Patent Publication Number: US-11639283-B2

Title: Floor position detection device of an elevator installation and method for generating a floor signal

Description:
FIELD 
     The invention relates to a floor position detection device of an elevator installation and a method for generating a floor signal in an elevator installation. 
     BACKGROUND 
     The EP 2516304 B1 describes a floor position detection device of an elevator installation having a sensor unit and an evaluation unit for generating a floor signal which has two states. The sensor unit arranged on an elevator car has a total of five Hall effect sensors. In the range of a floor, a permanent magnet is arranged in such a manner that, when approaching the floor, the Hall effect sensors mentioned output a floor position characteristic value which depends on the distance of the corresponding Hall effect sensor from the permanent magnet. Two of the Hall effect sensors are designated as so-called main sensors, whose floor position characteristic values are compared with each other to generate the floor signal. If the two floor position characteristic values of the two main sensors are of the same size and the floor position characteristic values of the other Hall effect sensors meet the specified conditions, the evaluation device changes the state of the floor signal. The other three Hall effect sensors are particularly needed to ensure that the evaluation unit only reacts when the permanent magnet is near the sensor unit. 
     SUMMARY 
     By contrast, it is an object of the invention in particular to propose an inexpensive floor position detection device for an elevator installation and a method for generating a floor signal in an elevator installation which can be implemented cost-effectively. According to the invention, this object is solved with a floor position detection device having the features and a method with the features described below. 
     According to the invention, the floor position detection device of an elevator installation has a sensor unit and an evaluation unit for generating a floor signal which has two states. The floor signal can assume the two states “in the range of the floor” or “outside the range of the floor”, wherein further states are also conceivable. The sensor unit has a first Hall effect sensor for generating a first floor position characteristic value and a second Hall effect sensor for generating a second floor position characteristic value. The evaluation unit is intended to generate the floor signal based on a comparison of the first and second floor position characteristic values. According to the invention, the evaluation unit is intended to verify whether the first and/or second floor position characteristic value is greater than a first threshold value and to generate the floor signal based on the result of the mentioned verification. 
     The combination of comparing the two floor position characteristic values and verifying whether one or both floor position characteristic values are greater than a first threshold value provides a cost-effective floor position detection device that also allows accurate determination of the position of the elevator car relative to a floor of the elevator installation. By comparing the first and/or second floor position characteristic value with the mentioned first threshold, it is easy to determine whether or not the floor position detection device is within the range of magnetic means. In this regard, “being in the range of magnetic means” means that a Hall effect sensor is located in a magnetic field of a magnetic means in such a manner that the magnetic field leads to a significant or measurable increase in the sensor signal and therefore the floor position characteristic value. 
     The floor position detection device or the evaluation unit transmits the floor signal via a communication connection to an elevator control of the elevator installation. The elevator control uses the floor signal particularly for the accurate positioning of an elevator car that can be moved in an elevator shaft on a floor or a shaft door associated to a floor. To indicate the position of a floor in a travel direction of the elevator car, at least one magnetic means is placed in the elevator shaft at a position characterizing the location of the floor. For example, the magnetic means can be arranged on the shaft door associated to the floor and the floor position detection device on the elevator car, particularly on a car door of the elevator car. This allows the elevator control to use the floor signal to position the car door and therefore the car accurately opposite the shaft door of the floor. The mentioned magnetic means may also be considered as part of the floor position detection device. 
     When the magnetic means is at the correct position in the elevator shaft and the floor position detection device is at the correct position on the elevator car, the “in the range of the floor” state of the floor signal shows that the elevator car is correctly positioned opposite the floor. The car door, in particular, can then be opened, which in the usual manner also opens the shaft door associated with the floor. In this case, the state “outside the range of the floor” of the floor range shows that the elevator car is not positioned in the immediate vicinity of a floor or at least not yet completely correctly opposite the floor and that in particular the car door cannot be opened. 
     The designations “in the range of the floor” and “outside the range of the floor” are only exemplary designations for two different states of the floor signal. 
     In this regard, a “floor position characteristic value” is to be understood in particular as a sensor signal or a processed sensor signal of a Hall effect sensor which is generated by the magnetic field of magnetic means. In this regard, an “evaluation unit” is to be understood in particular as an electronic unit for processing analog and/or digital electrical signals. In this regard, “is intended” is to be understood in particular as specifically equipped, laid out and/or programmed. In this regard, “magnetic means” is to be understood in particular as means for generating a magnetic field, in particular a permanent magnet in cylindrical or cuboid shape. Preferably, the two Hall effect sensors mentioned above are arranged at a known spatial distance from each other, which allows a very accurate determination of the position of the floor. 
     The evaluation unit can in particular be implemented as a programmable microcontroller which controls an output module, for example in the shape of a so-called high-side switch or a so-called PNP transistor. The output module then generates the floor signal transmitted to the elevator control. It is also conceivable that the floor signal is transmitted directly from the evaluation unit to the elevator control. 
     The individual components of the floor position detection device are arranged together in one housing, preferably in a plastic housing. The plastic housing, for example, has a length of 60-120 mm in the travel direction of the elevator car. In particular, the sensor unit can also have more than two Hall effect sensors, for example three or four Hall effect sensors. In particular, the Hall effect sensors are arranged side by side in such a manner that they have a distance from sensor center to sensor center of 20-30 mm. The Hall effect sensors are arranged in such a manner that in the mounted state of the floor position detection device they are arranged next to each other in the travel direction of the elevator car. The floor position detection device and the magnetic means are arranged in such a manner that the Hall effect sensors have a distance perpendicular to the travel direction of the elevator car of, for example, 5-25 mm to the magnetic means. 
     The first Hall effect sensor and the second Hall effect sensor are arranged in such a manner that, when approaching a floor, the approach can be derived from the first floor position characteristic value before the second floor position characteristic value. This means that when the floor position detection device approaches a floor and therefore magnetic means, the first floor position characteristic value rises before the second floor position characteristic value and thus shows immersion in a magnetic field. The two Hall effect sensors are arranged in such a manner that the first Hall effect sensor is immersed in the magnetic field of the magnetic means before the second Hall effect sensor. 
     The evaluation unit is also intended to assign to the floor signal the state “in the range of the floor” if the second floor position characteristic value is greater than or equal to the first floor position characteristic value and at the same time the first and/or second floor position characteristic value, in particular the second floor position characteristic value, is greater than the mentioned first threshold value. The first threshold value is selected in such a manner that the floor position characteristic value is only greater than the first threshold value if the corresponding Hall effect sensor is located in the range of the magnetic means, i. e. the floor position characteristic value has risen above the first threshold value as a result of the approach to the magnetic means. 
     In the described arrangement of the first and second Hall effect sensors, the second floor position characteristic value becomes equal to or greater than the first floor position characteristic value when the magnetic means is located between the two Hall effect sensors. The position of the floor position detection device in relation to the magnetic means and therefore opposite a floor can be determined very accurately. The comparison of the two floor position characteristic values can, however, only provide a meaningful result if at least one of the two Hall effect sensors is located in the range of magnetic means. If a Hall effect sensor is not within the range of magnetic means, the floor position characteristic value it supplies randomly fluctuates by a so-called quiescent level. If two floor position characteristic values that fluctuate randomly around the quiescent levels are compared with each other, the result of the comparison is also random and cannot be used to generate the floor signal. The further condition that the first and/or second floor position characteristic value must be greater than the first threshold value, in addition to the comparison of the two floor position characteristic values, ensures that the floor signal is only assigned the state “in the range of the floor” if the first and/or second Hall effect sensor and therefore the floor position detection device is located in the range of magnetic means. 
     The described quiescent level of the Hall effect sensors can also be used to specify the first threshold value. For example, the first threshold value can be set to a multiple, such as three to five times of the quiescent level of the corresponding Hall effect sensor. The quiescent level can be fixed for a certain type of Hall effect sensor, measured during production of the floor position detection device or determined after installation of the floor position detection device in an elevator installation in a so-called learning travel. For example, the first threshold value can be between 20 and 40 mV when the Hall effect sensor is supplied with 2 V. 
     The above-mentioned object is also solved by a method according to the invention for generating a floor signal in an elevator installation. The floor signal can assume two states “in the range of the floor” or “outside the range of the floor”. A first floor position characteristic value is generated by a first Hall effect sensor and a second floor position characteristic value is generated by a second Hall effect sensor of a sensor unit, wherein the first Hall effect sensor and the second Hall effect sensor are arranged in such manner that, when approaching a floor, the approach can be derived from the first floor position characteristic value before the second floor position characteristic value. The floor signal is generated by an evaluation unit based on a comparison of the first and second floor position characteristic values. According to the invention, the evaluation unit verifies whether the first and/or second floor position characteristic value is greater than a first threshold value and generates the floor signal based on the result of the mentioned verification. The evaluation unit assigns the state “in the range of the floor” to the floor signal if the second floor position characteristic value is greater than or equal to the first floor position characteristic value and the first floor position characteristic value and/or the second floor position characteristic value is greater than the first threshold value. 
     The explanations and further attributes of the floor position detection device according to the invention also apply analogously to the method according to the invention. 
     In the design of the invention, the evaluation unit is intended to post-process a first sensor signal of the first Hall effect sensor and/or a second sensor signal of the second Hall effect sensor in order to determine the first and/or second floor position characteristic value. This enables a particularly high accuracy of the floor position detection device. Post-processing can take the shape of filtering, for example a low-pass filter. 
     The evaluation unit is particularly intended to calibrate the first and/or second sensor signal. In this regard, it should be understood that the two sensor signals are converted into floor position characteristic values in such a manner that both floor position characteristic values have the same maximum value. Different Hall effect sensors can output different sensor signals even at the same distance from the same magnetic means and therefore the same magnetic field. The Hall effect sensors can therefore exhibit a so-called scattering. This scattering is compensated by the described post-processing. Therefore, it can be ensured that even with different floor position detection devices, the floor signal is always assigned the state “in the range of the floor” at almost exactly the same position of the floor position detection device opposite the magnetic means and therefore opposite the floor. 
     In particular, the sensor signals are calibrated by storing a so-called calibration factor or amplification factor associated to a Hall effect sensor in the evaluation unit. To calculate the floor position characteristic value from the sensor signal of the Hall effect sensor, the evaluation unit multiplies the value of the sensor signal by the calibration factor. This multiplication can also be realized in an analog circuit. For example, the calibration factors can be selected so that both floor position characteristic values have the same specified maximum value. This maximum value can be 200-400 mV, for example, when the Hall effect sensors are supplied with 2 V. Determining the calibration factors is designated here as “calibration”. 
     The described calibration can, for example, be carried out after the installation of the floor position detection device in an elevator installation during a so-called learning travel. The elevator car is moved slowly in the elevator shaft having the floor position detection device arranged on it. The floor position detection device passes magnetic means and the evaluation unit detects the sensor signals of the Hall effect sensors. It can determine the maximum sensor signals of the individual Hall effect sensors and carry out the calibration as described. It is also possible that information from another position detection system, for example an absolute position detection system, is evaluated during a learning travel. 
     Calibration can also be carried out directly during production of the floor position detection device. For example, the same magnetic means can be arranged one after the other at the same distance from the Hall effect sensors, wherein the evaluation unit determines the maximum sensor signal. Subsequently, the evaluation unit can carry out the calibration as described. It is also possible that two similar magnetic means, which generate the same magnetic field, are arranged simultaneously at the same distance in front of the Hall effect sensors and the evaluation unit therefore generates the maximum sensor signals. 
     In the design of the invention, the evaluation unit is intended to assign a specifiable time span to the floor signal after a change from the state “outside the range of the floor” to the state “in the range of the floor” and back to the state “outside the range of the floor”. The floor signal therefore has only one flank if the second floor position characteristic value becomes greater than or equal to the first floor position characteristic value and the first floor position characteristic value and/or the second floor position characteristic value is greater than the first threshold. Therefore, only two Hall effect sensors are advantageously required, which enables a particularly cost-effective and space-saving embodiment of the floor position detection device. This design may be advantageous, for example, if the floor position detection device is intended to replace an older floor position detection device that generates such a floor signal. For example, the mentioned time span can have a duration between 1 and 100 ms, in particular 10 ms. 
     In the design of the invention, the sensor unit has a third Hall effect sensor for generating a third floor position characteristic value, which is arranged opposite the second Hall effect sensor in such a manner that, when moving away from one floor, the moving away can be derived from the second floor position characteristic value before the third floor position characteristic value. This means that when the floor position detection device moves away from a floor and therefore from magnetic means, the second floor position characteristic value falls before the third floor position characteristic value. The two Hall effect sensors are therefore arranged in such a manner that the second Hall effect sensor moves away from the magnetic field of the magnetic means before the third Hall effect sensor. The evaluation unit is also intended to assign the state “outside the range of the floor” to the floor signal on the basis of the state “in the range of the floor” if the third floor position characteristic value is greater than the second floor position characteristic value and the second and/or third floor position characteristic value is greater than a second threshold value. 
     Therefore, with only one additional Hall effect sensor, it can be reliably and accurately detected when the floor position detection device and therefore the elevator car move away again from magnetic means and therefore from a floor. The floor position detection device is therefore particularly cost-effective. 
     In particular, it is verified whether the second floor position characteristic value is greater than the second threshold value. In particular, the second threshold value may be the same as the first threshold value. For the generation of the third floor position characteristic value from the third sensor signal of the third Hall effect sensor, the same applies as for the generation of the first and second floor position characteristic value. 
     In the design of the invention, the sensor unit includes a third Hall effect sensor for generating a third floor position characteristic value and a fourth Hall effect sensor for generating a fourth floor position characteristic value. The third Hall effect sensor and the fourth Hall effect sensor are arranged in such a manner that when moving away from a floor, the moving away can be derived from the third floor position characteristic value before the fourth floor position characteristic value. The evaluation unit is intended to assign the state “outside the range of the floor” to the floor signal if the fourth floor position characteristic value is greater than the third floor position characteristic value and the third and/or fourth floor position characteristic value is greater than a third threshold value. 
     Therefore, the range in which the floor signal has the state “in the range of the floor” when passing magnetic means and therefore a floor can be set very flexibly. It can, for example, be set so that the mentioned range has a length of 20-30 mm. Flexibility is achieved by assigning the state “in the range of the floor” as a function of the first and second floor position characteristic values and resetting it to the state “outside the range of the floor” as a function of the third and fourth floor position characteristic values. Setting and resetting are independent of each other. 
     In particular, it is verified whether the third floor position characteristic value is greater than the third threshold value. In particular, the third threshold value may be equal to the first and/or second threshold value. For the generation of the third and fourth floor position characteristic values from the third and fourth sensor signals of the third and fourth Hall effect sensors, the same applies as for the generation of the first and second floor position characteristic values. In particular, there is also post-processing, in particular the sensor signals are calibrated. 
     In the design of the invention, the evaluation unit is intended to automatically perform a calibration if all sensor signals are greater than a fourth threshold value. 
     Due to the automated carrying out of the calibration, the evaluation unit does not have to have an input interface with which a calibration can be started. Therefore, the evaluation unit is simple and cost-effective to realize. 
     To carry out the calibration, for example, four similar magnetic means, i.e. magnetic means having the same magnetic field, can be arranged at the same distance from each of the four Hall effect sensors to complete the production of the floor position detection device. The distance is selected so that all four sensor signals are reliably greater than the fourth threshold value. If this condition is fulfilled, the evaluation unit automatically carries out a calibration. A calibration factor is determined for each Hall effect sensor, by which the respective sensor signal is multiplied when the floor position characteristic value is generated. The calibration factors are determined so that all floor position characteristic values have the same maximum value. It would also be possible to determine the calibration factors in such a manner that only the first and second as well as the third and fourth floor position characteristic values each have the same maximum values. 
     In particular, the fourth threshold value may be equal to the first, second and/or third threshold value. 
     If the fourth threshold is specified correctly, it will never happen that all four floor position characteristic values are greater than the fourth threshold value during real operation of the floor position detection device in an elevator installation. It is therefore impossible for a new calibration to be carried out in real operation. 
     In the design of the invention, the floor position detection device has a power supply unit which supplies the Hall effect sensors and the evaluation unit with the same supply voltage. Therefore, a simple and cost-effective power supply unit can be used. 
     The mentioned supply voltage can be, for example, between 1 and 4 V, in particular 2 V. 
     The output module can be supplied with a different supply voltage, in particular a higher supply voltage of, for example, 24 V. 
     The floor position detection device according to the invention and an elevator control are components of an elevator control system of an elevator installation. The elevator control system comprises in particular other sensors and actuators and is used to control the entire elevator installation. 
     Additional advantages, features, and details of the invention result using the following description of embodiment examples and using drawings in which the same or functionally identical elements are provided having identical reference signs. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       In which: 
         FIG.  1    is a part of an elevator installation having an elevator car, on which a floor position detection device is arranged, in an elevator shaft, 
         FIG.  2    is a schematic representation of a floor position detection device, 
         FIG.  3    is the progression of floor position characteristic values and a floor signal when an elevator car having one of the floor position detection devices according to  FIG.  2    passes magnetic means characterizing a floor, 
         FIG.  4    is a schematic representation of an alternative floor position detection device and 
         FIG.  5    is the progression of floor position characteristic values and a floor signal when an elevator car having one of the floor position detection devices according to  FIG.  4    passes magnetic means characterizing a floor. 
     
    
    
     DETAILED DESCRIPTION 
     According to  FIG.  1   , an elevator installation  10  has an elevator car  14  movable in an elevator shaft  12 . The elevator car  14  is suspended in the shape of a rope or a belt by carrying means  16  and can be driven up and down in the lift elevator shaft  12 , i.e. in one travel direction  13 , by means of an unrepresented drive machine. The elevator installation  10  is controlled by an elevator control  18 , which, among other things, has a signal connection with the drive machine via unrepresented communication connections. 
     In the elevator shaft  12 , magnetic means  22  in the shape of a permanent magnet is arranged at a location  20  that characterizes a floor. The magnetic means  22  is surrounded by a magnetic field  24 , which is symbolically represented by some magnetic field lines. The magnetic means  22  characterizes the floor in the vertical direction, i.e. in the travel direction  13  of the elevator car  14 . For example, it can be arranged on a shaft door that is not represented. 
     A floor position detection device  26  is arranged on the elevator car  14 , which is in communication connection with the elevator control  18  and whose structure is represented in more detail in  FIG.  2   . The floor position detection device  26  is arranged on the elevator car  14  in such a manner that it has a horizontal distance between 5 and 25 mm to the magnetic means  22  when passing the magnetic means  22 . The floor position detection device  26  can be arranged, for example, on a car door that is not represented. 
     The floor position detection device  26  and the elevator control  18  are components of an elevator control system of the elevator installation  10 . The elevator control system comprises in particular other sensors and actuators that are not represented. 
     According to  FIG.  2   , the floor position detection device  26  has a first Hall effect sensor  28 , a second Hall effect sensor  30 , a third Hall effect sensor  32  and a fourth Hall effect sensor  34  arranged side by side. The four Hall effect sensors  28 ,  30 ,  32  and  34  form a sensor unit  35 . When the floor position detection device  26  is located on the elevator car  14 , the four Hall effect sensors  28 ,  30 ,  32 ,  34  are arranged side by side in the travel direction  13  in such a manner that they all have the same horizontal distance to the magnet means  22 . 
     Sensor signals of the four Hall effect sensors  28 ,  30 ,  32 ,  34  are forwarded to an evaluation unit  36 , which is implemented as a programmable microprocessor. The evaluation unit  36  first calculates four floor position characteristic values from the sensor signals mentioned and links them to a floor signal, which passes them to an output module  38 . The output module  38  amplifies the floor signal and forwards it to the elevator control  18 . Progressions of the floor position characteristic values and the floor signal are represented in  FIG.  3   . 
     To calculate the floor position characteristic values, the evaluation unit  36  calibrates the sensor signals of the four Hall effect sensors  28 ,  30 ,  32 ,  34 . For this purpose, the evaluation unit  36  multiplies each sensor signal by a corresponding calibration factor. The calibration factors are determined during a calibration of the floor position detection device  26  to complete production of the floor position detection device  26 . For this purpose, one of each four identical magnetic means is arranged at a fixed distance in front of the four Hall effect sensors  28 ,  30 ,  32 ,  34 . The mentioned distance is selected so that each of the four sensor signals of the four Hall effect sensors  28 ,  30 ,  32 ,  34  safely exceeds a fourth threshold value. As soon as the evaluation unit  36  detects that all four sensor signals are greater than the fourth threshold value, it automatically starts a calibration. The calibration factors are determined in such a manner that during calibration each floor position characteristic value resulting from the multiplication of the sensor signal with the corresponding calibration factor has the same value of, for example, 300 mV. 
     The floor position detection device  26  also has a power supply unit  40 , which supplies the four Hall effect sensors  28 ,  30 ,  32 ,  34 , the evaluation unit  36  and the output module  38  with a supply voltage. The power supply unit  40  supplies the four Hall effect sensors  28 ,  30 ,  32 ,  34  and the evaluation unit  36  with the same 2 V supply voltage and the output module  38  with a different 24 V supply voltage. The power supply unit  40  and therefore the floor position detection device  26  are supplied with an input voltage of 24 V for this purpose. 
     In  FIG.  3   , the progressions of floor position characteristic values, as well as of a floor signal when passing the magnetic means  22  of the elevator car  14  and therefore of the floor position detection device  26  are from top to bottom. Curve  48  shows the first floor position characteristic value of the first Hall effect sensor  28 , curve  50  shows the second floor position characteristic value of the second Hall effect sensor  30 , curve  52  shows the third floor position characteristic value of the third Hall effect sensor  32  and curve  54  shows the fourth floor position characteristic value of the fourth Hall effect sensor  34 . Curve  56  shows the progression of the floor signal. The floor signal  56  can assume the state “outside the range of the floor” and “in the range of the floor”, wherein in  FIG.  3    the state “outside the range of the floor” is characterized with “0” and the state “in the range of the floor” with “1”. 
     The floor position characteristic values  48 ,  50 ,  52  and  54  rise from a quiescent level when the Hall effect sensor in question  28 ,  30 ,  32  and  34  enters the range of the magnetic means  22 , i.e. is immersed in the magnetic field  24 . They reach their maximum when the Hall effect sensor  28 ,  30 ,  32  and  34  in question is accurately at the level of the magnetic means  22 , to sink back to the quiescent level when moving away from the magnetic means  22 . From the size of the associated floor position characteristic values  48 ,  50 ,  52  and  54 , therefore, the distance of the corresponding Hall effect sensor  28 ,  30 ,  32 ,  34  from the magnetic means  22  in travel direction  13  can be inferred. 
     The first Hall effect sensor  28  and the second Hall effect sensor  30  are arranged in such a manner that when the floor position detection device  26  approaches the magnetic means  22  and therefore one floor, the approach can be derived from the first floor position characteristic value  48  before the second floor position characteristic value  50 . This can be seen from the fact that the first floor position characteristic value  48  rises before the second floor position characteristic value  50 . The evaluation unit  36  assigns the floor signal  56  the state “in the range of the floor” starting from the state “outside the range of the floor” if the second floor position characteristic value  50  becomes larger than the first floor position characteristic value  48  and at the same time the second floor position characteristic value  50  is larger than a first threshold value  58 . 
     The third Hall effect sensor  32  and the fourth Hall effect sensor  34  are arranged in such a manner that when the floor position detection device  26  moves away from the magnetic means  22  and therefore from one floor, the moving away from the third floor position characteristic value  52  can be derived before the fourth floor position characteristic value  54 . This can be seen from the fact that the third floor position characteristic value  52  decreases before the fourth floor position characteristic value  54  after reaching the maximum. The evaluation unit  36  then assigns the state “outside the range of the floor” to the floor signal  56  starting from the state “in the range of the floor” if the fourth floor position characteristic value  54  becomes larger than the third floor position characteristic value  52  and at the same time the third floor position characteristic value  52  is larger than a second threshold value  60  which is identical with the first threshold value  58 . 
     The magnetic means  22  and the floor position detection device  26  are arranged in such a manner that the floor signal has the state “in the range of the floor” when the elevator car  14  is positioned opposite a floor in such a manner that the car door and therefore also the shaft door can be opened at the same time. 
     The numbering used for the Hall effect sensors and therefore for the floor position characteristic values applies from top to bottom when passing the magnetic means as described above. When passing from bottom to top, the numbering is reversed. It is also possible that the floor position detection device has only three Hall effect sensors instead of four. In this case, the evaluation unit assigns the condition “outside the range of the floor” to the floor signal based on the state “in the range of the floor” as a function of the second and third floor position characteristic value. The evaluation unit evaluates the second floor position characteristic value for the third floor and the third for the fourth floor position characteristic value. 
     In  FIG.  4    an alternative floor position detection device  126  to the floor position detection device  26  from  FIG.  2    is represented. The floor position detection device  126  has a similar structure to the floor position detection device  26 , so that only the differences between the two floor position detection devices are dealt with. Similar or equivalent component parts are characterized in  FIG.  4    with a reference sign that is bigger by 100 as in  FIG.  2   . 
     The sensor unit  135  of the floor position detection device  126  has only a first Hall effect sensor  128  and a second Hall effect sensor  130 , which are also arranged side by side. 
     An evaluation unit  136  determines a floor signal from the sensor signals of the two Hall effect sensors  128 ,  130 . Progressions of the floor position characteristic values and the floor signal are represented in  FIG.  5   . 
     In  FIG.  5    the progression of floor position characteristic values, as well as of a floor signal when passing the magnetic means  22  of the elevator car  14  and therefore of the floor position detection device  126  are from top to bottom. The curve  148  shows the first floor position characteristic value of the first Hall effect sensor  128  and the curve  50  the second floor position characteristic value of the second Hall effect sensor  130 . The curve  156  shows the progression of the floor signal. The floor signal  156  can assume the state “outside the range of the floor” and “in the range of the floor”, wherein in  FIG.  5    the state “outside the range of the floor” is characterized with “0” and the state “in the range of the floor” with “1”. 
     The floor position characteristic values  148  and  150  rise from a quiescent level each time the Hall effect sensor  128 ,  130  in question enters the range of the magnetic means  22 , i.e. is immersed in the magnetic field  24 . They reach their maximum when the Hall effect sensor  128 ,  130  in question is accurately at the height of the magnetic means  22 , to sink back to the quiescent level when moving away from the magnetic means  22 . From the size of the associated floor position characteristic value  148 ,  150 , therefore, the distance of the corresponding Hall effect sensor  128 ,  130  from the magnetic means  22  in travel direction  13  can be inferred. 
     The first Hall effect sensor  128  and the second Hall effect sensor  130  are arranged in such a manner that when the floor position detection device  126  approaches the magnetic means  22  and therefore a floor, the approach can be derived from the first floor position characteristic value  148  before the second floor position characteristic value  150 . This can be seen from the fact that the first floor position characteristic value  148  rises before the second floor position characteristic value  150 . The evaluation unit  136  assigns the floor signal  156  the state “in the range of the floor” starting from the state “outside the range of the floor” if the second floor position characteristic value  150  becomes larger than the first floor position characteristic value  148  and at the same time the second floor position characteristic value  150  is larger than a first threshold value  158 . After the expiry of a specifiable time span of, for example, 1 and 100 ms, in particular 10 ms, after the described change of the floor signal  156  from the state “outside the range of the floor” to the state “in the range of the floor”, the evaluation unit  136  resets the floor signal  156  to the state “outside the range of the floor”. 
     The numbering used for the Hall effect sensors and therefore for the floor position characteristic values applies from top to bottom when passing the magnetic means as described above. When passing from bottom to top, the numbering is reversed. 
     Finally, it should be noted that terms such as “have”, “comprising”, etc. do not exclude any other elements or steps and terms such as “an” or “a” do not exclude any plurality. Further, it should be noted that features or steps which have been described with reference to one of the above embodiment examples can also be used in combination with other features or steps of other embodiment examples described above. 
     In accordance with the provisions of the patent statutes, the present invention has been described in what is considered to represent its preferred embodiment. However, it should be noted that the invention can be practiced otherwise than as specifically illustrated and described without departing from its spirit or scope.