Patent Publication Number: US-2023143497-A1

Title: Device for closing the input opening in the sample chamber in an x-ray fluorescence spectrometer

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The invention relates to a closure device for gas-tight closing of the input opening in a sample chamber of an x-ray analysis apparatus, in particular an x-ray fluorescence spectrometer, by means of a slider which is displaceable laterally over the input opening on a linear guide. Such a closure device is disclosed in the document JP 6077812 B2. 
     Description of the Related Art 
     The present invention is concerned very generally with the sphere of x-ray analysis apparatuses and in particular with closure devices for gas-tightly closing input openings in the sample chambers of x-ray analysis apparatuses, such as, for example, x-ray fluorescence spectrometers. 
     In most x-ray fluorescence spectrometers, a sample is excited in a measurement chamber by x-ray radiation. The excited sample emits characteristic x-ray radiation which is analyzed by a system of various x-ray optical components or using an energy-dispersive detector, in order to determine the concentration of the elements in the sample. 
     So that the x-ray radiation is attenuated as little as possible along the beam path of the x-ray radiation, the beam path is located under vacuum or in an atmosphere which has little absorbency and is chemically inert (e.g., He or N 2 ). Since, in general, readily volatile samples (such as, for example, liquids) which cannot be measured under a negative pressure are also investigated, a positive pressure - which is generally relatively less than the outside atmosphere - is produced in the measurement chamber for flushing the measurement chamber with an inert gas. A suitable measurement chamber therefore has to have a controlled closure so that the sample can be brought into the measurement position by a more or less automatable handling system or by hand and can subsequently be kept closed radiation-tightly and, furthermore - at least during the measurement - closed both vacuum-tightly and tightly to positive pressure. 
     A closure device for gas-tightly closing the input opening by means of a slider has been disclosed, for example, in the x-ray fluorescence spectrometer “S8 TIGER Series 2” from Bruker Corporation, Billerica (Massachusetts, USA), (cf. https://www.bruker.com/de/products-and-solutions/elemental-analyzers/xrf-spectrometers/s8-tiaer.html (retrieved Oct. 22, 2021). 
     In the TIGER, a slider is pushed in a guide track over the input opening to the sample by a linear movement. The guide track is designed in such a manner that the slider is pressed in the end position onto the seal of the input opening by gravitational force. When evacuating the sample chamber, the difference in pressure generates a force leading to the sealing of the input opening. The linear movement of the slider is realized by a lever on a direct-current geared motor (DC geared motor). 
     However, a disadvantage in this case is that the slider is pressed only by its own weight onto the seal of the input opening, as a result of which the positive pressure tightness is ensured only up to a very small differential pressure in relation to the outside atmosphere. Furthermore, when flushing the sample chamber with inert gas, large quantities of inert gas may be lost, as a result of which the operating costs increase. 
     Further examples of closure devices for gas-tightly closing the input openings by means of a slider are found, for example, in the x-ray fluorescence spectrometer “S2 PUMA Series 2”, cf. https://www.bruker.com/en/products-and-solutions/elemental-analyzers/xrf-spectrometers/s2-puma-series2.html (retrieved Oct. 22, 2021), in the x-ray fluorescence spectrometer “S2 POLAR”, cf. https://www.bruker.com/en/products-and-solutions/elemental-analyzers/xrf-spectrometers/s2-polar.html (retrieved Oct. 22, 2021), and in the x-ray fluorescence spectrometer “S6 JAGUAR”, cf. https://www.bruker.com/en/products-and-solutions/elemental-analyzers/xrf-spectrometers/s6-jaguar.html (retrieved Oct. 22, 2021), all from the Bruker Corporation, Billerica (Massachusetts, USA). 
     The general configuration of the PUMA, POLAR and JAGUAR are similar to the TIGER. The linear movement of the slider is undertaken here by a rack and pinion drive, and the slider, in the closed position (end position), is pulled downward onto the seal of the input opening additionally with the aid of electromagnets. 
     A disadvantage of the solution using electromagnets is that the adjustment of the electromagnets is normally very complicated. In the event of faults or irregularities in the magnetic field that obstruct or even prevent secure closing of the input opening, it may frequently be quite difficult and time-consuming to readjust the electromagnets. 
     Further closure devices which are provided with a pivoting mechanism or a folding cover mechanism are known in the prior art. 
     The spectrometers equipped in such a way can also be provided with a sampler changer, wherein the sample chamber can be loaded with a sample by means of a movable gripping arm. The input opening is then covered by a closure cap. The closure cap is fastened to a connecting plate which can be pivoted by means of a deflecting roller. 
     Disadvantages of the closure devices from the prior art mentioned include the fact that the pivoting or folding mechanism in the respective configuration may frequently take up a large amount of space because of the intended pivotability, and it is generally relatively complex and thus causes non-negligible costs for the production and subsequent maintenance thereof. 
     A particular disadvantage is that the cover, since it has merely been placed on, is not arranged completely parallel to the sealing ring and may also slightly slip and therefore generally ensures only a low degree of tightness in relation to positive pressure. 
     JP 6077812 B2 cited at the beginning describes a - exclusively laterally - displaceable slider for gas-tightly closing the input opening in the sample chamber of a transportable sample holder. Measurement and sample preparation are carried out in different vacuum surroundings. For the sample preparation, the sample is inserted into the sample holder under reduced atmospheric pressure. The slider then closes the opening in the sample holder. This takes place by the slider being moved laterally over the sample holder. The sample holder has recesses into which the slider lying above it drops because of its own weight. By this means, the sample chamber of the sample holder is closed and a certain initial tightness produced. The sample holder is then retrieved from the surroundings with a reduced atmospheric pressure and transported to the spectrometer under the customary outside atmosphere. The force which arises from the surface and the pressure difference from the customary outside atmosphere and the artificially generated atmosphere in the sample chamber of the sample holder then acts as a sealing force on the slider. The sample holder is introduced into the measurement chamber of the spectrometer and then the measurement chamber is evacuated. The slider can then be opened by motor and, for example, an XRF measurement started. 
     It is likewise disadvantageous here that closing of the sample chamber with secure tightness to positive pressure is in turn possible only to a limited extent. However, specifically in the case of measuring liquid samples, it is virtually always necessary to keep the sample chamber under a protective gas atmosphere. Measurements of liquid samples under vacuum are often possible only with extreme difficulty, and generally not possible at all since - depending on the solvent of the liquid sample - the boiling point of the liquid sample is always reduced under vacuum and the liquid sample passes at its surface into the gas phase. 
     Furthermore, the measurements may be made difficult by the fact that the sample preparation, on the one hand, and the measurement, on the other hand, are undertaken in various surroundings which are spatially separated from one another. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to a closure device of the type described at the beginning for gas-tight closing of the input opening in a sample chamber of an x-ray fluorescence spectrometer with uncomplicated, easily creatable or available technical means, and includes configuring a slider, which is displaceable laterally over the input opening, in such a manner that the slider can easily reliably close the input opening to the sample both vacuum-tightly and also tightly to positive pressure. 
     In the present invention, the slider comprises a closure plate and a carriage which is configured in such a manner that it can be displaced over the input opening in the sample chamber on the linear guide which is arranged on a baseplate connected fixedly to the sample chamber. The closure plate is connected in an articulated manner to the carriage via deflecting elements which, upon butting against an end stop connected rigidly to the baseplate, deflect the lateral movement of the carriage into a movement perpendicular thereto in order to press the closure plate onto the input opening. The slider is displaceable laterally on the linear guide by a drive motor, which is connected to the carriage via a drive means. 
     The present invention therefore involves configuring the slider of the closure device in such a manner that a lateral movement onto the slider is deflected into a movement perpendicular to said lateral movement and, therefore, the input opening in the sample chamber (“sample chamber opening”) can be closed both vacuum-tightly and also tightly in relation to a positive pressure in the interior of the sample chamber relative to the outside atmosphere. 
     For this purpose, the slider comprises a closure plate and a carriage. The carriage can be displaced along the linear guide. The linear guide is arranged on a baseplate. The baseplate is fixedly connected to the sample chamber. The carriage (and therefore also the closure plate) can be displaced in a linear movement over the input opening in the sample chamber. The closure plate then lies over the input opening in the sample chamber (in a closed position). 
     Furthermore, the closure plate is connected movably, in particular in an articulated manner, to the carriage via deflecting elements (“connecting lever”). 
     The baseplate comprises an end stop connected rigidly thereto (“stop point”). The carriage is displaced or moved laterally into the closed position. The deflecting elements then collide with the end stop. The carriage is moved further, as a result of which the movable deflecting elements move. This movement is transmitted to the closure plate. The closure plate moves perpendicularly to the lateral movement of the carriage. The deflecting elements therefore deflect the lateral movement of the carriage into a perpendicular movement of the closure plate. The closure plate is then pushed or placed uniformly onto the input opening. Whether the pushing-on movement takes place upward or downward depends, inter alia, on the respective geometry of the x-ray analysis apparatus. 
     The force which acts here on the input opening can be adjusted by the length of extent of the displacement of the carriage and resultantly caused movement of the deflecting elements against the end stop of the baseplate. If the carriage is moved away from the end stop, the closure plate is lifted off from the input opening and the pressure against the input opening released. 
     Alternatively, instead of moving the deflecting elements against the end stop, the closure plate may also be moved against a protrusion of the baseplate. In this case, the deflecting elements likewise deflect the lateral movement of the carriage into a vertical movement of the closure plate onto the input opening. 
     The slider is displaced laterally on the linear guide via a drive motor. The drive motor is connected to the carriage of the slider via a drive means. By means of the drive motor, a uniform displacement can be undertaken and the contact pressure of the closure plate against the input opening in the sample chamber can be adjusted to a desired degree. 
     The closure device is configured in such a manner that only one drive motor is needed both for the lateral movement and for the movement perpendicular thereto, of the closure plate of the slider. The movement with which the input opening in the sample chamber is covered and opened by the closure plate, and the movement with which the closure plate is pressed onto the input opening in the sample chamber and lifted off from the input opening in the sample chamber, are therefore carried out only by a single active element, namely the drive motor. The size of the design, in particular the overall height, can thereby be kept small. In addition, further drive motors are unnecessary and the costs thereby reduced. 
     In a preferred class of embodiments of the closure device according to the invention, it is provided that at least some of the deflecting elements are configured as rotary levers, in particular as a (preferably curved) rigid lever which is mounted on the carriage so as to be rotatable about a rigid shaft. 
     By means of the rotary levers, the lateral movement of the carriage can be deflected particularly readily into a vertical movement with respect thereto. In addition, the rotary lever can transmit the force acting thereon in a particularly precise and defined manner to the closure plate by means of the lateral movement of the carriage. 
     In advantageous developments of this class of embodiments, it is furthermore provided that the rotary lever has a portion with an elongated hole in which a pin connected rigidly to the closure plate engages. The elongated hole is used as a guide element for the pin. By means of the elongated hole and the pin engaging in the elongated hole, the rotary lever and the closure plate can be displaced and correspondingly adjusted in relation to one another and tolerances can be compensated for. 
     Alternatively or additionally, in other developments, the closure plate can be shaped rectangularly, and the deflecting elements can comprise at least three rotary levers. 
     A rectangularly shaped closure plate is advantageous to produce and can be moved particularly simply in a linear movement. In addition, such a rectangularly shaped closure plate can press particularly uniformly onto the input opening in the sample chamber. 
     The at least three rotary levers make it possible for the vertical movement, with which the closure plate is pressed onto the input opening, to run parallel and a contact pressure of the closure plate to be distributed uniformly to the input opening. It is noted that the at least three rotary levers are attached to the closure plate and the carriage in such a manner that the contact pressure of the closure plate onto the input opening is as uniform as possible around the circumference thereof. Three rotary levers are therefore advantageous in particular in the case of circular closure plates; in the case of rectangularly shaped closure plates, four rotary levers which are each arranged at the corners of the closure plate are more advantageous for a uniform contact pressure. 
     Embodiments of the closure device according to the invention in which the linear guide comprises a guide rail which is arranged in particular in or on the baseplate are likewise preferred. The guide rail makes it possible to achieve a particularly precise, uniform and reliable movement of the carriage. 
     Embodiments in which there is a vertical guide device for guiding the movement of the closure plate in a direction perpendicular to its lateral movement, are also advantageous. In this way, the perpendicular movement of the closure plate can be reliably guided and a possible slipping during the perpendicular movement prevented. Furthermore, by means of the vertical guide device, the closure plate can be lowered very precisely onto the input opening and lifted from the input opening. 
     In further preferred embodiments, spring elements are arranged between the closure plate and the carriage, said spring elements being used to hold the closure plate and the carriage apart at a determined distance. By this means, the closure plate is already reliably prevented from colliding or coming into contact with the input opening or further components which are attached to the baseplate in the lateral movement of the carriage. 
     Furthermore, embodiments of the invention which are distinguished in that stop bolts, with which the closure plate butts against a stop on or in the baseplate, or vice versa, are attached to the closure plate, are preferred. The stop bolts can easily be attached to the closure plate. During a lateral movement of the closure plate, the stop bolts can butt particularly precisely against the stop. After butting against it, the lateral movement is then deflected via the deflecting elements into a movement of the closure plate perpendicular thereto. 
     Embodiments of the closure device according to the invention, in which the drive motor is in the form of an electric motor, preferably a stepping motor, are likewise advantageous. This can be realized particularly simply in practice. The slider with the closure plate can be moved precisely, in particular spatially very precisely in terms of target, in this way. 
     A class of embodiments of the closure device according to the invention that are distinguished in that the drive means via which the drive motor is connected to the carriage comprises a toothed belt drive and/or a drive chain and/or a push rod and/or a threaded spindle and/or a hydraulic slider and/or a pneumatic cylinder, is particularly preferred. In advantageous developments of this class of embodiments, the toothed belt drive and/or the drive chain run via a drive deflection roller and via a belt pulley. The drive deflection roller makes it possible to transmit the driving movement of the drive motor to the toothed belt drive or to the drive chain, and the drive motor. By this means, the drive motor can be flexibly positioned and the space required by the closure device is reduced. The toothed belt drive or the drive chain is tensioned via the belt pulley and the drive deflection roller. 
     Furthermore, variants of these developments, in which the drive deflection roller and/or the belt pulley are mounted resiliently, and preferably tensioned with a predefined force, in the direction of the carriage in relation to the baseplate, in particular in relation to the guide, via a spring tensioning element, are beneficial. 
     By means of the spring tensioning, the toothed drive belt and/or the drive chain can be tensioned with a predefined force. The pre-tensioning of the springs remains the same even if the toothed belt drive and/or the drive chain are distorted. Furthermore, by this means, the wear due to extending the toothed belt drive and/or the drive chain can be compensated for relatively simply. 
     Embodiments of the closure device according to the invention, in which the closure plate and/or the sample chamber have sealing elements in the region around the input opening, said sealing elements being configured in particular as sealing rings and optionally as grooves suitable for them or sealing surfaces, as counterparts, are likewise preferred. By this means, the sample chamber can be closed particularly effectively both in a manner tight to positive pressure and also vacuum-tightly. 
     An x-ray analysis apparatus, in particular an x-ray fluorescence spectrometer, containing a closure device according to the invention of the above-described type for gas-tight closing of the input opening in a sample chamber, also falls within the scope of the present invention. 
     This enables measurements to be carried out with the x-ray analysis apparatus, in which the sample chamber is intended to be kept both under vacuum (for example in the case of solid samples) and under pressure (for example for measuring liquids). The design of the closure device according to the invention has a particularly low overall height and is consequently usable in a particularly space-saving manner. By this means, in turn, the entire amount of space required by the x-ray analysis apparatus equipped with the invention can be reduced. 
     A method for operating a closure device according to the invention, as described above, or an x-ray analysis apparatus, as likewise described above, which method is distinguished in that the movements of the closure plate are carried out in a determined, specified, non-changeable sequence, likewise falls within the scope of the present invention. 
     During a forward movement, the carriage moves laterally together with the closure plate until the closure plate lies over the input opening and the deflecting elements butt against the stop, which is connected to the baseplate. The deflecting elements transfer the lateral movement, which acts on the carriage, into the movement which is perpendicular with respect thereto and which acts on the closure plate. During a return movement, the previously described steps proceed in the reverse sequence. The forward and return movement, and the lateral movement and the movement perpendicular thereto, can be realized by just one single drive motor. 
     Further advantages of the invention will become apparent from the description and the drawings. The features mentioned above and those presented below can likewise be used in each case according to the invention individually or together in any desired combinations. The embodiments shown and described should not be understood as an exclusive enumeration; on the contrary, they are of an exemplary character intended to describe the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention is illustrated in detail in the drawings and will be explained in more detail with reference to exemplary embodiments. 
         FIG.  1   a    shows a vertical sectional view of an exemplary first embodiment of the closure device according to the invention from the side; 
         FIG.  1   b    shows a plan view from above of the exemplary first embodiment of the closure device according to the invention from  FIG.  1   a   ; 
         FIG.  2   a    shows a schematic side view of the slider and the baseplate of an exemplary further embodiment of the closure device according to the invention with a deflecting element which is designed as a rotary lever, with the respective direction of movement of the interacting components being shown by arrows; 
         FIG.  2   b    shows a schematic side view of the slider and the baseplate of an exemplary further embodiment of the closure device according to the invention with a deflecting element which is in the form of a toothed wheel with an eccentrically arranged axis, with the respective direction of movement of the interacting components being shown by arrows, and 
         FIG.  3    shows a schematic measurement set-up for carrying out x-ray fluorescence measurements with an x-ray analysis apparatus using the closure device according to the invention. 
     
    
    
     DETAILED DESCRIPTION 
       FIG.  1   a    and  FIG.  1   b    show an exemplary first embodiment of a closure device  10  according to the invention in different views. The closure device  10  comprises an input opening  11 , a slider  14  with a closure plate  14   a  for closing the input opening  11 , a baseplate  15  with here two end stops  15   a  and a drive motor  16 . It is noted that part of the closure plate  14   a  is not shown in  FIG.  1   b    so as to therefore permit a better view of the components located under the closure plate  14   a . 
     In the embodiment shown here, the input opening  11  is formed radially with a diameter of 90 mm. The input opening  11  is recessed here into the baseplate  15 . In the figures shown here, the input opening  11  is arranged centrally in a first region  22   a  of the baseplate  15 . 
     Arranged in the region around the input opening  11  are sealing elements  20  which are configured here as a sealing ring  20   a  with a groove  20   b  in which the sealing ring  20   a  can be embedded. The groove  20   b  serves as a counter part to the sealing ring  20   a , and the input opening  11  can be reliably closed pressure-tightly and vacuum-tightly with the aid of the sealing ring  20   a  and the groove  20   b . 
     In a further embodiment, not illustrated specifically here, it is also possible for the sealing elements  20  to be attached to the closure plate  14   a . The sealing elements  20  are attached in that region of the closure plate  14   a  which comes to rest directly above the input opening  11  during closing of the input opening  11 . The closure plate  14   a  can then close the input opening  11  pressure-tightly and vacuum-tightly. 
     In the embodiment shown here, the slider  14  comprises, in addition to the closure plate  14   a , a carriage  14   b , four deflecting elements  14   c  and two stop bolts  14   d . The closure plate  14   a  is configured here as a flat, irregularly shaped plate with a thickness of 9 mm and is located here in the first region  22   a  of the baseplate  15 . The closure plate  14   a  is connected to the carriage  14   b  via the four deflecting elements  14   c . In this case, two deflecting elements  14   c  are arranged on a front side  24   a  and two deflecting elements on a rear side  24   b  of the closure device  10 . The stop bolts  14   d  are attached to the closure plate  14   a  and, in  FIG.  1   b   , butt against the two end stops  15   a  of the baseplate  15 . 
     Furthermore, in the embodiment shown here, four spring spacer elements  21  are arranged between the closure plate  14   a  and the carriage  14   b  in order to space the closure plate  14   a  and the carriage  14   b  from each other. The spring spacer elements  21  are distributed uniformly near the edges of the closure plate  14   a  so that the spring force of the spring spacer elements  21  can be distributed uniformly over the closure plate  14   a  and the distance between the closure plate  14   a  and the carriage  14   b  is particularly consistent. A distance of here 2 mm is set out between the closure plate  14   a  and the carriage  14   b  by the spring spacer elements  21 . By this means, the closure plate  14   a  can be sufficiently spaced apart from further components of the closure device  10 , and a collision-free movement of the closure plate  14   a  by means of the carriage  14   b  achieved. 
     In the embodiment shown here, the baseplate  15  is rectangular. The baseplate  15  can be divided into the first region  22   a  and into a second region  22   b . Here two linear guides  13  are arranged on the baseplate  15 . The carriage  14   b  is configured in such a manner that it can be moved along the linear guides  13 . In the embodiment shown here, the linear guides  13  each comprise a guide rail (concealed in the illustration of  FIGS.  1   a  and  1   b   ) by means of which the carriage  14   b  can be precisely moved. 
     In the embodiment shown here, the drive motor  16  is in the form of an electric motor  16   a , more precisely a stepping motor  16   a ′. The drive motor  16  is arranged here at a second end  23   b  of the baseplate  15 . The force of the drive motor  16  is transmitted to the carriage  14   b  via here two drive means  17 . The drive means  17  here comprise toothed belt drives  17 ′. Alternatively, the use of other drive means  17 , such as, for example, drive chains and/or push rods, is also possible. 
     In the embodiment shown, the toothed belt drives  17 ′ run over a drive deflection roller  17   a  and a belt pulley  17   b . The drive deflection roller  17   a  is located in the immediate vicinity of the drive motor  16  at the second end  23   b  of the baseplate  15 . The drive motor  16  can transmit a driving force which is generated to the drive deflection roller  17   a . The belt pulley  17   b  is arranged opposite the drive deflection roller  17   a  at a first end  23   a  of the baseplate  15 . The belt pulley  17   b  is mounted resiliently here on the baseplate  15  in the direction of the slider  14   b  in relation to the guide  13  via two spring tensioning elements  19 . By means of the spring tensioning elements  19 , the toothed belt drive  17 ′ is automatically tensioned with a defined force. The pre-tensioning of the spring tensioning elements  19  remains the same even if the toothed belt drive  17 ′ is distorted. In addition, the wear due to extension of the toothed belt drive  17 ′ can be compensated for fairly easily. 
     In the embodiment shown here, the closure device  10  has an overall height H ges  of 33 mm, an overall length L ges  of 410 mm and an overall width B ges  of 303 mm. The length and width are essentially determined by the size of the sample chamber. The baseplate serves at the same time as a cover for the sample chamber. The advantage resides here primarily in the low overall height. The closure device  10  thus takes up little space and is therefore particularly space-saving. 
     Function of the Closure Device 
     In the following paragraphs, the function of the closure device  10  will be explained by way of example. 
     At the beginning, the slider  14  is in an open position. In said open position, the carriage  14   b  is arranged together with the closure plate  14   a  partially in the first region  22   a , is arranged completely in the second region  22   b  and is moved to the second end  23   b  of the baseplate  15  (not illustrated specifically). 
     The drive motor  16  is started and transmits its driving force to the drive deflection roller  17   a . The drive deflection roller  17   a  moves the drive means  17  running over it. The drive means  17  are connected to the carriage  14   b . The carriage  14   b  together with the closure plate  14   a  is moved laterally along the linear guide  13  via the drive means  17 . The lateral movement takes place here until the carriage  14   b  has arrived at the first end  23   a  of the baseplate  15  and the stop bolts  14   d , which are connected to the closure plate  14   a , strike against the stops  15   a . The closure plate  14   a  is then located directly above the input opening  11  in the first region  22   a  of the baseplate  15  in a closure position. 
     In order to press the closure plate  14   a  onto the input opening  11 , the carriage  14   b  is moved further up to the first end  23   a  of the baseplate  15 . Since the closure plate  14   a  can no longer be moved further laterally in the direction of the first end  23   a , the movement of the carriage  14   b  is deflected via the four deflecting elements  14   c  into a movement perpendicular to the lateral movement. By this means, the closure plate  14   a  is moved toward the input opening  11  and the input opening  11  can therefore be closed gas-tightly. 
     In order to be able to close the input opening  11  gas-tightly, a closure force F cl , which is exerted on the input opening  11  by the slider  14 , has to be greater than the sum of the spring forces F sp  of the four spring spacer elements  21  and the force F gp , which is exerted on the input opening  11  by the gas pressure in the interior of the sample chamber, that is to say F cl  &gt; F sp  + F gp . A resistance force F Res , which presses onto the input opening  11 , can then be determined by F res  = F cl  - F sp  - F gp . 
     In order to lift the closure plate  14   a  off again from the input opening  11 , the drive motor  16  is adjusted in such a manner that the drive means  17  are now moved in the opposite direction. The carriage  14   b  is therefore moved onto the second end  23   b  of the baseplate  15 . The closure plate  14   a  is lifted off from the input opening  11  only perpendicularly to the movement of the carriage  14   b . The closure plate  14   a  is then moved back from the closure position into the open position via the carriage  14   b . The input opening  11  is then free. 
     Further Embodiments According to the Invention 
       FIG.  2   a    shows a schematic side view of the slider  14  and the baseplate  15  with the stop  15   a  of an exemplary further embodiment of a closure device  10  according to the invention. For the sake of clarity, the drive motor  16  is not illustrated specifically in this figure. However, it is pointed out that the slider  14  which is illustrated here is likewise moved by a drive motor  16 . 
     In the embodiment shown here, the slider  14  comprises the rectangularly shaped closure plate  14   a , the carriage  14   b  and the deflecting element  14   c . The deflecting element  14   c  is configured here as a rotary lever  25 , more precisely as a rotatably mounted curved, rigid lever  25 ′. A long arm  27   a  of the rotary lever  25  points in the direction of the baseplate  15  and a short arm  27   b  of the rotary lever  25  points in the direction of the closure plate  14   a . The rotary lever  25  is mounted rotatably on the carriage  14   b  via a rigid shaft  14   b ′, which is embedded in the carriage  14   b , in a connecting region  27  in which the long arm  27   a  and the short arm  27   b  of the rotary lever  25  meet. 
     At the end of the short arm  27   b  of the rotary lever  25 , the short arm  27   b  has an elongated hole  14   c ′. A pin  14   a ′ which is rigidly connected to the closure plate  14   a  engages in said elongated hole  14   c ′. The closure plate  14   a  and the rotary lever  25  are thereby connected to each other. Furthermore, the embodiment shown here shows two vertical guide devices  18  which each partially protrude into here two cylindrical guide recesses  18   a  recessed in the closure plate  14   a . 
     The functioning of the embodiment shown here will be briefly described once again below. 
     The carriage  14   b  is moved in a lateral movement (see movement arrow I) in the direction of the stop  15   a  which, in the embodiment shown here, is configured in the form of a stop protrusion  15   a ′. As soon as the rotary lever  25  butts against the stop  15   a , the further lateral movement of the carriage  14   b  is deflected via the rotary lever  25  into a movement perpendicular to the lateral movement (see movement arrow II). By this means, the deflected perpendicular movement is transmitted to the closure plate  14   a  and the closure plate  14   a  is pulled downward (see movement arrow III) and pressed onto the input opening (not illustrated specifically). 
     So that the closure plate  14   a  does not slip during the perpendicular movement, it is guided by its guide recesses  18   a  along the vertical guide devices  18 . In order to reverse the movement, the carriage  14   b  is moved laterally in the opposite direction of the stop  15   a . 
       FIG.  2   b    shows a schematic side view of the slider  14  and the baseplate  15  with the stop  15   a  of an exemplary further embodiment of a closure device according to the invention. For the sake of simplicity, the drive motor  16  is not illustrated specifically in this figure either. However, it is pointed out that the slider  14  which is illustrated here is likewise moved by a drive motor  16 . 
     In the embodiment shown here, the slider  14  comprises the rectangularly shaped closure plate  14   a , the carriage  14   b  and the deflecting element  14   c . The deflecting element  14   c  is configured here as a toothed wheel  26  with six toothed wheel teeth  28 . Instead, a completely toothed wheel may also be used here. The permissible overall height is the criterion which defines the structural form. A rack  29  which is connected here to the carriage  14   b  so as to be movable in the direction i and in spring-mounted fashion is guided over the baseplate  15 . At said rack  29 , the motor force is initiated and the entire slider  14  moved. The guide device  18  is fixedly connected to the carriage  14   b . Seven rack teeth  30  are recessed in the rack  29 . A completely toothed rack can also be used here. In the figure, this is intended to be a schematic indication of the teeth. The toothed wheel  26  and the rack  29  intermesh via the teeth  28 ,  30  thereof. The toothed wheel  26  is mounted rotatably on the carriage  14   b  via the rigid shaft  14   b ′ which is embedded in the carriage  14   b . The closure plate  14   a  is connected to the toothed wheel  26  via the pin  14   a ′, which is rigidly connected to the closure plate  14   a . The pin  14   a ′ is arranged eccentrically here with respect to the toothed wheel axis. Furthermore, the embodiment which is shown here shows the two vertical guide devices  18 . 
     The functioning of the embodiment shown here will be briefly described once again below. 
     The carriage  14   b  with the rack  29  is moved in a lateral movement (see movement arrow i) in the direction of the stop  15   a  which, in the embodiment shown here, is in the form of a stop element  15   a ″ which is fastened to the baseplate  15 . As soon as the closure plate  14   a  butts against the stop  15   a , the further lateral movement of the carriage  14   b  is deflected via the toothed wheel  26 , which is moved via the rack teeth  30  of the rack  29 , into a movement perpendicular to the lateral movement (see movement arrow ii). By this means, the deflected, perpendicular movement is transmitted to the closure plate  14   a  and the closure plate  14   a  is pulled downward (see movement arrow iii). 
     So that the closure plate  14   a  does not slip, the closure plate  14   a  is guided along the vertical guide devices  18 . In order to reverse the movement, the carriage  14   b  is moved laterally in the opposite direction of the stop  15   a . 
     Schematic Measurement Set-Up 
       FIG.  3    shows a schematic measurement set-up  100  in which the closure device  10  according to the invention is used. 
     The measurement set-up  100  comprises an x-ray analysis apparatus  101  which is embodied here as x-ray fluorescence spectrometer  101   a . The x-ray fluorescence spectrometer  101   a  comprises a sample chamber  12  with a measurement sample  102  (for example a liquid measurement sample) inserted into the sample chamber  12 , the closure device  10 , an x-ray source  103 , a detector  104  and a detector chamber  104   a  in which the detector  104  is arranged. 
     In the illustration shown here, the closure device  10  closes the sample chamber  12  gas-tightly (as described with reference to  FIGS.  1   a  and  1   b   ; also see the movement arrow  107  in  FIG.  3   ). A protective gas, generally argon, is introduced into the sample chamber  12 , and a slight positive pressure prevails in the sample chamber  12 . The positive pressure presses against the input opening (not illustrated specifically here, but see  FIG.  1   b   ) in the sample chamber  12 . The closure plate (not illustrated specifically, but see  FIG.  2   a   , for example) is pressed onto the input opening in the sample chamber  12 . The measurement sample  102  is then excited with highly energetic radiation  105  via the x-ray source  103  and the x-ray radiation  106  emitted by the measurement sample  102  is captured at the detector and evaluated. 
     After the measurement, the closure device  10  can be opened in a simple manner and the measurement sample  102  retrieved from the sample chamber  12  via the input opening. A further measurement sample  102  can then be inserted into the sample chamber  12  and the input opening closed tightly to positive pressure (or optionally also vacuum-tightly) by the closure device  10  for the next measurement.