should not be construed as limiting the scope.LIST OF REFERENCE SIGNS:

[0055] 100connector 110first connection unit 111first contact elements 112first one of the first contact elements 115first central contact element 120second connection unit 121second contact elements 122first one of the second contact elements 123second one of the second contact elements 125second central contact element 131first orientation 132second orientation 133third orientation 141plug 142receptacle 151protrusion 152first recess 153second recess 154third recess 200X-ray tube 205cathode cup 210power drain 211first filament 212second filament 213third filament 215main filament LFstrong filament SFweak filament CMcommon

Examples

Embodiment Construction

[0037]Fig. 1 shows a schematic design of a cathode cup 205 for an X-ray tube 200 with two cavities for filaments. Two filaments 211 and 212 are incorporated in a cathode cup 205 of an X-ray tube 200. This type of tube may use electrostatic focusing of the electron beam and these cathodes can be utilized also in a pulsed imaging mode where a high voltage between emitter and cathode cup can be applied to switch the electron beam on and off. Typical cut-off voltages are in the range of some (single digit) kV. The additional emitter may be incorporated in different ways between the electrodes. This additional emitter can be operated after its predecessor reaches its end-of-life. All parameters such as emitter currents and voltages, the emission, and electron beam cut-off voltages remain unchanged. The lifetime of the X-ray tube can thus be extended as compared to having a single filament.

[0038]Fig. 2 shows a schematic design of a cathode cup 205 for an X-ray tube 200 with three cavities...

Claims

1. A connector (100) for selecting an active power drain (210) of an X-ray tube (200), the connector (100) comprising: a first connection unit (110) comprising a plurality of first contact elements (111), and a second connection unit (120) comprising a plurality of second contact elements (121); wherein the first connection unit (110) and the second connection unit (S120) are configured to be detachably connectable to each other in at least a first orientation (131) and a second orientation (132), wherein the first contact elements (111) and the second contact elements (121) are configured to engage with each other when the first connection unit (110) is connected to the second connection unit (120) such that an electrical contact of at least a subset of the first contact elements (111) with a respective one of the second contact elements (121) is established; and wherein at least one (112) of the first contact elements (111) is configured to establish the electric contact with a first one (122) of the second contact elements (121) when the first connection unit (110) and the second connection unit (120) are connected in the first orientation (131), and to establish the electric contact with a second one (123) of the second contact elements (121) when the first connection unit (110) and the second connection unit (120) are connected in the second orientation (132), wherein the first one (122) of the second contact elements (121) and the second one (123) of the second contact elements (121) are different from each other.

2. The connector (100) according to claim 1, wherein the first one (122) of the second contact elements (121) is connectable to a first filament (211) of the X-ray tube (200), and wherein the second one (123) of the second contact elements (121) is connectable to a second filament (212) of the X-ray tube (200).

3. The connector (100) according to claim 2, wherein the connector (100) is configured for switching between the first filament (211) and the second filament (212) of the X-ray tube (200) as active filament when the connector (100) is moved from one of the first orientation (131) and the second orientation (132) to the other one of the first orientation (131) and the second orientation (132).

4. The connector (100) according to any one of the preceding claims, wherein the first orientation (131) and the second orientation (132) differ from each other in that one of the first connection unit (110) and the second connection unit (120) is rotated with respect to the other one of the first connection unit (110) and the second connection unit (120) along a connection axis by a predefined angle.

5. The connector (100) according to claim 4, wherein the connection axis is defined by a direction in which the connection between the first connection unit (110) and the second connection unit (120) is established.

6. The connector (100) according to any one of the preceding claims, wherein one of the first connection unit (110) and the second connection unit (120) is a plug (141), and wherein the other one of the first connection unit (110) and the second connection unit (120) is a receptacle (142) configured for receiving the plug (141).

7. The connector (100) according to any one of the preceding claims, wherein one of the first connection unit (110) and the second connection unit (120) comprises a protrusion (151), and wherein the other one of the first connection unit (110) and the second connection unit (120) comprises a first recess (152) and a second recess (153) configured for receiving the protrusion (151), such that when the protrusion (151) is received in the first recess (152), the first connection unit (110) and the second connection unit (120) are connected in the first orientation (131), and when the protrusion (151) is received in the second recess (153), the first connection unit (110) and the second connection unit (120) are connected in the second orientation (132).

8. The connector (100) according to any one of the preceding claims, wherein the first connection unit (110) comprises a first central contact element (115), and wherein the second connection unit (120) comprises a second central contact element (125), and wherein the first central contact element (115) is configured to establish the electric contact with the second central contact element (125) when the first connection unit (110) and the second connection unit (120) are connected in both the first orientation (131) and the second orientation (132).

9. The connector (100) according to any one of claims 1 to 8, wherein the connector (100) is a high-voltage connector configured for connecting the X-ray tube (200) to a set of power sources on high-voltage potential.

10. The connector (100) according to claim 9, wherein the first connection unit (110) comprises three first contact elements (111), and wherein the second connection unit (120) comprises five or six second contact elements (121).

11. The connector (100) according to any one of claims 1 to 8, wherein the connector (100) is a dedicated filament selector configured to be attached to the X-ray tube (200).

12. The connector (100) according to claim 11, wherein the first connection unit (110) comprises two first contact elements (111), and wherein the second connection unit (120) comprises at least three second contact elements (121).

13. An X-ray system comprising an X-ray tube (200) comprising at least a first filament (211) and a second filament (212); and a connector (100) for selecting an active power drain (210) of the X-ray tube (200) according to any one of claims 1 to 12.

14. The X-ray system according to claim 13, wherein the X-ray tube (200) further comprises a main filament (213), the main filament (213) preferably having a focal spot larger than a focal spot of each of the first filament (211) and the second filament (212), and wherein the connector (100) is configured for connecting the main filament (213) to a same main filament current source in each of the first orientation (131) and the second orientation (132), and selectively connecting either the first filament (211) or the second filament (212) to a weak filament current source in the first orientation (131) or in the second orientation (132), respectively.

15. A method for selecting an active power drain (210) of an X-ray tube (200), the method comprising: providing (S110) an X-ray system according to claim 13 or 14; disconnecting (S120) the first connection unit (110) from the second connection unit (120) in the first orientation (131); rotating (S130) the first connection unit (110) to the second orientation (132); and connecting (S140) the first connection unit (110) to the second connection unit (120) in the second orientation (132).

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