Abstract:
A stand having an automatically correctable balancing system and balancing mechanisms electrically controlled by a computer ( 10 ). Replaceable accessories can be joined to a component ( 9 ) movably joined to the stand ( 6 ). Associated with the computer ( 10 ) are a calculation program and an information system that, by means of a reading device, reads correction information from data media of the accessories and conveys it to the computer.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
         [0001]    This invention claims priority of the Swiss patent application 2000 1898/00 filed Sep. 28, 2000 which is incorporated by reference herein.  
         FIELD OF THE INVENTION  
         [0002]    The invention concerns a stand having a balancing device.  
         BACKGROUND OF THE INVENTION  
         [0003]    Stands, in particular for surgical microscopy or the like, should be properly balanced so that the microscope can be pivoted, lifted, lowered, and moved in space with relatively little application of force. The existing art discloses several methods for balancing, including semi-automatic or automatic balancing methods, in which a balance status is measured via a force or displacement sensor and an electrically controlled balancing action is performed on the basis of that measurement.  
           [0004]    The term “electrically controlled balancing action” is to be understood, for example, as the activation of an electric drive that displaces balancing weights. One example of such a balancing device has been disclosed in the applicant&#39;s PCT international patent application WO-A-97/13997.  
           [0005]    The conventional and hitherto published balancing systems with electrical or electronic assistance are based on the assumption that the imbalance is measured as a physical magnitude, and the balancing operation is performed on the basis of the measurement result. This requires corresponding force measurement sensors and a corresponding measurement operation; only after that can the balancing operation take place. Because they are located on moving systems, such force measurement sensors and the electronic amplifiers necessary for them are usually complex and expensive. Leaving this aside, the balancing operation is always reactive, since first measurement occurs and then balancing. With some stands of the existing art with semi-automatic balancing, for example, after an accessory change a button on the stand that initiates the balancing operation must be pressed.  
           [0006]    With such systems, a certain time therefore also elapses before the balanced state is achieved.  
           [0007]    The fully automatic balancing systems described in the literature have, compared with the button-controlled systems, the (sometimes undesirable) characteristic that they balance out a stand even when the balancing operation is not desired. For example, when the stand is balanced and a surgeon then leans against or holds onto the microscope, in fully automatic systems this can immediately result in a balancing operation. When the bracing forces on the microscope are released, e.g. when the hands are released or the head pulled back, this balance operation can result in a severe imbalance. This must first be detected and compensated for by another balancing operation. During this period the microscope is not fully usable by the surgeon, thus in some circumstances preventing him or her, during this detection and balancing operation, from continuing the surgical procedure until this new balancing operation is complete. In the case of an automatically operating stand of the applicant (OHS), this balancing is therefore performed not continuously but only after switching into balancing mode. But if an assistant adjusts or replaces accessory parts during the procedure, the microscope is then at first no longer balanced. To allow the surgeon to work unhindered, another time-consuming balancing action (switching over into balancing mode) is necessary, and the surgery must be interrupted during this period.  
           [0008]    The Möller-Wedel company has proceeded from another consideration in its stand design. First a mechanical balance is achieved. If components on the microscope are then replaced, this balance is not disturbed at all but rather adjustments intended to re-establish balance are performed on the components themselves, or on other components present on the microscope. For example, the assistant&#39;s tube is pivoted so that a balanced state is achieved.  
           [0009]    This is often unsatisfactory, however, since a position that does not conform to the desired working position is thereby established.  
         SUMMARY OF THE INVENTION  
         [0010]    It is the object of the invention to find a new balancing system which dispenses with complex and expensive force or displacement sensors and performs a balancing operation, avoiding any interruption of the surgical procedure, as immediately and quickly as possible as soon as any modification to the accessories of the microscope occurs, without previously performing a measurement operation of physical magnitudes such as forces, deformations, or the like; and in which an undesired balancing operation resulting from bracing forces, as described above, is prevented.  
           [0011]    The particular aspect of the present invention is a completely new philosophy: there is no intention to measure physical forces or displacements (deformations) that provide some information about the balance state; instead a complete computer-assisted mathematical model of the stand is provided. The addition or removal of components to or from this model (addition or removal of accessories to or from the microscope or change in the position of essential components) causes the computational model to be correspondingly modified; the corresponding change in the model is taken into account computationally, and on the basis of the computational model the control commands for the electrical activation of counterweights are initiated.  
           [0012]    As compared to the existing more or less intelligent balancing systems (imbalance is measured by means of intelligence and balanced out by means of an intelligent control system), for the first time according to the present invention an intelligent stand is put into service. The intelligent use of a computer and corresponding programming or calibration means that the stand “knows” its configuration and recognizes any change to its configuration, in order to carry out corresponding balancing actions by means of direct activation of counterweights or the like.  
           [0013]    What is provided first of all according to the present invention is therefore a computer that contains a program with which the balance states can be calculated and the absence of balance is ascertained computationally, by the fact that the added or removed components (e.g. accessory parts on the microscope) are entered along with their properties that influence the overall model. This input is preferably accomplished in coded form, so that information about the accessory part added to or removed from the microscope can be entered into the computer, for example manually or by means of a barcode reader or the like.  
           [0014]    For example, each accessory part bears a number that the user communicates to the computer via a keypad before installing the component. In accordance with a particular embodiment of the invention, automatic recognition of the accessory parts is provided for in order to speed up this operation. This is accomplished, for example, by way of an automatically readable barcode that is applied to a location on the accessory part that is automatically sensed by a reading device upon installation.  
           [0015]    According to a further particular embodiment of the invention, a microchip having the corresponding information written into it (for example, a microchip like that on a check card) is provided instead of a barcode.  
           [0016]    Of course magnetic or other data media or the like could also take care of the corresponding information transfer between accessory part and computer. What is favorable with this configuration is that the computer automatically and immediately detects, without further intervention, which accessory parts have been removed from the microscope and which have been added. Since all these components are included in the computational model, the correct balance position of the counterweights can be set directly and immediately.  
           [0017]    Balancing thus takes place substantially more quickly than with conventional stands. The intelligence for the actual balancing operation can in fact be reduced (and can thus be cheaper) as compared to the known semi-automatic or automatic balancing systems.  
           [0018]    With a configuration according to the present invention, once a balancing operation has been performed it is also not influenced by pressure from the operator&#39;s head or hands. Such operations are not even encompassed by the computer or the mathematical model.  
           [0019]    A further particular embodiment of the invention provides for the provision, in addition or alternatively to the information-transferring part (chip, barcode, or the like), of angle sensors or displacement sensors which sense the positions of pivotable parts of the accessories and, on the basis of a specific pivot position of said parts, signal to the computer (optionally via the chip) and to the computational model of the balancing system a change that makes possible or triggers a balance correction. In contrast to the force measurement sensor systems used hitherto in balancing systems, angle sensors are very inexpensive; in addition, the demands made on them are not particularly great, since slight changes in the angular position of, for example, a tube do not have a substantial effect on the imbalance of a fully balanced stand.  
           [0020]    As part of a development of this inventive embodiment, there is provided for the angle sensor and for the chip connected to it a suitable logic system that continuously supplies the corresponding balance information to the computer. In this case it is not absolutely necessary for the accessory part information to be coded and stored in tabular form in the computer; instead the mathematical model is calculated automatically in each case on the basis of the balance information read in automatically by the respective accessories.  
           [0021]    The specific configuration of the stand is not critical for implementation of the actions according to the present invention described above. The assemblage can have parallelogram supports or standard beam supports or the like. Conventional stands can easily be retrofitted with what is proposed according to the present invention, since as a rule only additional data lines and data acquisition elements need to be installed.  
           [0022]    As an alternative to data lines and electronically connected systems, accessory parts that can be connected to the computer by means of infrared sensors or other telecommunication devices (for example ultrasound or radio waves) are also conceivable. For example infrared light-emitting diodes or reflectors, for example such as those described in the applicant&#39;s European Patent Application EP-A-822 436, can be constructed. In other words, light pulses proceeding from the accessory part communicate their balance characteristics information to the computer via corresponding light pulse receivers.  
           [0023]    The invention also makes it possible to develop a standard for accessory parts that permits the universal utilization of accessory parts on different systems having a balance computer according to the present invention. The invention also allows a customer&#39;s own accessory parts to be calibrated at the manufacturer&#39;s facility by providing there a reference stand on which, by means of conventional balancing system measurement devices, the balance characteristic of the corresponding accessory part is determined and is then coded thereon. This can be accomplished, for example, by way of the barcode, a chip, or another code that is optionally supplied additionally by means of a computer diskette.  
           [0024]    Of course the invention is not limited to a pure balancing apparatus corresponding to the above inventive features; on the contrary it also allows for a combination with conventional automatic or semi-automatic balancing systems if advantages for the user may be derived therefrom. What is critical in any event is that by way of the balancing system according to the present invention, optimum and immediate balancing can be effected directly without further measurement operations.  
           [0025]    The present invention is also particularly suitable for balancing directly at the optics support, i.e. for pivoting movements of the microscope about a horizontal axis and at least one farther axis that is arranged at an angle to the horizontal axis. For balancing according to the present invention in the context of a pivot support (a pivot support is that component which directly holds the microscope and which gives the microscope mobility in space by way of at least one, as a rule two to three, pivot axes, and which in turn is mounted on supporting elements of the stand) according to the present invention balancing is performed in such a way that by way of the electrical drives, the center-of-gravity axes and the intersection of the pivot axes of the stand are displaced relative to one another in such a way that the intersection of at least two pivot axes (or even three or more pivot axes) ends up at the center of gravity of the microscope or of the microscope having the assemblage joined directly to the microscope.  
           [0026]    This balancing action can be brought about by the displacement of counterweights that displace the center of gravity of the microscope or of the assemblage; or by the displacement of pivot axes so that their intersection ends up at the center of gravity; or by displacement of the microscope or the relevant accessory parts relative to the corresponding pivot axes of the microscope, so that its center of gravity is placed on the intersection of the axes.  
           [0027]    Optimal balancing of the pivot support exists when the intersection of all the pivot axes is located exactly at the center of gravity of the movable assemblage (microscope with accessories).  
           [0028]    In an embodiment, the invention provides in particular for balancing to occur according to the present invention on a stand both in the pivot support and on the other supports. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0029]    The invention will be explained in more detail below with reference to the exemplary embodiments that depict it in exemplary and symbolic fashion. In the drawings:  
         [0030]    [0030]FIG. 1 shows an X-Y-Z coordinate system in which the intersections of the pivot axes and the center-of-gravity axes are displaced with respect to one another;  
         [0031]    [0031]FIGS. 2 through 4 show conventional surgical microscope assemblages having a pivot support and novel balancing drives;  
         [0032]    [0032]FIG. 5 shows a conventional stand assemblage with internally located coded data at the interfaces;  
         [0033]    [0033]FIG. 6 shows an assemblage corresponding to FIG. 11 of the aforementioned WO-A-97/13997, but having a code reading device and a computer;  
         [0034]    [0034]FIG. 7 shows a symbolic stand assemblage having electric motors (positioning motors) which displace the counterweights in computer-assisted fashion;  
         [0035]    [0035]FIG. 8 shows a stand beam with a computer and two counterweights;  
         [0036]    [0036]FIG. 9 shows a detail of the assemblage shown in FIG. 6;  
         [0037]    [0037]FIG. 10 shows a symbolic depiction of an accessory assemblage with coded data media;  
         [0038]    [0038]FIG. 11 shows, by way of example, a plurality of accessory parts each of which is coded;  
         [0039]    [0039]FIGS. 12 and 13 show examples of different variants of data media;  
         [0040]    [0040]FIG. 14 shows an accessory part with angle sensor and barcode;  
         [0041]    [0041]FIG. 15 shows a model of the overall assemblage;  
         [0042]    [0042]FIG. 16 symbolically shows a microscope assemblage having three components and geometrically arranged signal generators. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0043]    The computer-assisted relative displacement of intersection D of pivot axes x DA /y DA  and z DA  and intersection SP of center-of-gravity axes x SP /y SP and Zsp in an X-Y-Z coordinate system of a pivot support is shown in FIG. 1. This relative displacement is necessary so that the system is balanced, can be moved with little effort, and is in equilibrium in every desired operating position.  
         [0044]    [0044]FIGS. 2 through 4 show modified conventional surgical microscopy assemblages having a pivot support 1 and an automatic balancing system that is activated according to the present invention. Located on the microscope, instead of the hand screws hitherto used for balancing, are electric motors  2 ,  3 , and  4  activated by the computer. The computer receives its data via the coding components, which are not visible in FIGS.  2 - 4  since they are each located in the device attachment region (interface).  
         [0045]    In the conventional stand assemblage shown in FIG. 5, having a stand foot  5  and support column  6 , the one bracing point  7  of a bracing spring  8  is displaced under computer control as a function of weight changes in the region of microscope  9 . A computer  10  arranged on support column  6  learns of the weight changes due to the exchange or adjustment of accessory parts by way of the coded data that are automatically forwarded to computer  10  by the respectively added accessory parts (e.g. a swiveling tube) from interfaces  11 ,  12 ,  13 , and  14 . Additional information is received by computer  10  from angle sensors  15 ,  16 , and  17 , which are arranged in the region of the joints and detect the respective position of the accessory and forward it to computer  10 .  
         [0046]    The angle sensors indicated in FIG. 5 are generally not needed in an assemblage having a bracing spring  8  and parallelogram supports, since the change in the position of the components at the end of the parallelogram support does not result in any change in balance. If, however, bracing spring  8  is stiffened or immobilized, or if the parallelogram support is replaced by a simple horizontal beam, the change in angle about the angle sensors shown here also results in changes in balance. On the other hand, no matter what the approach, the aforementioned angle changes result in a change in the tipover resistance of the stand by way of stand foot  5 . Angle sensors of this kind may thus also be provided in order to ascertain information regarding tipover resistance and enter it into the balancing system, which warns of imminent tipover of the stand, for example, by means of an alarm signal.  
         [0047]    A tipover warning system of this kind constitutes a separate, independent invention, since it can usefully be applied to any surgical microscope stand.  
         [0048]    The assemblage shown in FIG. 6 corresponds to that in FIG. 11 of the aforementioned WO-A-97/13997. In contrast to the assemblage defined in WO-A-97/13997, an electric motor  20  for displacing counter weight  21  is controlled not by an equilibrium sensor but by a computer  18 ; computer  18  receives its data in coded form, via a reading device  19 , from the accessory parts mounted in front beneath component  22 .  
         [0049]    In the symbolic depiction visible in FIG. 7, counterweights  23 ,  24  are displaced in computer-assisted fashion by means of electric motors (positioning motors)  25 ,  26 . The data for computer  27  come, according to the present invention, directly from load  28  and/or from an angle sensor  29  via electrical connecting lines.  
         [0050]    The stand assemblage shown in FIG. 8 comprises a computer  27 , adjusting motors  31 , a control line  32 , and (symbolically) a chip  33  on microscope  34  that contains the relevant information for computer  27 . Also indicated is an angle sensor  29  that senses pivoting motions about a vertical plane and forwards them to computer  27 .  
         [0051]    [0051]FIG. 9 shows a detail of the assemblage of FIG. 6 at enlarged scale. Electric motor  20  for adjusting counterweights  21  is clearly evident here. Also apparent are a conventional brake  30  for retaining a position, and an angle sensor  29  which indicates the pivot position.  
         [0052]    The arrangement depicted in FIG. 10 symbolically shows an assemblage of accessory parts; accessory parts  36  and  37  are detachably joined to a component  35 . The addition of accessory parts  36 ,  37  causes a shift in the overall center of gravity SP of the system. Accessory parts  36 ,  37  are equipped with data media  38 ,  39  from which the necessary correction data (which can also be letters or numerical codes) can be read manually or automatically by a reading device and forwarded to the computer.  
         [0053]    [0053]FIG. 11 depicts, by way of example, a plurality of accessory parts that belong to an accessory system. Each accessory part is individually coded and can be used on a surgical microscope individually or in combination with other accessory parts.  
         [0054]    [0054]FIG. 12 shows a data medium, equipped with a so-called barcode, for the correction data for the balance control system that are to be applied to the accessory parts. This data medium  40  is configured, for example, as a self-adhesive label.  
         [0055]    Shown in FIG. 13 is a further data medium  41  having a microchip such as the one used, for example, on credit cards. Microchips of this kind—or also magnetic strips that are also used, for example, on credit cards—can be programmed by the manufacturer of the accessory part, or optionally also later on by the user.  
         [0056]    Accessory part  42  symbolically depicted in FIG. 14 comprises, for example, a so-called swiveling tube  43 , a barcode data medium  44 , and an angle sensor  45 . Angle sensor  45  serves to sense the respective position of the adjustable swiveling tube  43 , which also can influence the balance of the system.  
         [0057]    The schematic model of an overall assemblage evident from FIG. 15 shows an information system  46  that conveys to a central computer  48  the fixed data stored on accessory parts  47  as well as any data dependent on the working position of accessory parts  47 . This computer  48  determines the necessary correction values and forwards them, as setpoints, to balancing system  49 ,  50 . The balancing system can also simply positionally displace the actual weight, i.e. the microscope or the corresponding component, in order to achieve the balancing effect. The correction data can also be read off from accessory part  47  visually and entered into computer  48  manually via a keypad  51 . A digital display  52 , for example, can serve to check the values that are entered.  
         [0058]    The system can additionally be equipped with an intelligent component  53  (for example a microchip) which can perform queries or, for example, can be used for calibration of new accessory parts.  
         [0059]    As an alternative to the aforementioned displacement of counterweights in balancing systems  49  or  50 , provision is made according to the present invention for the entire system being balanced to be shifted over the corresponding balance axis, or for the center of gravity to be placed into this corresponding axis. Provision is thus made, for example, for providing on the vertical column, below the mounting point for the transverse beam, an X-Y adjusting unit which modifies the position of the transverse beam relative to the column as soon as the weight in the context of balancing system  49  is modified by the addition of additional components or the removal of such components. This is merely an indication by way of example, intended to illustrate the principle.  
         [0060]    [0060]FIG. 16 symbolically shows a microscope such as that which can be mounted on an axis  96   c  on a stand. The microscope comprises three components  104   a,    104   b,  and  104   c  that are independent of one another but joined to one another. Each of these components  104  is equipped with signal transducers  102  that can have a dual function. In the context of the one function, they can emit in coded form signals that provide information about the property of the corresponding component. These signals can be received by receiver  72  and can thus be used to identify the components that are added or taken away. Suitable signal transmitters are, for example, light-emitting diodes, ultrasonic transmitters, radio transmitters, or light reflectors that are excited by external light and make identification possible with a corresponding reflection datum. As a second variant function within the context of the invention, thanks to their geometrical arrangement these sensors can also contribute to the identification of specific positions and locations of the corresponding components. These positions and locations are also recorded via receiver  72  and converted by the computer into the corresponding balance data.  
         [0061]    In a further independent step of the invention, in the context of an assemblage of this kind in which the sensing of the components and their properties and position is accomplished entirely from outside, it is possible conversely for the balancing drives also to be controlled from outside. The invention in this context provides for the signals received by receiver  72  to be processed, after conversion in the computer, into control signals that are sent back via a comparable transmitting system to the microscope or stand, in order to activate the corresponding balance positioning drives therein. In the specific FIG. 16, for example, it may be imagined that a pivoting of component  104   a  about axis  96   c  results in an imbalance that is compensated for by a pivoting of component  104   c  about axis  96   a.    
         [0062]    In no case is an imbalance measured in this context. On the contrary, according to the present invention in this example the change in the position of diodes D 5  and D 6  is detected by receiver  72 , the imbalance is calculated, and the corresponding control signals are conveyed to a positioning motor (not depicted) to adjust part  104   c  in space, e.g. about or with axis  96   a.    
         [0063]    The positioning motor is either a stepper motor that travels to a predefined position or a motor of any kind that adjusts component  104   c  until the receiver, based on the modified position of diodes D 1 , D 2 , D 3 , and D 4 , detects the correct computationally ascertained balance position and terminates the adjustment operation. Component  104   b  is correspondingly equipped with diodes D 7 , D 8 , D 9 , and D 10 .  
         [0064]    For illustration, FIG. 16 also depicts the corresponding coordinate systems  105 ,  106 , and  103  as well as (symbolically) a specimen  93 .  
                                         PARTS LIST                                 1   Pivot support        2   Electric motor        3   Electric motor        4   Electric motor        5   Stand foot        6   Support column        7   Bracing point        8   Bracing spring        9   Microscope        10   Computer        11   Interface        12   Interface        13   Interface        14   Interface        15   Angle sensor        16   Angle sensor        17   Angle sensor        18   Computer        19   Reading device        20   Electric motor        21   Counterweight        22   Component        23   Counterweight        24   Counterweight        25   Electric motor        26   Electric motor        27   Computer        28   Load        29   Angle sensor        30   Brake        31   Adjusting motor        32   Control line        33   Chip        34   Microscope        35   Component        36   Accessory part        37   Accessory part        38   Data medium        39   Data medium        40   Barcode data medium        41   Microchip data medium        42   Accessory part        43   Swiveling tube        44   Barcode data medium        45   Angle sensor        46   Information system        47   Accessory part        48   Computer        49   Balancing system        50   Balancing system        51   Keypad        52   Display        53   Intelligent component        72   Signal receiver and/or transmitter        96a, 96b, 96c   Axes       102a, 102b, 102c   Signal transducers       104a, 104b, 104c   Component       D1 through D10   Diodes (signal transmitters and/or receivers)