Abstract:
A high-voltage supply for an x-ray emitter, in particular to provide a cathode current and a cathode voltage, has at least two electrical conductors, which are incorporated in a common insulating body. Each conductor is assigned a connector element, which is configured for electrically conducting contact with a corresponding connector of the x-ray emitter. Such a high-voltage supply for supplying the cathode voltage and the cathode current is provided in an x-ray emitter. The high-voltage supply extends at least in part over an inner region of a radiation protection housing of the x-ray emitter.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the priority, under 35 U.S.C. §119, of German application DE 10 2015 213 810.0, filed Jul. 22, 2015; the prior application is herewith incorporated by reference in its entirety. 
       BACKGROUND OF THE INVENTION 
     Field of the Invention 
       [0002]    The invention relates to a high-voltage supply for an x-ray emitter, in particular to supply voltage to a cathode of the x-ray emitter. The invention further relates to an x-ray emitter having such a high-voltage supply with at least one cathode and one anode, which are arranged in a vacuum housing, which is enclosed by a radiation protection housing. 
         [0003]    Space economies in the area of high-voltage components are problematic, as they generally reduce the distance between components at different electrical potentials, thus increasing the risk of short circuits or dielectric flashover. The technology of x-ray emitters typically requires potential differences of several 10 kV to 200 kV, depending on the field of application. Also in the case of medical applications the required x-ray voltage or potential difference is a function of both the object to be examined and the desired contrast. 
         [0004]    In the case of x-ray emitters a cathode current for heating a cathode is generally supplied at the voltage level of the cathode, which is for example 150 kV lower than the voltage level of an anode when used for medical diagnostics. To generate the cathode current it is known for example from published European patent application EP 0 810 815 A1 (corresponding to U.S. Pat. No. 5,878,109) to use heater transformers which contains in particular a primary and secondary coil. Such heater transformers or converters can be incorporated in the radiation protection housing so that the cathode current can be supplied at voltages which are much lower than the high-voltage level. However such embodiments require more space in the radiation protection housing. Published, European patent application EP 0 810 815 A1 therefore proposes a concentric arrangement of the primary and secondary coil to compensate at least partially for the greater space requirement. An air gap of at least several millimeters is present between the primary and secondary coil for insulation purposes. 
         [0005]    Based on this prior art it is the object of the present invention to specify a high-voltage supply for x-ray emitters, in particular for x-ray emitters of imaging facilities for medical diagnostics, which have sufficient flashover resistance but are still compact in structure. 
       SUMMARY OF THE INVENTION 
       [0006]    It is accordingly an object of the invention to provide a high-voltage supply and an x-ray emitter having the high-voltage supply that overcome the above-mentioned disadvantages of the prior art devices this general type. 
         [0007]    According to the invention a high-voltage supply for an x-ray emitter, in particular for providing a cathode current and a cathode voltage, has at least two electrical conductors, which are incorporated in a common insulating body. Each conductor is assigned a connector element, which is configured for electrically conducting contact with a corresponding connector of the x-ray emitter. 
         [0008]    The high-voltage supply has been structured in the form of a through passage, which satisfies the requirements of at least two-pole contact with the cathode. The electrical conductor carrying the high voltage and the conductor carrying the cathode current are incorporated in the insulating body in such a manner that the cathode voltage can be supplied to the cathode insulated from the cathode current. The cathode current here is supplied essentially at the voltage level of the cathode voltage, which—as mentioned above—can be at a voltage potential of more than −75 kV compared to earth according to possible exemplary embodiments. The anode voltage in this instance can be for example at a higher voltage level of +75 kV compared to earth. 
         [0009]    No restrictions are required with regard to the structure and mode of operation of the cathode. In particular the cathode can be configured for the thermal emission of electrons and can comprise one or more filaments. Depending on the number of filaments provided, the high-voltage supply is then embodied with a corresponding number of poles. In other exemplary embodiments a thermoionic flat emitter is provided. However the high-voltage supply is equally suited to supplying a cathode current to a cathode which releases electrons generated by field emission. 
         [0010]    The high-voltage supply is particularly suited to use in x-ray emitters of medical imaging facilities, in particular computed tomography, mammography or angiography facilities. 
         [0011]    The insulating body of the high-voltage supply preferably has a flange for connection to a radiation protection housing of the x-ray emitter. The flange is used for the mechanical fastening of the high-voltage supply, which in the mounted state extends within a radiation protection housing of the x-ray emitter. A mechanically stable connection can minimize the risk of a break in contact in the region of the connectors. 
         [0012]    The insulating body consists for example of an electrically insulating casting compound, for example an epoxy grout. 
         [0013]    According to possible exemplary embodiments of the invention the connector elements of the high-voltage supply are arranged on a board. Each connector element is connected to the assigned electrical conductor in an electrically conducting manner by way of conduction paths. The board is sufficiently stable mechanically to meet the requirements for use in x-ray facilities. The conduction paths are arranged at a sufficient distance from one another so that voltage differences in the region of at least 200 V can be tolerated. Such embodiments correspond to a modular design, in which the board is provided as a separate part to supply the cathode currents and the cathode voltage. The insulating body with the electrical conductors incorporated therein serves as a high-voltage plug making contact with the board. It is thus possible to combine boards and high-voltage plugs of different types to meet the requirements for use in differently configured x-ray emitters. 
         [0014]    As a development of the invention at least one electrically insulating insulation element is provided to brace the board against a wall of the radiation protection housing. The insulation element is used for the mechanically stable connection of the board which is to be mounted on the cathode connector of the x-ray emitter. 
         [0015]    The at least one insulation element preferably has a ribbed shape to lengthen a creep distance. Such high-voltage technology parts can have in particular an essentially cylindrical shape with projections extending radially in the manner of plates. The lengthening of the creep distance also reduces the risk of dielectric flashover. 
         [0016]    To reduce the space required for the high-voltage supply further it has proven advantageous, depending on the spatial dimensions of the x-ray emitter, to provide angled embodiments, in which the at least two electrical conductors run in a curved manner within the insulating body. 
         [0017]    The connector elements are preferably configured to provide a plug-type connection to corresponding and complementarily configured connectors of the x-ray emitter. The connector elements of the high-voltage supply are particularly preferably configured as connector pins, connector sockets or blade contacts. 
         [0018]    The cited object is also achieved by an x-ray emitter with one of the high-voltage supplies described above so reference is first made to the embodiments relating thereto. 
         [0019]    The x-ray emitter comprises at least one vacuum housing serving as an x-ray tube, in which at least one cathode and one anode are arranged, and a radiation protection housing enclosing the vacuum housing. 
         [0020]    The anode here can be embodied as a fixed or stationary anode or preferably as a rotating anode in a manner known per se. In another exemplary embodiment a rotary piston anode is provided, the anode forming a wall of a rotatably supported vacuum housing. 
         [0021]    The radiation protection housing has in particular a shield, for example in the form of a lead covering. The x-ray radiation generated exits from the radiation housing through a window that is essentially transparent to the wavelength range in question. 
         [0022]    According to the invention the high-voltage supply makes contact with connectors of the cathode which are arranged within the radiation protection housing, to ensure provision of the cathode voltage or cathode current. The high-voltage supply here is arranged at least partially within the radiation protection housing. In other words the high-voltage supply forms a type of through passage to provide the high-voltage supply and the cathode current supply. The high-voltage supply here extends at least in part over an inner region of the radiation protection housing. The high-voltage supply is configured as at least two-pole. In other words at least two electrical conductors are provided for the voltage and current supply, being incorporated in a common insulating body. Each conductor is assigned a respective connector element, which is connected to a corresponding connector in an electrically conducting manner. 
         [0023]    The cathode current is supplied electrically insulated from the high-voltage supply of the cathode voltage, which determines the voltage difference between cathode and anode. 
         [0024]    A liquid or gaseous, electrically insulating medium, in particular an electrically non-conducting oil, is preferably introduced in the inner region within the radiation housing of the x-ray emitter. During appropriate use of the x-ray emitter the medium is used for electrical insulation. Liquid media can also be used to dissipate heat, therefore as coolants. During operation the high-voltage supply is therefore enclosed by the liquid or gaseous medium, the electrically insulating properties of which additionally increase the flashover resistance of the arrangement, thus reducing the risk of short circuits further. 
         [0025]    The high-voltage supply is preferably connected to the radiation protection housing by a flange arranged on the insulating body. Such a configuration is mechanically stable, so the corresponding connector elements of the high-voltage supply can make reliable contact with the connectors of the cathode. 
         [0026]    According to possible exemplary embodiments the connector elements are arranged on a board. Each connector element is connected to the assigned electrical conductor in an electrically conducting manner by way of conduction paths. It is particularly preferably for the board, which is configured as flat, to be fastened by at least one electrically insulating insulation element to a wall of the radiation protection housing. Such increased stability is particularly expedient for exemplary embodiments in which the x-ray emitter is used as a rotating emitter of a computed tomography facility, to enable it to withstand the centrifugal forces that occur. 
         [0027]    In the simplest instance the connector elements or connectors can be solder joints for connection. The connector elements are preferably provided for plug-type connection to corresponding complementarily configured connectors. Plug-type connections are particularly desirable for simplified mounting. In the mounted state the connector elements of the high-voltage supply form a mechanically robust plug-type connection with the connectors of the x-ray emitter to supply the cathode current and the cathode voltage. 
         [0028]    The properties, features and advantages of the present invention as described above and the manner in which these are achieved will become clearer and more comprehensible in conjunction with the description which follows of the exemplary embodiments described in more detail with reference to the drawings. 
         [0029]    Other features which are considered as characteristic for the invention are set forth in the appended claims. 
         [0030]    Although the invention is illustrated and described herein as embodied in a high voltage supply for an X-ray emitter, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims. 
         [0031]    The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
         [0032]      FIG. 1  is a diagrammatic, perspective view of a partial segment of an x-ray emitter with a high-voltage supply according to a first exemplary embodiment of the invention; 
           [0033]      FIG. 2  is a further perspective view of the high-voltage supply of the first exemplary embodiment anchored in a housing part; 
           [0034]      FIG. 3  is a perspective view of a partial segment of the x-ray emitter with the high-voltage supply according to a second exemplary embodiment of the invention; and 
           [0035]      FIG. 4  is shows a perspective view of a partial segment of the x-ray emitter with the high-voltage supply according to a third exemplary embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0036]    Corresponding parts are shown with the same reference characters in all the figures. 
         [0037]    Referring now to the figures of the drawings in detail and first, particularly to  FIGS. 1 and 2  thereof, there is shown a perspective view of a section from an x-ray emitter  1  with a high-voltage supply  2 . To show the relevant components more clearly a housing part  3 . 1 , which in the mounted state encloses a cathode connector part  4  and the high-voltage supply  2 , is omitted. However the housing part  3 . 1  in question is shown in  FIG. 2 . 
         [0038]    The housing part  3 . 1  forms a segment of a radiation protection housing  3  of the x-ray emitter  1 . The radiation protection housing  3  largely shields the generated x-ray radiation during operation. The radiation protection housing  3  also has a window, which is permeable for at least a wavelength range of the generated x-ray radiation, so that it can leave the radiation protection housing  3  in a defined spatial angle range to capture image data. 
         [0039]    The x-ray emitter  1  is of the type having rotating anodes. A vacuum housing is arranged in a region of the radiation protection housing  3  separated from a wall  3 . 2  in a manner not shown in detail, the vacuum housing functioning as an x-ray tube. Arranged within the vacuum housing  5  are a rotatably supported anode and a cathode, which is supplied with a cathode current by way of the cathode connector part  4 . High-voltage is supplied to the cathode voltage equally by way of the cathode connector part  4  and the high-voltage supply  2  connected thereto. The cathode current is supplied by the high-voltage supply  2  at the potential of the cathode voltage. Cathode insulation  5  insulates the cathode electrically from the anode or from the vacuum housing, which is at earth potential in the illustrated exemplary embodiment. 
         [0040]    The high-voltage supply  2  of the first exemplary embodiment shown in  FIGS. 1 and 2  has an insulating body  2 . 1  made of an electrically insulating material, in which four electrical conductors  2 . 2  are incorporated in such a manner that they are insulated from one another. The electrical conductors  2 . 2  are provided with connector elements  2 . 3  at one end, these being configured for electrical contact with correspondingly configured connectors  4 . 1  of the cathode connector part  4 . The connector elements  2 . 3  of the first exemplary embodiment are in the form of connector sockets which make contact with connectors  4 . 1 , which are configured as connector pins, in the mounted state. 
         [0041]    The high-voltage supply  2  of the first exemplary embodiment has an angled outer shape, in order to utilize the available space optimally. The four electrical conductors  2 . 2  therefore run along curved paths within the insulating body  2 . 1 . In the mounted state the front, angled part of the high-voltage supply  2  makes contact with the connector elements  2 . 3  of the cathode connector part  4  arranged there. To this end the high-voltage supply  2 . 1  is fastened in such a manner in relation to the radiation protection housing  3  in the mounted state that the angled part of the high-voltage supply  2  is held in a stable manner in the desired position. The insulating body  2 . 1  has a fastening device in the form of a flange  2 . 4 , to which the housing part  3 . 1  can be fastened in a fixed manner by screws, rivets or the like. 
         [0042]    In the mounted state the housing part  3 . 1  is connected in a fixed manner to the wall  3 . 2 . The inner region separated from the wall  3 . 2  and the housing part  3 . 1  is fluid-tight. In the operating state a liquid or gaseous and electrically insulating medium, for example oil, is introduced in the inner region, enclosing the high-voltage supply  2  and thus increasing flashover resistance. The liquid medium can also serve as a coolant and in particular to dissipate heat that occurs when the x-ray radiation is generated. 
         [0043]    In other exemplary embodiments the medium is nitrogen or SF 6 . 
         [0044]      FIGS. 3 and 4  show further exemplary embodiments of the invention. Essentially the second exemplary embodiment shown in  FIG. 3  and the third exemplary embodiment shown in  FIG. 4  correspond to the first exemplary embodiment, so reference should be made to the description relating to  FIGS. 1 and 2 . The further descriptions in the following are mainly restricted to the differences in relation to the first exemplary embodiment. 
         [0045]    The second and third exemplary embodiments have boards  2 . 5  to supply the cathode current and cathode voltage. The board  2 . 5  is in electrical contact with the electrical conductors  2 . 2  incorporated in the insulating body  2 . 1 . The connector elements  2 . 3  assigned to the conductors  2 . 2  are arranged on the board  2 . 5  and connected to the corresponding conductors  2 . 2  in an electrically conducting manner by way of conduction paths. In the operating state the boards  2 . 5  are enclosed by the liquid or gaseous, electrically insulating medium which has been introduced in the inner region between wall  3 . 2  and housing part  3 . 1 . 
         [0046]    In contrast to the first exemplary embodiment only three electrical conductors  2 . 2  are provided to supply the cathode current and cathode voltage in the second and third exemplary embodiments. In other words the high-voltage supply  2  of the embodiments shown by way of example in  FIGS. 3 and 4  is configured as three-pole. The connector elements  2 . 3  are pin-shaped, being thus embodied as connector pins. In other exemplary embodiments blade contacts are provided as connector elements  2 . 3 , making contact with correspondingly configured socket-type connectors  4 . 1 . 
         [0047]    In the second exemplary embodiment in  FIG. 3  the plug-type insulating body  2 . 1  is straight. The electrical conductors  2 . 3  are passed through the insulating body  2 . 1  and make contact with conduction paths on the board  2 . 5 , which are connected to the connector elements  2 . 3  in an electrically conducting manner. The board  2 . 5  is fastened in the illustrated position by way of the insulating body  2 . 1 , which is fastened to the housing part  3 . 1  by the flange  2 . 4  according to the arrangement of the first exemplary embodiment. The latter housing part  3 . 1  is however not shown in  FIG. 3 . 
         [0048]    In the third exemplary embodiment in  FIG. 4  the insulating body  2 . 1  forms an angled plug. The three electrical conductors incorporated in the insulating body therefore run in a curved manner. To improve mechanical stability, insulation elements  2 . 6  are also provided which brace the board  2 . 5  in relation to the wall  3 . 2 . The insulation elements  2 . 6  have a cylindrically symmetrical shape and have plate-like extensions projecting in the radial direction. Such an embodiment increases the creep distance, thus ensuring adequate flashover resistance with voltage differences from 10 kV up to 200 kV. 
         [0049]    Although the invention has been illustrated and described in detail using the preferred exemplary embodiment, the invention is not restricted by the exemplary embodiments illustrated in the figures. Other variations and combinations can be derived therefrom by the person skilled in the art without departing from the scope of protection of the invention.