22 February 2022

RETRACTABLE WHEEL ASSEMBLY

TECHNICAL FIELD

[0001] The present disclosure generally relates to adjustable wheel mechanisms and particularly to retractable wheel mechanisms. More particularly, the present disclosure relates to a self-opening and self-retracting wheel assembly.

BACKGROUND

[0002] Objects and devices that are used in homes or offices may need to be moved occasionally for redecoration, cleaning, or relocation. Some of these objects and devices may be large or bulky objects, such as furniture, washing machines, stoves, refrigerators, file cabinets, and the like, which are difficult to move manually or without any special equipment. [0003] Some objects and devices, such as refrigerators and furniture are wheeled to address some of the difficulties associated with moving them. Wheels and casters may be mounted under large, bulky, and unwieldly items to allow for an easier movement of such items across a support surface with minimum effort.

[0004] However, most of the objects and devices need to be stable or perfectly balanced on the support surfaces when they are not moved or relocated. For example, a washing machine that has rotating components needs to be perfectly balanced and level side-to-side and back-to-back or the washing machine may bounce around. Furthermore, visually visible wheels under some objects, such as furniture may not be aesthetically pleasing.

[0005] One way to address the above-mentioned problems with wheeled items is to utilize retractable wheels. Retractable wheels or casters may have two states, namely, an operative state where the wheels serve to allow the item to be easily moved along the support surface and an inoperative state where the wheels are retracted not allowing the item to be moved along the support surface. In their retracted or inoperative state, the wheels or casters are not visible and may further allow for a stable positioning of the item on the support surface.

[0006] Previous approaches to design retractable wheel mechanisms have often resulted in complex caster or wheel mechanisms that are difficult to manufacture and use. Consequently, there remains a need for a simple and easy-to-use retractable wheel mechanism that may allow for both moving an item along a support surface when desired and statically support an item on a support surface. SUMMARY

[0010] This summary is intended to provide an overview of the subject matter of the present disclosure and is not intended to identify essential elements or key elements of the subject matter, nor is it intended to be used to determine the scope of the claimed implementations. The proper scope of the present disclosure may be ascertained from the claims set forth below in view of the detailed description and the drawings.

[0007] According to one or more exemplary embodiments, the present disclosure is directed to an exemplary retractable wheel assembly. A retractable wheel assembly may include a fork that may be attached to an object. A retractable wheel assembly may further include a wheel body that may be pivotally coupled to an exemplary fork by utilizing an exemplary axle. An exemplary wheel body may include a guide slot that may extend along a first axis between a first end of an exemplary guide slot and a second end of an exemplary guide slot. An exemplary axle may be configured to extend through an exemplary guide slot along a pivot axis. An exemplary pivot axis may be perpendicular to an exemplary first axis. An exemplary wheel body may be pivotable around an exemplary axle relative to an exemplary fork about an exemplary pivot axis.

[0008] An exemplary wheel body may further include a housing that may extend along a second axis. An exemplary housing may be connected to or integrally formed with an exemplary guide slot. An exemplary second axis may be perpendicular to an exemplary first axis. An exemplary wheel body may further include a spring-loaded ball that may be disposed within an exemplary housing. An exemplary spring-loaded ball may be configured to be compressible along an exemplary second axis. An exemplary spring loaded ball may be compressible between a compressed position and an extended position. An exemplary compressed position may correspond to an exemplary spring-loaded ball being compressed within an exemplary housing. An exemplary extended position may correspond to an exemplary spring-loaded ball being extended at least partially into an exemplary guide slot.

[0009] An exemplary wheel body may further include at least one weight compartment, and at least one weight that may be disposed within the at least one weight compartment. In an exemplary embodiment, responsive to an exemplary spring-loaded ball being in an exemplary compressed position, ax exemplary axle may be moveable between an exemplary first end and an exemplary second end of an exemplary guide slot along an exemplary first axis. In an exemplary embodiment, responsive to an exemplary spring-loaded ball being in the extended position a translational passage of an exemplary axle within an exemplary guide slot along an exemplary first axis is blocked by an exemplary spring-loaded ball.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The novel features which are believed to be characteristic of the present disclosure, as to its structure, organization, use and method of operation, together with further objectives and advantages thereof, will be better understood from the following drawings in which a presently preferred embodiment of the present disclosure will now be illustrated by way of example. It is expressly understood, however, that the drawings are for illustration and description only and are not intended as a definition of the limits of the present disclosure. Embodiments of the present disclosure will now be described by way of example in association with the accompanying drawings in which:

[0012] FIG. 1A illustrates a perspective view of a retractable wheel assembly, consistent with one or more exemplary embodiments of the present disclosure;

[0013] FIG. IB illustrates an exploded view of a retractable wheel assembly, consistent with one or more exemplary embodiments of the present disclosure;

[0014] FIG. 1C illustrates a sectional side-view of a retractable wheel assembly, consistent with one or more exemplary embodiments of the present disclosure;

[0015] FIG. ID illustrates an exploded view of a wheel body and an outer ring of a retractable wheel assembly, consistent with one or more exemplary embodiments of the present disclosure; [0016] FIGs. 2A-2D illustrate stages of a retractable wheel assembly extending out into an active position from under an object, consistent with one or more exemplary embodiments of the present disclosure;

[0017] FIGs. 3A-3D illustrate stages of a retractable wheel assembly retracting back into a concealed position under an object, consistent with one or more exemplary embodiments of the present disclosure;

[0018] FIG. 4A illustrates a schematic side-view of a spring-loaded ball in an extended position, consistent with one or more exemplary embodiments of the present disclosure; and [0019] FIG. 4B illustrates a schematic side-view of a spring-loaded ball in a compressed position, consistent with one or more exemplary embodiments of the present disclosure.

DETAILED DESCRIPTION [0020] The novel features which are believed to be characteristic of the present disclosure, as to its structure, organization, use and method of operation, together with further objectives and advantages thereof, will be better understood from the following discussion.

[0021] The present disclosure is directed to exemplary embodiments of an exemplary retractable wheel assembly that may be coupled to an object to facilitate displacement of that object. An exemplary retractable wheel assembly may be normally placed under an object in a retracted position and may be opened by lifting the object from the ground and then placing the object back on the ground. An exemplary retractable wheel assembly may freely dangle below an exemplary object when an exemplary object is lifted from the ground and when an exemplary object is placed back on the ground the weight of an exemplary object may urge an exemplary dangling retractable wheel to further pivot to a fully extended position.

[0022] An exemplary wheel may be retracted from an open or extended position back to a retracted position by lifting the object again and then placing the object back on the ground. Here, an exemplary retractable wheel assembly may freely dangle below an exemplary object when an exemplary object is lifted from the ground and when an exemplary object is placed back on the ground the weight of an exemplary object may urge an exemplary dangling retractable wheel to be retracted back under the object.

[0023] An exemplary retractable wheel assembly may be utilized for moving and transporting an object. An exemplary retractable wheel assembly may include a wheel body that may be pivotally coupled to a fork at a relocatable pivot point. Such relocation of pivot point between an exemplary wheel body and an exemplary fork may allow for retractable wheel assembly to be self-opening and self-retracting. An exemplary retractable wheel assembly may either open or retract when an object is lifted up and then placed back down on a support surface. Exemplary, weights mounted within an exemplary wheel body at locations determined based at least in part on pivot point location, may cause asymmetry in a center of gravity of wheel body and a geometric center of an exemplary wheel body. Such asymmetry of center of gravity combined with relocatable pivot point may allow for an exemplary retractable wheel assembly to open or retract based at least in part on a position of an exemplary pivot point relative to the position of an exemplary center of gravity of an exemplary wheel assembly, which will be discussed in the following sections of the present disclosure.

[0024] FIG. 1A illustrates a perspective view of a retractable wheel assembly 100, consistent with one or more exemplary embodiments of the present disclosure. FIG. IB illustrates an exploded view of retractable wheel assembly 100, consistent with one or more exemplary embodiments of the present disclosure. FIG. 1C illustrates a sectional side-view of retractable wheel assembly 100, consistent with one or more exemplary embodiments of the present disclosure.

[0025] In an exemplary embodiment, retractable wheel assembly 100 may include a fork 102 that may be pivotally coupled to a wheel 104 by utilizing an axle 106. In an exemplary embodiment, wheel 104 may include a wheel body 108 that may peripherally be enclosed by an outer ring 110. In an exemplary embodiment, a wheel body 108 may further be laterally enclosed by at least one lateral cover 112. In an exemplary embodiment, outer ring 110 may be configured to provide the surface upon which retractable wheel assembly 100 rotates on a support surface. In an exemplary embodiment, outer ring 110 may be configured to assume a rotational movement about a central axis 114 of outer ring 110. As used herein, central axis 114 may refer to an axis perpendicular to a circular plane of outer ring 110 passing through a center of the circular plane of outer ring 110. In an exemplary embodiment, wheel body 108 may be coupled to outer ring 110 by utilizing a plurality of rollers 116 to facilitate rotational motion of outer ring 110 about central axis 114 around and relative to wheel body 108.

[0026] FIG. ID illustrates an exploded view of wheel body 108 and outer ring 110 of retractable wheel assembly 100, consistent with one or more exemplary embodiments of the present disclosure. In an exemplary embodiment, wheel body 108 may include a plurality of semi-cylindrical slots 118 formed on an outer periphery 120 of wheel body 108. In an exemplary embodiment, each semi-cylindrical slot of plurality of semi-cylindrical slots 118 may be configured to receive a respective roller of plurality of rollers 116. For example, semi- cylindrical slot 118a may be configured to receive roller 116a. As used herein, a semi- cylindrical slot of plurality of semi-cylindrical slots 118 receiving a respective roller of plurality of rollers 116 may refer to a respective roller of plurality of rollers 116 being rotatably housed within a respective semi-cylindrical slot of plurality of semi-cylindrical slots 118. In an exemplary embodiment, rotational motions of plurality of rollers 116 between wheel body 108 and outer ring 110 may allow for facilitating rotational motion of outer ring 110 about central axis 114 around and relative to wheel body 108. In other words, wheel body 108 and outer ring 110 with plurality of rollers 116 disposed between wheel body 108 and outer ring 110 may form a roller bearing rotatable about central axis 114 of outer ring 110. [0027] In an exemplary embodiment, wheel body 108 may further include a guide slot 122 formed within wheel body 108, where guide slot 122 may be extended along a first axis 124 between a first end 126 of guide slot 122 and a second end 128 of guide slot 122. In an exemplary embodiment, guide slot 122 may be laterally extended an entire thickness 130 of wheel body 108 and may be laterally open to either side of wheel body 108. Such extension of guide slot 122 through thickness 130 of wheel body 108 may allow for axle 106 to pass through guide slot 122 along a pivot axis 132 perpendicular to first axis 124 and parallel with central axis 114. For example, axle 106 may pass through guide slot 122 and may be positioned at first end 126 of guide slot 122 as illustrated in FIG. 1C.

[0028] In an exemplary embodiment, axle 106 may include an axle bolt 160 that may pass through lower lateral holes (162a, 162ft) of fork 102 and guide slot 122 of wheel body 108 and thereby may pivotally couple fork 102 and wheel body 108. In an exemplary embodiment, axle 106 may further include an axle nut 164 that may be fastened to axle bolt 160 to ensure a firm attachment of axle bolt 160 between lower lateral holes (162a, 162ft) of fork 102. In an exemplary embodiment, lateral cover 112 may further include a corresponding guide slot 113 that may be aligned with guide slot 122 of wheel body 108. In an exemplary embodiment, retractable wheel assembly 100 may include an opposite lateral cover obscured from view that may cover other lateral side of wheel body 108 and may be structurally similar to lateral cover 112. In an exemplary embodiment, such corresponding guide slot 113 may further facilitate moveable and rotatable passage of axle bolt 160 through lateral cover 112. In an exemplary embodiment, lateral cover 112 may be attached to wheel body 108 by utilizing a plurality of fastening members, such as screws 115. In an exemplary embodiment, lateral cover 112 may further include corresponding holes (149, 151) that may be configured to allow first stop pin 148 and second stop pin 150 to extend out of lateral cover 112.

[0029] In an exemplary embodiment, such coupling of axle 106 and wheel body 108 by disposing axle 106 within guide slot 122 of wheel body 108 may allow for pivotally coupling fork 102 and wheel 104, such that wheel 104 may be pivotally moveable relative to fork 102 about pivot axis 132. In other words, in an exemplary embodiment, axle 106 may be configured to extend through guide slot 122 along pivot axis 132 perpendicular to first axis 124, where wheel body 108 may be pivotable around axle 106 relative to fork 102 about pivot axis 132. [0030] FIG. 4A illustrates a schematic side-view of spring-loaded ball 138 in an extended position, consistent with one or more exemplary embodiments of the present disclosure. FIG. 4B illustrates a schematic side-view of spring-loaded ball 138 in a compressed position, consistent with one or more exemplary embodiments of the present disclosure.

[0031] In an exemplary embodiment, wheel body 108 may further include a housing 134 that may be extended along a second axis 136 perpendicular to first axis 124. In an exemplary embodiment, housing 134 and guide slot 122 may be disposed on a circular plane of wheel body 108 and housing 134 may be connected to or integrally formed with guide slot 122 forming a T-shaped opening through thickness 130 of wheel body 108. In an exemplary embodiment, a spring-loaded ball 138 may be disposed within housing 134. In an exemplary embodiment, spring-loaded ball 138 may be configured to be compressible along second axis 136. In an exemplary embodiment, spring-loaded ball 138 may include a spring 140 attached from one end to a first end 133 of housing 134 and attached to a ball 142 from an opposing end. In an exemplary embodiment, first end 133 of housing 134 may refer to an end of housing 134 close to a periphery of wheel body 108 opposite a second end 135 of housing 134 connected to guide slot 122.

[0032] In an exemplary embodiment, spring 140 of spring-loaded ball 138 may be linearly compressible along second axis 136 between a compressed position as illustrated in FIG. 4B and an extended position as illustrated in FIG. 4A. In an exemplary embodiment, the compressed position of spring-loaded ball 138 may correspond to spring-loaded ball 138 being compressed and positioned at least partially within housing 134. In an exemplary embodiment, the extended position of spring-loaded ball 138 may correspond to spring-loaded ball 138 extended at least partially out of housing 134 and into guide slot 122. In an exemplary embodiment, in the extended position, ball 142 of spring-loaded ball 138 may be positioned at least partially within guide slot 122 blocking a linear passage provided by guide slot 122 for axle 106 along first axis 124, as illustrated in FIG. 4A.

[0033] In an exemplary embodiment, with enough force exerted on axle 106 along first axis 124, axle 106 may move along first axis 124 and push spring-loaded ball 138 along second axis 136 back into the compressed position, as illustrated in FIG. 4B, and reach the other end of guide slot 122. For example, responsive to a large enough force exerted on axle 106 along first axis 124, axle 106 may be urged to assume a translational motion from first end 126 of guide slot 122 along first axis in a direction shown by arrow 400. Here, axle 106 may push spring- loaded ball 138 along second axis 136 back into the compressed position and then may continue its translational motion toward second end 128 of guide slot 122. In an exemplary embodiment, translational movement of axle 106 along first axis 124 under a large enough force exerted on axle 106 is possible responsive to either first stop pin 148 or second stop pin 150 engaging fork 102 and preventing wheel body 108 from pivoting about axle 106.

[0034] In an exemplary embodiment, the extent of force that is considered enough may be determined at least by the stiffness of spring 140 of spring -loaded ball 138. For example, for a stiffer spring 140, more force must be exerted on axle 106 for axle 106 to be able to push back spring-loaded ball 138 and move to the other end of guide slot 122. In an exemplary embodiment, such configuration of spring-loaded ball 138 may allow for holding axle 106 in place within either ends (first end 126 or second end 128) of guide slot 122 when axle 106 is pivoting about pivot axis 132. Such spring-loaded mechanism for holding ball 142 in place may allow for ball 142 to be pushed back when necessary to make room for translational motion of axle 106 within guide slot 122 along first axis 124, as discussed in this paragraph.

[0035] In an exemplary embodiment, when axle 106 assumes a translational motion under the exerted force from first end 126 to second end 128 of guide slot 122 or vice versa, pivot axis 132 may accordingly be displaced along first axis 124 from first end 126 to second end 128 or vice versa. Such displacement of pivot point between axle 106 and wheel body 108 may allow for wheel 104 to be self-opening/closing, as will be discussed.

[0036] In an exemplary embodiment, wheel body 108 may further include at least one weight compartment that may be formed within wheel body 108. For example, wheel body 108 may include a first weight compartment 144a and a second weight compartment 144/? that may be formed at both sides of housing 134 and guide slot 122. In an exemplary embodiment, first weight compartment 144a may be configured to receive a first weight 146a within first weight compartment 144a and second weight compartment 144/? may be configured to receive a second weight 1466 within second weight compartment 144/?. To this end, first weight compartment 144a and second weight compartment 1446 may include openings extending the entire thickness 130 of wheel body 108, where first weight 146a and second weight 1466 may be shaped and sized to be disposed within respective first weight compartment 144a and second weight compartment 1446. In an exemplary embodiment, first weight 146a and second weight 1466 may be positioned close to housing 134 and guide slot 122 so that a center of mass of wheel body 108 may be shifted toward housing 134 and guide slot 122. In other words, such arrangement and placement of first weight 146a within first weight compartment 144a and second weight 1466 within second weight compartment 1446 may allow for shifting a center of mass of wheel assembly 100 towards the engagement point of axle 106 and wheel body 108. As used herein, engagement point may refer to a pivot point about which wheel body 108 pivots around axle 106.

[0037] In an exemplary embodiment, wheel body 108 may further include a first stop pin 148 and a second stop pin 150 mounted on a lateral side of wheel body 108, where first stop pin 148 and second stop pin 150 may extend along central axis 114. In an exemplary embodiment, first stop pin 148 and second stop pin 150 may be configured to limit pivotal movement of wheel body 108 about pivot axis 132 by being mounted opposite each other, for example between 130° and 210° apart on the lateral side of wheel body 108. In an exemplary embodiment, first stop pin 148 may provide a leaning point upon which wheel body 108 engages fork 102 in a fully retracted position of retractable wheel assembly 100 as illustrated in FIG. 1C. In an exemplary embodiment, when first stop pin 148 engages fork 102, any pivotal movement of wheel body 108 relative to fork 102 about axle 106 in a counterclockwise manner would be impossible. In an exemplary embodiment, when wheel body 108 rotates relative to the retracted position, an opposite side of fork 102 may engage second stop pin 150 and thereby any pivotal motion of wheel body 108 relative to fork 102 in a clockwise manner may be stopped by second stop pin 150.

[0038] FIGs. 2A-2D illustrate stages of retractable wheel assembly 100 extending out into an active position from under an object 202, consistent with one or more exemplary embodiments of the present disclosure. In an exemplary embodiment, retractable wheel assembly 100 may be attached to object 202 by attaching fork 102 to object 202, where fork 102 may be fixed in position relative to object 202.

[0039] Referring to FIG. 2A, in an exemplary embodiment, when object 202 is not to be moved over support surface 204, retractable wheel assembly 100 may be in a fully retracted position concealed beneath object 202. Such retraction of retractable wheel assembly 100 under object 202 may be beneficial both from a practical point of view and an aesthetic point of view. Regarding the functionality, when retractable wheel assembly 100 is retracted under object 202, object 202 may rest upon support surface 204 in a more stable manner. Regarding the looks of object 202, when object 202 is not to be moved, retractable wheel assembly 100 being concealed under object 202 may allow for object 202 to look more beautiful. For example, this is the case for kitchen appliances, such as refrigerators or stoves, where the view of wheels under the appliance is not aesthetically desirable. [0040] In an exemplary embodiment, in a fully retracted position, axle 106 may be positioned in first end 126 of guide slot 122 and spring-loaded ball 138 may be in a fully extended position. In a fully retracted position, fork 102 may be engaged with first stop pin 148 and thereby no upward force may be exerted from support surface 204 on axle 106, consequently axle 106 may not move upward pushing spring-loaded ball 138 aside. Here, retractable wheel assembly 100 maintains its fully retracted position until object 202 is moved upward in a direction shown by arrow 206.

[0041] Referring to FIG. 2B, in an exemplary embodiment, responsive to object 202 being lifted from support surface 204 along a direction shown by arrow 206, wheel 104 may pivot about axle 106 in a clockwise manner and may dangle below object 202. In an exemplary embodiment, since axle 106 is position within first end 126 of guide slot 122, such clockwise pivotal motion of wheel 104 may place weights (146a, 1466) to the right of central axis 114 of wheel 104. Referring to FIG. 2C, in an exemplary embodiment, such off-center placement of center of mass of wheel 104 may cause wheel 104 to further pivot about axle 106 in a clockwise manner (direction shown by arrow 207) under object 202 responsive to object 202 being placed back down on support surface 204 along a direction shown by arrow 208.

[0042] Referring to FIG. 2D, in an exemplary embodiment, when object 202 is completely put down along a direction shown by arrow 208, second stop pin 150 engages fork 102 and the weight of object 202 may exert a downward force onto axle 106 and may cause axle 106 to move downward along guide slot 122 and push aside spring-loaded assembly 138. Here, axle 106 may move to second end 128 of guide slot 122. In an exemplary embodiment, the fact that fork 102 is engaged with second stop pin 150 prevents wheel 104 from pivoting further about axle 106.

[0043] In an exemplary embodiment, retractable wheel assembly 100 may maintain this fully extended position under object 202 until object 202 is lifted one more time off support surface 204. In an exemplary embodiment, in a fully extended position of retractable wheel assembly 100, wheel 104 may rotate about central axis 114 and thereby allow object 202 to be moved on support surface 204.

[0044] FIGs. 3A-3D illustrate stages of a retractable wheel assembly 200 retracting back into a concealed position under object 202, consistent with one or more exemplary embodiments of the present disclosure. [0045] Referring to FIG. 3A, in a fully extended position or otherwise in an active position of retractable wheel assembly 100, object 202 may be moveable over support surface 204 on retractable wheel assembly 100 just like a normal wheel or caster under an object. In an exemplary embodiment, wheel body 108 may be locked in place due to the engagement of fork 102 and first stop pin 148 and wheel 104 may only assume a rotational movement about central axis 114. As mentioned before, outer ring 110 coupled to wheel body 108 by utilizing plurality of rollers 116 may facilitate such rotational movement. However, retractable wheel assembly 100 may maintain such fully extended position until object 202 is lifted from support surface 204 along a direction shown by arrow 210.

[0046] Referring to FIG. 3B, in an exemplary embodiment, responsive to object 202 being lifted off support surface 204 in a direction shown by arrow 210, wheel 104 may pivot relative to fork 102 about axle 106 in a counter-clockwise manner and may dangle under object 202.

[0047] Referring to FIG. 3C, in an exemplary embodiment, since axle 106 is positioned within second end 128 of guide slot 122, the center of mass of wheel 104 may be positioned to the left of axle 106 and when object 202 is placed back down along a direction shown by arrow 212, wheel 104 may further pivot about axle 106 in a counterclockwise manner.

[0048] Referring to FIG. 3D, in an exemplary embodiment, when object 202 is completely released to move downward under the weight of object 202, first stop pin 148 engages fork 102 and a downward force is exerted on axle 106 causes axle 106 to move downward and by pushing aside spring-loaded ball 138 once again axle 106 may be positioned within first end 126 of guide slot 122. Here, retractable wheel assembly 100 is once again in its fully retracted position under object 202.

[0049] In exemplary embodiments, an exemplary retractable wheel assembly, such as retractable wheel assembly 100 may be configured to contain all the mechanism required for making an exemplary retractable wheel assembly to be self -retractable. For example, weights (146a, 146/>). guide slot 122 and spring-loaded ball 138 may all be disposed within an exemplary rotating retractable wheel assembly. Such design may allow for easily scaling up an exemplary retractable wheel without a need for scaling up any external components.

[0050] The embodiments have been described above with the aid of functional building blocks illustrating the implementation of specified functions and relationships thereof. The boundaries of these functional building blocks have been arbitrarily defined herein for the convenience of the description. Alternate boundaries can be defined so long as the specified functions and relationships thereof are appropriately performed.

[0051] The foregoing description of the specific embodiments will so fully reveal the general nature of the disclosure that others can, by applying knowledge within the skill of the art, readily modify and/or adapt for various applications such specific embodiments, without undue experimentation, without departing from the general concept of the present disclosure. Therefore, such adaptations and modifications are intended to be within the meaning and range of equivalents of the disclosed embodiments, based on the teaching and guidance presented herein. It is to be understood that the phraseology or terminology herein is for description and not of limitation, such that the terminology or phraseology of the present specification is to be interpreted by the skilled artisan in light of the teachings and guidance.

[0052] The breadth and scope of the present disclosure should not be limited by any of the above-described exemplary embodiments but should be defined only in accordance with the following claims and their equivalents.

[0053] Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not to the exclusion of any other integer or step or group of integers or steps.

[0054] Moreover, the word "substantially" when used with an adjective or adverb is intended to enhance the scope of the particular characteristic, e.g., substantially planar is intended to mean planar, nearly planar and/or exhibiting characteristics associated with a planar element. Further use of relative terms such as “vertical”, “horizontal”, “up”, “down”, and “side-to-side” are used in a relative sense to the normal orientation of the apparatus.