Abstract:
A balance with a draft shield enclosing a weighing pan ( 33 ) has slidable walls ( 6, 7, 8 ) with slide handles ( 10, 110, 210 ) to open and close the weighing compartment ( 2 ). A connector body ( 22 ) serves to couple non-adjoining slidable walls ( 6, 7, 8 ) to each other. Besides for pushing the slidable walls open and closed, the slide handles ( 10, 110, 210 ) also serve to couple and uncouple the slidable walls, so that more than one wall can be moved simultaneously using only one hand, or a wall can be moved by pushing a handle on the opposite side. The slide handles are configured as pairs of handle elements that are attached either to adjoining walls or to a wall and an adjoining place on the connector body. In the coupled state, the pairs of handle elements are folded or swiveled into each other, working as a single handle, e.g., for two adjoining walls. In the uncoupled state, they move the walls individually.

Description:
BACKGROUND OF THE INVENTION 
   The invention relates to a balance, in particular a precision balance or an analytical balance with a weighing pan enclosed in a weighing compartment, wherein the weighing compartment is delimited by a draft shield in which at least two walls are slidable to open and close the weighing compartment, and wherein the slidable walls are coupled to each other to allow a simultaneous opening and closing of both walls. 
   Balances of this type belong to the familiar state of the art and are used primarily in laboratories, e.g., for dispensing substances by weight when performing chemical analyses. 
   The European patent application EP 0 234 008 A2 discloses a balance of this type, wherein the draft shield has a fixed glass window at the front, rearwards-slidable doors at the sides, and a rearwards-slidable cover panel on top. The two lateral sliding doors can be connected to each other by way of a plate that is slidably arranged underneath the balance. Latches that are preferably configured as bolts engaging a recess by sliding back and forth are integrated in the door handles and allow the sliding doors and the cover panel to be coupled to each other as needed. By means of the plate connecting the door handles that are fastened at the bottom of each of the two sliding doors, it is possible to move both doors simultaneously as well as move either one of the doors by pushing the handle on the opposite side. 
   The concept of moving sliding windows together as well as opening and closing a lateral sliding window through actuation from the opposite side is also shown for the balance disclosed in EP 0 547 298 A1, where each of the two lateral sliding windows preferably consists of two panels set at an obtuse angle to each other, which requires that the windows slide in curved guide tracks. The mechanism which is arranged at the underside of the balance for moving the two lateral sliding windows therefore has two flat actuation levers protruding on both sides of the housing, which are pivoted on the floor of the housing so that they can be swiveled back and forth, and which are connected by a flat coupling element in the form of a slidable plate that is likewise arranged on the floor of the housing. The lateral sliding windows are in this case coupled to the slidable plate either through a vertically movable bolt or through a small latch arranged in the lower part of the two-part handle and engaging a recess in the upper part of the handle. 
   In both types of balances of the foregoing description, the connecting- or coupling element, in particular the bolt or latch, is substantially hidden inside the handle. A person standing several meters away from the balance, e.g., when entering the laboratory, will therefore not be able to tell which of the different operating positions the balance is currently set for with regard to the coupling of the sliding windows to each other and/or to the sliding mechanism or the connecting plate. 
   OBJECT OF THE INVENTION 
   It is therefore the object of the present invention to propose a balance whose operating position in respect to the opening and closing function of the sliding windows is conspicuously evident even when looking at the balance only casually and/or from a larger distance. 
   SUMMARY OF THE INVENTION 
   In accordance with the invention, a balance, in particular a precision balance or an analytical balance, has a weighing pan enclosed in a weighing compartment. The weighing compartment is delimited by a draft shield in which at least two walls are slidable to open and close the weighing compartment. A slidable connector body serves to couple slidable walls that are not adjoining each other. The balance is equipped with slide handles that are configured for coupling and uncoupling either the connection of the slidable walls to each other, or the connection of one of the slidable walls to the connector body. A slide handle of the foregoing configuration is constituted by two handle elements that complement each other as a pair and are connected either to adjoining slidable walls, or to the connector body and a movable wall adjoining the connector body, where each of the handle elements by itself is configured as a handle to slide the individual wall or the connector body that the handle element is attached to. In each pair of handle elements, a first handle element is configured with a recess, and a second element is configured to engage the recess through a swiveling movement of the first and/or the second handle element in order to couple the pair of handle elements together. A pair of elements in their coupled condition has substantially the same outward contour and size as the first handle element with the recess. 
   This arrangement, where the function of a handle for manually moving a wall is combined with the function of coupling slidable walls to each other, has the particular advantage that the coupled state and the uncoupled state are conspicuously different so that a user of the inventive balance will be able to recognize immediately which handle or handle element to use, e.g., to open the balance for placing a weighing sample on the weighing pan. A balance with handle elements that can be combined into a slide handle, where each element by itself can also be used as a handle to slide one of the walls, is also particularly advantageous from an ergonomics-oriented perspective. 
   In a preferred embodiment, the second handle element as well as the recess where the second handle element is received in the first handle element are configured to produce a self-centering effect when the second handle element is folded into the first handle element. It is therefore not necessary to exactly align the two handle elements vertically above one another in order to swivel them together into a single combined slide handle. This facilitates the work flow. 
   A slide handle as well as the handle elements that fit together as a slide handle are configured substantially resembling oblong discs, particularly wing-shaped discs, wherein at least one of the handle elements can be swiveled about an axis that traverses the handle element at an off-center point of the handling element. In a further developed version of the invention, the outward-facing surfaces of the handle elements have ergonomically shaped shallow concavities to give the user a secure grip on the handle elements. 
   A swiveling handle element is preferably designed so that it snaps into two stable detent positions, one of which represents the coupled state where the pair of handle elements are combined into the slide handle. The swiveling handle element is firmly retained in the currently selected position by means of a spring. 
   In a particularly advantageous embodiment, the balance has guide elements for sliding the walls, where a handle element associated with the wall is arranged at one of the guide elements. In particular the swiveling handle element is attached through its swivel axle (rotatable about the latter) to a slidable wall, more particularly to a guide device that is connected to the slidable wall, and/or the swiveling handle element is attached through its swivel axle to the connector body. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention is set forth below through an exemplary embodiment of a balance according to the invention as well as different embodiments of an inventive slide handle, as shown in schematically idealized and/or simplified drawings, wherein 
       FIG. 1  represents a balance in a three-dimensional view without display- and operator-input unit, 
       FIG. 2  represents a sectional view of the under-floor compartment of the balance as seen in a sectional plane parallel to the front wall panel, 
       FIGS. 3   a-d  represent a first embodiment of a slide handle as seen from different viewing directions, 
       FIGS. 4   a-d  represent a second embodiment of a slide handle as seen from different viewing directions, 
       FIGS. 5   a-d  represent a third embodiment of a slide handle as seen from different viewing directions, 
   

   DESCRIPTION OF PREFERRED EMBODIMENTS 
     FIG. 1  illustrates a balance of the type that is used for example in laboratories as an analytical balance. The balance has a balance housing  1  that is occupied primarily by the weighing mechanism and the weighing electronics, and it further has a weighing compartment  2  surrounding a weighing pan that is not visible in this drawing (shown in FIG.  2 ). The rear wall  3  and the floor  4  of the weighing compartment  2  constitute the spatially fixed part of the balance. The weighing compartment  2  is further delimited by a front wall  5 , two side walls  6 ,  7 , and a top cover panel  8 . The two side walls  6 ,  7  and the top cover panel  8  (also collectively referred to as sliding walls  6 ,  7 ,  8 ) can be slid to the rear along the balance housing to open up and close off the weighing compartment  2 . The balance stands on three feet  13 , only one of which is visible in the drawing. 
   A grip handle  9  is arranged on top of the balance housing  1 . In addition to its function as a carrying handle, the grip handle  9  also serves as a guide track for opening and closing the top cover panel  8 . The two side walls  6 ,  7  are fastened to a guide device (not shown in  FIG. 1 ) and can be moved by means of a slide handle  10 , for example rearwards along the balance housing  1  to open the weighing compartment  2 . The slide handle  10  is composed of two handle elements  11 ,  12 . One of the two handle elements, the handle element  11 , is rigidly connected to its respective side wall  6 ,  7  and/or to the guide device, while a second handle element is arranged so that it can swivel in a plane that extends substantially perpendicular to the side walls  6 ,  7 . Either of the handle elements  11 ,  12  by itself can also be used as a handle to move a side wall  6 ,  7 , as shown in  FIG. 1 , where the side wall  7  is moved to the rear with the handle element  11 . If the side wall  7  is positioned so that the rigidly connected handle element  11  is positioned vertically above the swiveling handle element  12 , a swivel movement of the handle element  12  will bring the handle element  11  into engagement with the recess  14  of the handle element  12 , so that the two handle elements are combined into a slide handle  10 . The two handle elements  11 ,  12  are shaped so that the engagement is self-centering, as will subsequently be explained in detail in the context of FIG.  3 . 
   In short, the two handle elements  11 ,  12  form a pair that can be combined through a swivel movement into one slide handle  10 . The dimensions and outside contour shape of the slide handle  10  substantially correspond to the size and shape of the swiveling handle element  12 . 
     FIG. 2  represents the lower portion of a balance that is set up in a working condition, as seen in a sectional view in a plane parallel to the front wall. The weighing compartment  2  surrounds a weighing pan  33 , which preferably is connected to the weighing mechanism inside the balance housing  1  by a coupling arrangement at the rear wall  3  of the weighing compartment  2 . A floor compartment  15  below the floor  4  of the weighing compartment  2  contains, e.g., a calibration device (not shown in FIG.  2 ). Each of the two side walls  6 ,  7  is attached to a guide device  17  by means of a holder element  16 , preferably through a releasable connection. The guide device on each side has a guide rail  18  connected rigidly to the floor compartment  15  and extending preferably over the entire length (perpendicular to the sectional plane of the drawing) of the floor compartment. On each side of the balance, a carriage  21  has guide grooves  19 ,  20  embracing the top and bottom of the guide rail  18 . When a side wall  6 ,  7  is moved, the associated carriage  21  glides along its guide rail  18 . The outer end of each carriage  21  extends laterally beyond the weighing compartment  2  into a rigidly connected handle element  11  which can be grasped to manually move the side wall  7 , as shown in  FIG. 1 , for opening and closing the weighing compartment  2 . Thus, the carriage  21  and side wall  7 , which are connected by the holder element  16 , can be considered as a slidable wall unit. Of course, it is also possible to attach the rigid handle element  11  directly to the side wall  7  or to the holder element  16 . 
   Arranged below the floor compartment  15  is a connector body  22  consisting of a plate  23  that extends below the housing floor  24  over the entire width of the floor compartment  15 . The connector body  22  is movable along the floor compartment in a direction perpendicular to the sectional plane of the drawing by means of four rollers  25  (only two rollers being visible in the drawing) each of which is guided on a projection  26  that is fastened to the housing floor  24 . 
   Connected to both sides of the plate  23  are holder devices  27  to which the swiveling handle elements  12  are fastened, protruding laterally from the weighing compartment  2 . Each of the swiveling handle elements  12  is arranged in such a manner that it can embrace the rigid handle element  11  if the two handle elements  11  and  12  are positioned vertically above one another (as they are on the right-hand side of FIG.  2 ), so that the rigid handle element  11  is received in a recess  14  of the swiveling handle element  12 , whereby the two handle elements are combined into a slide handle  10  (as shown on the left-hand side of FIG.  2 ). 
   If a rigid handle-element  11  and a swiveling handle element  12  are combined into a slide handle  10  (as shown on the left-hand side of FIG.  2 ), the guide device  17  of the corresponding side wall  6  is thereby coupled to the connector body  22 , so that the left side wall  6  can be moved together with the connector body  22 . According to the positions of the handle elements shown in the drawing, the left side wall  6  and connector body  22  can be moved either by means of the slide handle  10  on the left-hand side or by means of the handle element  12  on the right-hand side. This arrangement allows an operator of the balance to use one hand to move the wall on the opposite side of the balance in order to open and close the weighing compartment  2 . To move both side walls  6 ,  7  simultaneously by pushing only one handle, the rigid handle element  11  and the swiveling handle element  12  on both sides are coupled together to form slide handles  10 . 
   The swiveling handle element  12  is configured to snap into two stable positions, one of which represents the coupled condition of the pair of handle elements as a slide handle  10 . The handle element  12  is firmly held in either of the stable positions by means of a spring  29 . 
     FIGS. 3  to  5  illustrate different embodiments of slide handles  10 ,  110 ,  210 , each seen from different directions.  FIGS. 3   a ,  4   a  and  5   a  each show an embodiment of a slide handle  10 ,  110 ,  210  in a three-dimensional view.  FIGS. 3   b ,  4   b  and  5   b  show the respective handles in a side view, i.e., viewed in the same direction as in FIG.  2 . The  FIGS. 3   c ,  4   c  and  5   c  represent a view in the direction of the arrow A that is indicated in the  FIGS. 3   b ,  4   b  and  5   b .  FIGS. 3   d ,  4   d  and  5   d  offer a view in the direction of the arrow B that is indicated in the  FIGS. 3   b ,  4   b  and  5   b . In all of the illustrated embodiments, the rigid handle element  11 ,  111 ,  211 , is snapped into the recessed space  14 ,  114 ,  214  of the respective swiveling handle element  12 ,  112 ,  212 , so that the carriage  21  of the guide device  17  of a side wall is coupled to the holder device  27  of the connector body  22 . The fastening lugs  30  attached to the carriage  21  serve for the connection of the holder elements  16  for the side walls  6 ,  7 . 
   All of the illustrated embodiments of a slide handle  10 ,  110 ,  210  have in common that the slide handle has the shape of an oblong disc, i.e., resembles a wing, and that at least one of the handle elements  12 ,  112 ,  212  can be swiveled about a swivel axle  28 . The swivel axle  28 , which connects a handle element  12 ,  112 ,  212  to the holder device  27 , traverses the substantially disc-shaped swiveling handle element  12 ,  112 ,  212  in a direction substantially perpendicular to the outer surfaces of the handle element  12 ,  112 ,  212  at an off-center point of the handle element. As can be seen in  FIGS. 3   d ,  4   d  and  5   d , each of the swiveling handle elements  12 ,  112 ,  212  has an end stop  31 , so that the position of a pair of handle elements folded into one another is positively defined. 
   Each of the handle elements  12 ,  112  shown in  FIGS. 3 and 4 , and likewise a slide handle  10 ,  110  formed by these handle elements, has a depression  32 ,  132  for secure gripping. To illustrate another possibility, the swiveling handle element  212  of  FIG. 5  has an ergonomically shaped outside surface. 
   Particularly preferred is an embodiment of a pair of handle elements as shown in FIG.  3 . The rigid handle element  11  in this case has on both sides concave outer surfaces (also see FIG.  1 ), and the inner surfaces of the recess  14  of the swiveling handle element  12  are shaped to exactly conform to the concave surfaces of the element  11 . This facilitates the centering and effortless swiveling of the handle elements  11 ,  12  into each other. In particular, this embodiment of the two handle elements  11 ,  12  is self-centering. It is therefore not absolutely required to exactly position the two handle elements  11 ,  12  vertically above one another in order to combine them into a slide handle  10  by swiveling them into one another. It is sufficient if at least a portion of a handle element  11  is positioned vertically above a portion of a handle element  12 . 
   As is self-evident, handle elements of the foregoing description, forming a pair which can be coupled as a slide handle and at least one of which has to be free to swivel, can also be arranged in the upper part of the balance, for example at the top cover panel and the two side walls, in order to couple the top cover panel and side walls through a mutual engagement so that they will move together. Furthermore, the arrangement of the inventive slide handles is not limited to a balance with a rectangular cross-section. 
   LIST OF REFERENCE SYMBOLS 
   
       
         1  balance housing 
         2  weighing compartment 
         3  rear wall 
         4  floor of weighing compartment 
         5  front wall 
         6  side wall 
         7  side wall 
         8  top cover panel 
         9  grip handle 
         10 ,  110 ,  210  slide handle 
         11 ,  111 ,  211  rigid handle element 
         12 ,  112 ,  212  swiveling handle element 
         13  foot 
         14 ,  114 ,  214  recess 
         15  floor compartment 
         16  holder element 
         17  guide device 
         18  guide rail 
         19  upper guide groove 
         20  lower guide groove 
         21  carriage 
         22  connector body 
         23  plate 
         24  housing floor 
         25  roller 
         26  projection 
         27  holder device 
         28  axle 
         29  spring 
         30  fastening lug 
         31  end stop 
         32 ,  132  depression for gripping 
         33  weighing pan