Patent Publication Number: US-2018036511-A1

Title: Improved catheter handle

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a national phase entry under 35 U.S.C. § 371 of International Patent Application PCT/AU2016/050007, filed Jan. 12, 2016, designating the United States of America and published in English as International Patent Publication WO 2016/127203 A1 on Aug. 18, 2016, which claims the benefit under Article 8 of the Patent Cooperation Treaty to Australian Patent Application Serial No. 2015900675, filed Feb. 26, 2015, and to Australian Patent Application Serial No. 2015900471, filed Feb. 13, 2015. 
    
    
     TECHNICAL FIELD 
     The present invention generally relates to a gear mechanism assembly and, more particularly, to a catheter handle assembly including the gear mechanism assembly. 
     BACKGROUND 
     In the field of cardiac procedures, use is made of a catheter that is steered through a patient&#39;s vasculature and placed at the desired site. Generally, the site is within a heart of the patient and a distal part of the catheter needs to be maneuvered into position against heart wall tissue. To be able to manipulate the distal part of the catheter to place it in tissue contact, the end of the catheter is flexible and steerable. A deflectable stylet is associated with the catheter for deflecting the distal part of the catheter. 
     Often, the part of the heart wall that needs to be accessed is awkwardly situated resulting in it being difficult to place the distal part of the catheter in contact with the desired part of the tissue to be treated or diagnosed. 
     Known catheters usually use a pull-wire arrangement in order to manipulate a stylet within a catheter sheath. These wire arrangements can use a 1:1 ratio pulley system to effect manipulate the end of a catheter sheath. Some known catheters include a gear mechanism comprising a rack and pinion mechanisms housed within a catheter handle. Actuation of these gear mechanisms usually effects the deflection of the distal end of a catheter to track along a tortuous anatomy. However, these single rack mechanisms usually require a significant amount of force to manipulate and may cause unnecessary strain on a clinician or physician when using the device over multiple procedures/multiple deflection cycles. It would be advantageous for a catheter to include a gear mechanism that reduced unnecessary strain/force required to apply a deflection. It would be further advantageous to have a higher gear ratio to effect manipulation. 
     Further, while not commonly used, these rack and pinion gear mechanisms usually take up a significant amount of internal space within the catheter handle. As such, it would be advantageous for a gear mechanism to be of a compact size. Further, it would be beneficial to manufacture a gear mechanism that is of a low manufacturing cost. 
     Often, the use of a catheter can impart a great stress for a clinician or physician due to the strain during manipulation of the catheter. It would be advantageous to have a catheter in which the stress and/or strain felt by the clinician or physician could be reduced. 
     Other gear mechanisms including a rack and pinion have been known to malfunction or have the pinion come off of the rack under relatively large amounts of force. It would be advantageous for a gear mechanism that resisted separation of the pinion from the rack under relatively large amounts of force. 
     Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of common general knowledge in the field. 
     BRIEF SUMMARY 
     It may be an object of the present disclosure to provide an improved gearing mechanism adapted for use with catheters. 
     It is an object of the present disclosure to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative. 
     A first aspect of the present disclosure may relate to a catheter handle assembly comprising; a handle body having a proximal end and a distal end with a passage extending therebetween; an adjustment unit disposed in the passage of the handle body, the adjustment unit comprising a gear mechanism that acts on a deflection stylet for adjusting deflection of the distal part of the stylet; and wherein the gear mechanism comprises a first rack, a second rack and a pinion such that rotation of the pinion causes relative movement of the first rack and the second rack in opposing directions. 
     The catheter handle may further comprise a carrier arrangement projecting from the distal end of the handle body, the carrier arrangement configured for mounting a catheter sheath and at least a part of a deflection stylet of a catheter thereto during use of the catheter handle assembly. 
     The second rack may be stationary relative to the catheter handle. Further, the adjustment unit may have a gear ratio of at least 1.0:1.1. Wherein the adjustment unit may have a gear ratio of 1.0:2.0. Wherein the adjustment unit may have a gear ratio of 1.0:3.0. Wherein the first rack and the second rack may be facing the stylet holder when the catheter is not in use. Wherein a shell may be disposed around an axis of the gear mechanism to retain the pinion on at least one of the first rack and the second rack. The second rack may be disposed on the shell of the gear mechanism. The shell may comprise an inner shell portion and an outer shell portion. the first rack may be disposed on a stylet mount. The stylet mount may engage the catheter sheath and the stylet holder may engage the stylet such that movement of the pinion may cause a relative movement between the stylet and the catheter sheath. 
     In a further aspect of the present disclosure there is provided a gear mechanism for a catheter handle assembly, the gear mechanism comprising; a first rack disposed on a stylet mount; a second rack disposed on a portion of a shell wherein the rotation of a pinion causes opposing relative movement of the first rack and the second rack in the catheter handle. 
     In yet another aspect of the present disclosure there is provided a gear mechanism comprising at least one novel and inventive feature as disclosed in the present specification. 
     In another aspect of the present disclosure there is provided a catheter handle comprising a gear mechanism with at least one novel and inventive feature as disclosed in the specification. 
     In at least one embodiment, the frictional force applied by the gear mechanism can be altered via a friction-inducing device such as a tapered pinion shaft. Wherein the friction can be tuned by the user to suit the desired range. 
     In the context of the present invention, the words “comprise,” “comprising” and the like are to be construed in their inclusive, as opposed to their exclusive, sense, that is in the sense of “including, but not limited to.” 
     The invention is to be interpreted with reference to the at least one of the technical problems described or affiliated with the background art. The present disclosure aims to solve or ameliorate at least one of the technical problems and this may result in one or more advantageous effects as defined by this specification and described in detail with reference to the preferred embodiments of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a perspective view of an embodiment of a catheter assembly; 
         FIG. 2  shows a partial cutaway view of the catheter assembly; 
         FIG. 3  shows an exploded view of a gear mechanism of the catheter assembly; 
         FIG. 4A  shows a perspective view of the gear mechanism of the catheter assembly; 
         FIG. 4B  shows a front view of an embodiment of the gear mechanism of the catheter assembly; 
         FIG. 4C  shows a side view of an embodiment of the gear mechanism of the catheter assembly; 
         FIG. 5A  shows a further embodiment of the gear mechanism of the catheter assembly; 
         FIG. 5B  shows a front view of a further embodiment of the gear mechanism of the catheter assembly; 
         FIG. 5C  shows a side view of a further embodiment of the gear mechanism of the catheter assembly; 
         FIG. 6  shows a perspective view of another embodiment of a catheter assembly with two control knobs. 
     
    
    
     DETAILED DESCRIPTION 
     Preferred embodiments of the present disclosure will now be described with reference to the accompanying drawings and non-limiting examples. 
     In the drawings, reference numeral  10  generally designates a preferred embodiment of a catheter assembly  10 . The catheter assembly  10  includes a handle assembly  12 . A catheter sheath  14  extends from a distal part  16  of the handle assembly  12 . The catheter sheath  14  defines a lumen, which is a deflection stylet lumen for receiving a deflection stylet. 
     In a further embodiment, the catheter sheath  14  defines a plurality of lumens. One of the lumens is a conductor lumen and has a plurality of conductors (not shown (including thermocouple conductors)) received therein. The plurality of conductors extend from electrodes carried on a distal part (not shown) of the catheter sheath  14  toward a proximal end of the catheter sheath  14 . The plurality of conductors further extend through the handle assembly  12  to an electrical connector  32  ( FIG. 1 ) arranged at a proximal end  34  of the handle assembly  12 . The catheter sheath  14  is releasably connected to the distal part  16  of the handle assembly  12 . The catheter sheath  14  and the handle assembly  12  each comprise suitable connectors (not shown in detail) for connecting the plurality of conductors from the catheter sheath  14  to the distal end  16  of the catheter handle assembly  12 . The stylet is arranged to fit through the connectors of the catheter sheath  14  and the distal end  16  of the handle into the deflection stylet lumen. One of the lumens is an irrigation lumen for providing irrigating fluid to the electrodes at a distal part  30  of the catheter sheath  14 . This lumen communicates with a fluid conduit  36  ( FIG. 6 ). A luer connector  38  is arranged at a proximal end of the conduit for connection to a supply of irrigation fluid (not shown). 
     An embodiment of the handle assembly  12  is now described in greater detail with reference to  FIG. 1  of the drawings. 
     The handle assembly  12  includes a tubular handle body  40  defining the proximal end  34  to which the connector  32  ( FIG. 1 ) is integrated and a distal end  42 . A carrier arrangement projects from the distal end  42  of the tubular handle body  40 . The carrier arrangement mounts the catheter sheath  14 , via a strain relief unit  46 , and at least a part of a proximal region of the deflection stylet. An adjustment unit is arranged in a passage of the handle body. 
     The carrier unit comprises a deflection unit in the form of a first tubular member or tube  52  having a control knob  54  arranged at a distal end of the tube  52 . Optionally, the carrier arrangement further comprises a size selector unit in the form of a second tubular member or second tube  56 . Once again, the second tube  56  carries a control knob  58  (see  FIG. 6 ) at a distal end of the second tube  56 . The tubes  52  and  56  are telescopically arranged with respect to each other and with respect to the distal end of the handle body. Thus, the tube  52  can be slid axially with respect to the catheter handle  12 , and in the direction of arrows  60  and  61  ( FIGS. 1 and 6 ) as will be described in greater detail below. 
     The adjustment unit comprises a gear mechanism  62  associated with the tube  52 . The deflection stylet comprises a tubular member having a bend-enhancing portion (not shown) proximate its distal end. An actuator, which may be in the form of a wire, is received in the tubular member and a distal end of the actuator is fastened with a distal part of the tubular member, distally of the bend-enhancing portion of the tubular member. The bend-enhancing portion may comprise any suitable bend-enhancing region, which forms a zone of weakness at the distal part of the catheter to allow bending around the bend-enhancing portion. For example, the bend-enhancing portion could be groups of slots, a longitudinally extending scalloped region, or the like. 
     The stylet optionally includes a size selector in the form of a sleeve, which is displaceably arranged with respect to the tubular member of the stylet for interacting with the bend-enhancing portion to increase or reduce the size of the bend-enhancing portion and, in so doing, to control the degree of curvature of the distal part  30  of the catheter sheath  14  (in which the stylet is received). 
     The sleeve is mounted over the tubular member. It will, however, be appreciated that the sleeve could be received within the tubular member so that it is interposed between the tubular member and the actuator. 
     The gear mechanism  62  comprises a drive gear in the form of a stylet mount  72  ( FIG. 3 ) extending proximally from a proximal end of the tube  52  of the carrier arrangement. The stylet mount  72  comprises a proximal end  200 , a distal end  202 , a head portion  204  and a longitudinal body portion  206  extending proximally from the head portion  204 . The head portion  204  of the stylet mount  72  is adapted to receive the catheter sheath  14  in aperture  208 . Referring to  FIGS. 4A and 5A , head portion  204  can optionally be of a larger dimension compared to that of the longitudinal body portion  206  such that the catheter sheath  14  can be mounted in the aperture  208 . In some embodiments, the larger dimension of the head portion  204  can be used to resist stresses applied to an adjustment unit  48  during use and can also be used as a strain relief for the catheter sheath  14 . 
     In at least one embodiment, the catheter sheath  14  is anchored to the stylet mount  72  via grub screw  210  in aperture  250 , but it will be appreciated that any suitable means can be used for securing the catheter sheath  14  to the stylet mount  72 . The longitudinal body portion  206  of the stylet mount  72  comprises a first rack  212 , which is in a cooperative relationship with a pinion  74  of a shuttle  214  for effecting relative movement between the stylet and the catheter sheath  14 , and thus causing deflection of the distal end of the catheter sheath  14 . 
     The pinion  74  is rotatably mounted to the shuttle  214 , wherein the shuttle  214  is in the form of a stylet holder  214 , which retains the stylet  24  in aperture  216 .  FIG. 3  illustrates a grub screw  218  for releasably retaining the stylet within the stylet holder  214 , however it will be appreciated that other suitable means can be used to retain the stylet in the aperture  216 , such as gluing. Pinion  74  is rotatably attached to the stylet holder  214  such that rotation of the pinion  74  causes relative movement between the pinion and at least the first rack  212 . In at least one embodiment, a side of the stylet holder is in an abutting relationship with the stylet mount and wherein the abutting sides of the stylet holder and the stylet mount are flush or otherwise in a substantially corresponding surface relationship. The stylet holder can have a rounded proximal end illustrated in  FIG. 4A . Further the stylet holder  214  can also have a protrusion  280  for abutting the head portion  204 . 
     Shell  100  illustrated in  FIG. 2  and  FIG. 3  can be used to assist in retaining pinion  74  on the stylet mount  72 . Further, shell  100  can isolate the gear mechanism  62  from other components in the passage of the catheter handle assembly  12  to reduce the possibility of damage to the other components within the passage. The shell  100  comprises an outer shell portion  102  and an inner shell portion  104 . The inner shell portion  104  and the outer shell portion  102  can comprise at least one male component  106  and at least one female component  108 , respectively, and operatively associated such that the outer shell portion  102  and inner shell portions  104  can be press-fit together to form shell  100 . It will be appreciated that outer shell portion  102  and inner shell portion  104  can be connected by any other suitable means such as screws, tongue-in-groove, glue, press-fit lock, rail slide arrangements or the like. 
     The inner shell portion  104  further comprises a second rack  76  which is in a cooperative relationship with pinion  74 . When the second tube  56  is withdrawn proximally fully into the tube  52 , the pinion moves linearly along both the first rack  212  and the second rack  76  such that the pinion  74  effects relative movement between first rack  212  and the second rack. This relative movement is an opposing directional movement such that when the first rack  212  moves proximally relative to the pinion  74 , the second rack  76  moves distally relative to the pinion  74 . The gear ratio of the first rack  212  relative to the second rack can be in the range of 1.0:0.5 to 1.0:3.5. Preferably the gear ratio is greater than 1.0:1.0. More preferably, the gear ratio is in the range of 1.0:1.0 to 1.0:2.0. Even more preferably, the gear ratio is 1.0:1.5. The two shell portions  102 ,  104  form an aperture which receives at least a portion of the stylet mount, more particularly the longitudinal body portion, and the stylet holder  214 . In this configuration the pinion  74  is rotatable such that it can impart movement to at least one of the first rack and the second rack. 
     In at least one embodiment, the shell  100  is fixed to the catheter handle such that the second rack  76  is stationary relative to the catheter handle assembly  12 . The shell  100  can be removably attached or fixed to the catheter handle assembly  12  at connection portions  120  disposed on the outer surface of the shell  100 . Alternatively the connection portions  120  can be used for providing a resistive force to another component within the catheter handle assembly  12  (not shown). A protrusion  150 , illustrated in  FIG. 2 , is formed in the passage of the catheter handle assembly  12  to retain the gear mechanism  62  at the desired location in the passage. Preferably the connection portion  120  engages the interior wall of the catheter handle assembly  12  to secure the shell  100  in a desired location. 
     The outer shell portion  102  comprises two wing portions  130 ,  132  that can be used to retain the inner shell portion  104  at sides  134 ,  136 . The inner shell portion  104  can have a cutaway portion  260  such that the gear mechanism  62  can be viewed to ensure alignment on the on the first and second racks  212 ,  76 , respectively, or otherwise view the rotation of the pinion  74 . The cutaway portion  260  can also be used to allow additional flexure of the inner portion  104  during connection of the outer shell portion  102  and the inner shell portion  104 . 
     Referring to  FIGS. 4A through 4C , there is illustrated an embodiment of the gear mechanism  62  of the present disclosure. The shell  100  of the gear mechanism  62  has a compact configuration to reduce the space occupied within the passage of the catheter handle. 
     The adjustment unit is of a compact size and allows for a reduction of forces during operation. More particularly, the adjustment unit can reduce the forces experienced by a user by up to around ⅔. More particularly, the reduction of forces experienced by a user is around half. This reduction of forces can also be experienced by the adjustment unit and gear mechanism in the passage of the catheter handle. Further, a friction inducer (not shown) allows the clinician or physician to adjust or tune the stickion-friction of the catheter assembly such that the friction of the catheter can be increased or decreased. Further, adjusting the stickion-friction of the catheter assembly can reduce wear and tear of the internal components. 
     In at least one embodiment, the frictional force applied by the gear mechanism can be altered via a friction inducing device (not shown) such as a tapered pinion shaft. This allows for greater ease of use of the catheter and reduces the stresses experienced by the physician during use. 
       FIGS. 5A to 5C  illustrate an alternative embodiment of the gear mechanism  62  of the present disclosure. The shell  100  of the gear mechanism has an enlarged cross-section to extend to the sides of the passage of the catheter handle for larger catheter handles. This configuration can have at least one depression  500  on at least one outer surface of the shell  100  as seen in  FIG. 5A . 
     The first rack  212  and the second rack  76  are facing the stylet holder  214  such that the pinion  74  is simultaneously operatively engaged with the first rack  212  and the second rack  76 . 
     The catheter handle assembly  12  may also comprise a grip portion  290  ( FIG. 2 .) to reduce repetitive stress or user stress experienced by the clinician or physician using the catheter. The grip portion comprises a plurality of scalloped portions around the exterior of the catheter handle. 
     In at least one embodiment ( FIG. 6 ), pinion  74  is rotatably received in the passage of the handle body and a stylet holder  214  arranged in the passage of the tubular handle body. The stylet holder  214  mounts a proximal end of the actuator (stylet). The tubular member of the stylet is anchored within the tubular handle body  40 . Thus, by displacing the deflector unit of first tubular member  52  and control knob  54  in the direction of arrows  61  ( FIG. 6 ), relative movement between the tubular member and the actuator occurs, resulting in deflection of the distal part of the catheter sheath  14 . The distal part  30  can deflect in a direction by appropriate manipulation of the deflector unit of first tubular member  52  and control knob  54  in the opposite direction of the longitudinal axis of the catheter sheath  14  but within a plane. The in-plane deflection is enhanced by having the stylet lumen eccentrically arranged within the catheter sheath  14 . 
     To facilitate the bi-directional deflection of the distal part of the catheter sheath  14 , when the deflector unit of first tubular member  52  is in a rest position, i.e., the position in which the distal part  30  extends longitudinally, the pinion  74  is substantially centrally arranged on the racks  212  and  76 , i.e., inwardly of ends of the racks  212  and  76 . This allows push-pull movement of the actuator  68  in the direction of arrows  60 ,  61  ( FIG. 6 ) so that bi-directional deflection occurs. 
     When the second tube  56  is withdrawn proximally fully into the tube  52 , the first rack  212  drives the pinion  74  and second rack  76  to urge the sleeve into the stylet lumen of the catheter sheath  14  to occlude a part of the bend-enhancing portion of the stylet, resulting in a tighter radius of curvature. Conversely, when the second tube  56  is extended distally with respect to the tube  52 , the first rack  212  drives the pinion  74  and second rack  76  to withdraw the sleeve from the stylet lumen, exposing more of the bend-enhancing portion of the stylet and allowing for a greater radius of curvature. 
     The handle body is made up of mating parts so that the parts can be separated to enable access to be gained to the passage of the handle body. The proximal end of the actuator is releasably attached to the stylet holder  214  and the tubular member of the stylet is, likewise, releasably mounted in the passage of the handle body. The releasable connection is preferably arranged by molding a slot or another similar receiving formation  216  on the stylet holder  214  where the proximal end of the actuator can be securely fitted. Likewise, the handle body comprises a slot or another suitable receiving formation molded in the passage for securely but releasably fitting the proximal end of the tubular member of the stylet into the handle body. The proximal end of the actuator and the proximal end of the tubular member each have a mounting formation (not shown in figures) such as an enlarged fitting at the respective proximal ends. The mounting formation is a snug fit in the corresponding receiving formation in the stylet holder  214  and the handle body. The sleeve is attached in a similar fashion to the stylet mount  72  having a suitable receiving formation  208  for the sleeve. One or more screws may be used to ensure that each of the actuator, tubular member, and sleeve are securely anchored while the catheter is in use. 
     In an alternative embodiment of the invention, the sleeve is connected directly to the size selector tube  56  so that the adjustment unit only comprises one gear mechanism  62  for deflecting the distal end of the catheter sheath  14 . In this embodiment, displacing the size selector tube  56  and control knob  58  in the direction of arrows  60 ,  61  ( FIG. 6 ) results in displacement of the sleeve directly within the catheter sheath  14 . 
     In at least one embodiment, the first rack  212  and the second rack  76  are generally parallel with respect to one another and the respective racks of the first and second racks  212 ,  76  are facing towards the pinion. In this configuration, the rotation of the pinion  74  causes the first rack  212  to move in an opposing direction relative to that of the second rack  76 . It will be appreciated in some embodiments that the second rack  76  is fixed to the catheter handle such that proximal movement of the pinion  74  causes a proximal movement of the stylet mount  72 . 
     The handle body can be opened by separating the mating parts, the component parts of the deflection stylet disconnected from the adjustment unit and the deflection stylet removed. Similarly, the catheter sheath  14  is removably mounted to the distal end  16  of the handle assembly  12 . Thus, the catheter sheath  14  can also be removed from the handle assembly  12 . In this way, the component parts of the catheter assembly  10 , comprising the handle assembly  12 , the deflection stylet and the catheter sheath  14  can be removed for reprocessing and/or replacement. It is envisaged that, in general, the handle assembly  12  and the deflection stylet can be reprocessed between twenty and fifty times, whereas the catheter sheath  14  can be reprocessed for approximately five re-uses. In this regard, the term “reprocessing” (and derivatives) is to be understood in a broad sense to include reprocessing, remanufacturing, refurbishment, or the like. 
     It will be appreciated that the gear mechanism of the present disclosure can be used with any catheter. In at least some embodiments at least one gear mechanism can be used to effect at least one of deflection of a stylet, impart a shape to a stylet, or otherwise manipulate a stylet in a predetermined manner. It will further be appreciated that more than one gear mechanism can be used within a catheter assembly. 
     Hence, it is an advantage of the disclosed embodiments that a modular catheter assembly  10  is shown that lends itself to reprocessing. It will be appreciated by those skilled in the art that using a catheter only once is a very expensive procedure as the costs of production of the catheter are significant. By reprocessing the catheter and using its constituent parts a number of times, a substantial reduction in costs for the institution and, as an end result, for the patient using the catheters, can be achieved. 
     It is a further advantage of the disclosed embodiments that a handle assembly  12  is disclosed having positive drive, i.e., the gear arrangement, for effecting deflection and size selection. Using a positive drive results in more accurate control over deflection and size selection and improved tactility for the clinician. 
     Reference throughout this specification to “one embodiment,” “some embodiments” or “an embodiment” means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases “in one embodiment,” “in some embodiments” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment, but may. Furthermore, the particular features, structures or characteristics may be combined in any suitable manner, as would be apparent to one of ordinary skill in the art from this disclosure, in one or more embodiments. 
     As used herein, unless otherwise specified, the use of ordinal adjectives “first,” “second,” “third,” etc., to describe a common object, merely indicate that different instances of like objects are referred to, and are not intended to imply that the objects so described must be in a given sequence, either temporally, spatially, in ranking, or in any other manner. 
     In the appended claims and the description herein, any one of the terms “comprising,” “comprised of,” or “which comprises” is an open term that means including at least the elements/features that follow, but not excluding others. Thus, the term “comprising,” when used in the claims, should not be interpreted as being limitative to the means or elements or steps listed thereafter. For example, the scope of the expression “a device comprising A and B” should not be limited to devices consisting only of elements A and B. Any one of the terms “including,” “which includes,” or “that includes,” as used herein, is also an open term that also means including at least the elements/features that follow the term, but not excluding others. Thus, “including” is synonymous with and means “comprising.” 
     It should be appreciated that in the above description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspects. This method of disclosure, however, is not to be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment. Thus, the claims following the Detailed Description are hereby expressly incorporated into this Detailed Description, with each claim standing on its own as a separate embodiment of this invention. 
     Furthermore, while some embodiments described herein include some, but not other, features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the invention, and form different embodiments, as would be understood by those skilled in the art. For example, in the appended claims, any of the claimed embodiments can be used in any combination. 
     In the description provided herein, numerous specific details are set forth. However, it is understood that embodiments of the invention may be practiced without these specific details. In other instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description. 
     Similarly, it is to be noticed that the term “coupled,” when used in the claims, should not be interpreted as being limited to direct connections only. The terms “coupled” and “connected,” along with their derivatives, may be used. It should be understood that these terms are not intended as synonyms for each other. Thus, the scope of the expression “a device A coupled to a device B” should not be limited to devices or systems wherein an output of device A is directly connected to an input of device B. It means that there exists a path between an output of A and an input of B, which may be a path including other devices or means. “Coupled” may mean that two or more elements are either in direct physical or electrical contact, or that two or more elements are not in direct contact with each other but yet still cooperate or interact with each other. 
     Thus, while there has been described what are believed to be the preferred embodiments of the invention, those skilled in the art will recognize that other and further modifications may be made thereto without departing from the spirit of the invention, and it is intended to claim all such changes and modifications as falling within the scope of the invention. For example, any formulas given above are merely representative of procedures that may be used. Functionality may be added or deleted from the block diagrams and operations may be interchanged among functional blocks. Steps may be added or deleted to methods described within the scope of the invention. 
     It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the disclosure as shown in the specific embodiments without departing from the scope of the disclosure as broadly described. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive. 
     Although the invention has been described with reference to specific examples, it will be appreciated by those skilled in the art that the invention may be embodied in many other forms, in keeping with the broad principles and the spirit of the invention described herein. The present invention and the described preferred embodiments specifically include at least one feature that is industrial applicable.