Abstract:
An operating device ( 10 ) for controlling a medical apparatus ( 100 ), comprising a device body ( 11 ) and at least one switching element ( 12 ) arranged at the device body ( 11 ) and operable by a user by pressing, wherein the medical apparatus ( 100 ) is controllable via a switching state of the switching element ( 12 ), characterized by a radio transmitter ( 20 ) included in the device body ( 11 ) and coupled to the switching element ( 12 ) for outputting a radio switching signal indicating the switching state, a radio receiver ( 102 ) provided separately from the device body ( 11 ) and coupleable to the medical apparatus ( 100 ) for receiving the radio switching signal output by the radio transmitter ( 20 ), and an energy supply unit ( 16 ) for supplying at least the device body ( 11 ) with energy, wherein the device body ( 11 ) comprises a means for being attached to a hand and/or an arm of the user.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    Applicant hereby claims foreign priority benefits under U.S.C. §119 from German Utility Model Application No. DE 10 2014 105 509.8 filed on Apr. 17, 2014, the contents of which are incorporated by reference herein. 
       TECHNICAL FIELD 
       [0002]    The invention relates to an operating device for controlling a medical apparatus, comprising a device body and at least one switching element arranged at the device body and operable by a user by pressing, wherein the medical apparatus is controllable via a switching state of the switching element. 
       BACKGROUND 
       [0003]    In surgery, an operator in many cases uses medical apparatuses which support him during surgery. As an example for this an assistance system is to be mentioned, which allows for tracking of an imaging endoscope during laparoscopic surgery. 
         [0004]    In order to operate such a medical apparatus, the operator working under sterile conditions has to give control commands to the apparatus in order to initiate the desired actions. This happens for example by means of a switching element, which the operator presses with a finger. 
         [0005]    For performing the surgery the operator works with different surgical instruments, which he changes in the course of the surgery. To be able to operate the medical apparatus during surgery as well, the operator has to be given a possibility for interaction with the apparatus without him having to put down his surgical instruments for this and thus being limited or impeded in his surgical activity. 
         [0006]    In principle, it is possible to fix a switching element at the surgical or laparoscopic element itself, so that the operator can operate the medical apparatus with a finger of the hand which also holds the instrument. With respect hereto, it is exemplarily referred to Documents DE 10 2009 018 918 A1 and EP 1 937 177 A1, wherein operating devices are described which can be attached to laparoscopic instruments in order to control an assistance system for endoscope tracking. 
         [0007]    A disadvantage of these conventional solutions is that for each individual instrument a distinct switching element is to be provided. Thus, these solutions become technically complex and expensive. 
       SUMMARY 
       [0008]    It is the object of the invention to amend an operating device of the above-mentioned type such that it allows an operator to control a medical apparatus in a technical uncomplex and simple manner without him having to put down the respectively used surgical instrument. 
         [0009]    The invention solves this object by a radio transmitter included in the device body and coupled to the switching element for outputting a radio switching signal indicating the switching state, a radio receiver provided separately from the device body and coupleable to the medical apparatus for receiving the radio switching signal output by the radio transmitter, and an energy supply unit for supplying at least the device body with energy, wherein the device body comprises a means for being attached to a hand and/or an arm of the user. 
         [0010]    According to the invention the instrument body, at which the switching element is located, is formed such that the user can attach it to his hand, e.g. to a finger and/or to an arm. For example, it is possible to attach the device body to the index finger of that hand with which the user also holds the surgical instruments during a surgery. By pressing the switching element on the instrument just being used, he causes the operating device to output the radio switching signal in order to control the apparatus in accordance to this signal. 
         [0011]    In contrast to the solutions known from prior art, the operating device according to the invention does not require anymore to remount the switching element from one instrument to another. Rather, the switching element arranged at the device body remains on the finger or the hand of the user during the entire surgery, which significantly simplifies the handling of the operating device. In the following, a switching element according to the invention shall indicate any type of operating element, which can be operated by pressing, such as e.g. a pushbutton, which returns to its starting position after pressing. 
         [0012]    As the operating device according to the invention has a radio transmitter included in the device body and a radio receiver being separate therefrom and coupleable to the medical apparatus, additional cable connections between the operating device and the medical apparatus become redundant. Due to such a wireless radio control (RF control) of the medical apparatus, possible pitfalls are avoided. Further, the usual freedom of movement of the operator is maintained. 
         [0013]    The operating device has an energy supply unit, which supplies at least the device body, i.e. the functional components included therein, with the energy required for the device operation. The radio receiver provided separately from the device body can also be supplied with the required energy via the medical apparatus with which it is coupled. However, it is also possible that the energy supply unit does not only supply the energy to the device body but also to the radio receiver. In a further alternative embodiment the radio receiver can also have a distinct energy supply, e.g. a battery. 
         [0014]    Preferably, the radio receiver is connected to the medical apparatus via an electrical wire. The coupling of the radio receiver to the medical apparatus is also possible in another manner, e.g. via an optical fiber or via radio (RF). 
         [0015]    The operating device preferably has a control module coupled to the switching element, which includes the radio transmitter and a signal processor for generating the radio switching signal to be output by the radio transmitter. This control module can be integrated in the device body itself or be provided as separate assembly, which is connected via electrical wires to the device body. 
         [0016]    In a preferred embodiment, the radio transmitter transmits a pairing signal to the radio receiver for a first time establishment of communication. Via the pairing signal the radio transmitter and thus the device body including the radio transmitter are identified as a device component which is allowed to communicate with the radio receiver and thus the medical apparatus coupled with the radio receiver. Thus, a secure and reliable control of the medical apparatus is possible. This is in particular true, if the device body of the operating device including the radio transmitter is designed as disposable, i.e. is disposed of after single use and replaced by a new device body, while the radio receiver coupled with the medical apparatus remains in operation over many surgeries. The pairing ensures that each device body to be newly used is first examined as to whether it is compatible with the usually re-usable radio receiver. 
         [0017]    A particularly preferred embodiment provides a first radio-transmitting-receiving unit, which includes the radio transmitter and a further radio receiver, and a second radio-transmitting-receiving unit coupleable with the medical apparatus, which includes the radio receiver and a further radio transmitter. In this embodiment, the device body can not only transmit radio signals, but also receive such radio signals. 
         [0018]    Preferably, the energy supply unit comprises suitable means for supplying electro-magnetic energy to the device body. This embodiment can be used for the components included in the device body to be supplied with energy in the manner of a passive RFID, which energy the device body receives e.g. via an antenna in the form of the electromagnetic radiation generating the radio signal. Thus, the energy supply can be provided by the same bidirectional radio connection by which also the radio switching signal is transmitted. However, it is also possible to provide a distinct radio connection for this. 
         [0019]    In an alternative embodiment, supplying energy to the device body can also be carried out by means of an energy storage, e.g. a battery or an accumulator, included in the control module. 
         [0020]    In a particularly preferred embodiment, the device body comprises a ring which can be put on a finger of the user. The ring is preferably formed such that its ring diameter can be adjusted variably. This may be realized by a correspondingly deformable ring material or a suitable adjustment device, e.g. a toothed belt, a spring assembly or the like. It is also possible to coat the inner circumferential surface of the ring with a foam layer, which distributes the pressure exerted by the ring on the finger equally to exclude e.g. circulatory disorders in the finger. 
         [0021]    The switching element is preferably arranged on an outer circumferential surface of the ring, e.g. at a position at which the ring abuts the bottom side of the fingertip. Thus, the switching element can be operated easily. 
         [0022]    In an alternative embodiment, the device body comprises a flat, flexible material piece of a medical plaster type having an area of adhesion, which is bondable onto the hand and/or the arm of the user. In this embodiment, the device body forms a “switching plaster”, which can be manufactured easily and cost-efficiently. For example, a biocompatible adhesive is positioned on the area of adhesion, the adhesive strength of which is determined such that the switching plaster adheres reliably on the target surface, e.g. the surface of a surgical glove or the skin of the operator. In addition, the adhesive strength shall be determined such that the switching plaster can be released without any greater impairment, e.g. without damage of the surgical glove, from the target surface. The area of adhesion is preferably formed such that the switching plaster, after it has once been removed from the target surface, can be adhered again with sufficient adhesive strength on the target surface. In an alternative embodiment, the area of adhesion, can also be realized as separate adhesive tape, which is coated on both sides with an adhesive and is adhered with one side on the device body and with the other side on the hand of the operator for use. 
         [0023]    In a further alternative embodiment, the device body comprises a cover at least partially surrounding the hand of the user. At this cover, which the user slips over the hand, the switching element is positioned. Preferably, the cover is positioned at the hand, with which the user also holds the surgical instrument. Thus, the user can press the switching element on the instrument just being used in order to control the medical apparatus. 
         [0024]    The cover according to the invention can for example be formed in the shape of a thimble, which only covers the last phalanx, two phalanxes or the entire finger. The cover can also be designed such that it covers several or all fingers of a hand in the manner of a glove. 
         [0025]    The cover consists preferably of an elastic material, which adapts to the finger or hand shape when the operator puts the cover on. For this, in particular materials are suitable which are also used for surgery gloves. Due to its elasticity, the cover adapts well to the individual finger or hand shape of the operator. Therefore, despite of individually different hand and finger sizes, it will usually be sufficient to keep the cover at hand in only one standard size or at least in only few sizes. 
         [0026]    The cover can be worn under or over the sterile surgical glove, which the operator uses during surgery. However, due to reasons of ergonomics and usability it seems to be advantageous to wear the cover over the surgical glove. The elasticity of the cover allows it to be fitted in a crease-free and tight manner to the finger or hand of the operator without limiting the freedom of movement significantly. 
         [0027]    Preferably, the switching element is arranged at a position of the cover at which a fingertip of the operator is located. Thus, it is possible to operate the switching element directly with the fingertip, which makes handling of the operating device particularly easy. 
         [0028]    The switching element is for example designed as microswitch/micro key, i.e. as electric switch/electric key, the switching contacts of which only have a slight distance of a few millimeters with respect to each other in the open state. Such a microswitch/micro key is in particular suited for the switching of small loads and thus for the generation of a switching signal according to the invention. Due to the small switching contact distance the microswitch/micro key can be operated in a particularly easy manner. Thereby, it communicates a tactile perception to the operator, which shows the operator, when the switching signal has been generated by his pressing the switching element. 
         [0029]    The switching element can also be designed as pushbutton switch with two switch steps, a first switch step thereof being operable by pressing the pushbutton switch up to a predetermined first pushbutton travel and a second switch step thereof being operable by further pressing the pushbutton switch starting from the first switch step up to a predetermined second pushbutton travel. The pushbutton switch is preferably designed such that each switch step communicates a distinct tactile perception to the operator, which indicates reaching of the respective switch step. By providing two distinguishable switch steps two different switching signals can be generated, one of which is associated to the first and the other one is associated to the second switch step. If, however, only a single switching signal shall be generated, the provision of two switch steps provides the possibility to increase the first-fault security, as in case of failure of one of the two switch steps, the respective other switch step is still available for generating the switching signal and it thus does not lead to the failure of the system. 
         [0030]    In a specific embodiment, the device body is formed in one piece, so that all components of the operating device, with the exception of the separate radio receiver, are integrated in the device body. This is in particular true for the control module coupled with the switching element. Alternatively the device body may be formed from two separate parts, electrically connectable via a wire structure, one of which parts includes the switching element and the other one includes the control module. This embodiment has the advantage that the part holding the switching element can be manufactured particularly small and thus does not restrict the operator during gripping and manipulating of the instruments and the tissue structures to be treated. 
         [0031]    In a possible embodiment, the part of the device body including the control module is designed as elastic bangle. Said bangle can be attached in the region of the wrist, at the forearm or at the upper arm of the operator. Instead of an elastic bangle also a Velcro strip can be used at which the control module is attached. 
         [0032]    Preferably, the cover includes a wire structure for the electrical connection of the switching element with the control unit. The wire structure comprises for example one or more micro cables. In order to connect the wire structure included in the cover electrically with the control module, for example a plug connection is provided, which is formed from one or more plugs attached to the end of the wire structure and one or more sockets mounted on the control unit. 
         [0033]    In order to guarantee the elasticity of the cover, also the wire structure integrated in the cover is preferably designed elastically. This can for example be achieved by a meander-shaped arrangement of the micro cables forming the wire structure. 
         [0034]    In a particularly preferred embodiment, the operating device has a sensor assembly for detecting the switching element within a predetermined activation zone, wherein the output of the radio switching signal by the switching element to the medical apparatus is enabled, if the sensor assembly detects the switching element within the activation zone, and the output of the radio switching signal by the switching element to the medical apparatus is blocked, if the sensor assembly does not detect the switching element within the activation zone. 
         [0035]    In principle, it is possible to operate the switching element according to the invention only by pressing it onto an arbitrary position which provides a sufficient resistance for triggering the switching element. However, in this case an unintended operation of the switching element is likely to occur, e.g. if the operator touches accidentally with his finger, at which the switching element is positioned, the surgical instrument or another object. The above-mentioned sensor assembly now ensures that the switching element is only activated for the output of the radio switching signal to the medical apparatus, if the sensor assembly detects the switching element within a predetermined activation zone. Outside of this activation zone the key function of the switching element is deactivated. The sensor assembly can operate according to an arbitrary functional principle provided that it detects the switching element within the activation zone, so that the switching element is activated only there. 
         [0036]    For example, a mechanically operating sensor assembly has a first form closure part arranged at the switching element and a second form closure part positionable within the activation zone, wherein the switching element is operable by pressing for outputting the radio switching signal, when the first form closure part and the second form closure part engage. Such a sensor assembly works according to a lock-and-key principle, in which one of the two form closure parts forms quasi the key and the other one the lock. Thus, for example the second form closure part can be attached to the surgical instrument. In this case, the position at which the second form closure part is located, forms the activation zone. Only if the operator moves the switching element to this position and engages the two form closure parts there, the switching element is activated. An accidental operation of the switching element is thus largely excluded. 
         [0037]    Preferably, the switching element has a push button, which is arranged in a sunk-in manner within one of the ring elements forming the first form closure part. In this case, the second form closure part has a raised counter piece which engages the ring element for applying pressure to the push button. In this embodiment, it is ensured that the push button is only operated, if the ring element forming the first form-closure part is put positively on the raised counter piece, which then positively abuts the inner circumferential surface of the ring element. 
         [0038]    In an alternative embodiment, the sensor assembly comprises a magnetic switch. This magnetic switch is formed from an element switchable by a magnetic field and an element generating the magnetic field. One of the elements forming the magnetic switch is arranged at the switching element, while the other element is positionable within the activation zone. For example, it is possible to attach a magnet to the medical instrument. If the operator moves the magnetically switchable element arranged at the cover in a region surrounding the magnet, the magnetic field generated by the magnet acts on the switchable element causing it to be activated. If the switching element is operated by pressing in this activated state, the generated control signal is transmitted to the medical apparatus. If, in contrast, the switching element is pressed, while it is in a region in which the magnetic field does not act on the magnetically switchable element, the transmission of the control signal to the medical apparatus is blocked. 
         [0039]    The magnetically switchable element is for example a reed-switch or a Hall sensor. 
         [0040]    Further, the invention relates to a method for providing an operating device for controlling a medical apparatus according to independent claim  22 . 
         [0041]    In this method, preferably a disposable is manufactured. For this, in particular one of the above-described embodiments such as a switching plaster or a ring may be used. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0042]    The invention will be explained in more detail in the following on the basis of the Figures, wherein: 
           [0043]      FIG. 1  shows an operating device according to the invention for controlling a medical apparatus as block diagram, 
           [0044]      FIG. 2  shows a schematic illustration of the operating device according to  FIG. 1  when a switching plaster is used as device body, 
           [0045]      FIG. 3  shows a modification of the operating device according to  FIG. 1  as block diagram, 
           [0046]      FIG. 4  shows a schematic illustration of the operating device according to  FIG. 3  when a switching plaster is used as device body, 
           [0047]      FIG. 5  shows a schematic illustration showing different suitable positions, in which the switching plaster can be attached to the hand of the user, 
           [0048]      FIG. 6  shows a further embodiment of the operating device according to the invention, in which the device body is formed by an integral elastic ring, 
           [0049]      FIG. 7  shows a schematic illustration of a pushbutton switch with two switch steps, which constitutes an exemplary embodiment of the switching element according to the invention, 
           [0050]      FIG. 8  shows a further embodiment of the operating device, in which the two-part device body is formed from an elastic cover and a bangle, 
           [0051]      FIG. 9  shows the operating device according to  FIG. 8  in a further schematic illustration, 
           [0052]      FIG. 10  shows a modification of the embodiment shown in  FIG. 8 , in which a mechanical sensor assembly is used, 
           [0053]      FIG. 11  shows the operating device according to  FIG. 10  in a further schematic illustration, 
           [0054]      FIG. 12  shows a further modification of the embodiment shown in  FIG. 8 , in which a magnetic sensor assembly is used, and 
           [0055]      FIG. 13  shows the operating device according to  FIG. 12  in a further schematic illustration. 
       
    
    
     DETAILED DESCRIPTION 
       [0056]      FIG. 1  shows the operating device  10  according to the invention in a block diagram. 
         [0057]    The operating device  10  has a pushbutton  12  as switching element, which an operator can press for operating the operating device  10 . The operating device  10  further comprises a control module  14  coupled to the pushbutton  12 , which control module  14  includes a battery  16  as energy storage, a signal processor  18  and a radio transmitter  20 . In the embodiment according to  FIG. 1 , the pushbutton  12  and the control module  14  are integrated in a one-piece device body  11 . As will be later described in detail, it is however also possible to provide a two-piece device body, wherein at one part of such a device body the pushbutton  12  is arranged, while the other part of the device body includes the control module  14 . 
         [0058]    The operating device  10  further has a radio receiver  102 , which is e.g. coupled via an electric wire with a medical apparatus  100 . The apparatus  100  is for example an imaging assistance system, which tracks an endoscope equipped with a camera during a laparoscopic surgery. The radio receiver  102  forms an assembly separate from the device body  11 . 
         [0059]    The battery  16  included in the control module  14  supplies electro-magnetic energy both to the components also included in the control module  14 , namely the signal processor  18  and the radio transmitter  20 , as well as to the pushbutton  12  coupled to the control module  14 . The signal processor  18  receives an operation signal, which the pushbutton  12  outputs to the control module  14 , when the operator operates the pushbutton  12  by pressing. This operation signal indicates the switching state of the pushbutton  12 . The signal processor  18  converts the operation signal received from the pushbutton  12  and outputs it to the radio transmitter  20 . The radio transmitter  20  transmits the radio switching signal generated by the signal processor  18  to the radio receiver  102  which is coupled to the medical apparatus  100 . As a consequence, in the apparatus  100  an action is initiated corresponding to the received radio switching signal, e.g. an automatic tracking of an endoscope directed to the surgical site. 
         [0060]    In  FIG. 2 , an embodiment is schematically shown, which operates according to the functional principle shown in  FIG. 1 . In the embodiment according to  FIG. 2 , a one-piece device body  11  is formed from a switching plaster, i.e. from a flat, flexible material piece, which is bondable like a medical plaster. In the present embodiment, the switching plaster  11  is directly bonded onto the skin of a finger  13  or onto a surgical glove, which the operator wears during surgery.  FIG. 2  illustrates how the switching plaster  11  transmits the radio switching signal to the radio receiver  102 . In the embodiment according to  FIG. 2 , the switching plaster  11  is supplied by the battery  16  shown in  FIG. 1 , which is integrated in the switching plaster  11 . 
         [0061]      FIG. 3  shows an embodiment of the operating device  10  which is modified with respect to the embodiment according to  FIG. 1  in that the device body  11  is not supplied via a battery, but in the manner of a passive RFID element via an externally supplied radio signal. For this, a further radio transmitter  101  is provided, which is part of a separate radio-transmitting-receiving unit  103 , coupleable to the medical apparatus  100 , which radio-transmitting-receiving unit  103  also includes the radio receiver  102 . Correspondingly, the control module  14  arranged in the device body  11  includes a radio-transmitting-receiving unit  21 , which includes in addition to the radio transmitter  20  a further radio receiver  23 . In order to supply energy to the device body  11 , the radio receiver  23  absorbs the energy, which the radio transmitter  101  emits in the form of a radio signal. This absorbed radio energy is then converted into electric energy in the control module  14 . 
         [0062]      FIG. 4  illustrates the bidirectional radio communication for the embodiment according to  FIG. 3 . In particular,  FIG. 4  shows as supplement to the embodiment illustrated in  FIG. 2  how the switching plaster forming the device body  11  is supplied with energy by the radio-transmitting-receiving unit  101 . 
         [0063]    In  FIG. 5  it is illustrated that the switching plaster  11 , depending on requirements, is bondable onto different positions on the hand of the operator. In this context, it is to be pointed out that the invention is not limited to the use of a single switching plaster  11  (or an alternatively designed device body  11 ). Thus, it is also possible to attach a plurality of switching plasters  11  to the hand of the operator. 
         [0064]    In  FIG. 6 , an embodiment is illustrated, in which the device body  11  is formed from an elastic ring  70 , which the operator can put on his finger  13 . In order to strengthen the fixation of the ring  70  to the finger  13  an adhesive may be applied to the inner circumferential surface of the ring  70 . Also in this embodiment, the device body formed by the ring  70  is formed in one piece. Both the pushbutton  12  and the control module  14 , which includes the battery  16 , the signal processor  18  and the radio transmitter  20 , are arranged on the outer circumferential surface in an angular distance of approximately 180° with respect to each other. However, it is also possible that the ring  70  only forms one part holding the switching element  12  of a two-part device body. In this case, a second part holding the control module  14  would have to be provided, which is both coupled via a wire structure (not shown) to the ring and as well coupled via radio to the radio receiver  102 . 
         [0065]      FIG. 7  shows an exemplary embodiment in which the switching element  12  is formed as pushbutton switch with two switch steps. The two switch steps are activated by operating forces of different strengths. In the specific example according to  FIG. 7 , if an operating force F of 2N is applied, a first pushbutton travel of 0.5 mm is generated. The reaching of this pushbutton travel is tactilely communicated by a click to the operator. If the operator then starting from the first switch step fully presses the pushbutton switch  12  with a force of 5N, a second pushbutton travel of further 0.4 mm and thus a total stroke of 0.9 mm is generated. With this pushbutton travel the second switch step is reached, which is again tactilely communicated to the operator by a click. 
         [0066]    In the further embodiments according to  FIGS. 8 to 13  described below, the device body  11  is formed from two separate parts coupleable to each other, namely an elastic cover  22  and a bangle  32 , in contrast to the embodiments above. 
         [0067]    The operating device  10  according to  FIG. 8  includes the elastic cover  22 , which is adapted to the hand of the operator indicated with  24  in  FIG. 8  such that it can be pulled over an index finger  26 . The pushbutton  12  is arranged at the cover  22  at a position at which it is located on the bottom side of the tip of the index finger  12 , when the cover  22  is pulled on the index finger  26  of the operator. Thus, the operator can operate the pushbutton  12  with his fingertip. 
         [0068]    The pushbutton  12  has a flat rectangular housing on which a push button is arranged, e.g. in the form of a switching membrane  30 , which is deformable by pressing. By pressing the switching membrane  30 , switching contacts (not explicitly shown in  FIGS. 8 and 9 ) included in the housing  28 , contact each other. By closing these switching contacts, the pushbutton  12  is prompted to output the switching signal. 
         [0069]    The operating device  10  according to  FIG. 8  further includes the elastic bangle  32 , which the operator puts on the wrist. The bangle  32  carries the control module  14  electrically connected to the pushbutton  12 . The pushbutton  12  and the control module  14  are connected to each other via two cables  34  and  36 , which are respectively guided with one of their ends out of the housing  28  of the pushbutton  12  and coupled with their other end to the control module  14 . The cables  34  and  36  are coupled to the control module  14  via two plug connectors  38  and  40  (cf.  FIG. 11 ), which are respectively formed from a plug  54 ,  56  arranged at the corresponding cable  34  or  36  and a socket  58 ,  60  associated to said plug  54 ,  56 , which socket  58 ,  60  is positioned at the control module  14 . One of these two cables  34  and  36  is connected to the battery  16  inside the control module  14  and thus serves for supplying electro-magnetic energy to the pushbutton  12 , while the other cable is coupled to the signal processor  18 . Correspondingly, the pushbutton  12  transmits the switching signal via the other one of the two cables  34  and  36  to the signal processor  18 , which switching signal is generated with operating the switching membrane  30 . 
         [0070]    In  FIG. 9 , once again the two-part structure of the device body  11  is illustrated. 
         [0071]    In  FIGS. 10 and 11 , a further embodiment of the operating device  10  is shown. This embodiment differs from the embodiment of  FIG. 8  in an assembly, which allows the operator to activate the pushbutton  12  for outputting the switching signal only as required. 
         [0072]    This assembly includes a form closure part  42  cooperating with the pushbutton  12  in a manner explained below, in order to activate said pushbutton for outputting the switching signal. The form closure part  42  comprises a plate-like element  44 , on the top side of which a raised, circular counter piece  46  is arranged. The counter piece  46  is adapted with respect to shape and size to the switching membrane  30  of the pushbutton  12  such that it presses onto the switching membrane  30 , when the operator positions the pushbutton element  12  onto the form closure part  42 . In order to allow a positive positioning of the pushbutton  12  onto the form closure part  42  a form closure part  48 , corresponding to the form closure part  42 , is formed at the pushbutton  12 , the form closure part being  48  being a circular ring surrounding the switching membrane  30  concentrically. If the operator presses the pushbutton  12  in an accurately fitting manner onto the form closure part  42 , the ring  48  is positioned on the top side of the form closure part  42  such that it abuts the circumference of the raised counter piece  46 . In this positive abutment, the counter piece  46  then presses onto the switching membrane  30  causing the switching contacts included in the housing  28  of the pushbutton  12  to be closed. 
         [0073]      FIG. 11  also shows the pushbutton  12  provided with the ring  48  in cross section. This cross sectional view shows that the switching membrane  30  is arranged in a sunk-in manner within the ring  48 . This sunk-in arrangement means that the ring  48  in cross section projects over the switching membrane  30 , so that the switching membrane  30  is not operated, when the pushbutton  12  and thus the projecting ring  48  is for example positioned onto a planar or only slightly curved surface. Only if the pushbutton  12  is positioned in an accurately fitting manner onto the form closure part  42  the counter piece  46  engaging the ring  48  allows for an operation of the switching membrane  30 . 
         [0074]    Thus, the two form closure parts  42  and  48  form a sensor assembly, generally indicated with  52  in  FIG. 10 , which allows the pushbutton  12  to be detected in a predetermined activation zone and an output of the switching signal to the control module  14  to be enabled only, if the pushbutton  12  is in the activation zone. The activation zone is thereby defined by the location of the form closure part  42 , which is for example attached on a surgical instrument. 
         [0075]    In  FIGS. 12 and 13  a further embodiment is shown which differs from the embodiment according to  FIGS. 10 and 11  in a different type of sensor assembly  52 . 
         [0076]    While in the embodiment according to  FIGS. 10 and 11  the two form closure parts  42  and  48  quasi form a mechanically operating sensor assembly for detecting a release status of the pushbutton element  12 , in this embodiment the sensor assembly is an electro-magnetically operating assembly. 
         [0077]    The sensor assembly  52  shown in  FIGS. 12 and 13  is formed from a magnetic switch, which comprises a magnetically switchable element in the form of a reed-switch  62 , arranged adjacent to the housing  28  of the pushbutton  12 , and a magnetic plate  50  magnetically interacting with the reed-switch  62 . The magnetic plate  50  generates a magnetic field, which can be used for defining an activation zone within which the pushbutton  12  is activated for outputting the switching signal. The activation zone in turn is defined by the location of the magnetic plate  50 , wherein the magnetic plate  50  is preferably attached to the surgical instrument. If the operator moves the pushbutton  12  held at its index finger  26  in the magnetic field generated by the magnetic plate  50 , it acts such on the reed-switch  62  arranged at the pushbutton  12  that the reed-switch  62  is closed and thus the pushbutton  12  is activated via a corresponding signal. If the operator then presses the pushbutton  12  in the activated state with its switching membrane  30  on the magnetic plate  50 , the pushbutton  12  transmits the switching signal via the radio transmitter  20  included in the control module  14  to the medical apparatus  100 . 
         [0078]    If, however, the pushbutton  12  is operated outside of the activation zone, i.e. outside of the sphere of action of the magnetic field generated by the magnetic plate  50 , the output of the switching signal from the reed-switch  62  included in the pushbutton  12  is blocked. Consequently, in this state, an operation of the switching membrane  30  of the pushbutton  12  does not cause an output of the switching signal to the medical apparatus  100 . 
         [0079]    The embodiments of the sensor assembly explained above are only intended as examples. Thus, e.g. the reed-switch  62  can also be replaced by a mechanically switchable element of another type, e.g. a Hall sensor. 
         [0080]    Generally, also sensor assemblies other than the mechanical assembly according to the embodiment shown in  FIGS. 10 and 11  or the electromagnetical assembly according to the embodiment shown in  FIGS. 12 and 13  can be used for detecting the pushbutton  12  in the activation zone, e.g. an assembly operating with optical means such as an illuminating diode and a photodiode. Alternatively, also a sensor assembly may be used, in which the activation zone is marked by a chemical substance and detected via a corresponding chemical sensor, which is arranged at the pushbutton  12 . 
         [0081]    The above-described embodiments are only intended for the exemplary illustration of the subject-matter of the invention. In particular, the different aspects described for the individual embodiments can be combined in a reasonable manner. This applies in particular to the concrete design of the one- or multi-part device body  11  as well as to the concrete design of the switching element  12 . The same applies to the energy supply of the device body  11 . Thus, for example the control module  14  shown in  FIGS. 8 to 13  can also be supplied with energy externally in the manner of a passive RFID element.