You are an expert at summarizing long articles. Proceed to summarize the following text:

You are an expert at summarizing long articles. Proceed to summarize the following text: 
This application claims Paris Convention priority of DE 10 2008 020 729.2 filed Apr. 25, 2008 the complete disclosure of which is hereby incorporated by reference. 
     BACKGROUND OF THE INVENTION 
     The invention concerns a door configuration, comprising a door for opening and closing an access, wherein the door can be pivoted about an axis S relative to a main frame of the door configuration, wherein the door has a sliding door that is disposed on a casement of the door such that it can be displaced in a direction V, and wherein the casement can be pivoted about the axis S relative to the main frame. 
     Door configurations of this type are known e.g. from doors with sliding windows (see http:/www.woelfleder.at/tuere.htm, April 2008). 
     Door configurations are generally used to reversibly close an access, in particular, block, cover or seal it. A door configuration thereby comprises a movable part, in the present case called door, and a non-movable part, in the present case called main frame. The door is thereby movably disposed on the main frame. An access that can be closed by a door may e.g. be a passage into a room of a building, or also an engagement opening into a cabinet or a housing. 
     Folding doors are widely used, which are disposed on the main frame (e.g. a door frame or a wall unit) such that they can be pivoted about a (usually vertical) axis. The overall access that is covered by the door can be opened by pivoting the folding door. The door may be simply borne via hinges or joints. When a folding door is opened, a relatively large amount of space is required in front of the access as a pivoting area for the door. 
     In practice, it is often not required or not desired to open the entire access that can be closed by a door. In such cases, another, smaller door is conventionally integrated in a folding door. In former times, for example, town or castle gates often had so-called “manholes”. Such a manhole is merely a head-high folding door that is inserted into a door wing, through which individuals could pass. To allow passage of vehicles, the town or castle gate was completely opened. The further smaller door only opens part of the access that can be closed by the entire door. Operation of the further, smaller door is generally easier than opening the entire gate, and also requires a smaller amount of free space in front of the access. 
     The above-mentioned doors having sliding windows basically represent doors on which, in turn, a sliding door is supported for opening part of the access that can be closed by the entire door. The sliding door can be used without requiring any free space in front of the access, and can therefore be used, in particular, when space is limited. 
     The pivotable part of the door, on which the sliding door is disposed and with respect to which the sliding door can be moved, is called a casement in the present case. 
     Door configurations having a double function, i.e. a casement and sliding door function, conventionally have independent operating and locking mechanisms for each function. This results in a relatively complex construction, and frequent change between the functions makes handling complicated. 
     It is therefore the object of the present invention to improve the operating and locking mechanism of a door configuration of the above-mentioned kind having a casement and sliding door function and, in particular, simplify the construction and handling. 
     SUMMARY OF THE INVENTION 
     This object is achieved by a door configuration of the above-mentioned type, which is characterized in that a latch is provided for locking and unlocking the casement in its closed state with respect to the main frame, an operating element is disposed on the sliding door, which can be moved with the sliding door and can be switched over between a first position and a second position, wherein, in the first position of the operating element, the operating element does not obstruct movement of the sliding door on the casement, and movement of the sliding door does not influence the latch position, and wherein, in the second position of the operating element, the operating element engages in the latch or a carrier that is rigidly connected or hinged to the latch, such that, when the casement is closed, the latch is operated by moving the sliding door in the second position of the operating element. 
     The invention provides simple and reliable operation both of the casement function (pivoting or swinging open the casement or the entire door) and of the sliding frame function (movement of the sliding door when the casement is closed). The sliding door has an operating element that is preferably integrated in a handle that is supported on the sliding door. The operating element can be switched over between the first and the second position by a human operator (at least and preferably only when the casement is closed), e.g. by exerting a pressure onto the operating element. 
     In order to be able to operate the sliding door function, the operating element is in the first position. In this first position, the latch locks the casement such that it is maintained in the closed position. By manually laterally pulling the sliding door (or an associated handle), the sliding door can be moved with respect to the casement in order to open part of the access opening. The first position is the standard position for the operating element. The operating element is typically pretensioned in this first position. 
     In order to be able to operate the casement function, the operating element is switched into the second position. The latch is operated by a manual lateral pulling action on the sliding door and the sliding door is also moved with respect to the casement, but typically only within a narrow range (“unlocking path”). As soon as the latch is unlocked, the casement can be opened by pulling forward the sliding door. 
     The inventive door configuration realizes the mechanical change between the two operating modes of the door mechanism in the simplest fashion (sliding door function and folding door function). Only one operating element is required to handle the sliding door (or an associated handle). Operation of the different operating modes at the same time is preferably prevented by locking and blocking mechanisms, i.e. when the sliding door is opened, the folding door cannot be unlocked, and when the casement is open, the sliding door cannot be opened. In particular, switching over of the operating element from the first position to the second position is preferably blocked when the sliding door is not closed. 
     In accordance with the invention, the door with pivoting function (“folding door”) has an additional sliding door function. The overall access can be opened via the pivotable casement that also pivots the sliding door. This is useful, in particular, for moving large objects or persons through the access. When only a smaller part of the access is required, e.g. for moving only relatively small objects through the access, the sliding door function can be used while the casement is closed, wherein generally only a small part of the access is opened. The sliding door does, in particular, not require any free space in front of the access, such that in case of space shortage, it is not necessary to maintain a minimum separation from any oppositely disposed devices for the sliding door function. If the sliding door is narrow in the direction of displacement V, it can be displaced only in front of the access without requiring any free space. If a wider sliding door is used, space is required only on the sides of the access, which, however, often only minimally impairs the options of using the space. 
     In one preferred embodiment of the inventive safety housing, the closed sliding door covers the entire access that can be closed by the door when the casement is closed. In other words, the overall door is designed as a sliding door that can also be pivoted as a folding door. The casement can then be limited to its function as a bearing for the sliding door. In this case, it is not necessary to provide (partial) covers for the access on the casement. 
     In another embodiment, the sliding door extends in a direction perpendicularly to the direction V over the entire height of the access that can be closed by the door. In this case, the sliding door opens a maximum part of the access without requiring additional space in front of the access. 
     In a particularly preferred embodiment, 
     a partial cover for the access is rigidly mounted to the casement, and, 
     when the casement is closed and the sliding door is closed, 
     
         
         
           
             the sliding door extends over a first partial area of the access in a direction parallel to the direction V, and 
             the partial cover that is rigidly mounted to the casement, extends over a second partial area of the access in a direction parallel to the direction V,
 
wherein the first plus second partial areas cover the entire width of the access that can be closed by the door, in particular, wherein the first and the second partial areas overlap. In this embodiment, a movable partial cover of the sliding door and the partial cover that is rigidly disposed in the casement supplement each other. When the sliding door is opened, its partial cover is preferably slid over the partial cover that is rigidly disposed in the casement, such that no free space is required next to the access for opening the sliding door. In this embodiment, the surface portion of the displaceable partial cover of the door can be further reduced in order to simplify the construction.
 
           
         
       
    
     In one preferred further development of this embodiment, the first partial area extends approximately over half the width of the access parallel to the direction V when the casement and the sliding door are closed. The second partial area also extends over approximately half the width of the access (namely its other half). This opens a maximum part of the access by opening the sliding door without requiring free space next to the access. 
     In another preferred embodiment, the sliding door covers the access in a border area of the access remote from the axis S, when the sliding door and the casement are closed, and the sliding door can be slid open from its closed position towards the axis S. This reduces the bearing forces that act on the suspensions (hinges, pivot joints) of the casement when the sliding door is open. This is also facilitated by combined actuation of the casement and the sliding door by means of the same handle and operating element. 
     In one particularly preferred embodiment, in the second position of the operating element, a latch position associated with the closed sliding door locks the casement and a locked position associated with a moved sliding door releases the casement. In this embodiment, it is sufficient to operate only one single safety locking per door (with sliding and casement function) to secure access (with respect to both functions). The safety lock only needs to check or ensure that the sliding door is closed, since in this case, the folding door is inevitably also locked. 
     In a preferred further embodiment, the range of movement of the sliding door away from the closed position in the second position of the operating element is defined by a mechanical stop to an unlocking path EW which is shorter than the maximum sliding path SW of the sliding door on the casement in the first position of the operating element, in particular, wherein EW≦0.2*SW, and in particular wherein EW≦5 cm. The mechanical stop marks a sliding door position in which the latch is unlocked. Any further unnecessary and tedious movement of the sliding door is avoided. When the casement is displaced, the sliding door is largely closed such that the sliding door does not obstruct opening of the casement. 
     In a preferred further development of this embodiment, a locking mechanism is provided on the door, which blocks movement of the sliding door out of the position of movement of the sliding door on the mechanical stop when the casement is not closed and when the operating element is located in the second position, in particular, wherein a movable locking element is provided on the casement, which is pretensioned by a spring force into a locking position, in which it blocks the movement path of the operating element or of the latch or the carrier in the second position, and is moved out of the path of movement of the operating element or the latch or the carrier in the second position when the casement is closed through interaction with a counter means that is rigidly formed on the main frame. This further development prevents operating errors of the door mechanism (in particular locking mechanism). The latch that is operated via the operating element remains in the unlocked position when the casement is opened in order to ensure smooth closing of the casement. The sliding door is typically blocked on the mechanical stop through positive fit with a locking element that is movably disposed on the casement. This positive fit may be realized in the simplest form directly with the operating element, or also with the latch or any carrier, which are respectively coupled to the operating element, thereby blocking the sliding door. 
     In a further development, a blocking mechanism is alternatively or additionally provided, which blocks a movement position of the sliding door on the mechanical stop. This also prevents operating errors of the door mechanism. 
     The blocking mechanism comprises e.g. a resilient ball in the casement, which engages in a recess on the latch to provide a resistance to movement of the sliding door, which is very easy to realize. 
     In another example, the blocking mechanism is provided by a third position of the operating element, in which a holding element of the casement blocks movement of the operating element, in particular, wherein the operating element is driven by the force of a spring from the second position into the third position and in particular, wherein the third position is formed between the first and the second position. 
     In a particularly preferred embodiment, a guidance is provided on the casement, which holds the operating element in the second position when the sliding door is moved out of its closed position, when the operating element is in the second position, and which only permits changing between the first and the second position when the sliding door is closed. This also prevents operation errors of the door mechanism (in particular locking mechanism). In particular, when the casement is open, the sliding door cannot be normally moved (i.e. as in the first position of the operating element). 
     In a preferred further development thereof, the guidance comprises a recessed rail along which the operating element (in the second position) can be guided within a notch in the operating element. The recessed rail has a widening through which the operating element can be displaced between a first and a second position when the sliding door is closed. The guidance can thereby be realized in a very simple mechanical fashion. The widening is typically provided at one end of the recessed rail. 
     In another preferred embodiment, the operating element comprises a pin that can be retracted and extended and is pretensioned by a spring force into a retracted position which corresponds to the first position of the operating element, and which can be pushed by hand into an extended position which corresponds to the second position of the operating element. This simplifies utilization of the sliding door function that is normally used more often, and inadvertent activation of the folding door function is impeded. 
     In another preferred embodiment, the latch is disposed on the casement such that it can be displaced in a direction R, wherein the direction R and the direction V extend parallel to each other. Bearing and guiding the latch on the casement facilitates control of the operating element by the latch. 
     In an alternative fashion, the latch may also be disposed on the main frame such that it can be displaced in a direction R′, wherein the direction R′ and the direction V extend parallel to each other when the casement is closed. This facilitates a particularly robust design of the latch mechanism. 
     In another preferred embodiment, a lock is provided on the main frame, which blocks and releases the position of movement of the sliding door when the casement and the sliding door are closed. Any opening of the door, i.e. of the casement or the sliding door, requires movement of the sliding door out of its closed position. For this reason, one single lock is sufficient (that secures the position of movement of the sliding door) for locking the entire door including both functions. 
     In a further preferred embodiment, the direction V, in which the sliding door can be moved with respect to the casement, extends perpendicularly to the axis S. This has turned out to be useful in practice, in particular, in that the overall motion for opening the casement is facilitated. The axis S typically extends in a vertical direction and the direction V extends in a horizontal direction. 
     In another preferred embodiment, the casement has the shape of a C, wherein the open side of the C-shaped frame faces away from the axis S. This improves accessibility to the working chamber, in particular, in case of a double-wing door configuration. 
     Finally, in another particularly preferred embodiment, two adjacent doors are provided, wherein the two doors form two opposite wings of a double door, in particular, wherein the door protection elements of the two doors overlap. The partial areas of the accesses to the working chamber, which are opened in each case by sliding door functions, can then be used together. 
     The door (i.e. the casement including sliding door) of an inventive door configuration is also preferably designed such that it can be unhinged, e.g. by means of hinges on the main frame, out of which the door can be lifted. This facilitates assembly and transport of the door configuration components. 
     Further advantages of the invention can be extracted from the description and the drawing. The features mentioned above and below may be used in accordance with the invention either individually or collectively in arbitrary combination. The embodiments shown and described are not to be understood as exhaustive enumeration but have exemplary character for describing the invention. 
     The invention is illustrated in the drawing and is explained in more detail with reference to embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         FIG. 1   a  shows a schematic perspective view of a cabinet-like housing with two inventive door configurations, with two doors with closed casement and closed sliding door; 
         FIG. 1   b  shows the cabinet-like housing of  FIG. 1   a  with closed casement and opened sliding door; 
         FIG. 1   c  shows the cabinet-like housing of  FIG. 1   a  with open casement; 
         FIG. 2  shows a schematic view of an inventive door configuration with a partial cover that is rigidly mounted to the casement; 
         FIGS. 3   a  to  3   d  show schematic views of the process of changing the operating modes of a door of an inventive door configuration; 
         FIG. 3   e  shows a schematic view similar to  FIG. 3   a  but with a latch that is disposed on the main frame; 
         FIG. 4   a  shows a schematic sectional view of a locking mechanism of a door of an inventive door configuration in a first position of the operating element; 
         FIG. 4   b  shows the locking mechanism of  FIG. 4   a  in a second position of the operating element with locked casement; 
         FIG. 4   c  shows the locking mechanism of  FIG. 4   a  in a second position of the operating element with unlocked casement; 
         FIG. 5   a  shows a schematic view of a further locking mechanism of a door of an inventive door configuration with an unlocked locking element with closed casement; 
         FIG. 5   b  shows the locking mechanism of  FIG. 5   a , in which the casement is opened and the locking element is in the locking position. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       FIGS. 1   a  through  1   c  each show a cabinet-like housing, on which two inventive door configurations  1   a ,  1   b  are formed. In this example, the cabinet-like housing is designed as a safety housing  1  for an X-ray apparatus, e.g. an X-ray diffractometer or an X-ray fluorescence analysis device or a different instrumental-analytical X-ray measuring means (not shown). The safety housing  1  surrounds a working chamber  2  inside the safety housing  1 , in which the X-ray apparatus can be disposed. The safety housing  1  has a plurality of stationary protection elements  3   a - 3   c , which are impermeable to X-ray radiation, e.g. lead-containing side walls  3   a , ceiling plates  3   b  and floor plates  3   c.    
     The working chamber  2  has a front access  4  ( FIGS. 1   a - 1   c ), which can be covered by door protection elements  5   a ,  5   b  (in the present case lead glass panes) that are impermeable to X-ray radiation. The door protection elements  5   a ,  5   b  belong to two doors  6   a ,  6   b  of the inventive door configurations  1   a ,  1   b.    
     The doors  6   a ,  6   b  have two functions. Each door  6   a ,  6   b  has a (in the present case C-shaped) casement  7   a ,  7   b  which is pivotably disposed on a stationary main frame  9  of the safety housing  1  via hinges  8  (see pivot axes S). Each casement  7   a ,  7   b , in turn, bears one sliding door  10   a ,  10   b , which can be moved on the casements  7   a ,  7   b , respectively (see direction of movement V). Each sliding door  10   a ,  10   b  has a handle  11  that has a manually operable push button  12  of an operating element for actuating the latch. The main frame  9  can be associated with the respective door configurations  1   a ,  1   b  as far as it is used to suspend the doors  6   a ,  6   b . The main frame  9  typically also completely surrounds the access  4 . 
       FIG. 1   a  shows the safety housing  1  with closed sliding doors  10   a ,  10   b  and closed casements  7   a ,  7   b , as required during X-ray measurement for shielding the X-ray radiation that is released in the working chamber  2 . In order to perform minor manipulations in the working chamber  2 , e.g. change the sample, it is sufficient to only open the two sliding doors  10   a ,  10   b , thereby opening approximately half of the width of the maximum access  4  ( FIG. 1   b ). This requires only a relatively little amount of space on the left and right-hand side of the safety housing  1  or the access  4 . 
     For lager-scale manipulation, e.g. exchange of the X-ray apparatus, in the working chamber  2 , the casements  7   a ,  7   b  can be pivoted open, wherein the (largely) closed sliding doors  10   a ,  10   b  are also pivoted and the overall maximum access  4  is opened ( FIG. 1   c ). 
     The door mechanism preferably permits movement of the sliding doors  10   a ,  10   b  only when the casements  7   a ,  7   b  are closed and vice versa, the casements  7   a ,  7   b  can only be pivoted when the sliding doors are (largely) closed. 
     In the illustrated embodiment, each door protection element  5   a ,  5   b  extends over the full width B and the full height H of the area of the access  4  that is covered by the associated door  6   a ,  6   b.    
       FIG. 2  shows a schematic front view of a different design of a door  6   a  of an inventive door configuration  1   a.    
     The door  6   a  has a rectangular casement  7   a  (shown in hatched lines, the covered inner border is shown with dashed lines), which is mounted by hinges  8  to the main frame (not shown) of the door configuration  1   a  and can be pivoted about a vertical pivot axis S. 
     In this case, a door protection element (that can also be called rigid partial cover  21 ) is rigidly mounted to the casement  7   a  with rivets  22 . Two rails  23  are also mounted to the casement  7   a , which extend over the entire width B of the door  6   a  and are used as a bearing for a sliding door  10   a . The sliding door  10   a  can be moved on the rails  23  in the direction V. The sliding door  10   a  has a door protection element  5   a  (that can also be called movable partial cover), which can be moved with the sliding door  10   a . The sliding door  10   a  can be handled via the handle  11 . 
     In  FIG. 2 , the sliding door  10   a  is closed such that the door  6   a  with the two door protection elements  21 ,  5   a , completely covers the access to the working chamber, disposed behind it (e.g. with respect to X-ray radiation, see the safety housing of  FIGS. 1   a - 1   c ), in particular, over the entire width B of the door  6   a  or the access. The rigid door protection element  21  thereby covers a left-hand partial area LTB and the door protection element  5   a  of the sliding door  10   a  covers a right-hand partial area RTB of the door  6   a  or the access. Each partial area LTB, RTB corresponds to approximately half the full width B, wherein there is a slight overlap. Both door protection elements  21 ,  5   a  extend over the full height H of the door  6   a  or the access located behind it. 
     When the sliding door  10   a  is moved to the left out of the closed position, the access to the working chamber is opened in the right-hand partial area RTB. Towards this end, the sliding door  10   a  does not require any free space on the side of the door (e.g. on the left-hand side of the door) or in front of the door  6   a , since the sliding door  10   a  can be easily moved in front of the rigid door protection element  21 . When full access via both partial areas RTB, LTB is required, the casement  7   a  can be pivoted open. 
       FIGS. 3   a - 3   d  schematically explain a door mechanism, in particular a latch mechanism, which is used in accordance with the invention in an inventive door configuration  1   a . Different operating states are thereby schematically shown in cross section. 
       FIG. 3   a  shows in a first operating mode (sliding door function) a door with a casement  7   a , which is pivotably mounted by means of hinges (pivot joints)  8  to a main frame  9  (shown in dashed lines). A sliding door  10   a  is disposed (borne) on the casement  7   a , which can be displaced in the direction V parallel to the casement  7   a . An operating element  31  in a first (extended) position does thereby not impair the movement of the sliding door  10   a . The sliding door  10   a  can be moved by a maximum path of displacement SW (in  FIG. 3   a  stated for the right-hand end of the sliding door), which corresponds in this case to approximately half the width of the casement  7   a . The path of displacement SW is limited to ensure the stability of the sliding door bearing and delimit the lateral space requirements (area of risk of collision). 
     The casement  7   a , however, is locked. A latch  32 , which is disposed on the casement  7   a  such that it can be displaced in a direction R, engages at its right end in a (schematically shown) lug  33  of the main frame  9  such that the casement  7   a  cannot be pivoted open. 
       FIG. 3   b  shows a first phase of switching over the operating modes. When the sliding door  10   a  is closed (i.e. the sliding door  10  is on the very right) the operating element  31  is inserted. The operating element  31  penetrates through the casement  7   a  in this second position and engages in a recess  32   a  of the latch  32  such that the movement of the latch  32  is coupled to the movement of the sliding door  10   a.    
       FIG. 3   c  shows the second phase of switching over the operating modes. When the operating element  31  is inserted, the sliding door  10   a  including operating element  31  is slightly moved to the left by the amount EW (unlocking path) until the latch  32  contacts the mechanical stop  34 . The carried-along latch  32  is thereby removed from the lug  33 , thereby unlocking the casement  7   a . It must be noted that the unlocking path EW thereby amounts to approximately ⅕ of the maximum sliding path SW. 
       FIG. 3   d  shows the second operating mode (folding door function) of the door. The casement  7   a  can be pivoted about the hinge  8 . The operating element  31  thereby typically remains in the second position and the sliding door  10   a  is preferably locked in the movement position on the mechanical stop  34  when the casement  7   a  is opened ( FIGS. 5   a ,  5   b  show a feasible realization thereof). 
       FIG. 3   e  shows an alternative inventive door mechanism similar to  FIG. 3   a . In this door mechanism, the latch  32  is not disposed on the casement  7   a  but on the main frame  9  such that it can be displaced in a direction R′. A rigid lug  33   a  is formed on the casement  7   a , into which the latch  32  can engage in order to lock the casement  7   a  on the main frame  9 .  FIG. 3   e  shows the locked (and closed) state of the casement  7   a . The operating element  31  is retracted (in the first position), such that the sliding door  10   a  can be moved in front of the casement in the direction V, wherein the directions V and R′ extend parallel to each other. 
       FIGS. 4   a  through  4   c  show the door locking mechanism of an inventive door configuration in greater detail, which is inserted into a safety housing similar to  FIG. 1 . 
     Each section shows one sliding door  10   a , to which a handle  11  with an inserted substantially pin-shaped operating element  31  (with push button  12 ) is mounted. The sliding door  10   a  is displaceably disposed on a casement  7   a  by means of a rail (linear guidance)  23 . The casement  7   a  abuts a main frame  9  that is stationary during all door operations. A carrier  41  is disposed in the casement  7   a , which can be displaced in a direction R. The carrier  41  is rigidly connected to a latch  32  that can engage behind a hook (only indicated by reference numeral  42 ) that is fixed to the main frame  9 . The carrier  41  has a recess  41   a  for engagement of the operating element  31 . An actuator  43  is moreover rigidly connected to the sliding door  10   a  and can engage in a lock (in the present case a safety module)  44 . 
       FIG. 4   a  initially shows the sliding door function. The operating element  31  is in a first position in which it does not engage in the recess  41   a . The operating element  31  is thereby pretensioned into this first position by a pressure spring  45 . The sliding door  10   a  can then be freely moved on the casement  7   a  in the direction V. 
     The latch  32  engages behind the hook  42 , such that the casement  7   a  is locked on the main frame  9  and, in particular, cannot be pivoted open to the front. 
     In the position of the sliding door  10   a  shown in  FIG. 4   a  (completely closed), the actuator  43  is inserted into the lock (safety module)  44 . In this position, an X-ray experiment may be started and continued in the safety housing. The lock  44  blocks opening of the sliding door, and thereby also opening of the casement function, on the actuator (on the safety bracket)  43 . 
       FIG. 4   b  illustrates the first step for switching over the operating mode. When the sliding door  10   a  is closed, the operating element  31  is pushed in against the spring force. In this second position, the front end of the operating element  31  engages into the recess  41   a  of the carrier  41 . A widening  46  in the recessed rail  47  is thereby penetrated, which is formed on the casement  7   a  (see  FIG. 4   a ). A notch  48  in the operating element  31  is then aligned with the recessed rail  47 . Accordingly, the recessed rail  47  only permits switching over of the operating element  31  from the first into the second position via the widening  46  when the sliding door  10   a  is completely closed (see  FIG. 4   a ). The completely closed sliding door position is defined by a mechanical auxiliary stop  49   a.    
     The engaging operating element  31  couples the motions of the sliding door  10   a  and the carrier  41  and thereby also of the latch  32 . When the sliding door  10   a  is moved to the left with the operating element  31  in the second pushed-in position, the latch  32  is carried along by the carrier  41  such that the casement  7   a  is unlatched. The directions R and V are parallel. 
       FIG. 4   c  shows the door mechanism with the sliding door  10   a  moved to the left and retracted latch  32 , i.e. with unlocked casement  7   a . The notch  48  in the operating element  31  engages the recessed rail  47 . The operating element  31  can be displaced along the recessed rail up to abutment with the left-hand side at the end of the recessed rail  47 , which accordingly functions as a mechanical stop  49  (“unlocked position of movement”). The mechanical stop  49  delimits the unlocking path EW of the sliding door  10   a  (it must be noted that as an alternative or additionally, the carrier  41  or the latch  32  could also be moved to a corresponding mechanical stop). Since the recessed rail  47  engages in the notch  48 , the operating element  31  cannot move back from the second pushed-in position. 
     In the unlocked position of movement of the sliding door  10   a , the actuator (the safety bracket)  43  is completely removed from the lock (safety module)  44 . For this reason, the actuator  43  no longer obstructs opening of the casement  7   a . It may be required to initially unlock the lock  44  for moving the sliding door  10   a  into the unlocked position of movement. 
     The sliding door  10   a  is fixed in the position of movement abutting the mechanical stop  49  by a blocking mechanism. In the illustrated example, the blocking mechanism has two resilient balls  50  that are formed on the casement  7   a  and engage in depressions (not shown in detail) on the latch  32 . In order to move the sliding door  10   a  (and thereby also the latch  42 ) with respect to the casement  7   a  out of the unlocked position of movement, the mechanical resistance of the resilient balls (pressure balls)  50  must be overcome. This secures handling of the handle  11  for opening and closing the casement  7   a , in particular when the casement  7   a  is open. 
     After pivoting the casement, e.g. for exchanging an X-ray apparatus in the working chamber of the safety housing, the casement  7   a  is disposed again at the main frame  9  (is closed), and the sliding door  10   a  is moved from its unlocked position of movement on the left-hand side mechanical stop  49  back to the locked (completely closed) position of movement on the right-hand side mechanical auxiliary stop  49   a . The latch  32  is thereby carried along, which finally locks again the casement  7   a  on the main frame  9 . In the completely closed position of the sliding door  10   a , the operating element  31  moves back into the first position due to the pressure spring  45 , and thereby into the sliding door mode. 
     Securing the unlocked position of movement of the sliding door in the folding door mode may alternatively or additionally not only be impeded but also be mechanically locked by a locking mechanism, which is illustrated in  FIGS. 5   a  and  5   b . These show a perspective approximately front-side view of an inventive door mechanism similar to the door mechanism shown in  FIGS. 4   a - 4   c .  FIG. 5   a  shows a closed and locked casement, while  FIG. 5   b  shows a pivoted-open unlocked casement. 
     The casement  7   a  has an approximately cylindrical locking element  51 , which is disposed in a depression  52   a  and extends through a bearing bushing (guiding bushing)  52   b . The bearing bushing  52   b  is glued into the depression  52   a  or fastened in a different mechanical fashion (e.g. screwed). The locking element  51  is pretensioned by a pressure spring (not shown in detail) at an inside  53  of the locking element  51  into a position projecting towards the main frame  9  (see  FIG. 5   b ). In this position, the locking element  51  blocks movement of the latch  32 . The left-hand side of the latch  32  contacts (in  FIG. 5   b ) the locking element  51 . This also blocks movement of the sliding door  10   a  (which is hinged to the latch  32  with the operating element and the carrier in  FIG. 5   b ) towards the left-hand side (towards the locked position). The latch  32  is then fixed in the unlocked position. The sliding door  10   a  remains held in an unlocked position of movement on a mechanical stop (not shown in  FIG. 5   b ). 
     When the casement is closed (i.e. applied to the main frame  9 , see  FIG. 5   a ), the locking element  51  is pressed into the depression  52   a  by a counter means (guiding bolt)  54  that is rigidly formed on the main frame  9 . The locking element  51  is then no longer in the path of movement of the latch  32 . There is only a narrowing  55  of the counter means  54  in the area of the path of movement of the latch  32 , which can, however, be surrounded by the latch  32  that is approximately C-shaped in its end area, such that the counter means  54  does not block the path of movement of the latch  32 . When the casement  7   a  is closed, the latch  32  can be actuated by the sliding door  10   a  and, in particular, be locked (i.e. be moved to the left in  FIG. 5   a ). In  FIG. 5   a , the latch is in the locked position, wherein the left-hand bracket-like part of the latch  32  is not shown for reasons of simplicity. The thickened, free end of the counter means  54  thereby acts as engagement hook for the latch  32  in order to fix the casement  7   a  to the main frame  9 . 
     In summary, the present invention describes a door configuration for locking an access with a door, wherein the door configuration has a double frame system which permits both a pivoting function and a sliding function of the door. This double function saves space in front of the access when only the sliding door function is used. Both functions can be operated via one single operating element via the sliding door, wherein slight movement of the sliding door in a second position of the operating element is used to operate a latch (or a latch system with several individual latches). This achieves high operational comfort and simple construction. In particular, no external tools or auxiliary means are required for switching over between the functions. When the sliding door function is activated, the folding door function is mechanically locked, and when the folding door function is activated, the sliding door is mechanically locked. The access can be secured by one single lock.

Summary:
A door configuration, which improves the operating and locking mechanism and facilitates construction and handling, comprising a door having a sliding door disposed on a casement such that it can be slidably displaced and the casement can he pivoted about an axis relative to a main frame. A lock is provided for locking and unlocking the casement with respect to the main frame, and an operating element is disposed on the sliding door, which can be moved with the sliding door and can be switched between a first position and a second position, wherein, in the first position, the operating element does not obstruct movement of the sliding door on the casement, and, in the second position, the operating element engages with the latch or a carrier, such that, when the casement is closed, the latch is operated when the sliding door is moved.