Abstract:
A sensor device for an oxygen module mountable on board an aircraft includes an electrical conducting element, a defining device for defining at least one measurement section, assigned to the oxygen module, on the electrical conducting element, and an evaluating unit for determining an electrical resistance present along the at least one measurement section, the evaluating unit further being configured to ascertain, based on the determined electrical resistance, whether the oxygen module is present. An aircraft has at least one oxygen module mounted on board the aircraft and at least one sensor device of the above type.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is entitled to and claims the benefit of German Application No. DE 10 2012 008 266.5 filed Apr. 25, 2012 and U.S. Provisional Application No. 61/637,873, filed Apr. 25, 2012, the disclosures of each of which, including the specification, claims, drawings and abstract, are incorporated herein by reference in their entirety. 
     
    
     FIELD 
       [0002]    The present invention relates to a sensor device for an oxygen module mountable on board an aircraft and to an aircraft having at least one oxygen module mounted on board the aircraft and at least one sensor device of this type. 
       BACKGROUND 
       [0003]    In conventional cabin architectures of aircraft, the seats and accordingly also the seat rows are arranged at fixed seat positions, i.e. aircraft usually have a fixed cabin architecture. To each seat row there is usually assigned a respective oxygen module. Accordingly, each of the oxygen modules is normally arranged and installed above the seat row assigned to it. For this purpose, the oxygen modules are normally connected to a supply duct extending in the aircraft. 
         [0004]    In order to be able to carry more or fewer passengers, if required, in subregions of the aircraft cabin or the entire aircraft cabin, increasingly a more flexible cabin layout is sought. For this purpose, the seats may be displaced to increase or decrease the seat spacing in the longitudinal direction of the aircraft. In order to ensure the correct assignment between oxygen module and seat row, it is desirable for all the required oxygen modules to be installed on board the aircraft. To check the correct layout of the variable cabin architecture, it is desirable to ascertain whether each oxygen module is situated at the respectively correct position (in the longitudinal direction of the aircraft) above the seat row assigned to it. 
       SUMMARY 
       [0005]    It is an object of the present invention to provide a sensor device and an aircraft having at least one such sensor device, it being possible by means of the sensor device to reliably determine in a simple manner whether oxygen modules mountable on board the aircraft are installed. 
         [0006]    This object is achieved by the subject matter of attached claims. Specific embodiments emerge in each case from the dependent claims. 
         [0007]    According to a first aspect, a sensor device for an oxygen module mountable on board an aircraft is provided. The sensor device comprises an electrical conducting element, a defining device and an evaluating unit. The defining device is configured to define at least one measurement section, assigned to the oxygen module, on the electrical conducting element. The evaluating unit is configured to determine an electrical resistance present along the at least one measurement section. Furthermore, the evaluating unit is configured to ascertain, based on the determined electrical resistance, whether the oxygen module is present, for example is correctly fitted and installed. 
         [0008]    The electrical conducting element may comprise an electrical conductor, such as, for example, an electrically conductive wire. It is, for example, conceivable that the electrical conductor, such as the electrical conductive wire, is wound in the form of a coil and comprises a multiplicity of turns. The electrical conducting element may be connectable or connected at both of its ends to a voltage source and be supplied with a voltage via the latter, in order to carry an electric current. 
         [0009]    The defining device is configured to define on the electrical conducting element, for example on the electrical conductor, such as the electrically conductive wire, a measurement section at which the associated resistance is to be measured (on application of a predetermined voltage). For defining the measurement section, for example a first (fixed) measurement point may be predetermined and the defining device may define at least one second (variable) measurement point and hence the measurement section. The first measurement point may, for example, be the beginning or the end of the electrical conductor. The at least one second measurement point may be any desired point along the electrical conductor. For example, the at least one second measurement point may be assigned to the oxygen module, for example the position of the oxygen module in the longitudinal direction of the aircraft. Accordingly, the measurement section may be the region of the electrical conductor extending between the first and the at least one second measurement point. 
         [0010]    It is, however, also conceivable that two or more measurement points are defined by the defining device and accordingly the measurement section is defined by these two or more measurement points. The electrical resistance present along this defined measurement section can then be determined by the evaluating unit. For example, the evaluating unit may have an ohmmeter component which can directly measure the electrical resistance along the measurement section. It is, however, also conceivable that the evaluating unit can determine the resistance value based on a measured current and a voltage applied and thereby known to the evaluating unit. 
         [0011]    The defined measurement section may be a continuous section along the electrical conductor between the first and the second measurement point. It is, however, also conceivable that the defined measurement section is composed of two or more measurement subsections along the electrical conductor. It is, for example, conceivable that a first measurement subsection runs from the first measurement point to the second measurement point along the electrical conductor, a second measurement subsection runs from a third measurement point to a fourth measurement point along the electrical conductor, etc. 
         [0012]    Based on the determined electrical resistance, the evaluating unit can infer whether the oxygen module is present, e.g. correctly installed. 
         [0013]    For example, the evaluating unit may be configured to compare the determined electrical resistance with a predetermined reference resistance and from the comparison derive whether the oxygen module is present. For example, the evaluating unit may be configured to ascertain that the oxygen module is present when the determined electrical resistance is less than a predetermined reference resistance, for example by at least a preset deviation from the predetermined reference resistance. The reference resistance may, for example, be the electrical resistance along a preset section of the electrical conductor or the electrical resistance along the entire electrical conductor. 
         [0014]    Since the oxygen module is assigned to the measurement section, the evaluating unit can, for example, only ascertain a deviation between the determined electrical resistance and the predetermined reference resistance, such as, for example, ascertain that the determined electrical resistance is less than the predetermined reference resistance (for example by at least a preset deviation), when an oxygen module is present at all, for example is installed. The assignment may be effected via a physical connection, e.g. in the form of a string, cord or lanyard connection, between the sensor device and the oxygen module. It is conceivable that, only when the physical connection between sensor device and oxygen module exists, does the defining device define the measurement section and accordingly only then is a deviation of the measured electrical resistance from the predetermined reference resistance ascertainable. By contrast, if no deviation from the reference resistance is ascertained, the evaluating unit can infer that the oxygen module is not installed. 
         [0015]    Through the resistance measurement, it is therefore reliably determined in a simple manner whether the oxygen module is present. 
         [0016]    Furthermore, with the aid of the sensor device, it is possible to determine the position of the oxygen module, e.g. the position of the oxygen module in the longitudinal direction of the aircraft or the position of the oxygen module with respect to a supply duct extending in the longitudinal direction of the aircraft. For this purpose, the evaluating unit may be configured to derive the position of the oxygen module by comparing the determined electrical resistance with the reference resistance. For example, the evaluating unit may derive the position of the oxygen module from the quotient between the determined electrical resistance and the reference resistance. The reference resistance may, for example, be previously known to the evaluating unit or be firstly predetermined, e.g. in a calibrating operation, by the evaluating unit. The reference resistance may be the electrical resistance along the entire length of the electrical conducting element. If now a section of the electrical conducting element is defined as the measurement section, the evaluating unit can infer the length of the subsection from the multiplication of the length, assigned to the reference resistance, of the electrical conductor (which may, for example, be stored in the evaluating unit) by the quotient of the determined electrical resistance along the measurement section and the resistance along the entire section (the quotient results from the rule of three method). The length l of an electrical conductor can be calculated from the following formula: 
         [0000]    
       
         
           
             
               
                 
                   R 
                   = 
                     
                    
                   
                     
                       l 
                       A 
                     
                     * 
                     ρ 
                   
                 
               
             
             
               
                 
                   = 
                     
                    
                   
                     &gt; 
                     l 
                   
                 
               
             
             
               
                 
                   = 
                     
                    
                   
                     
                       R 
                       * 
                       A 
                     
                     ρ 
                   
                 
               
             
           
         
       
     
         [0017]    In the above formula, R denotes the electrical resistance of the electrical conductor, A denotes the cross-sectional area of the electrical conductor and ρ denotes the resistivity (material constant) of the electrical conductor. 
         [0018]    This gives for the length l 1  of the measurement section 
         [0000]    
       
         
           
             
               l 
                
               
                   
               
                
               1 
             
             = 
             
               
                 
                   R 
                    
                   
                       
                   
                    
                   1 
                 
                 
                   R 
                    
                   
                       
                   
                    
                   2 
                 
               
               * 
               l 
                
               
                   
               
                
               2 
             
           
         
       
     
         [0000]    where R 1  denotes the determined electrical resistance of the measurement section, R 2  denotes the reference resistance (e.g. the electrical resistance on the entire electrical conductor) and l 2  denotes the length of the electrical conductor assigned to the reference resistance (e.g. the length of the entire electrical conductor). 
         [0019]    As already stated above, the defining device may define two or more measurement subsections, the electrical resistances of which are accordingly added up, so that the total resistance present on the measurement section (which is formed by these measurement subsections) can be compared with the reference resistance. The above-mentioned formulae enable the evaluating unit to determine the resistance and the length of the measurement section, irrespective of whether the measurement section is composed of only one, of two or more than two measurement subsections. Since the oxygen module is assigned to the measurement section, the evaluating unit can infer the position of the oxygen module in the longitudinal direction of the aircraft from the length of the measurement section. For example, the position of the oxygen module in the longitudinal direction of the aircraft may correlate with or be related to the length of the measurement section. As one possible simple configuration, it is conceivable that the measurement section is defined by the beginning of the electrical conductor (as the first measurement point) and a second measurement point, defined by the defining device, along the electrical conductor, the second measurement point being related to the position of the oxygen module in the longitudinal direction of the aircraft. For example, the position of the second measurement point in the longitudinal direction of the aircraft corresponds to the position of the oxygen module in the longitudinal direction of the aircraft, i.e. it is possible that the second measurement point is defined at the position at which the oxygen module is arranged. Both for the position of the oxygen module and for the second measurement point, the first measurement point may in this case represent the reference point (e.g. the zero point) for the length calculation. This simple configuration is, however, to be understood as being purely by way of example, i.e. other configurations are also conceivable in which e.g. two or more measurement points are flexibly defined, two or more measurement subsections are defined or the like. 
         [0020]    Through the comparison of the electrical resistance of the measurement section with the reference resistance, it is possible to reliably determine the position of the oxygen module in a simple manner. 
         [0021]    The defining device may comprise a contacting device for contacting the electrical conducting element, for example the electrical conductor of the electrical conducting element, at at least one contacting location, the at least one contacting location being assigned to the oxygen module and defining the at least one measurement section on the electrical conducting element. For example, the at least one contacting location may correspond to the at least one second (flexible) measurement point and thereby, as described above, define the at least one measurement section. Accordingly, it is also conceivable that the contacting device contacts the electrical conducting element at two or more contacting locations and accordingly defines two or more second measurement points defining the at least one measurement section. The contacting device may comprise at least one contact element for establishing an electrical contact between the contact element and the electrical conducting element at the at least one contacting location. For this purpose, the contact element may be formed from a conducting material such as metal. The contact element may, for example, be connectable or connected at both of its ends to the above-mentioned voltage source. When the contact element is brought into contact with the electrical conducting element, for example the electrical conductor, at the contacting location, a circuit closes via the measurement section of the electrical conductor and the electrical contact, and it is possible to measure the electrical resistance present at the measurement section. The at least one contact element may, for example, be of strip-shaped form and extend along the electrical conducting element, e.g. along the entire length of the electrical conducting element. Furthermore, two or more contact elements may also be provided beside one another, e.g. running parallel in the longitudinal direction of the electrical conducting element. 
         [0022]    The contacting device may further comprise at least one triggering element which can be positioned relative to the at least one contact element and which is configured to cause the at least one contact element to establish the electrical contact. For example, the triggering element may be arranged so as to be movable or repositionable in the longitudinal direction of the electrical conducting element (possibly also in the longitudinal direction of the contact element, depending on the shape of the contact element). A displacement of the at least one triggering element is also conceivable. The at least one triggering element may, for example, be of pin-shaped or nail-shaped form. It is conceivable that the at least one contact element is arranged at a flexible covering of the electrical conducting element in a manner spaced from the electrical conducting element and the triggering element, for example the pin-shaped triggering element, is configured to press the contact element at the at least one contacting location against the electrical conducting element. By positioning two or more triggering elements, the contact element may accordingly be pressed against the electrical conducting element at two or more contacting locations. If, for example, two or more contact elements are provided in the longitudinal direction of the electrical conducting element, the triggering element may also comprise one or more projections, with the aid of which selectively one or more of the two or more contact elements may be pressed against the electrical conducting element. 
         [0023]    The contacting device may further comprise a positioning unit, it being possible for the triggering element to be positioned in the positioning unit to establish the electrical contact between the electrical conducting element and the contact element at the contacting location. For example, the positioning unit may extend along the electrical conducting element and comprise in the longitudinal direction a multiplicity of positioning receptacles. The positioning receptacles are each configured to receive the at least one triggering element for establishing the electrical contact. For example, the positioning receptacles may be formed as holes or as mutually opposite hole pairs, through which the triggering element, for example the pin-shaped triggering element, may be inserted and held. As a result, the contact between contact element and electrical conducting element may be established and a circuit closed along the measurement section. For example, the positioning unit may have along its longitudinal axis a multiplicity of such holes or hole pairs, in which a respective triggering element may be positioned. 
         [0024]    According to a second aspect, an aircraft comprising at least one oxygen module mounted on board the aircraft and at least one sensor device, as is/has been described herein, is provided. The at least one oxygen module may be arranged so as to be movable, for example also displaceable, in the longitudinal direction of the aircraft. 
         [0025]    The evaluating unit of the sensor device may be configured to derive the position of the oxygen module in the longitudinal direction of the aircraft based on the determined electrical resistance. 
         [0026]    It is conceivable that a multiplicity of oxygen modules are arranged in the aircraft (e.g. along the longitudinal axis of the aircraft), for example one oxygen module being assigned to each seat row, e.g. in that one oxygen module is situated above each seat row. Accordingly, for each of the multiplicity of oxygen modules, a sensor device may be provided and arranged in the aircraft. For each seat row, it is possible with the aid of the sensor device, as described above, to determine the length of the measurement section and hence the position of the corresponding oxygen module in the longitudinal direction of the aircraft (of the supply duct of the aircraft). It is thereby possible to check in a simple manner whether the oxygen module of the corresponding seat row is situated at the correct position in the longitudinal direction of the aircraft. If one or more of the multiplicity of oxygen modules are not correctly positioned, this or these oxygen modules may be accordingly repositioned and the new position may then be determined again in a simple manner by the associated sensor device. 
         [0027]    It is conceivable that the sensor device is arranged on a closure flap of the oxygen module. In a non-triggered normal state, such a closure flap, behind which are situated the oxygen module and the oxygen masks assigned to the seats of the seat row, is closed. In the event of a drop in pressure in the cabin, e.g. the closure flap is automatically opened. For example, a device for retaining the masks in the emergency oxygen module is opened by a physical connection, for example a cord, string or lanyard connection, and the masks drop out. 
         [0028]    The sensor device may be connected to the oxygen module via a physical connection, such as a cord, string or lanyard connection. For example, the lanyard connection may be connected on the one side to the oxygen module and on the other side to the triggering element, so that when the triggering element is positioned in the positioning device the electrical conducting element is contacted, a measurement section is defined and accordingly a changed resistance (compared with the predetermined reference resistance) is detected by the evaluating unit. From this, the evaluating unit can derive that the oxygen module is installed. By contrast, if it is ascertained that the determined electrical resistance corresponds to the reference resistance, it can be deduced from this that the oxygen module associated with the seat row is not installed or at least the triggering element is not (has not been) connected to the closure flap via the positioning unit. 
         [0029]    The sensor device may be connected, for example, in such a manner to the at least one oxygen module via the cord, string or lanyard connection that a release (e.g. an automatic opening) of the closure flap of the oxygen module causes or occasions oxygen masks assigned to the oxygen module to drop out. As a result, the mechanical connection between oxygen module and closure flap can be reliably detected or checked. 
         [0030]    Even though some of the above-described aspects have been described with reference to the evaluating unit or the aircraft, these aspects may also be implemented as a method or as a computer program which carries out the method. For example, the evaluating unit may comprise, for carrying out at least some of the above-described aspects, a computer program with program code means which, when it is loaded in a computer or a processor (for example a microprocessor or microcontroller), or runs on a computer or processor (e.g. a microprocessor or microcontroller), causes the computer or processor (e.g. the microprocessor or microcontroller) to carry out the above-described aspects. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0031]    Preferred embodiments of the present invention are explained below with the aid of the appended schematic figures, in which: 
           [0032]      FIG. 1   a  shows a schematic illustration of an embodiment of a sensor device; 
           [0033]      FIG. 1   b  shows a schematic illustration of a part of the sensor device from  FIG. 1   a;    
           [0034]      FIG. 1   c  is shows a schematic illustration of a detail of the sensor device from  FIG. 1   a;    
           [0035]      FIG. 2   a  shows a schematic illustration of a front view of the sensor device from  FIG. 1   a  in a non-triggered state; 
           [0036]      FIG. 2   b  shows a schematic illustration of a front view of the sensor device from  FIG. 1   a  in a triggered state; 
           [0037]      FIG. 3  shows a schematic illustration of the sensor device from  FIGS. 1   a  to  2   b  according to one possible circuit arrangement having an evaluating unit of the sensor device; 
           [0038]      FIGS. 4   a  to  4   h  shows the sensor device from  FIG. 3  in different measurement configurations; and 
           [0039]      FIG. 5  shows the sensor device from  FIG. 1   a  in the installed state. 
       
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
       [0040]    In what follows, without being limited thereto, specific details are set out in order to provide a complete understanding of the present invention. However, it is clear to a person skilled in the art that the present invention may be used in other embodiments which may deviate from the details set out below. 
         [0041]    It is clear to a person skilled in the art that the explanations set out below may be implemented using hardware circuits, software means or a combination thereof. The software means may be associated with programmed microprocessors or a general computer, an ASCI (Application Specific Integrated Circuit) and/or DSPs (Digital Signal Processors). Moreover, it is clear that even though the following details are described with reference to a method, the latter may also be realised in a suitable apparatus unit, a computer processor or storage connected to a processor, the storage being provided with one or more programs which carry out the method when they are executed by the processor. 
         [0042]      FIGS. 1   a  and  2   b  schematically show an embodiment of a sensor device. With reference to  FIGS. 1   a  to  2   b , mainly the electrical and mechanical components of the sensor device are described without going into detail on the functioning of the sensor device, which is explained subsequently with reference to  FIGS. 3 to 4   h . Therefore, the evaluating unit of the sensor device is not illustrated in  FIGS. 1   a  to  2   b . However, it is clear to a person skilled in the art that the illustrations from Figures is to  2   b  may be connected in a suitable manner to an evaluating unit, as is described for example with reference to  FIGS. 3 to 4   h.    
         [0043]    The sensor device  10  according to the embodiment has a positioning unit  20  which comprises an at least approximately U-shaped hollow profile. In the lateral surfaces of the positioning unit  20 , there are arranged in each case a multiplicity of mutually opposite holes  22  which form in each case hole pairs in the mutually opposite lateral surfaces. The holes  22  are in each case of such a diameter that a triggering element  24 , illustrated with reference to the first embodiment by way of example as a pin-shaped triggering element  24 , can be pushed through them. The diameter of the pin-shaped triggering element  24  is matched to the holes  22  and at one end, however, is larger in order to prevent the triggering element  24  from penetrating too far into the holes  22 . On account of the enlarged diameter at the one end, the triggering element  24  may also be referred to as nail-shaped or screw-shaped. At the end of the triggering element  24  with the enlarged diameter, a lanyard cable  40  is attached. In the U-shaped hollow profile of the positioning unit  20 , there is arranged an electrical conducting element  30 , which can be seen in greater detail in  FIG. 1   b , the electrical conducting element  30  comprising, for example, either a shielding with respect to the positioning unit  20  or the positioning unit  20  being composed of a non-conducting material. 
         [0044]    The electrical conducting element  30  comprises a base body  38  made of a non-conductive material, and an electrical conductor  36  which is wound in the form of a coil around the base body  38 . For the shielding of the electrical conductor  36  from external influences, a flexible covering  32  made of an insulating material is provided. On the upper side of the flexible covering  32  facing the electrical conductor  36 , there are arranged two strip-shaped contact elements  34   a ,  34   b . Even though two strip-shaped contact elements  34   a ,  34   b  are shown by way of example in  FIGS. 1   a  to  2   b , it is also possible for only one contact element or more than two contact elements to be provided on the flexible covering  32 . As the simplest variant, only a single such contact element is arranged on the covering  32 . In order to increase the redundancy stepwise, the number of contact elements may be increased. In  FIGS. 1   b ,  1   c  and  2   a , the electrical conducting element  30  is in a non-triggered initial state. 
         [0045]    As can be seen in  FIG. 1   c  and  2   a , in this initial state the flexible covering  32  and the strip-shaped contact elements  34   a ,  34   b  are arranged in manner spaced from the base body  38  and hence also from the electrical conductor  36 . Put another way, in the initial state according to  FIG. 2   a , there is no contact between the electrical conductor  36  and one or more of the two contact elements  34   a ,  34   b . In the initial situation from  FIG. 2   a , there exists no closed circuit running via the electrical conductor  36  and the strip-shaped contact elements  34   a ,  34   b . By contrast, there exists a closed circuit along the entire length of the electrical conductor  36  when, accordingly, a voltage is applied to the ends of the latter or connecting lines run to a voltage source, as will be described in more detail with reference to  FIGS. 3 to 4   h.    
         [0046]    If now, as shown in  FIG. 2   b , the pin-shaped triggering element  24  is pushed through one of the holes  22  of the positioning unit  20  (see in this regard also  FIG. 1   a ), the triggering element  24  presses the flexible covering  32  and hence the contact elements  34   a ,  34   b  against the electrical conductor  36  and establishes at this contacting location an electrical contact between the contact elements  34   a ,  34   b  and the electrical conductor  36 . As a result, there is formed a measurement section between the end of the electrical conductor  36  as first measurement point (by way of example it is assumed that the end of the sensor device  10  and of the electrical conductor  36  lies at the rear in  FIG. 1   a  and the beginning of the sensor device  10  and of the electrical conductor  36  lies at the front in  FIG. 1   a ) and the contacting location as second measurement point. If a voltage is applied to one end of the electrical conductor  36  and one end of at least one of the electrical contact elements  34   a ,  34   b , current can be conducted by the electrical conductor  36  at the contacting location onto the strip-shaped contact element(s)  34   a ,  34   b  or vice versa. This is due to the fact that, as can be seen in  FIGS. 1   a  to  2   b , the cross-section of the electrical conductor  36  is minimally small compared with the cross-section of the contact elements  34   a ,  34   b . This means that the electrical conductor  36  has a substantially higher resistance than the contact elements  34   a ,  34   b , i.e. the resistance of the contact elements  34   a ,  34   b  is negligibly small compared with the resistance of the electrical conductor  36 . Consequently, the majority of the current or approximately the entire current is not transmitted via the electrical conductor  36  but led onto the contact element  34   a  and/or the contact element  34   b . In the circuit formed, the evaluating unit may be arranged, as will be described with reference to  FIGS. 3 to 4   h . Accordingly, the evaluating unit can evaluate the electrical resistance along the measurement section, as explained with reference to  FIGS. 3 to 4   h.    
         [0047]      FIG. 3  shows, in a greatly simplified and schematic manner, the basic construction of the sensor device  10  of  FIGS. 1   a  to  2   b  according to one possible circuit arrangement having an evaluating unit  200  of the sensor device  10 . In what follows, it is assumed, purely by way of example, that the beginning (the front part) of the sensor device  10  is also situated at the front in  FIG. 1   a . This front part of the sensor device  10  is situated, purely by way of example, on the left side in  FIGS. 3 to 4   h . This has the result, purely by way of example in  FIGS. 3 to 4   h , that the rear part of the sensor device  10  (which part is also illustrated at the rear in  FIG. 1   a ) is connected to the evaluating unit  200 . This configuration may be exactly the other way round. 
         [0048]    As can be seen in  FIG. 3 , a plurality of lines  102 ,  104 ,  106   a  and  108  run into the evaluating unit  200 . Instead of the four lines shown, it is also possible for only two lines or more than four lines to run into the evaluating unit  200 . According to a first variant shown in  FIG. 3 , three cables, namely the lines  104 ,  106   a  and  108 , run into the rear part of the sensor device  10  and only the line  102  runs into the front part of the sensor device. According to a second variant, however, one of the lines may also be run into the front part instead of into the rear part, as is shown with regard to the line  106   b . For the sake of simplicity, it is assumed below that only a single strip-shaped contact element  34  is arranged on the covering  32  instead of the two strip-shaped contact elements  34   a ,  34   b.    
         [0049]    The circles in  FIG. 3  symbolise, by way of example, two contacting locations  100   a ,  100   b  in a purely schematic illustration, which represent two measurement points for defining one or more measurement sections and accordingly are referred to below also alternately as measurement points  100   a ,  100   b  The measurement points  100   a ,  100   b  are formed, in the example shown in  FIGS. 3 to 4   h , by establishing a contact between the electrical conductor  36  and the electrical contact element  34  at the positions corresponding to the measurement points by inserting two triggering elements  24  at precisely these positions. The measurement points  100   a ,  100   b  define one or more measurement sections, along which the electrical resistance is measured by the evaluating unit  200 . It will be understood that only one of the measurement points  100   a ,  100   b  is sufficient to define a measurement section or else more than two measurement points  100   a ,  100   b  may be provided. One of the measurement points  100   a ,  100   b  is sufficient, for example, when the front or rear end of the electrical conductor  36  is used as the other measurement point. One of the lines  102 ,  104 ,  106   a  (or  106   b ),  108  may be connected selectively to the front end of the strip-shaped contact element  34  and another of the lines  102 ,  104 ,  106   a  (or  106   b ),  108  may be connected selectively to the rear end of the strip-shaped contact element  34 . Another of the lines  102 ,  104 ,  106   a  (or  106   b ),  108  may be connected selectively to the front end of the electrical conductor  36  and the last of the lines  102 ,  104 ,  106   a  (or  106   b ),  108  may be connected selectively to the rear end of the electrical conductor  36 . 
         [0050]    In  FIGS. 4   a  to  4   h , the contact element  34  which extends in the longitudinal direction of the control device  10  can be seen schematically. Furthermore, an electrical conductor  36  is indicated, which conductor may be configured in the same manner as the electrical conductor  36  from Figures is to  2   b .  FIGS. 4   a  to  4   h  show, by way of example, one possible circuit arrangement, in which the line  102  is connected to the front end of the electrical conductor  36 , the line  104  is connected to the rear end of the electrical conductor  36 , the line  106  is connected to the front end of the contact element  34  and the line  108  is connected to the rear end of the contact element  34 . Purely by way of example, it can be seen in  FIGS. 4   a  to  4   h  how the electrical conductor  36  may contacted at two measurement points (contacting locations)  100   a ,  100   b  by the contact element  34 . It is likewise conceivable that the electrical conductor  36  may be contacted only at one variable contacting location  100   a ,  100   b  by the contact element  34 , and the measurement section is defined by this variable contacting location  100   a ,  100   b  and a fixed reference point, e.g. the front or rear end of the electrical conductor  36 . It is likewise conceivable that more than two measurement points may be provided, which points may each be established by one and the same contact element  34  or further contact elements. 
         [0051]    The functioning of the sensor device  10  will now be explained with the aid of  FIGS. 4   a  to  4   h.    
         [0052]    As can be seen in  FIGS. 4   a  to  4   h , the contacting locations and hence the measurement points  100   a ,  100   b  define at least one measurement section from the measurement sections x 1 , x 2 , x 3 , as will be explained below. In all the  FIGS. 4   a  to  4   h , the dashed lines represent current-carrying lines. The continuous lines are, accordingly, without current. Which lines  102 ,  104 ,  106 ,  108  are used for measurement is defined by control logic in the evaluating unit  200  in dependence on the measurement to be carried out. 
         [0053]    An initial state, as may be used, for example, for calibrating the evaluating unit  200 , is shown in  FIG. 4   a . This means that  FIG. 4   a  represents a kind of check measurement which may be carried out, for example, during the calibration of the evaluating unit  200 . In the check measurement, the contact element does not contact the electrical conductor  36  at any of the measurement points  100   a ,  100   b , there is no triggering element  24  arranged in the positioning unit  30 . In  FIG. 4   a , the lines  102  and  104  serve, by way of example, for the measurement, i.e. the evaluating unit  200  applies a voltage to these lines, so that a current flows via the line  102  onto the electrical conductor  36  and finally via the line  104  into the evaluating unit  200 . The current flows over the entire length of the electrical conductor  36 , since the contact element  34  does not contact the electrical conductor  36  at any location. If it is assumed in simplified terms that the resistance of the lines  102 ,  104  is negligibly small compared with the resistance of the electrical conductor  36 , the resistance value of the entire conductor  36  is determined by the check measurement and saved (stored) in the evaluating unit  200 . Otherwise, the resistance present along the lines  102 ,  104  has to be taken into account in this and subsequent measurements as well. In the embodiment, the cross-section, the length and the material of the lines  102  to  108  are chosen, however, such that the resistance of the lines  102  to  108  is negligibly small compared with the resistance of the electrical conductor  36 . After the check measurement, a reference resistance or reference resistance value is therefore known in the evaluating unit  200 , namely the resistance of the entire conductor  36 . 
         [0054]    In  FIG. 4   b , by way of example, the line pair  106 ,  108  is selected by the evaluating unit  200  as the line pair for the measurement and is supplied with current. Here, too, no triggering element  24  is inserted into the positioning unit  20 , i.e. here too there is no contact between the electrical conductor  36  and the contact element  34 . The current accordingly flows via the line  106  to the almost resistanceless contact element  34  and via the line  108  back to the evaluating unit  200 . If it is assumed in simplified terms that not only the contact element  34  but also the lines  106 ,  108  have a negligible small resistance, the evaluating unit  200  measures almost no resistance (resistance approximately 0; short-circuit state). If the lines  106 ,  108  have a resistance, only the resistance of the lines  106 ,  108  is measured by the evaluating unit  200 . 
         [0055]    In  FIG. 4   c , it can be seen how the lines  102 ,  106  are selected for the measurement by the evaluating unit  200 , i.e. the evaluating unit  200  applies a voltage to these lines  102 ,  106 . Furthermore, a triggering element  24  is positioned in the positioning unit  20  at the contacting location corresponding to the measurement point  100   a , since the oxygen module is situated at a corresponding or the same position in the longitudinal direction of the aircraft. As a result, the current flows from the conductor  102  firstly onto the electrical conductor  36 . Since, however, there is a contact between the contact element  34  and the electrical conductor  36  at the measurement point  100   a , on account of the substantially smaller resistance of the contact element  34  the current does not flow on into the evaluating unit  200  via the electrical conductor  36  but via the contact element  34  and the line  106 . As a result, the measurement section x 1  defined by the measurement point  100   a , to be more precise the resistance present there, is measured by the evaluating unit  200 . The measurement section x 1  is defined by the beginning of the electrical conductor  36  and the measurement point  100   a . From the quotient of the resistance along the measurement section x 1  and the total resistance along the electrical conductor  36 , i.e. the reference resistance, the evaluating unit  200  can determine the length of the measurement section x 1  (by multiplying the quotient by the length of the electrical conductor  36 ). From the length of the measurement section x 1 , the evaluating unit  200  can deduce at which point in the longitudinal direction of the sensor device  10  and hence in the longitudinal direction of the aircraft the contacting location and hence also the oxygen module are situated. 
         [0056]      FIG. 4   d  illustrates how the same measurement section x 1  can be measured in an alternative manner. Here, the evaluating unit  200  selects the lines  102  and  108  and applies a voltage to these lines. The current flows via the line  102  into the electrical conductor  36  and on account of the contact existing at the measurement point  100   a  into the contact element  34  and from there via the line  108  into the evaluating unit  200 . The evaluating unit  200  now measures the same resistance as in  FIG. 4   c , namely the resistance along the measurement section x 1 , and can thereby determine the position of the oxygen module. 
         [0057]      FIGS. 4   e  and  4   f  now show how the measurement section x 3  can be measured in a different manner. The measurement section x 3  is defined by the contact element  34  contacting the electrical conductor  36  at the contacting location corresponding to the measurement point  100   b  (by inserting the triggering element  24  at the corresponding location into the positioning unit  20 ), because, for example, the oxygen module is arranged at the same location  100   b  in the longitudinal direction of the aircraft (or at a corresponding location). The measurement section x 3  is therefore defined by the end of the electrical conductor  36  and the measurement point  100   b . The evaluating unit  200  now applies a voltage to the lines  104  and  108  in  FIG. 4   e . As a result, current flows via the line  104  into the electrical conductor  36 , from there into the contact element  34  and back into the evaluating unit  200  via the line  108 . In  FIG. 4   f , a voltage is applied to the lines  104  and  106 , so that the current flows via the line  104  through the electrical conductor  36 , the contact element  34  and via the line  106  into the evaluating unit  200 . Both times, the evaluating unit  200  measures the resistance along the measurement section x 3  (thereby knows the length of the measurement section x 3 ) and can thereby determine at which location the contact is arranged and hence also at which location the oxygen module is arranged. 
         [0058]      FIG. 4   g  illustrates how the part of the electrical conductor  36  formed from the measurement sections x 2  and x 3  and hence the resistance along the measurement section x 1  can be derived. The triggering element  24  is placed at the contacting location corresponding to the measurement point  100   a , since the oxygen module is arranged at the corresponding location. The evaluating unit  200  applies a voltage to the lines  104 ,  108 , so that the current flows via the line  104 , the electrical conductor  36 , via the contacting location  100   a  onto the contact element  34  and the line  108  finally into the evaluating unit  200 . The measured resistance corresponds to the resistance present along the measurement section x 2 +x 3 . By obtaining the difference between reference resistance and the determined resistance, it is possible to derive the resistance along the measurement section x 1 . As a result, the evaluating unit can determine the length of the measurement section x 1  and therefore also the contacting location and the position of the oxygen module. 
         [0059]    In  FIG. 4   h , the triggering element  24  is positioned in the positioning unit  20  at the same contacting location  100   a , but the evaluating unit  200  applies a voltage to the lines  102  and  108 . As a result, current flows via the line  102 , the electrical conductor  36 , the contacting location  100   a , the contact element  34  and the line  108  into the evaluating unit  200 . The evaluating unit  200  measures the resistance along the measurement section x 1 , from this derives the length x 1  and from this deduces at which location the oxygen module is positioned. 
         [0060]    Even though the current has always flowed clockwise in  FIGS. 4   a  to  4   h , purely by way of example, the current may also flow anticlockwise if the voltage is applied accordingly the other way round. 
         [0061]      FIG. 5  illustrates, by way of example, how the sensor device  10  can be installed in an aircraft. As can be seen, the sensor device  10  is arranged on a closure flap  50  of the oxygen module. The sensor device  10  is connected to the oxygen module  60  via the lanyard connection  40 . As a result of the fact that the lanyard connection  40  is arranged on the triggering element  24 , in the inserted state of the triggering element  24 , a resistance different from the reference resistance is measured. From this, the evaluating unit  200  recognises that the triggering element  24  is inserted and hence also the oxygen module is installed. It is thereby checked in a simple manner whether the oxygen module  60  is correctly installed. The physical connection between the oxygen module  40  and the closure flap  50  ensures that in the event of a drop in pressure in the cabin (e.g. in an emergency) and the ensuing opening of the closure flap  50 , the sheet surrounding the oxygen masks is torn out and the oxygen masks drop out. Thus, correct connection between sensor device  10  and oxygen module further ensures that the oxygen masks are released.