Patent Publication Number: US-2011056035-A1

Title: Superior apparatus for cleaning windows

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims priority under 35 U.S.C. §119(e) to U.S. Provisional Application No. 61/276,244 filed Sep. 10, 2009. 
    
    
     FEDERALLY SPONSORED RESEARCH AND DEVELOPMENT 
     There are no rights that exist under any federally sponsored research and development. 
     BACKGROUND 
     There are hundreds of millions of residential and commercial buildings in the United States. The vast majority, if not all, of these buildings contain one or more windows. There are many benefits to having clean windows, including but not limited to a classier and more appealing look for residential buildings; a more professional and appealing look for commercial buildings; a better view of the outside; the ability for more sunlight to enter, which can bring many health benefits; better heat efficiency during the winter; and the prevention of glass degradation. To get these benefits, it is very important for both the inside and the outside of the window to be clean. However, when the ground-level windows are very tall, or the windows are higher than ground-level, many people find it either not feasible to clean the outside of their windows, or alternatively they find such cleaning to be a hassle and/or dangerous. 
     Some people attempt to clean their higher windows using ladders; however, this can easily lead to serious injury or even death, such as if one were to fall off the ladder or through a window while extending one&#39;s arms or body or simply while attempting to clean. Other people attempt to use extension poles to extend the reach of their cleaning tools; however, such poles can be unwieldy and are limited in their maximum range, and thus their use is precluded for the higher windows of taller commercial buildings, apartment buildings, and even for some tall residential houses. Additionally, it could be a hassle to have to store various lengths of extension poles just so that one can clean their windows. Still others attempt to use garden hose pipe attachments and pressure washers; however, such cleaning methods afford less control and precision, can easily damage glass and other external surroundings such as wood or climbing plants, and still require a separate means of removing the water or window cleaning solution that if left to dry on its own could result in spots or streaking, thus defeating the original purpose of washing the windows. Additionally, as with extension poles, such methods are ultimately limited in their maximum height and reach. Furthermore, such methods entail an unnecessary waste of both time and water. Another deterrent is that all of these methods require the window washer to be outside, frequently for extended periods of time in extreme heat and/or surrounded by pests such as allergens or insects. Other people simply cannot invest the time to be outside leaving the building unattended, especially in residential cases where there are young or infant children that need to be watched. 
     Consequently, many people do not even bother to try to clean the outside of their windows. Those people who do, rather than even attempt to clean the windows on their own, instead hire costly professional window cleaning services, who themselves use one or more the above-mentioned methods. For taller building, these methods cannot be used, and instead it becomes necessary to use scaffolding or to have the window washing person suspended from a suspension line anchored to the top of the building. In addition to being costly, these methods are very dangerous and result in high risk of death and injury, as scaffolding-related deaths and injuries number in the thousands each year. Such dangers have necessitated extensive window cleaning safety regulations in many jurisdictions. 
     Information relevant to attempts to address some of these problems can be found in U.S. Pat. Nos. 7,231,683 and 6,601,256. However, each one of these, and references similar thereto, suffers from one or more of the following disadvantages: the apparatus is complex and/or expensive; the apparatus is large and unwieldy; the apparatus does not give the user total control; the apparatus must first be attached or mounted to the roof in order to work; the apparatus must be somehow mounted to the exterior of the house before it can be used; installation of the apparatus creates risk of injury or death; the apparatus requires that it be permanently attached or mounted to the roof or exterior of the structure, creating structural damage or unsightly additions to the building; such devices, even if removed, are difficult or a hassle to store; the apparatus gives the user only one method, and no choice, as to how they will wash their window; the apparatus cannot be adapted for use on a variety of types of windows; the apparatus requires external sources of water or cleaning fluid, or if it has an internal source it is difficult to replace or impossible to replace during operation of the apparatus; the apparatus requires a motor, which can break and either requires costly and difficult replacement or renders the apparatus useless; the apparatus requires a source of electricity in order to operate; as well as other manifest disadvantages. 
     For the foregoing reasons, there is a need for an autonomous window cleaning apparatus that is flexible to the needs and control of the user, that can be used at any time by any person with ease and comfort, and that can be used safely and effectively at any height without putting the user at risk of injury or harm during any stage of its use. 
     SUMMARY 
     I have invented an adjustable pole that satisfies this need. An adjustable pole having features of the present invention comprises two housings. The two housings are connected to each other by an adjustable joint, allowing the two housings to be oriented at any angle desired by the user. Preferably, the housings are telescopic and have releases that allow for easy extending and retracting. Preferably, the pole is approximately 1.12 meters when fully retracted and approximately 1.65 meters when fully extended, which balances comfort, ease of use, and reach. For storage or transport, the housings can be folded about the adjustable joint for an even shorter length. The second housing is capable of receiving an attachment piece, which can directly be an attachment head. Preferably, the attachment piece is a fork that can further receive an attachment head. The fork allows for limited movement of the attachment head such that the attachment head can lay flat against the washing surface no matter the angle at which the two housings are oriented. Different attachment heads can be used depending on the surface to be cleaned and the needs of the user, such as a flat surface capable of holding pre-moistened fabrics, fluid-absorbing fabrics, dust-removing fabrics, or other wiping cloths; squeegees; sponges; mop-heads; brush-heads; broom heads; feather dusters; or any other suitable cleaning tool. The attachment head is easily removable to facilitate maximum ease and flexibility for the user. Preferably, the adjustable joint is controlled by a changing-angle button, which when pressed allows the user to easily and immediately change the desired orientation of the two housings, even when the pole is in the middle of being used. Preferably, there is a handle attached to the first housing to maximize the comfort of the user. The handle is capable of receiving a fluid bottle. Preferably, the handle would have one or more fluid level indicators so that the fluid bottle can be nearly completely housed within the handle so as not to add unnecessary length to the pole, and yet the user can still see how much fluid remains in the fluid bottle and whether a replacement will soon be necessary. Preferably, there is an inner tube that has one end residing within the handle in the cavity space where a fluid bottle can reside, and extends throughout the housings, with its other end connected to a fluid nozzle. The fluid nozzle allows fluid to be ejected from the pole. The inner tube from end to end resides completely within the housings, so as to prevent the tube from snagging or getting caught while the pole is being used, or accidentally getting torn or damaged even when not being used. Preferably, the inner tube is arranged in one or more circular loops as it extends through the adjustable joint so as to prevent tearing of the inner tube, entrapment of fluid, or impediments to the pressure gradient should the housings be oriented at certain angles. Preferably there is a fluid ejector button attached to the handle that when pressed, activates an internal pump that draws fluid out from the fluid bottle and transports it to the fluid nozzle. 
     A number of advantages are had by the present invention and embodiments thereof. One advantage is that the pole can be used to safely clean the exterior of a window from the safety and comfort of the inside of a building without fear of harm or injury, no matter how high up the window from the ground. Another advantage is that the user can easily replace the cleaning fluid even while cleaning the exterior of a window without having to stop what he/she is in the middle of doing and/or retract the pole back inside. Another advantage is that the pole can be easily and effectively adjusted at whim, even while in the middle of being used. Another advantage is that the pole can be used to clean the interior parts of windows or even whole windows that would otherwise be at difficult-to-reach angles or require additional tools such as a ladder or stepstool. Another advantage is that the pole is self-sufficient and does not require external sources in order to operate or function. Another advantage is that the user can customize the pole so as to suit their individual wants and needs. Another advantage is that there is no need for numerous extension parts or accessories, which must then be stored in addition to the base, but rather the user can select what parts will be necessary for their desired use. Another advantage is that the pole can be easily and conveniently stored away after use. Another advantage is that the pole is completely portable and can be used to clean the exterior of windows without having to first be mounted to the roof or exterior of the building. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other features, aspects, and advantages of the present invention will become better understood with regard to the following description, appended claims, and accompanying drawings where: 
         FIG. 1  shows a side elevation view of an embodiment of the present invention; 
         FIG. 2  shows a bottom plan view of a fork portion of the apparatus of  FIG. 1  as well as examples of different head attachments; 
         FIG. 3  shows a partial sectional view of a handle portion of the apparatus of  FIG. 1 ; 
         FIG. 4  shows a partial sectional bottom plan view of a changing-angle button portion of the apparatus of  FIG. 1 ; 
         FIG. 5  shows the use of the apparatus of  FIG. 1  to wash the exterior of a window while the user remains safely inside the building. 
     
    
    
     DESCRIPTION 
     The present invention is directed to an adjustable pole for washing windows. An embodiment of the invention is shown in  FIGS. 1-5 . As shown in  FIG. 1 , an adjustable pole comprises a first housing  12  and a second housing  14 , which are connected by an adjustable joint  16 . The adjustable joint  16  is comprised of a first hinge part  18  and a second hinge part  20 , which are held together by a hinge pin  22 . The adjustable joint  16  is operated through the use of a changing-angle button  24 . Encircling the first housing  12  is a first release  26  and encircling the second housing  14  is a second release  28 . Attached to the first housing  12  is a handle  30 . Handle  30  contains one or more fluid level indicators  32  and a fluid ejector button  34 . Attached to the handle  30  is a fluid bottle  36 . Attached to the second housing  14  is a fork  38 . Attached to the fork  38  is an attachment head  40 . As shown in  FIG. 2 , the fork  38  is connected to the second housing  14  at an attachment point  42  and the attachment head  40  is connected to the fork  38  at an attachment point  44 . The fork can be removed from the second housing  14  by pressing a detachment button  46 . Below the attachment point  42  is a fluid nozzle  48 . As is shown in  FIG. 3 , the fluid bottle  36  is screwed into a threaded mount  50 . There is an inner tube  52  that has one end extending into the fluid bottle  36  and is connected to an internal pump  54 . The internal pump  54  is connected to a pump spring  56  and when activated opens a valve  58  and a valve  60 . The inner tube  52  extends through the first housing  12 , the adjustable joint  16 , and the second housing  14 , with a second end of the inner tube  52  attaching to the fluid nozzle  48 . 
     The first housing  12  and the second housing  14  are cylindrical in shape and can be made, preferably of a material such as aluminum, but can be made out of any suitable material such as other metals or hard plastic. Although in the present embodiment the housings  12  and  14  are cylindrical, the housings  12  and  14  can have other shapes such as being octagonal, heptagonal, decagonal, and other similar shapes that are not cylindrical but that still are conducive for holding and gripping. The adjustable joint  16  comprises the first hinge part  18  and the second hinge part  20 , said hinge parts  18  and  20  being held together by the hinge pin  22 , so as to provide maximum rotation about the midpoint of the adjustable joint  16 . Although in the present embodiment the adjustable joint  16  uses the hinge parts  18  and  20 , other joints that allow for rotation and angling can be used such as pivot joints or even a flexible neck joint that can be bent to the desired angle and will stay in that position until sufficient force is used to bend it into another angle. The adjustable joint  16  can be made, preferably of a material such as hard plastic, but can be made of any suitable material such as a metal or soft plastic. The adjustable joint  16  is controlled by the circular changing-angle button  24 . Although in the present embodiment the changing-angle button is circular, it can be shaped differently, such as an oval, a square, a triangle, or any other suitable shape. As is shown in  FIG. 4 , when pressed, the changing-angle button  24  pushes on and unlocks an inner gear  62 , allowing the first and second hinge parts  18  and  20  to be rotated relative to each other and about the midpoint of the adjustable joint  16 . When the changing-angle button  24  is released, the changing-angle button  24  stops pushing on the inner gear  62 , causing the inner gear  62  to return to its locking position, thus allowing the first housing  12  and the second housing  14  to be stably oriented at any desired angle. Preferably, the first housing  12  and the second housing  14  are telescopic, and are controlled by the first release  26  and the second release  28 . Each release encircles a portion of the housing that it controls, and when twisted in one direction causes the housing to extend, and when twisted in the opposite direction causes the housing to retract. Although in the present embodiment the releases are operated by twisting, which allows the user to maintain precise control over the length of the housing, the releases can take other forms as well, such as buttons that when pressed release an inner locking mechanism and allow the housings to be extended and retracted. 
     Attached to the first housing  12  is the handle  30 . The handle  30  is cylindrical and slightly bent beginning approximately at the location of the ovular fluid ejector button  34  so that the user can comfortably hold the handle  30 . This also allows the user to keep their thumb on the fluid ejector button  34 , and not accidentally press the fluid ejector button  34  when not desired. Although in the present embodiment the handle  30  is cylindrical, in other embodiments where the housings  12  and  14  are shaped other than cylindrical, the handle  30  could be shaped accordingly. Although in the present embodiment the fluid ejector button  34  is on the top side of the handle, in other embodiments the fluid ejector button  34  could be placed on the underside of the handle  30 . The handle  30  is capable of receiving a fluid bottle  36 . Preferably the fluid bottle  36  screws into the threaded mount  50  contained within the handle  30 , which allows the user to easily attach and easily remove the fluid bottle  36  by simply twisting and untwisting the exposed bottom of the fluid bottle  36 . In the present embodiment, the fluid bottle  36  is ovular in shape and is sized so as to fit within the hollow receiving portion of the handle  30  without leaving any open space. In other embodiments where the handle  30  could be shaped other than cylindrical, the fluid bottle  36  could be reshaped accordingly. Preferably the handle  30  contains one or more fluid level indicators  32 , so that the fluid bottle  36  can reside nearly entirely within the handle  30 , and the user is still able to see the remaining fluid level in the fluid bottle  36 . This enables the user, before beginning or even during a cleaning job, to know whether a replacement fluid bottle or fluid refill will soon be necessary. In the present embodiment, the fluid level indicators  32  are elongated U-shaped recesses in the handle  30  that begin at the point where the fluid bottle  36  visibly protrudes from the handle  30 . The fluid level indicators  32  can take other shapes and forms, such as rectangular recesses or clear portions of the handle  30  without making recesses in the handle  30 , or can be placed at other locations on the handle  30 . 
     The inner tube  52  has one end residing within the handle  30  in the cavity where the fluid bottle  36  resides and continues through the internal pump  54 . When the fluid ejector button  34  is pressed, it compresses the coiled pump spring  56 , activating the internal pump  54 . The increased pressure causes valves  58  and  60  to open, allowing fluid to travel through the inner tube  52  until the fluid nozzle  48  within the second housing  14 , where the fluid is ejected from the second housing  14 . The inner tube  52  is preferably made of a material such as a bendable plastic, and resides loosely within the first housing  12  and the second housing  14 , with enough slack to enable the first and second housings  12  and  14  to be telescopically adjusted easily and without interference. As is shown in  FIG. 4 , within the adjustable joint  16  there are a plurality of dugouts  64  in which the inner tube  52  resides. The dugouts are designed so that the inner tube  52  forms one or more circular loops within the adjustable joint  16 . The loops have slack so that when the first and second housings  12  and  14  are telescopically extended, the loops tighten within the dugouts  64 , and when the housings  12  and  14  are retracted, the loops loosen within the dugouts  64 . The circular loops prevent tearing of the inner tube, entrapment of fluid, or impediments to the pressure gradient should the housings be oriented at certain angles. The number of loops is based on the maximum and minimum lengths of the telescopic housings  12  and  14 . In a preferred embodiment, the pole is approximately 1.12 meters when fully retracted and approximately 1.65 meters when fully extended—balancing comfort, ease of use, and reach—and thus the dugouts  64  form two loops. 
     Above the fluid nozzle  48  is the fork attachment point  42 . Preferably, the fork attachment point  42  is a circular hole that allows the fork  38  to be easily snapped into the second housing  14  and released from the circular fork attachment point  42  when the circular detachment button  46  is pressed, to ensure ease of attachment and detachment. As used herein, the “fork” is an intermediary attachment piece between the second housing  14  and attachment head  40 , whose form and function can differ based on its intended use. In other embodiments, the fluid nozzle  48  could be placed at other locations, such as above the fork attachment point  42 , in the attachment piece, or at other locations of the pole. In the present embodiment of  FIGS. 1-5 , where the attachment head  40  is a rectangular surface capable of holding various cloths for wiping a surface, the fork  38  is Y-shaped and allows the attachment head  40  to move back and forth about a fixed axis so that the surface of the attachment head  40  can lay flat against the cleaning surface and in addition will not fall off the surface while being used. The two arms of the fork  38  provide added stability for the attachment head  40 . The wiping cloths can be affixed to the attachment head  40  through a variety of connection methods such as clips, Velcro, buttons, connection slots, and any other suitable means of affixing the cloths to the attachment head  40 . In the present embodiment, the attachment head  40  is attached to the fork  38  by snapping into the two arms of the fork  38  at the head attachment point  44 . 
     The invention is used by attaching an appropriate attachment piece or pieces, such as a fork with an attachment head or just an attachment head, and then choosing an appropriate angle between the first and second housings  12  and  14  for the user&#39;s cleaning needs. Then, depending on the attachment head, the user cleans the cleaning surface using movements appropriate for that attachment head.  FIG. 5  illustrates an example of a woman using an embodiment of the invention to clean the exterior of a window  66  on a high-up floor of the apartment building in which she resides. The windows of the apartment building are too high off the ground for other conventional window washing methods to be used. The woman chooses to attach an attachment fork and an attachment head that has a flat rectangular surface that holds wiping cloths. The woman chooses an appropriate angle using the changing-angle button  24  and extends the first and second housings  12  and  14  using the first and second releases  26  and  28 . The woman opens the inner window of her apartment&#39;s sash window to allow her to extend the first housing  12  and the second housing  14  outside and upward at the appropriate angle. The fork  38  allows the wiping surface of the attachment head  40  to lie flat against the exterior of the window  66  and prevents it from slipping or falling off the surface of the window  66 . The woman stands comfortably and safely within her apartment building and holds the handle  30 . The woman presses the fluid ejector button  34 , which ejects fluid from the fluid bottle  36  onto the exterior of the window  66  through the fluid nozzle  48 . The woman easily and happily wipes and cleans the exterior of the window  66  with the fluid absorbing cloth attached to the attachment head  40  by moving the handle  30  back and forth, which creates a corresponding motion for the attachment head  40 . 
     Similarly, to clean the interiors of windows within the building, the user would simply choose the necessary angle, for example, an angle greater than one-hundred and eighty degrees for difficult-to-reach windows such as a skylight or a high-up window that would otherwise require a ladder or a stepstool to reach, and use the invention in the same manner. In other scenarios, such as in greenhouses, where there are a multitude of different sized windows at various slopes, angles, and positions, the user could easily clean the all of the windows without having to ever pause to remove the adjustable pole from the windows or make any adjustments, simply by using the changing-angle-button to change the angles of the first and second housings  12  and  14  while in use, as needed, as the user moves from window to window. For big cleaning projects, the user would also be able to easily remove the fluid bottle  36  and replace it with a replacement without having to pause the cleaning process, simply by unscrewing the fluid bottle  36  and replacing it with a new fluid bottle while using the embodiment of the invention. 
     One having ordinary skill in the art will recognize many of the novel features and advantages of the present invention, some of which are described herein. As the housings can be oriented at any angle, the pole can be used safely and effectively to wash the exterior of a window from within the safety and comfort of the building, and thus there is no need for dangerous ladders, scaffolding, or wires, no matter how high the window from the ground. As the user can stand in one position and clean the entire window, no injuries will result from overextension or contortion of the body. The user can remain inside at all times and does not have to deal with outside pests and allergens or intense heat. The user can also clean the window at the same time as doing all other cleaning, and does not have to arrange to have any young children watched or taken care of just so that the windows could be cleaned. The user does not have to waste money hiring outside professionals to clean their windows. 
     With its preferred construction and materials, the pole is lightweight and inexpensive. The pole is not too complex and is not too large or unwieldy. The pole does not have to be mounted to the exterior or roof of the building, preventing unnecessary risk of death or injury in installation and precluding damage or unsightly additions to the external structure or roof of the building. By having features such as a handle, and various buttons for fluid release or angle-changing or attachment release, the pole provides maximum use, control, and comfort for the user. As the pole can result in a high level of control for the user, the user will not have to worry about damaging or scratching the window, and can maximize the use of their time in cleaning the windows, thus making the task an enjoyable one rather than a time-consuming hassle. The pole allows the user to be extremely precise in cleaning only a particular area and not accidentally affecting other areas around or near the window. The pole can be completely self-sufficient and provides the user both with a means of washing and wiping the window, or any other means required or desired for the cleaning endeavor, without any need for external or secondary sources to function, operate, or complete various aspects of the cleaning 
     The pole allows the user to control the amount of fluid used, so as not to cause any wasteful fluid use or increased water bills. By having an internal fluid source that can be replaced easily and effectively even while in use, the pole can be used without having to make sure beforehand that there is sufficient fluid or having to worry that the fluid will run out while being used and will have to be difficultly or costly replaced, or that the cleaning apparatus will have to stop cleaning and that the user will have to difficultly, annoyingly, or dangerously replace the fluid. 
     The pole can be retracted to a very compact size easy for storage, and can even be folded to facilitate storage in even smaller locations. The ability to fold the pole also makes it very portable. By having a fork, the attachment head can lay flat against the cleaning surface at any angle and will not slide or fall off the cleaning surface. Having a fork as an intermediary between the second housing and attachment head allows the fork and attachment head to be detached from the remainder of the pole and function as a mini-cleaning pole, with the fork acting as a handle, which can be used for even more portability or where the user has to clean a small space where use of the full pole might be uncomfortable or unwieldy. By allowing the attachment head to be detached and replaced with a different attachment head, the pole can provide for full customization so that the user can use the pole in conjunction with any appropriate cleaning apparatus head that would be necessary and tailored for various cleaning jobs and functions, or tailor it for use with a variety of window, types without the need for multiple cleaning tools and apparatuses, extension parts, or accessories. 
     By having a changing-angle button, the pole can easily be adjusted and can be adjusted at whim even while in use, so that the user can clean in fluid motions without having to stop every couple of minutes to get a new tool or readjust the tool to use in the new angle or position. The pole can be used to clean the interiors of windows that are located at difficult to reach angles, or so high up that they would otherwise require a ladder or stepstool and could be easily damaged were other tools or methods to be used. By having an inner tube that resides entirely within the pole and does not extend outside the pole at any point, the user does not have to worry that tube will snag or get caught on anything while in use, or will accidentally get torn or damaged when not being used or when being put away. Not having to see a tube extending out of the pole also makes the tool more aesthetically pleasing. By arranging the inner tube in circular loops within the adjustable joint, the housings can be telescopic and can be oriented at any angle without impeding, damaging, or adversely affecting the inner tube. By having a fluid ejector button on the handle that can be easily pressed, the user can easily eject fluid from the pole at will without needing to exert any of their own force or pressure. 
     One having ordinary skill in the art will recognize that the present invention does not require that all advantageous features and all advantages need to be incorporated into every embodiment of the invention. For example, it may be advantageous for a user to have an embodiment of the invention where some of the advantageous features are absent from the embodiment. For example, as just one illustrative example, with some of the attachment heads illustrated in  FIG. 2  it might be preferable or even advantageous to not have a fork intermediary between the second housing and the attachment head. As another example, if an embodiment of the invention were made where the housings were not telescopic, there would be no need for releases on the housings. The advantageous features are described herein to illustrate some of the advantages of the present invention over the prior art, but are not required in all versions of the invention. Additionally, there are other advantageous features that can exist in certain embodiments of the present invention. 
     Although the present invention has been described in considerable detail with reference to certain preferred versions thereof, other versions are possible. For example, as mentioned the second housing can attach directly to the attachment head without an intermediary fork. Rather than just have a single housing on each side of the joint, there could be multiple housings with housings within housings, where the housings get progressively narrower and so are able to collapse into one another. Rather than having a fluid ejector button there could be a fluid ejector trigger. Rather than have the fluid bottle be screwed into a threaded mount, the fluid bottle could be snapped into place and released with a release button. Similarly, rather than having the various attachment points allowing for parts to be snapped in and corresponding release buttons, the connecting parts could be attached with connecting pieces such as threaded screws, nuts, or bolts, or could themselves screw into threaded mounts contained within the pieces to which they are supposed to attach. The circular buttons could be ovular and the ovular buttons could be circular, or could be any appropriate shape as desired. There could be multiple internal pumps throughout the pole so as to provide for greater pressure or enable the fluid to travel across longer distances. Rather than have the inner tube reside freely within the housings with slack, the inner tube could itself be telescopic. The fork can be designed based on a desired function and purpose, such as having no arms, or having more than two arms, or allowing for multiple heads to be attached so that the user can create their own combination head pieces. Rather than a removable fluid bottle, other items serving a similar function could be used, such as a fluid container or one-time or multiple-use fluid capsules. Rather than have both handles be telescopic, only one handle could be telescopic if so desired. These are just some of the additional variations that can be incorporated into the present invention. All features disclosed in this specification (including any accompanying claims, abstract, and drawings) may be replaced by alternative features serving the same, equivalent, or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features. Therefore, the spirit and scope of the appended claims should not be limited to the description of the preferred versions contained herein. 
     In the Summary and Description above, and the claims below, and in the accompanying drawings, reference is made to particular features of the invention. It is to be understood that the disclosure of the invention includes all possible combinations of such particular features. For example, where a particular feature is disclosed in the context of a particular aspect or embodiment of the invention, or a particular claim, that feature can be used, to the extent possible, in combination with and/or in the context of other particular aspects and embodiments of the invention, and in the invention generally. 
     The terms “comprises” and grammatical equivalents thereof are used herein to mean that other components are optionally present. For example, an article “comprising” (or “which comprises”) components A, B, and C can consist (i.e. contain only) components A, B, and C, or can contain not only components A, B, and C but also one or more other components.