(19)
(11)EP 3 461 740 B1

(12)EUROPEAN PATENT SPECIFICATION

(45)Mention of the grant of the patent:
29.07.2020 Bulletin 2020/31

(21)Application number: 18196944.5

(22)Date of filing:  26.09.2018
(51)International Patent Classification (IPC): 
B64C 13/04(2006.01)

(54)

POSITION DETECTION SYSTEM FOR A SLAT FLAP LEVER CONTROL

POSITIONSERFASSUNGSSYSTEM FÜR EINE LANDEKLAPPENHEBELSTEUERUNG

SYSTÈME DE DÉTECTION DE POSITION POUR UN LEVIER DE COMMANDE DE VOLETS


(84)Designated Contracting States:
AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

(30)Priority: 28.09.2017 US 201715718212

(43)Date of publication of application:
03.04.2019 Bulletin 2019/14

(73)Proprietor: Hamilton Sundstrand Corporation
Charlotte, NC 28217-4578 (US)

(72)Inventor:
  • ANKNEY, Darrell E.
    Dixon, IL Illinois 61021 (US)

(74)Representative: Dehns 
St. Bride's House 10 Salisbury Square
London EC4Y 8JD
London EC4Y 8JD (GB)


(56)References cited: : 
CN-A- 107 187 582
US-A1- 2014 116 194
US-A- 4 533 096
  
      
    Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention).


    Description

    BACKGROUND



    [0001] Exemplary embodiments pertain to the art of slat flap lever controls for aircrafts and, more particularly, to a position detection system and method associated with such slat flap lever controls.

    [0002] Aircraft slat and flap systems include slats and flaps that are extended and retracted at variable positions depending on the aircraft's take-off or landing situation to provide high lift to the aircraft at lower aircraft speeds. Actuation of the slats and flaps is provided in response to input from an aircraft operator. The input is made by movement of a slat flap control lever. Current levers are analog and implemented using a rotary variable differential transformer (RVDT). After many cycles, the reliability of the analog lever may deteriorate due to changes in the RVDT air gap and channel-to-channel variation. The use of RVDTs for determining rotation is taught in CN 107 187 582.

    BRIEF DESCRIPTION



    [0003] Disclosed herein is a slat flap lever control assembly as defined by claim 1.

    [0004] Further embodiments may include that the at least two RFID tags are in operative communication with a single channel of the RFID reader.

    [0005] Further embodiments may include at least one additional channel of the RFID reader, each additional channel respectively in operative communication with a plurality of additional RFID tags.

    [0006] Further embodiments may include that the numeral of total channels of the RFID reader corresponds to a total number of groups of RFID tags, the number of RFID tags in each of the total number of groups of RFID tags equaling a total number of discrete angular positions of the lever.

    [0007] Further embodiments may include that the total number of discrete angular positions is five.

    [0008] Further embodiments may include that the movable portion of the slat flap lever control assembly is a rotor operatively coupled to the lever.

    [0009] Further embodiments may include a communication system in operative communication with the RFID reader.

    [0010] Further embodiments may include that the communication system comprises a digital bus.

    [0011] Also disclosed is a method of monitoring a lever position of a slat flap lever control assembly as defined by claim 9.

    [0012] Further embodiments may include that the RFID reader comprises a plurality of channels, each of the channels in operative communication with respective groups of RFID tags to redundantly determine the angular position of the lever.

    [0013] Further embodiments may include that each of the groups of RFID tags include five RFID tags.

    [0014] Further embodiments may include communicating data received by the RFID reader to a digital bus.

    BRIEF DESCRIPTION OF THE DRAWINGS



    [0015] The following descriptions should not be considered limiting in any way. With reference to the accompanying drawings, like elements are numbered alike:

    FIG. 1 is a perspective view of a slat flap lever control assembly;

    FIG. 2 is a side, elevational schematic view of the slat flap lever control assembly; and

    FIG. 3 is a schematic view of a radio-frequency identification (RFID) system of the slat flap lever control assembly.


    DETAILED DESCRIPTION



    [0016] A detailed description of one or more embodiments of the disclosed apparatus and method are presented herein by way of exemplification and not limitation with reference to the Figures. The embodiments disclosed herein assist in the control of a slat flap control lever by precisely measuring its position and movement with respect to a stationary portion of a slat flap lever control assembly.

    [0017] FIG. 1 illustrates a slat flap lever control assembly and is generally referenced with numeral 10. The lever assembly 10 includes a hand grip 12 for grasping by an operator and lever 14 that controls actuation of slats and flaps associated with an aircraft wing. Also provided is a finger lift 16 that allows movement of the lever 14 when lifted by the operator.

    [0018] FIG. 2 illustrates the lever assembly 10 in more detail. In the illustrated embodiment, the lever 14 is movable over a range of five discrete angular positions. The lever 14 is rotatable over an angular range of positions, with discrete angular positions dictated by detents defined by a guide plate or the like. It is to be appreciated that five discrete angular positions is merely illustrative and that more or fewer discrete positions are contemplated. Verification that the lever 14 is in a desired angular position is provided with RFID technology via a RFID system 20, as described in detail herein.

    [0019] Referring now to FIGS 2 and 3, the RFID system 20 includes at least one RFID reader 22 configured on a stationary (unmovable) portion of the lever assembly 10. The RFID system 20 also includes a plurality of RFID tags 24 operatively coupled to one or more movable lever portions, such as the lever itself or a movable component 26 operatively coupled to the lever 14, such as a rotor. Movement of the movable component 26 corresponds to movement of the lever 14.

    [0020] In some aspects, RFID reader 22 is a multi-channel reader, with each channel outputting a predetermined carrier signal from the stationary portion of the lever 14 to one or more of the RFID tags 24. Each RFID tag 24 is configured to receive and reflect a carrier signal to the RFID reader 22. The RFID reader 22 is configured for signal output at multiple frequencies, where each of the output frequencies are different from each other. This may be facilitated by having a plurality of channels of the RFID reader 22, such as channels 28, 30, 32, 34 of the illustrated embodiment of FIG. 3. It is contemplated that more or fewer channels are present in some embodiments. In the illustrated embodiment, channel 28 is configured to interact with the column of RFID tags referenced with numeral 24a; channel 30 is configured to interact with the column of RFID tags referenced with numeral 24b; channel 32 is configured to interact with the column of RFID tags referenced with numeral 24c; and channel 34 is configured to interact with the column of RFID tags referenced with numeral 24d.

    [0021] The RFID reader 22 includes a signal generator, a signal transmitter, and a receiver, forming a RFID transceiver. The signal generator is configured to generate different carrier signals having different carrier frequencies. The signal transmitter includes one or more antenna configured to transmit the carrier signals generated by signal generator. Each of the signals generated have different carrier frequencies, such that when the signal is transmitted to an RFID tag 24, the reflected signal is received having the different frequency by one of the channels 28, 30, 32, 34.

    [0022] FIGS. 2 and 3 depict a movable lever portion 40 and a stationary lever portion 42 according to one embodiment. In some embodiments, the movable lever portion 40 is a rotor that facilitates movement of the lever 14. The RFID reader 22 is attachable to the stationary lever portion 42 and configured to communicate with at least two RFID tags, each of the RFID tags corresponding to a different angular position of the lever 14. In the illustrated embodiment, five positions are shown and represented with five rows of RFID tags. In the example with four channels 28, 30, 32, 34, a total of 20 RFID tags 24 are present. Each of the channels 28, 30, 32, 34 are unique RFID receiver channels that receive a signal that indicates the position of the lever.

    [0023] Since the signals transmitted from RFID reader 22 to the respective RFID tags are different from each other with respect to frequency, the system can accurately measure distance (e.g., within ±1 mm of accuracy) and motion (a change in distance with respect to time) between each of RFID tags 24 at the different positions and the RFID reader 22 based on the amount of change in phase between the reflected signals received by the receiving section and the carrier signals and the frequencies of the carrier signals (i.e., triangulation). The distances can accurately determine a position for the lever 14.

    [0024] Accordingly, RFID reader 22 can receive at least two reflected signals from RFID tags 24 at different angular positions of the lever 14, where each of the at least two reflected signals have a different carrier frequency. Although five rows of RFID tags are shown on movable lever portion 40, it should be appreciated that there may be any number of RFID tags configured as an array on a single movable lever portion, and there may be multiple RFID readers configured to transmit a plurality of different carrier signals and receive their reflections from the multiple RFID tags on the panel.

    [0025] The RFID reader 22 is operatively connected to one or more communication system 50. The communication system 50 is a signal translator and data bus in some embodiments. The communication system 50 translates the signals to angular positions of the lever 14 and communicates the position to a controller or other device that alerts an operator of the position and/or corrects the angular position to a desired position.

    [0026] In some embodiments, the RFID reader 22 communicates with four RFID tags of the plurality of RFID tags 24 to provide redundancy, and a controller. The controller includes a processor connected to the RFID reader 22. The processor transmits four channel carrier signals via the RFID reader 22 to the four RFID tags at an angular position (i.e., common row of FIG. 3). Each of the transmitted carrier signals have a unique carrier frequency. The processor also receives four reflected signals from RFID tags. The processor determines position based on the reflected signal from the four RFID tags. Each of the four RFID channels detects the lever's angle of rotation and the position of the lever 14. The data transmitted corresponds to the pilot's commanded slat and flap position on the wing. The data associated with the pilot's command is then used in the movement of the slats/flaps.

    [0027] The disclosed embodiments implement a four channel RFID between a positional rotary component and a four channel RFID transceiver. The rotational position from the RFID transceiver is translated to the communication system 50 (e.g., digital bus), such as CAN, ARINC 429, 1553, etc. The rotational positions are transmitted on the data bus as units of degrees and discrete in/out of detent position. The disclosed embodiments improve reliability due to the reduction in complexity of the system. This is attributed to contactless position sensors, precise sensing and a multi-channel redundant design. Additionally, the lever assembly weight is reduced by removing wire wound RVDT and reducing wiring harness weight by implementing a digital data bus.

    [0028] The term "about" is intended to include the degree of error associated with measurement of the particular quantity based upon the equipment available at the time of filing the application.

    [0029] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, element components, and/or groups thereof.

    [0030] The embodiments disclosed herein can be a system, a method, and/or a computer program product at any possible technical detail level of integration. The computer program product can include a computer readable storage medium (or media) having computer readable program instructions thereon for causing a processor to carry out aspects of the present disclosed embodiments.

    [0031] The computer readable storage medium can be a tangible device that can retain and store instructions for use by an instruction execution device. The computer readable storage medium can be, for example, but is not limited to, an electronic storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination of the foregoing. A non-exhaustive list of more specific examples of the computer readable storage medium includes the following: a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), a static random access memory (SRAM), a portable compact disc read-only memory (CD-ROM), a digital versatile disk (DVD), a memory stick, and any suitable combination of the foregoing. A computer readable storage medium, as used herein, is not to be construed as being transitory signals per se, such as radio waves or other freely propagating electromagnetic waves, electromagnetic waves propagating through a waveguide or other transmission media (e.g., light pulses passing through a fiber-optic cable), or electrical signals transmitted through a wire.

    [0032] Computer readable program instructions for carrying out operations of the disclosed embodiments can be assembler instructions, instruction-set-architecture (ISA) instructions, machine instructions, machine dependent instructions, microcode, firmware instructions, state-setting data, configuration data for integrated circuitry, or either source code or object code written in any combination of one or more programming languages, including an object oriented programming language such as Smalltalk, C++, or the like, and procedural programming languages, such as the "C" programming language or similar programming languages. The computer readable program instructions can execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. In the latter scenario, the remote computer can be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or the connection can be made to an external computer (for example, through the Internet using an Internet Service Provider). In some embodiments, electronic circuitry including, for example, programmable logic circuitry, field-programmable gate arrays (FPGA), or programmable logic arrays (PLA) can execute the computer readable program instructions by utilizing state information of the computer readable program instructions to personalize the electronic circuitry, in order to perform aspects of the disclosed embodiments.

    [0033] While the present disclosure has been described with reference to an exemplary embodiment or embodiments, it is intended that the present disclosure not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this present disclosure, but that the present disclosure will include all embodiments falling within the scope of the claims.


    Claims

    1. A slat flap lever control assembly (10) comprising:

    a moveable portion (40);

    a moveable lever (14) coupled to the moveable portion;

    a stationary portion (42); and

    a system for monitoring a position of the lever,

    characterised in that the system comprises :

    at least two radio frequency identification device, RFID, tags (24) operatively coupled to the movable portion (40);

    a RFID reader (22) operatively coupled to the stationary portion (42) of the slat flap lever control assembly (10) and in operative communication with the at least two RFID tags (24); and

    a controller comprising a processor operatively connected to the RFID reader, the processor configured to:

    transmit a carrier signal via the RFID reader to the at least two RFID tags;

    receive, via the RFID reader, at least two reflected signals from the at least two RFID tags, each of the at least two reflected signals comprising a different carrier frequency; and

    determine, via the processor, based on the reflected signal from the at least two RFID tags, an angular position of the movable portion relative to the stationary portion.


     
    2. The assembly of claim 1, wherein the at least two RFID tags are in operative communication with a single channel (28) of the RFID reader.
     
    3. The assembly of claim 2, further comprising at least one additional channel (28, 30, 32, 34) of the RFID reader, each additional channel respectively in operative communication with a plurality of additional RFID tags.
     
    4. The assembly of claim 3, wherein the numeral of total channels of the RFID reader corresponds to a total number of groups of RFID tags, the number of RFID tags in each of the total number of groups of RFID tags equaling a total number of discrete angular positions of the lever.
     
    5. The assembly of claim 4, wherein the total number of discrete angular positions is five.
     
    6. The assembly of any preceding claim, wherein the movable portion of the slat flap lever control assembly is a rotor operatively coupled to the lever.
     
    7. The assembly of any preceding claim, further comprising a communication system (50) in operative communication with the RFID reader.
     
    8. The assembly of claim 7, wherein the communication system comprises a digital bus.
     
    9. A method of monitoring a position of a slat flap lever control assembly that includes a moveable portion, a moveable lever operatively coupled to the movable portion, and a stationary portion, characterised in that the method comprises:

    transmitting, via a RFID reader coupled to the stationary portion, a carrier signal to at least two RFID tags coupled to the moveable portion;

    receiving, via the RFID reader, at least two reflected signals from the at least two RFID tags, wherein each of the at least two reflected signals comprise a different carrier frequency; and

    determining, via a processor, based on the reflected signal from the at least two RFID tags, an angular position of the moveable lever.


     
    10. The method of claim 9, wherein the RFID reader comprises a plurality of channels, each of the channels in operative communication with respective groups of RFID tags to redundantly determine the angular position of the lever.
     
    11. The method of claim 10, wherein each of the groups of RFID tags include five RFID tags.
     
    12. The method of claim 9, 10 or 11, further comprising communicating data received by the RFID reader to a digital bus.
     


    Ansprüche

    1. Landeklappenhebelsteuerungsbaugruppe (10), Folgendes umfassend:

    einen beweglichen Abschnitt (40);

    einen beweglichen Hebel (14), der an den beweglichen Abschnitt gekoppelt ist;

    einen stationären Abschnitt (42); und

    ein System zum Überwachen einer Position des Hebels, dadurch gekennzeichnet, dass das System Folgendes umfasst:

    mindestens zwei Radiofrequenzidentifikationsvorrichtungs-Tags (RFID-Tags) (24), die mit dem beweglichen Abschnitt (40) wirkverbunden sind;

    ein RFID-Lesegerät (22), das mit dem stationären Abschnitt (42) der Landeklappenhebelsteuerungsbaugruppe (10) wirkverbunden ist und in Wirkverbindung mit den mindestens zwei RFID-Tags (24) steht; und

    eine Steuerung, die einen Prozessor umfasst, der mit dem RFID-Lesegerät wirkverbunden ist, wobei der Prozessor zu Folgendem konfiguriert ist:

    Übertragen eines Trägersignals über das RFID-Lesegerät an die mindestens zwei RFID-Tags;

    Empfangen von mindestens zwei reflektierten Signalen von den mindestens zwei RFID-Tags über das RFID-Lesegerät, wobei jedes der mindestens zwei reflektierten Signale eine andere Trägerfrequenz umfasst; und

    Bestimmen einer Winkelposition des beweglichen Abschnitts in Bezug auf den stationären Abschnitt über den Prozessor, basierend auf dem reflektierten Signal von den mindestens zwei RFID-Tags.


     
    2. Baugruppe nach Anspruch 1, wobei die mindestens zwei RFID-Tags in Wirkverbindung mit einem einzigen Kanal (28) des RFID-Lesegeräts stehen.
     
    3. Baugruppe nach Anspruch 2, ferner mindestens einen zusätzlichen Kanal (28, 30, 32, 34) des RFID-Lesegeräts umfassend, wobei jeder entsprechende zusätzliche Kanal in Wirkverbindung mit einer Vielzahl von zusätzlichen RFID-Tags steht.
     
    4. Baugruppe nach Anspruch 3, wobei die Zahl von sämtlichen Kanälen des RFID-Lesegeräts einer Gesamtanzahl von Gruppen von RFID-Tags entspricht, wobei die Anzahl von RFID-Tags in jeder von der Gesamtanzahl von Gruppen von RFID-Tags gleich einer Gesamtzahl von diskreten Winkelpositionen des Hebels ist.
     
    5. Baugruppe nach Anspruch 4, wobei die Gesamtanzahl von diskreten Winkelpositionen fünf beträgt.
     
    6. Baugruppe nach einem der vorhergehenden Ansprüche, wobei der bewegliche Abschnitt der Landeklappenhebelsteuerungsbaugruppe ein Rotor ist, der mit dem Hebel wirkverbunden ist.
     
    7. Baugruppe nach einem der vorhergehenden Ansprüche, ferner ein Kommunikationssystem (50) umfassend, das in Wirkverbindung mit dem RFID-Lesegerät steht.
     
    8. Baugruppe nach Anspruch 7, wobei das Kommunikationssystem einen digitalen Bus umfasst.
     
    9. Verfahren zum Überwachen einer Position einer Landeklappenhebelsteuerungsbaugruppe, die einen beweglichen Abschnitt, einen beweglichen Hebel, der mit dem beweglichen Abschnitt wirkverbunden ist, und einen stationären Abschnitt beinhaltet, dadurch gekennzeichnet, dass das Verfahren Folgendes umfasst:

    Übertragen eines Trägersignals an mindestens zwei RFID-Tags, die an den beweglichen Abschnitt gekoppelt sind, über ein RFID-Lesegerät, das an den stationären Abschnitt gekoppelt ist;

    Empfangen von mindestens zwei reflektierten Signalen von den mindestens zwei RFID-Tags über das RFID-Lesegerät, wobei jedes von den mindestens zwei reflektierten Signalen eine andere Trägerfrequenz umfasst; und

    Bestimmen einer Winkelposition des beweglichen Hebels über einen Prozessor, basierend auf dem reflektierten Signal von den mindestens zwei RFID-Tags.


     
    10. Verfahren nach Anspruch 9, wobei das RFID-Lesegerät eine Vielzahl von Kanälen umfasst, wobei jeder der Kanäle in Wirkverbindung mit entsprechenden Gruppen von RFID-Tags steht, um die Winkelposition des Hebels redundant zu bestimmen.
     
    11. Verfahren nach Anspruch 10, wobei jede der Gruppen von RFID-Tags fünf RFID-Tags beinhaltet.
     
    12. Verfahren nach Anspruch 9, 10, oder 11, ferner umfassend, dass Daten, die durch das RFID-Lesegerät empfangen werden, an einen digitalen Bus kommuniziert werden.
     


    Revendications

    1. Ensemble levier de commande de volets (10) comprenant :

    une partie mobile (40) ;

    un levier mobile (14) couplé à la partie mobile ;

    une partie fixe (42) ; et

    un système de surveillance d'une position du levier, caractérisé en ce que le système comprend :

    au moins deux étiquettes de dispositif d'identification par radiofréquence, RFID, (24) couplées de manière opérationnelle à la partie mobile (40) ;

    un lecteur RFID (22) couplé de manière opérationnelle à la partie fixe (42) de l'ensemble levier de commande de volets (10) et en communication opérationnelle avec les au moins deux étiquettes RFID (24) ; et

    un dispositif de commande comprenant un processeur relié de manière opérationnelle au lecteur RFID, le processeur étant configuré pour :

    transmettre un signal de porteuse par l'intermédiaire du lecteur RFID aux au moins deux étiquettes RFID ;

    recevoir, par l'intermédiaire du lecteur RFID, au moins deux signaux réfléchis des au moins deux étiquettes RFID, chacun des au moins deux signaux réfléchis comprenant une fréquence porteuse différente ; et

    déterminer, par l'intermédiaire du processeur, sur la base du signal réfléchi des au moins deux étiquettes RFID, une position angulaire de la partie mobile par rapport à la partie fixe.


     
    2. Ensemble selon la revendication 1, dans lequel les au moins deux étiquettes RFID sont en communication opérationnelle avec un canal unique (28) du lecteur RFID.
     
    3. Ensemble selon la revendication 2, comprenant en outre au moins un canal supplémentaire (28, 30, 32, 34) du lecteur RFID, chaque canal supplémentaire étant respectivement en communication opérationnelle avec une pluralité d'étiquettes RFID supplémentaires.
     
    4. Ensemble selon la revendication 3, dans lequel le nombre total de canaux du lecteur RFID correspond à un nombre total de groupes d'étiquettes RFID, le nombre d'étiquettes RFID dans chacun du nombre total de groupes d'étiquettes RFID étant égal à un nombre total de positions angulaires distinctes du levier.
     
    5. Ensemble selon la revendication 4, dans lequel le nombre total de positions angulaires distinctes est de cinq.
     
    6. Ensemble selon une quelconque revendication précédente, dans lequel la partie mobile de l'ensemble levier de commande de volets est un rotor couplé de manière opérationnelle au levier.
     
    7. Ensemble selon une quelconque revendication précédente, comprenant en outre un système de communication (50) en communication opérationnelle avec le lecteur RFID.
     
    8. Ensemble selon la revendication 7, dans lequel le système de communication comprend un bus numérique.
     
    9. Procédé de surveillance d'une position d'un ensemble levier de commande de volets qui comporte une partie mobile, un levier mobile couplé de manière opérationnelle à la partie mobile, et une partie fixe, caractérisé en ce que le procédé comprend :

    la transmission, par l'intermédiaire d'un lecteur RFID couplé à la partie fixe, d'un signal de porteuse à au moins deux étiquettes RFID couplées à la partie mobile ;

    la réception, par l'intermédiaire du lecteur RFID, d'au moins deux signaux réfléchis des au moins deux étiquettes RFID, dans lequel chacun des au moins deux signaux réfléchis comprend une fréquence porteuse différente ; et

    la détermination, par l'intermédiaire d'un processeur, sur la base du signal réfléchi des au moins deux étiquettes RFID, d'une position angulaire du levier mobile.


     
    10. Procédé selon la revendication 9, dans lequel le lecteur RFID comprend une pluralité de canaux, chacun des canaux étant en communication opérationnelle avec des groupes respectifs d'étiquettes RFID pour déterminer de manière redondante la position angulaire du levier.
     
    11. Procédé selon la revendication 10, dans lequel chacun des groupes d'étiquettes RFID comporte cinq étiquettes RFID.
     
    12. Procédé selon la revendication 9, 10 ou 11, comprenant en outre la communication de données reçues par le lecteur RFID à un bus numérique.
     




    Drawing














    Cited references

    REFERENCES CITED IN THE DESCRIPTION



    This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.

    Patent documents cited in the description