Abstract:
A positioning unit ( 1 ) includes an accelerating nanodrive ( 2 ), which has a resolution of at least ±10 nm, a slider ( 5 ) and a module ( 6, 7 ), which has a stationary component ( 6 ) and a component ( 7 ) movable for this purpose. The component ( 7 ) has a mass of less than 500 g and is movably supported relative to the drive ( 2 ). The slider ( 5 ) and the movable component ( 7 ) of the module ( 6, 7 ) are securely connected one to the other and the drive ( 2 ) can exert accelerations higher than 10 G.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS  
       [0001]    This application claims the benefit of prior filed provisional application, Appl. No. 60/274,824, filed Mar. 9, 2001, pursuant to 35 U.S.C. 119(e), the subject matter of which is incorporated herein by reference. 
     
    
     
         [0002]    This application claims the priority of European Patent Application, Serial No. 01 105954.0, filed Mar. 9, 2001, pursuant to 35 U.S.C. 119(a)-(d), the subject matter of which is incorporated herein by reference.  
         BACKGROUND OF THE INVENTION  
         [0003]    The present invention relates to a positioning unit with an accelerating nanodrive, which has a resolution of at least ±10 nm, a slider and a module which has a stationary component and a component movable for this purpose, which has a mass of less than 500 g and is movably supported relative to the drive. The invention also relates to a positioning apparatus with at least two such positioning units.  
           [0004]    Such positioning units are used, for example, to move the object observed under a microscope. Here it is important that the drive makes for a preset position with an especially high resolution. This is achieved by the drive exerting acceleration on a slider and thereby moving the slider relative to the drive.  
           [0005]    As a rule, high resolution is achieved by repeatedly moving the slider merely a particularly short distance. This distance lies in the nanometer range and the slider can be positioned with extremely high resolution by means of a plurality of such small movement steps.  
           [0006]    In these nanodrives a distinction is made between clamping and accelerating methods. In clamping methods the slider is gripped, moved a short distance and then released again. The clamps quickly return to the initial position and grip the slider again to achieve another forward push again in the nanometer range.  
           [0007]    The other group of nanodrives uses relatively high accelerations, which are generally higher than 10 G, as the drive principle. These can be inertial drives or drives which accelerate their movable component, that is the slider, by means of mechanical pulse waves. This group of nanodrives generally has a simpler structure and can therefore be designed as a smaller structural unit. Particularly compact forms of such nanodrives are described in DE 38 44 821 C2, EP 0 611 485 B1 and DE 44 40 758 A. This type of nanodrive will subsequently be called an accelerating nanodrive.  
           [0008]    There is great interest in using said compact accelerating nanodrives for positioning a module which has a mass of less than 500 g and is supported relative to the drive. However, it has been found that the accelerating nanodrive is not suitable for this purpose.  
           [0009]    If such modules are brought in contact with an accelerating nanodrive, even if the components are correctly designed, no technically usable force transmission between the accelerating nanodrive and the module is achieved. Even if the accelerating nanodrive can exert many times the force which would be required to accelerate the module, the accelerating nanodrive is braked as soon as it comes in contact with the movable component of the guide module.  
           [0010]    All attempts to use such an accelerating nanodrive for positioning such a light module have failed in that enlarging the drive initially met with no success and from a certain size of drive, preference was given to drives using clamping movement.  
           [0011]    It would therefore be desirable and advantageous to provide an improved positioning unit which obviates prior art shortcomings and allows use of accelerating nanodrives.  
         SUMMARY OF THE INVENTION  
         [0012]    According to one aspect of the present invention, a positioning unit with an accelerating nanodrive, which has a resolution of at least ±10 nm, a slider and a module, which has a stationary component and a component movable for this purpose, which has a mass of less than 500 g and is movably supported relative to the drive, wherein the slider and the movable component of the module are securely connected one to the other and the drive can exert accelerations higher than 10 G.  
           [0013]    Surprisingly it has been found that when the slider and the module are securely connected, the entire performance capacity of the drive can be utilized although tests using accelerating drives where the drive was held onto the module resulted in failure.  
           [0014]    Precision engineers using nanodrives had first tested the interaction of drive and module in a loose structure, as is usually the case when using these actuating drives, before they securely connected the units one to the other. In these tests the accelerating drives were generally inferior to the clamping drives and thus only clamping drives were used for generic positioning units. This led the practical workers to recognize that accelerating drives with nanometer precision are not suitable for positioning modules having a mass of less than 500 g.  
           [0015]    Contrary to this knowledge, sliders and movable component of the module according to the invention were securely connected one to the other although preliminary tests using loose arrangements had failed.  
           [0016]    The invention thus makes it possible to achieve an especially compact construction of positioning units by using accelerating nanodrives having particularly compact structures.  
           [0017]    Particularly advantageous in practice is the use of drives which allow a positioning distance of more than 1 mm. In this way, simple adjustment positioning is achieved in a larger field of movement.  
           [0018]    For many technical applications it is advantageous if the drive has a resolution of at least ±1 nm. A resolution exceeding 1 nm allows the units to be used in a wide range of applications in micro-adjustment technology.  
           [0019]    In order to achieve an efficient drive, it is proposed that the drive can exert accelerations greater than 20 G, preferably greater than 40 G, on the slider. In a preferred embodiment the accelerations are below 500 G, preferably below 200 G, typically in a range between 50 and 100 G. As a rule, the acceleration plotted over time forms a saw-tooth line. However, the acceleration can also be applied to the slider with gentler curve profiles, such as rounded arcs of curves, for example.  
           [0020]    The acceleration applied to the slider according to the invention is above 10 G within the limits for quasi-static clamping movement.  
           [0021]    The modules can be supported using balls, rollers or needles. Supporting via sliding surfaces, air flow or magnetic, electric or electromagnetic fields is also possible. The module has one or several very easily movable component(s) and is supported on one or several stationary component(s) relative to a reference system. Here it is advantageous if the module is movably supported with respect to several degrees of freedom. This allows, for example, several drives to act on one module to bring the module into a desired spatial position with higher resolution.  
           [0022]    A compact, small structure can be achieved particularly if the module has a mass of less than 100 g. In practice, it has been found that functional units particularly having modules with a mass higher than 0.2 g should be constructed.  
           [0023]    A wide range of types of connection are suitable as the secure connection, such as sticking, soldering, welding, screwing, clamping or joining. Also detachable secure connections such as, for example, magnetic connections, are included in the types of connection proposed according to the invention.  
           [0024]    It is advantageous if the secure connection is substantially free from play and damping. This increases the security of the force transmission from the drive to the module.  
           [0025]    The object of the invention is also achieved using a positioning apparatus with at least two positioning units according to the invention, which are securely connected to the module. By using several positioning units it is possible to construct an xy table, an xyz stand, a tilting table, a goniometer, a rotating element, a portal system or a robot. Here the positioning units can be used as laterally or rotationally acting drives.  
           [0026]    It is to be understood that the secure connection between the slider and the module can be achieved by a direct connection between the slider and the module and that an intermediate element or a hinge, which is securely connected to the slider and the module, can be placed between the slider and the module Here drives and modules can be arranged side by side or one behind the other or partly side by side and partly one behind the other.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWING  
       [0027]    Other features and advantages of the present invention will be more readily apparent upon reading the following description of currently preferred exemplified embodiments of the invention with reference to the accompanying drawing, in which:  
         [0028]    [0028]FIG. 1 is a schematic diagram showing the interaction of an accelerating nanodrive with a linear guide module;  
         [0029]    [0029]FIG. 2 is a schematic diagram showing the interaction of an accelerating nanodrive with a linear guide module, which are coupled via a connecting element;  
         [0030]    [0030]FIG. 3 is a schematic diagram showing the interaction of an accelerating nanodrive with a linear guide module with an inserted hinge element;  
         [0031]    [0031]FIG. 4 is a schematic diagram showing the interaction of two accelerating nanodrives with a guide module constructed as an xy table; and  
         [0032]    [0032]FIG. 5 is a schematic diagram showing the interaction of an accelerating nanodrive with two linear guide modules.  
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0033]    The positioning unit  1  in FIG. 1 has a drive  2  and the guide module  3 . The drive is designed so that in the event of mere contact between the drive and the movable component, it is not possible to have any technically usable force transmission between the drive and the movable component of the module. The drive  2  substantially consists of the actuator  4  and the slider  5 . The guide module  3  consists of the stationary component  6  and the component  7  movable for this purpose. In the present case, the movable component  7  can be displaced along a straight line in accordance with the arrows  8  relative to the stationary component  6 . The movable component  7  of the guide module  3  is connected via a secure connection—as in the present case, a weld seam—to the slider  5  of the nanodrive  2 .  
         [0034]    Although no technically usable force transmission can be achieved if the nanodrive  2  and the movable component  6  of the guide module  3  are loosely connected, merely by introducing the secure connection  9 , the structure allows the movement drive to be used in connection with such a module.  
         [0035]    Another embodiment is shown in FIG. 2. In this arrangement  20 , the slider  25  of the drive  22  acts on a first secure connection  29  which connects the slider  25  with a connecting element  30 . The connecting element  30  is connected via another connection  31  to the movable component  27  of the guide module  23 . This allows the guide module and the drive to be arranged one next to the other.  
         [0036]    When the slider  25  moves, the movable component  27  of the guide module  23  is moved relative to the stationary component  26  in the direction of the arrow  28  via the connecting element  30 .  
         [0037]    Another example of embodiment of the positioning unit according to the invention is shown in FIG. 3. In this arrangement  40  the slider  45  of the drive  42  acts on the movable component  47  of a stationary axis of rotation  46  of the hinge joint  43 . The connection between the slider  45  and the movable component  47  of the hinge joint  43  is in the present case a hinge joint  49  which allows any angular position between the slider  45  and the movable component  47  but ensures that these parts are securely connected. The drive  42  is attached to the bearing  41  such that it can be rotated.  
         [0038]    When the slider  45  moves relative to the actuator  44  of the drive  42 , the movable component  47  of the hinge joint  43  is thus turned about the axis of rotation  46  in accordance with the arrow  48 .  
         [0039]    [0039]FIG. 4 shows the use of a positioning unit according to the invention for an xy table as configuration  50 . The drives  52  and  62  with their respective sliders  55  or  65  each act on a respective connecting element  51  or  61 . These connecting elements  51  or  61  are arranged substantially orthogonal one to the other and are connected to the movable component  57  of the xy table  58 . In order to allow the movable component  57  to move both in the direction of the arrow  58  and also in the direction of the perpendicularly arranged arrow  68 , the connections  51  and  61  are constructed as an at least slightly laterally flexible element. These connecting elements  51  or  61  can be constructed as simple wire, flat springs or as a complex mechanical hinge with bearings and counterbearings. The movable component  57  is connected to the xy table via an air support, an electrical or an electromagnetic support.  
         [0040]    In accordance with the examples of embodiment described previously, it is also important in the present case that both between the sliders  55  or  56  and the connecting elements  51  or  61 , and also between the connecting elements  51  or  61  and the movable component  57  of the xy table  58  there are provided secure connections  53  or  54  and  63  or  64 .  
         [0041]    The example of embodiment  70  shown in FIG. 5 shows a first guide module  73  which is arranged in a row in front of the accelerating nanodrive  72  and a second guide module  83  that is arranged parallel and staggered relative to the first guide module  73 . The slider  75  of the accelerating nanodrive  72  has a secure mechanical connection  79  to the movable component  77  of the guide module  73 . The movable component  77  also has a secure mechanical connection  74  to a connecting element  80  which can, for example, be a cover plate or an open frame. This connecting element  80  has a secure mechanical connection  84  to the movable component  87  of the second guide module  83 .  
         [0042]    The movement of the slider  75  thus results in a movement of the connecting element  80  in the direction of the arrows  78  and  88  relative to the stationary component  76  of the guide module  73  or  86  of the guide module  83 .  
         [0043]    These examples of embodiment show that any combinations of one or several accelerating nanodrives and one or several linear, rotating or multi-axis guide modules can be produced.  
         [0044]    While the invention has been illustrated and described as embodied in a positioning unit and positioning apparatus with at least two positioning units, it is not intended to be limited to the details shown since various modifications and structural changes may be made without departing in any way from the spirit of the present invention. The embodiments were chosen and described in order to best explain the principles of the invention and practical application to thereby enable a person skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated.  
         [0045]    What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims and their equivalents: