Abstract:
The present invention relates to an adjustable stand having a first arm ( 104 ) that is rotatable about a first rotation axis ( 102   a ), and a second arm ( 106 ) that is attached articulatedly at one end of the first arm ( 104 ), a mounting apparatus ( 110 ) being provided at the distal end of the second arm ( 106 ), further having a compensation mass ( 120, 130 ) operatively connected to the first arm ( 104 ), the compensation mass ( 120, 130 ) being provided at least partly displaceably back and forth along an axis ( 200 ) that is directed toward the first rotation axis ( 102   a ).

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority of German patent application number  10  2012 202 303.8 filed Feb. 15, 2012, the entire disclosure of which is incorporated by reference herein. 
       FIELD OF THE INVENTION 
       [0002]    The present invention relates to an adjustable stand. 
       BACKGROUND OF THE INVENTION 
       [0003]    For easy handling of heavy medical observation devices such as, for example, surgical microscopes, it is usual to provide adjustable stands on which the observation devices can be secured or mounted. It is usual in this context, in order to ensure sensitive and simple horizontal and vertical movability requiring little effort, to embody compensation weights on the stand that serve to counterbalance the weight of the optical observation device attached to the stand. Because it is moreover typical for different optical observation devices that correspondingly have different weights to be used together with a stand, it must also be possible to adapt the compensation weights to different medical observation devices. 
         [0004]    U.S. Pat. No. 6,050,530 A proposes for these purposes a displaceability of counterweights on the stand by means of corresponding horizontal and vertical slide mechanisms. These slide mechanisms are perceived as relatively complex; the need to position compensation weights at different positions on the stand and to immobilize (secure) them at those positions is also associated with a relatively high level of complexity. 
       SUMMARY OF THE INVENTION 
       [0005]    The object of the present invention is to provide an adjustable stand that is adaptable in a simple and reliable way to a plurality of medical observation devices of differing weights. 
         [0006]    This object is achieved by an adjustable stand described herein. 
         [0007]    The stand according to the present invention makes available a system which can be counterbalanced in simple fashion, and with which optical observation devices, for example surgical microscopes, can be handled in a simple and reliable way. According to the present invention, a displacement of a compensation mass in only a single direction is necessary. As a result, a very simple adjustment mechanism can be implemented. 
         [0008]    The at least partial displaceability of the compensation mass along an axis that is directed toward the first rotation axis of the stand proves to be particularly advantageous, this first rotation axis being the rotation axis about which the stand as a whole is rotatable or pivotable. Particularly effective compensation mass displacement is thereby provided. Be it noted that this axis can be a real or a virtual axis. 
         [0009]    Advantageous embodiments of the invention are described throughout the specification. 
         [0010]    Preferably, the compensation mass comprises a first mass that is not displaceable, and a second compensation mass that is displaceable back and forth in the direction toward the first rotation axis. This feature ensures that only a portion of the (total) compensation mass needs to be provided displaceably. The result is that corresponding drive systems for displacement of the compensation mass can be of smaller dimensions as compared with conventional approaches, so that the stand as a whole can be physically smaller and costs can be reduced. 
         [0011]    It proves to be particularly useful that the mounting apparatus provided on the second arm of the stand is rotatable about a second rotation axis that is provided on the second arm, this second rotation axis being oriented parallel to the first rotation axis, the second rotation axis extending through an (imaginary) prolongation of the axis on which the compensation mass is at least partly displaceable back and forth. 
         [0012]    In this context, the axis along which the compensation mass is at least partly displaceable back and forth usefully extends perpendicularly to the extension direction of the first rotation axis, and thus also perpendicularly to the second rotation axis. 
         [0013]    All in all, the so-called neutral axis of the stand extends along the axis on which the compensation mass is at least partly displaceable back and forth, and along its (imaginary) prolongation. Adjustments of the compensation mass along this neutral axis prove to be very effective, i.e. a relatively large torque can be compensated for with a relative short displacement. 
         [0014]    It proves to be particularly advantageous to provide the first arm as a parallel-member link or articulated parallelogram having an inner rod and an outer rod, the first rotation axis being implemented on the inner rod, the at least partly displaceable compensation mass being attached to a holder that is supported pivotably about a further rotation axis on a prolongation of a connecting rod of the first parallel-member link, the holder being provided with a guide into which a guide element, provided on the outer rod of the first parallel-member link, engages. This feature provides a design that is particularly simple mechanically, with which it is possible to ensure that the axis along which the compensation mass is at least partly displaceable back and forth, the first rotation axis, and the second rotation axis lie on the neutral axis of the stand. All that is necessary for this is to ensure that the guide element between the at least partly displaceable compensation mass and the first rotation axis likewise lies on this neutral axis. 
         [0015]    Expediently, the second arm is also embodied as a parallel-member link having a first and a second rod. 
         [0016]    Expediently, the stand according to the present invention comprises at least one sensor element by means of which moments (torques) acting on the stand can be sensed, as well as a control system, interacting with the at least one sensor element, that controls to a drive system in such a way that the compensation mass is displaceable. Components of this kind make possible in simple fashion an adjustment of the stand as a function of an optical apparatus, in particular a surgical microscope, attached to the mounting apparatus. 
         [0017]    The stand expediently comprises a braking device by means of which the positions of the stand can be immobilized once established. 
         [0018]    Further advantages and embodiments of the invention are evident from the description and the appended drawings. 
         [0019]    It is understood that the features recited above and those yet to be explained below are usable not only in the respective combination indicated, but also in other combinations or in isolation, without departing from the scope of the present invention. 
         [0020]    The invention is schematically depicted in the drawings on the basis of an exemplifying embodiment, and will be described below in detail with reference to the drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0021]    In the drawings: 
           [0022]      FIG. 1  is a schematic side view of a preferred embodiment of an adjustable stand according to the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0023]    A preferred embodiment of an adjustable stand according to the present invention is designated  100  in its entirety in  FIG. 1 . The stand has as a carrier element a carrier column  102  on which a parallel-member linkage is pivotably supported. 
         [0024]    The parallel-member linkage comprises, as a first arm, a first parallel-member link  104  having rods  104   a ,  104   b , and as a second arm a second parallel-member link  106  having rods  106   a ,  106   b . Parallel-member linkage  104 ,  106  is pivotable as a whole about a rotation axis  102   a  that is provided on carrier column  102 . Parallel-member link  106  is furthermore pivotable with respect to parallel-member link  104  by means of a mechanism  105  that comprises an angle element  105   a  and rotation axes  105   b ,  105   c . Parallel-member link  106  thus serves as an extension arm for parallel-member link  104 . Further rotation axes of the parallel-member linkage are depicted in the drawing by means of small circles, but for the sake of clarity not all are labeled with reference numerals. A braking or locking device  210 , with which the positions of the stand can be defined once established, is expediently provided. This device can be provided, for example, in the vicinity of rotation axis  102   a  or of a rotation axis at one end of one of rods  104   a . In  FIG. 1  this device  210  is provided, for example, at the lower end of rod  104   a.    
         [0025]    A medical optical apparatus, in particular a surgical microscope  112 , optionally comprising auxiliary apparatuses  114 ,  116 , is mounted at the free or distal end  106   c  of parallel-member link  106  by means of a mounting apparatus  110 . 
         [0026]    In order to counterbalance the moments (torques) generated by the weight of medical optical apparatus  112  (and optionally of auxiliary apparatuses  114 ,  116 ), a first compensation weight  120  is embodied on a prolongation of a horizontal connecting rod  104   c  of first parallel-member link  104 , which connects first or inner rod  104   a  and second or outer rod  104   b . A holder  180  for a second compensation mass  130  is furthermore provided at that end of the prolongation of connecting rod  104   c  at which first compensation mass  120  is also provided. This holder  180  is pivotable about a rotation axis  181  relative to the prolongation of connecting rod  104   c . Holder  180  comprises a first region  180   a  that is embodied as a linear guide on which second compensation mass  130  (constituting a linear carriage) is displaceable back and forth and can be immobilized at a desired position. The displaceability of second compensation mass  130  is limited by stops or other suitable means. For clarity, only one stop  180   b  is depicted in  FIG. 1 . 
         [0027]    Adjacent to this stop  180   b  is a second region  180   c  of holder  180 . This second region  180   c  comprises an elongated hole  180   d  the principal extension direction of which corresponds to the displaceability direction of second compensation mass  130 . First region  180   a  and second region  180   c  of holder  180  can expediently be provided in one piece, stop  180   b  being positionable and immobilizable at a desired location. 
         [0028]    Elongated hole  180   d  serves as a guide for a guide element  190  provided on outer rod  104   b  of first parallel-member link  104 . Guide element  190  can be provided, for example, as a guide pin. 
         [0029]    The position of guide element  190  on rod  104   b  is selected so that the guide element lies on an (imaginary) connecting line between rotation axis  181  and rotation axis  102   a  of first parallel-member link  104  on second rod  104   a . This line or axis is depicted in  FIG. 1  and labeled  200 . The consequence of this is that a displacement of second compensating mass  130  along first region  180   a , serving as a linear guide, of holder  180  always occurs along said line  200 , i.e. along an axis in the direction toward or away from rotation axis  102   a . At the same time, this displacement occurs perpendicular to rotation axes  181  and  102   a . 
         [0030]    It is evident that a further rotation axis, namely rotation axis  107  of mount  110  on the second or inner rod  106   b  of second parallel-member link  106 , lies on a (once again imaginary) prolongation of line  200 . Line  200  thus represents the neutral axis of the stand. 
         [0031]    A further rod  104   d  is provided between rods  104   a ,  104   b  of first parallel-member link  104 . This rod is pivotable at its first end about a pivot point  102   b  on carrier element  102 , and at its second end is connected to angle element  105   a  of mechanism  105 . 
         [0032]    It is further evident that mounting apparatus  110  is attached on a prolongation of a connecting rod  106   c  that connects to one another the two rods  106   a  and  106   b  of second parallel-member link  106 . 
         [0033]    Connecting rod  106   c  is pivotable on rotation axis  107  with respect to rod  106   b,  and on a rotation axis  108  with respect to rod  106   a . This pivotability ensures a perpendicular orientation of connecting rod  106   c  in any position of stand  100  that can be established, as will be further explained below. 
         [0034]    Let it be assumed firstly that stand  100  is in equilibrium in the position depicted in  FIG. 1 . This means that the moments acting on connecting rod  106   c , which are caused substantially by surgical microscope  112  and optionally by further components  114 ,  116  (and optionally by the weight of mounting apparatus  110 ), correspond to the moments caused by compensation masses  120 ,  130 . In order to establish this equilibrium, displaceable weight  130  is positioned and immobilized at a suitable position along first region  181  of holder  180 . 
         [0035]    If the mass attached to mounting apparatus  110  is modified, for example by installing a heavier surgical microscope  112  and/or attaching a further or heavier auxiliary apparatus  112 ,  114 , a torque sensor positioned at a suitable location detects a static imbalance resulting therefrom. The values acquired by a sensor of this kind are usefully forwarded to a control device (not depicted) that, by applying control to a drive system (not depicted), brings about a corresponding displacement outward, i.e. in the direction of pivot point  181 , of second compensation mass  130  along first region  180   a  of holder  180 . The additional moment acting on connecting rod  160   c  can thereby be effectively compensated for. 
         [0036]    The above-described equilibration of stand  100  makes possible a very rapid adjustment of the stand requiring very little energy, for example in the case of a displacement in the direction of one of arrows P. The mechanism depicted ensures that in all positions of pivot point  181  that can be established, guide element  190 , rotation axis  102   a , and rotation axis  107  lie on one line (neutral axis  200 ). 
         [0037]    The impingement of third rod  104   d  of first parallel-member link  104  on pivot mechanism  105  further causes transverse rod  106   c , and thus a surgical microscope attached thereto, always to be mounted or orientated perpendicularly. 
         [0038]    As depicted, with stand  100  in any position that can be established, it is possible in simple fashion to counterbalance the stand for surgical microscopes or auxiliary devices of different masses by displacing second compensation mass  130 . It proves to be particularly advantageous that in accordance with the approach depicted, only second compensation mass  130  needs to be displaced. First compensation mass  120  can be provided in stationary fashion with respect to the prolongation of connecting rod  104   c . In particular, second compensation mass  130  can be substantially smaller than first compensation mass  120 . A drive system of very small dimensions can therefore be used for the displacement of second compensation mass  130 . 
         [0039]    The invention is not to be limited to the specific embodiments disclosed, and modifications and other embodiments are intended to be included within the scope of the invention. 
       PARTS LIST 
       [0040]      100  Adjustable stand 
         [0041]      102  Carrier column or carrier element 
         [0042]      102   a  Rotation axis 
         [0043]      104  Parallel-member link 
         [0044]      104   a ,  104   b  Rods 
         [0045]      104   c  Connecting rod 
         [0046]      105  Pivot mechanism 
         [0047]      105   a  Angle element 
         [0048]      105   b ,  105   c  Rotation axes 
         [0049]      106  Parallel-member link 
         [0050]      106   a ,  106   b  Rods 
         [0051]      106   c  Free or distal end 
         [0052]      107 ,  108  Rotation axes 
         [0053]      110  Mounting apparatus 
         [0054]      112  Medical optical apparatus, in particular surgical microscope 
         [0055]      114 ,  116  Auxiliary apparatuses 
         [0056]      120  First compensation mass 
         [0057]      130  Second compensation mass 
         [0058]      160  Braking or locking device 
         [0059]      180  Holder 
         [0060]      180   a  First region of holder (linear guide) 
         [0061]      180   b  Stop 
         [0062]      180   c  Second region of holder 
         [0063]      180   d  Elongated hole 
         [0064]      181  Rotation axis 
         [0065]      190  Guide element 
         [0066]      200  Neutral axis (line) 
         [0067]      210  Braking or locking device