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Title:
MODULAR FLOOR UNIT AND METHOD FOR ASSEMBLING SUCH FLOOR UNIT
Document Type and Number:
WIPO Patent Application WO/2015/144901
Kind Code:
A1
Abstract:
The present invention is related to a modular floor unit such as a foot wiping mat comprising a plurality of elongate floor unit members (11) spaced apart and interconnected by connection members (12), wherein the floor unit members are provided with lateral grooves (14), and wherein the connection members (12) comprise a central portion (20) for bridging the gap between two adjacent floor unit members (11) and a pair of laterally placed resilient portions (21) inserted in said grooves. When the floor unit is placed on a level surface, the central portion is situated between said level surface and the upper surface of the floor unit. The invention is equally related to a method for assembling a floor unit according to the invention.

Inventors:
D HONT MARC (BE)
Application Number:
PCT/EP2015/056775
Publication Date:
October 01, 2015
Filing Date:
March 27, 2015
Export Citation:
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Assignee:
VERIMPEX GROUP NV (BE)
International Classes:
E04F15/16; A47L23/26; E04F19/10
Foreign References:
EP1149554A22001-10-31
EP1884182A22008-02-06
DE9401006U11994-03-17
US20050170129A12005-08-04
DE202004001764U12005-06-23
Attorney, Agent or Firm:
PRONOVEM - OFFICE VAN MALDEREN (Brussels, BE)
Download PDF:
Claims:
CLAIMS

1. Modular floor unit (10), comprising a plurality of elongate floor unit members (11) spaced apart and interconnected by connection members (12), wherein

· each pair of adjacent members, when placed on a level surface, extends between a first plane (100) defined by said level surface and a second plane (200) defined by the upper surface of said adjacent members,

• the floor unit members are provided with lateral grooves (14), said grooves being provided with a protrusion (35) on their interior surface,

• the connection members (12) comprise a central portion (20) for bridging the gap between two adjacent floor unit members (11) and a pair of laterally placed resilient portions (21) inserted in said grooves, said resilient portions (21) being formed as folded portions of a web material, said folded portions (21) comprising a first leg portion (23) attached to the central portion (20) of the connection member, a bend portion (24) and a second leg portion (25), the second leg portion being secured behind the protrusion (35) provided in the grooves,

wherein the central portion (20) is situated between said first and second plane (100,200).

2. Modular floor unit according to claim 1, wherein said grooves (14) have an inner edge (31) and an outer edge (30), the outer edge being located at a lower level than the inner edge when the profiles are placed on a support surface (100,101) with the opening of the grooves oriented away from the support surface, said levels being measured with respect to said support surface (100,101) and wherein the central portion (20) is situated between the levels of the inner and the outer edge.

3. Modular floor unit according to claim 1 or 2, wherein the central portion (20) and the resilient portions (21) are formed from a single piece of said web material .

4. Modular floor unit according to any one of claims 1 to 3, wherein the first leg portion (23) is essentially perpendicular to the central portion (20).

5. Modular floor unit according to claim 4, wherein at least one of the connection members (12) further comprises a longitudinal rib (22) placed perpendicularly on the central portion (20) of said connection member.

6. Modular floor unit according to claim 5, wherein said at least one connection member (12) further comprises a distancing strip (40) placed on said rib, for maintaining a fixed distance between two floor unit members (11) when the floor unit is rolled up.

7. Modular floor unit according to any one of the preceding claims, wherein at least the folded portions (21) of the connection members are formed of a polymer material.

8. Modular floor unit according to any one of the preceding claims, wherein the folded portions (21) exert an elastic force on the interior of the grooves (14) that is sufficient to obstruct any substantial longitudinal movement of the connection members (12) with respect to the grooves .

9. Modular floor unit according to any one of the preceding claims, wherein multiple connection members (12) are mounted between the same pair of floor unit members (11) .

10. Modular floor unit according to any one of the preceding claims, wherein the length of the connection members (12) is between 1 cm and 5 cm.

11. Modular floor unit according to any one of the preceding claims, wherein the floor unit is a modular foot wiping mat, the floor unit members comprising a means (13) for receiving and maintaining strips of matting material.

12. Method for assembling a floor unit (10) according to any one of the preceding claims, comprising the steps of :

• providing at least two floor unit members (11),

• attaching the connection members (12) to said floor unit members by inserting the folded portions (21) of said connection members into the grooves (14) of the floor unit members in a direction perpendicular to said grooves, whereby the folded portions (21) are compressed by the insertion process,

• securing the connection members (12) by pushing the folded portions past the protrusion (35) provided in the grooves so that the folded portions (21) snap back against the interior of the grooves, thereby securing the folded portions (21) in said grooves.

13. Method according to claim 12, wherein the first leg portion (23) of the folded portions of the connection members is essentially perpendicular to the central portion (20), and wherein the method comprises the steps of

• placing said floor unit members (11) on a flat horizontal surface (100), with the interior of the grooves (14) facing upward,

• gripping the connection members (12) and moving them in a direction perpendicular to the flat surface, towards the floor unit members (11), thereby inserting the folded portions (21) into the grooves, so that both folded portions (21) of a connection member are simultaneously secured into two grooves (14) of two adjacent floor unit members.

14. Method according to claim 12, wherein the first leg portion (23) of the folded portions of the connection members is essentially perpendicular to the central portion (20), and wherein the method comprises the steps of

• placing said floor unit members (11) on a convex surface (101), with the interior of the grooves (14) facing away from said surface, and two adjacent grooves of two adjacent floor unit members (11) facing away from each other as a consequence of the convex shape of the surface (101),

• gripping the connection members (12) and moving them in a direction perpendicular to the convex surface, towards the floor unit members (11), thereby inserting the folded portions (21) into the grooves, so that both folded portions (21) of a connection member are simultaneously secured into two grooves (14) of two adjacent floor unit members.

Description:
MODULAR FLOOR UNIT AND METHOD FOR ASSEMBLING SUCH FLOOR UNIT

Field of the invention

[0001] The present invention relates to modular floor units, in particular to modular floor mats, such as for wiping footwear as used at building entrances. Background of the invention

[0002] Floor mat systems of the above kind are known from e.g. CH 692 442 and DE 20 2004 009 095 Ul and typically comprise an array of elongate wiper units arranged parallel side-by-side and interconnected by connection members, which engage in T-slots provided in the wiper units. The wiper units are spaced apart by the connection members to allow dirt to fall in between. Also, the system can present a flexibility allowing the wiper units to be rolled up, such that the dirt collected underneath can be removed at regular intervals and/or to ease transporting and handling. This is obtained by making the connection members flexible, such as by having them made of rubber or another elastic material.

[0003] In both documents cited above, the connection members are short parts compared to the length of the wiper units, whereas the T-slots form channels all along the length of the wiper units. To assemble the system, the connection members are inserted in the T-slots at one end and are slid along until they are in place. To prevent the connection members from moving along, CH 692 442 proposes to slightly oversize the connection member's ends engaging in the T-slots. However, this makes sliding the connection members to their place along the units cumbersome, particularly for long wiper units, which require connection members at regular intervals.

[0004] Another solution is shown in US6434779B1.

This document shows a mat comprising longitudinal rail members assembled by connector members of extruded polymeric material. The rail members have leg portions while the connector members have U-shaped socket portions which are snap-fitted onto the leg portions. Anchor tabs are furthermore provided which are pushed laterally against the side walls of the U-portions after the assembly step, in order to secure the connector members and prevent the rail members from displacing longitudinally relative to the connector members. The presence of the U-portions complicates the design and fabrication of the connector members. Furthermore, the additional securing step involving the anchor tabs makes the assembly process complex .

[0005] The product described in document EP1149554 is another example of a foot mat comprising longitudinal matting profiles held together by connection elements. The connection elements are formed of a flat portion comprising a middle portion and two side portions. On each of the two side portions is a vertically upstanding securing element which can be a resilient hook-shaped element configured to be snap-fitted into corresponding vertical openings in the profiles. The middle portion is provided with a separating member, the height of which corresponds to the height of the profiles. These connection elements are technically quite complex. This is partly due to the fact that the connection elements serve not only for connecting and maintaining the profiles with respect to each other, but also for supporting the profiles. In other words, the profiles are resting on the two flat side portions, which therefore equally need to perform an anti-slip and a damping function with respect to the support surface onto which the mat is lying. This also implies that the connection elements need to extend along a considerable part of the length of the profiles. The presence of the separating member makes the connection elements quite visible which may decrease the aesthetic aspect of the mat. The force transfer between adjacent profiles is furthermore less than optimal due to the fact that the portion that is bridging the gap between two profiles is located to one side of the height of the profiles, so that a force that is pulling two profiles apart may result in a tilting movement of the profiles as well as in a high force exhibited on the vertically upstanding securing elements which are fitted inside the vertical openings. Summary of the invention

[0006] The present invention aims to provide an alternative modular system of the abovementioned type, which overcomes drawbacks of the prior art systems.

[0007] The present invention is generally related to a modular floor unit such as a foot wiping mat comprising a plurality of elongate floor unit members spaced apart and interconnected by connection members, wherein the floor unit members are provided with lateral grooves, and wherein the connection members comprise a central portion for bridging the gap between two adjacent floor unit members and a pair of laterally placed resilient portions inserted in said grooves. When the floor unit is placed on a level surface, the central portion is situated between said level surface and the upper surface of the floor unit. According to a preferred embodiment, the grooves have an outer edge and an inner edge, the outer edge being at a lower level than an inner edge when the profiles are placed on a surface, with the grooves facing upwards.

[0008] According to an aspect of the invention, there is hence provided a modular floor unit as set out in the appended claims. The invention is thus firstly related to a modular floor unit, comprising a plurality of elongate floor unit members arranged mutually parallel and spaced apart and interconnected by connection members, wherein

• each pair of adjacent members, when placed on a level surface, extends between a first plane defined by said level surface and a second plane defined by the upper surface of said adjacent members,

• the floor unit members are provided with lateral grooves, said grooves being provided with a protrusion on their interior surface,

• the connection members comprise a central portion for bridging the gap between two adjacent floor unit members and a pair of laterally placed resilient portions inserted in said grooves, said resilient portions being formed as folded portions of a web material, said folded portions comprising a first leg portion attached to the central portion of the connection member, a bend portion and a second leg portion, the second leg portion being secured behind the protrusion provided in the grooves,

wherein the central portion is situated between said first and second plane.

[0009] According to an embodiment, the grooves have an outer edge and an inner edge, the outer edge being at a lower level than an inner edge when the profiles are placed on a support surface with the opening of the grooves oriented away from the support surface, said levels being measured with respect to said support surface and the central portion is situated between the levels of the inner and the outer edge. This means that the central portion is situated between the levels at which the inner and outer edges of the grooves are situated with respect to the support surface, when the floor unit is placed on the support surface with the opening of the grooves facing towards or away from the support surface.

[0010] As stated, the second leg portion is secured behind the protrusion provided in the grooves. In other words, the end of the second leg portion is prevented by said protrusion from moving out of the groove in a direction perpendicular to the groove.

[0011] In a modular floor unit according to the invention, the resilient portions and said grooves are configured so that the resilient portions of a single connection element are fitted into the grooves of two adjacent mat units, and wherein said fitting is obtainable by pushing the connection member in a direction perpendicular to the grooves until the folded portions are inserted and secured in said grooves.

[0012] When secured in the grooves, the folded portions of the connection members are in a compressed state: the leg portions are compressed laterally so that they exert an elastic counterforce on the sidewalls of the grooves .

[0013] According to an embodiment, the central portion and the resilient portions are formed from a single piece of said web material.

[0014] According to an embodiment, the first leg portion is essentially perpendicular to the central portion . [0015] At least one of the connection members may further comprise a longitudinal rib placed perpendicularly on the central portion of said connection member. A distancing strip may further be placed on said rib, for maintaining a fixed distance between two floor unit members when the floor unit is rolled up.

[0016] In a modular floor unit according to the invention, at least the folded portions of the connection members may be formed of a polymer material. Preferably this is a rigid or semi-rigid material such as poly-oxy methylene .

[0017] In a floor unit according to preferred embodiments of the invention, the folded portions exert an elastic force on the interior of the grooves that is sufficient to obstruct any substantial longitudinal movement of the connection members with respect to the grooves .

[0018] According to the preferred embodiment, multiple connection members are mounted between the same pair of mat members. The length of the connection members is preferably between 1 cm and 5 cm.

[0019] According to an embodiment, the floor unit is a modular foot wiping mat, the floor unit members comprising a means for receiving and maintaining strips of matting material.

[0020] The invention is secondly related to a method for assembling a floor unit according to the invention, comprising the steps of :

• providing at least two floor unit members,

· attaching the connection members to said floor unit members by inserting the folded portions of said connection members into the grooves of the floor unit members in a direction perpendicular to said grooves, whereby the folded portions are compressed by the insertion process,

• securing the connection members by pushing the folded portions past the protrusion provided in the grooves so that the folded portions snap back against the interior of the grooves, thereby securing the folded portions in said grooves.

[0021] According to an embodiment of the method, the first leg portion of the folded portions of the connection members is essentially perpendicular to the central portion, and wherein the method comprises the steps of

• placing said floor unit members on a flat horizontal surface, with the interior of the grooves facing upward,

· gripping the connection members and moving them in a direction perpendicular to the flat surface, towards the floor unit members, thereby inserting the folded portions into the grooves, so that both folded portions of a connection member are simultaneously secured into two grooves of two adjacent floor unit members .

[0022] According to another embodiment of the method of the invention, the first leg portion of the folded portions of the connection members is essentially perpendicular to the central portion, and wherein the method comprises the steps of

• placing said floor unit members on a convex surface, with the interior of the grooves facing away from said surface, and two adjacent grooves of two adjacent floor unit members facing away from each other as a consequence of the convex shape of the surface,

• gripping the connection members and moving them in a direction perpendicular to the convex surface, towards the floor unit members, thereby inserting the folded portions into the grooves, so that both folded portions of a connection member are simultaneously secured into two grooves of two adjacent floor unit members .

Brief Description of the Drawings

[0023] Figure 1 represents a 3D view of a modular floor mat according to the invention.

[0024] Figure 2 represents front and top view of the mat of figure 1.

[0025] Figure 3 shows a detailed view of a connection member in a mat according to the invention.

[0026] Figure 4 illustrates the assembly method for assembling a floor mat according to the invention.

[0027] Figure 5 shows a further embodiment related to a specific shape of the connection member.

[0028] Figure 6 shows an alternative embodiment of the connection member.

[0029] Figure 7 illustrates a preferred assembly method for producing a floor unit according to the invention .

Detailed Description of the Invention

[0030] Figure 1 represents an example embodiment of a modular floor mat 10 according to the invention. The invention is mainly applicable to foot wiping mats but could be applicable also to floor units having other functionalities, e.g. sound damping, floor lighting etc.

[0031] The mat 10 is formed of a number of mat members 11, which are spaced apart and interconnected by connection members 12. Mat members 11 are disposed side- by-side and preferably parallel to one another, with the connection members 12 bridging the gaps in between two neighbouring mat members 11. Mat members 11 are preferably elongate, in that their length can be substantially larger than the dimensions along the other two directions in space .

[0032] The mat members 11 are advantageously provided in the form of elongate profiles, preferably made of an extruded material, such as aluminium or an aluminium alloy. The upper side of the profiles advantageously comprises a central upwardly open channel 13 for receiving a matting strip or other wiping means (not shown) . The lateral edges of the profiles 11 comprise a groove 14 that runs along at least a portion of the length of the units, preferably along the entire length. The grooves are shaped so as to cooperate with the connection members 12 in a manner described hereafter. The width of the profiles 11 is preferably the same for the majority of the profiles within one assembly, possibly with narrower profiles being placed at the edges of the assembly, such as profile 11' shown in figure 1, which could contain a narrower brush element or a scraper. Additional grooves 15 are formed on the underside of the profiles, for receiving rubber strips that may be inserted in said grooves 15 for damping the contact of the mat with the ground and/or for providing an anti-slip function.

[0033] The connection members 12 are preferably formed of a synthetic composite material of relatively high strength and rigidity such as poly-oxy methylene (POM) . As is best seen in the front and top views of Figure 2, the connection members extend over a given length L along the length of the mat members 11. Preferably more than one connection member 12 is placed between two adjacent mat profiles 11, the number of connection members 12 depending on the size of the mat. Each connection member 12 comprises a central horizontal portion 20 that bridges the gap between two adjacent profiles 11, and a pair of resilient portions 21, one on each side of the central portion 20, the resilient portions 21 being formed of folded web material, i.e. a flat sheet-like material shaped into the form of a fold. The central portion 20 and the folded portions 21 are preferably formed from a single piece of web material, as is the case in the embodiment shown in Figure 2. The folded portions 21 are fitted behind protrusions 35 provided on the interior surface of the lateral grooves 14 of the mat units.

[0034] Figure 2 shows a side view of the modular floor mat of the invention, placed on a level surface 100. Each pair of adjacent mat members 11 extends between a first plane 100 corresponding to the level surface and a second plane 200 corresponding to the upper surface of the adjacent mat members 11. As seen in the drawing, the central portion 20 of each connection member 12 is located between the first and second plane 100/200. Preferably the central portion 20 is centrally placed between the two planes, 'centrally' meaning for example between 40% and 60% of the distance between the planes 100 and 200, starting from one of said planes. The position of the second plane 200 is preferably determined when no brushes or tufts are present on the profiles. If not all the mat members are identical, the second plane 200 is determined by the upper surface of the highest mat member.

[0035] The intermediate position of the horizontal portion 20 means that this horizontal portion 20 is not in direct contact with the support surface 100, nor is it level with the upper surface of the mat members 11. The connection member 12 used in the invention does not have any function of supporting the mat members 11 nor of ensuring damping and/or anti/slip functions for these mat members 11. These functions are performed by the mat members 11 themselves, and may for example be realised by providing dampening and/or anti-slip elements in the grooves 15 on the opposite side of the grooves 14.

[0036] Contrary to the existing systems, the connection members 12 in a floor unit of the invention can thus be made more compact in the length direction of the mat members 11, leaving more space between 2 connection members 12 mounted between a given pair of mat members 11 so that dirt and water can be more easily evacuated. The length of the connection members 12 is preferably small compared to the length of the mat members 11. Preferably the length of the connection members 12 is between 1 and 5 cm, more preferably between 1.5 and 4cm, even more preferably between 2 and 3 cm. Also, the connection members 12 are less visible as they are located between the upper and lower levels of the mat members 11, which improves the aesthetic aspect of the floor unit. The design of the connection members 12 is also an improvement over the existing systems in terms of the forces acting between the profiles 11 and the connection members 12. As seen in the figures, the central position (in the direction between planes 100 and 200) of the central portion 20 of the connection members 12 and the fact that the connection members 12 are more compact allow for a more efficient force transfer between adjacent profiles, which leads to a stronger and more failsafe product.

[0037] In the preferred embodiment shown in the figures, the position of the central portion 20 is further defined with respect to a preferred shape of the grooves 14, as explained hereafter. With reference to Figures 2 and 4, when the mat members 11 are placed face downward on a support surface 100, so that the opening of the grooves 14 is facing away from the support surface, these grooves 14 have a lower edge 30 and an upper edge 31. The lower edge 30 extends further outwards laterally from the central vertical plane 32 of the mat member 11 than the upper edge 31. In other words, the lower edge 30 can be described as the 'outer edge' of the groove 14, while the upper edge 31 is the 'inner edge' of the groove 14, the terms 'inner' and 'outer' being referenced with respect to the central vertical plane 32 of the mat member 11. At the lower edge 30, the groove 14 has a vertically oriented rim portion 33 so as to form a receptacle 36 for receiving the connection member's resilient portion 21, said receptacle 36 being formed between the rim portion 33 and the side wall 34 of the groove 14. At the upper edge 31, the mat unit's side wall 34 is provided with a protrusion 35, i.e. a portion that projects away from the side wall 34 over a given distance, preferably oriented essentially perpendicularly to said side wall 34. The protrusion 35 extends along at least a portion of the longitudinal direction of the groove 14.

[0038] As seen in Figures 2 and 4, the central horizontal portion 20 of the connection member 12 is situated between the levels at which the lower and upper edges 30/31 of the grooves are situated with respect to the support surface 100. This is true whether the mat is upside down on the surface 100 (as in Figure 4, position for assembling the mat, see further) , or with the matting receiving areas 13 facing upward (as in Figure 2, normal use position) . This specific shape of the grooves 14 facilitates the assembly of the modular mat in a single movement with the central portion 20 of the connection members 12 being automatically secured in its intermediate position between the planes 100 and 200. The connection members can be pushed downward with the resilient folded side portions being snap fitted into the grooves, as will be explained in more detail hereafter. [0039] A centrally placed vertical strip 22 may be provided, whose function is related to the method of assembling the profiles into a mat, as described in more detail further in this text.

[0040] seen in the detail of Figure 3, with the connection member 12 held upside down, the folded portions 21 have the following parts, starting from the central horizontal portion 20 : a downwardly oriented first leg portion 23 that is essentially perpendicular to the central portion 20, a bend portion 24 and an upwardly oriented second leg portion 25. In the non-assembled state shown in figure 3a, the upwardly oriented leg 25 is preferably inclined outwardly with respect to the vertical symmetry plane of the connection member 12 over an angle a higher than 0° and lower than 90°. The dimensions and the material characteristics of the web material constituting the folded portions 21 are chosen such that the folded portions 21 exhibit a degree of resilience : when pushed together by a lateral compressive force F, the upwardly oriented leg portion 25 exhibits an elastic counter-force. Returning to Figure 2, it is seen that the second leg portion 25 is lodged behind a protrusion 35 provided in the grooves 14. The resilience of the folded portions 21, along with the protrusion 35 provided in the grooves 14, permits fast and easy assembly of the mat units, as illustrated with respect to Figure 4.

[0041] The assembly of the mat is done by placing the mat profiles 11 face down on a flat surface 100 as shown in figure 4a, at a predefined distance from each other corresponding to the size of the connection members 12. The connection members 12, preferably gripped by the central strip 22 are moved downward so that the folded portions 21 are inserted into the receptacles 36 formed by the rim portion 33 and the side wall 34 of the grooves 14. The shape and size of the grooves 14 causes the legs 23/25 of the folded portions 21 to be compressed by the insertion process, until the legs 25 are pushed past the protrusions 35, to thereby snap back and become secured behind said protrusions. This assembly of the mats can either be done manually or in an automated process.

[0042] According to a specific embodiment of the assembly method, the profiles are placed on a convex surface 101 before assembly, as illustrated in Figure 7. Two adjacent grooves 14 of adjacent mat members 11 are thereby slightly facing away from each other. This facilitates the entry of the folded portions 21 into the grooves 14 so that the securing operation by snap-fitting the legs 25 behind the protrusion 35 becomes easier, i.e. requires a lower force by which the connection members 12 are pushed into place.

[0043] The resilience of the folded portions 21 secures the connection members 12 in such a way that the mat profiles 11 are maintained at a fixed distance from each other. According to the preferred embodiment, the elastic force exhibited by the leg portions 23/25 of the compressed folded portions 21 on the side walls of the grooves 14 is such that the connection members 12, once secured in the grooves, prevent longitudinal displacement of the profiles 11 with respect to the connection members 12 or vice versa. No additional manipulation is required for obtaining this longitudinal securing.

[0044] Advantageously, the connection members 12 are sufficiently flexible to allow rolling up of the mat assembly. Rolling up with either the upper or lower side of the assembly facing outward in the roll is possible.

[0045] According to a preferred embodiment, a flat strip 40 is provided at the outer end of the positioning strip 22, preferably perpendicularly oriented with respect to said positioning strip, as illustrated in Figure 5. This flat strip is provided to maintain a fixed distance between two mat profiles 11 when the assembly is rolled up with wiper elements (secured in the spaces 13) facing outwards .

[0046] Advantageously, the connection members 12 are disposable elements which are breakable by manual manipulation of the profiles 11. Disassembling the mat unit then takes place by breaking the connection members.

[0047] The invention is not limited to the geometries illustrated in the drawings. Connection members 12 may have a central portion formed of another material than the folded portions 21. The folded portions may be oriented at another angle to the central portion than the essentially perpendicular orientation of said folded portions illustrated in the drawings. The perpendicular orientation is however preferred as it allows easy assembly of the floor unit. The shape of the grooves 14 may differ from the example shown in the drawings.

[0048] The protrusion 35 can be located on either of the two side walls of the groove 14. When placed on the opposite side wall compared to the embodiments shown in the drawings, the folded portions 21 must also be reversed : the free-ended leg portion 25 will then be placed closer to the centre line of the connection member than the fixed leg portion 23. This embodiment is illustrated in Figure 6.

[0049] While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive. Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope.