Abstract:
A reversible cartridge holding a plurality of paper products and for dispensing a controlled amount of the same from a dispenser housing. The cartridge includes a cartridge body having cartridge walls, the cartridge being insertable into an interior area of a dispenser housing. The cartridge may further include removable sections defined in the cartridge body, removal of at least a portion of the removable portions creating openings in the cartridge. The exterior walls define an interior surface and an interior area within the interior surface for receiving a cartridge holding a plurality of paper products. The cartridge further includes two dispensing throats, a first dispensing throat for dispensing multiple paper products, and the second dispensing throat for dispensing single paper products one at a time. Additional openings could be provided for controlling the dispensing and alignment of the paper products within the cartridge.

Description:
RELATED APPLICATIONS 
     The present application is a continuation application of application Ser. No. 09/578,240 filed on May 29, 2000, now granted as U.S. Pat. No. 6,415,949. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates generally to the field of dispensing devices and systems. More particularly, this invention relates to the field of devices and systems for dispensing paper products such as napkins, towels, bath tissue, etc. 
     Various types of dispensers for paper products have been developed to provide ready availability of the paper products to users. Such dispensers are often provided in public places such as restaurants or rest rooms where customers remove from the dispenser a desired amount of paper products for personal use. In some high traffic areas, such as fast food restaurants, a large number of customers may use a paper product dispenser such as a napkin dispenser in a short period of time. Therefore, dispensers have been developed that hold a large number of paper products for use by a large number of consumers. 
     Unfortunately, large dispensers are subject to a number of drawbacks. First, it is difficult to uniformly dispense individual paper products or a controlled amount of paper products from a large dispenser without dispensing more paper products than necessary to a user. Thus, too many paper products are removed by a user, and some of the paper products are wasted. If too many paper products are removed from a dispenser, the benefits provided by a larger dispenser are eliminated as the dispenser is emptied more rapidly. 
     Second, many dispensers are difficult to load, and that difficulty can increase with the size of the dispenser. If paper products are not properly loaded into the dispenser, the paper products may jam as they are removed thereby preventing further removal of paper products by users. Also, a person refilling a large dispenser is more likely, due to the larger number of paper products involved, to drop some of the paper products onto a floor. Any dropped paper products are then unsanitary and must be discarded, thereby creating more waste and again defeating the benefits of the larger dispenser. 
     Third, for many currently available dispensers regardless of size, it is impossible to determine without opening the dispenser how many paper products remain within the dispenser. Thus, a person must either periodically check the dispenser to determine how many paper products remain or be vigilant to refill the dispenser as soon as it is empty. Both alternatives involve much personal attention and, especially during peak usage, can lead to empty dispensers if the dispensers are not vigilantly monitored. 
     Some dispensers may be adapted to dispense paper products from preloaded cartridges. One drawback of these types of dispensers that the cartridge itself is designed to be loaded into and dispensed from a specific configuration of dispenser. This requires the facility to stock the appropriate cartridge for each type of dispenser used. Thus, the facility is required to monitor more than one reserve supply of paper products and to dedicate storage space for each type of preloaded cartridge used. 
     OBJECTS AND SUMMARY OF THE INVENTION 
     It is a principle object of the present invention to provide an improved cartridge for dispensing controlled amounts of paper products from a dispenser housing, the improved cartridge being readily adapted to various applications. 
     Another object of the present invention is to provide a cartridge for dispensing paper products that is simple and inexpensive to manufacture, and that is reliable in use. 
     Still another object of the present invention is to provide a cartridge for dispensing paper products that provide metered delivery of individual paper products or a controlled amount of paper products. 
     Yet another object of the present invention is to provide a cartridge for dispensing paper products that reduce the incidence of waste of the paper products, either due to dispensing of too many paper products to a user or due to dropping of the paper products during refilling of a container. 
     Still another object of the present invention is to provide a cartridge for dispensing paper products that provides an indication of the remaining amount of the paper products ready for dispensing to users. 
     Yet another object of the present invention is to provide a cartridge for dispensing paper products that reduces the incidence of jamming of paper products and the resultant inability to dispense further paper products. 
     Yet another object of the present invention is to provide a cartridge for dispensing paper products that can be used in more than one embodiment of dispenser housings or containers. 
     To achieve these objects and in accordance with the purposes of the invention, as embodied and broadly described herein, a cartridge for holding and dispensing a plurality of paper products includes a cartridge body having cartridge walls and may further include removable sections defined in the cartridge body. 
     Generally speaking, the cartridge includes a cartridge body having cartridge walls, the cartridge being insertable into an interior area of a dispenser housing. The cartridge may further include removable sections defined in the cartridge body, removal of at least a portion of the removable portions creating openings in the cartridge. In some embodiments, the cartridge wall may include a first slit, slot, orifice or channel that may serve to control access to the paper products held within. Desirably, the first slit is defined by a rear wall and a top wall of the cartridge. However, it is contemplated that other locations may be used. 
     The first slit is desirably sized so that its horizontal dimension or width is about the same as or slightly greater than the width of the paper products within the cartridge and its vertical dimension or height is large enough to permit the passage of a limited number of paper products. For example, if the paper products are in the form of folded paper napkins, the vertical dimension of the first slit may be sized so that a limited number of folded paper napkins may extracted. This could be achieved by making the vertical dimension some multiple of the thickness of an individual folded paper napkin (e.g., greater than about two and less than about ten thicknesses). 
     The paper product may be accessed by a thumb slot and/or a finger slot. Desirably, the thumb and finger slots are located on the rear and top walls of the cartridge. 
     It should be understood that any reference to topographical features used to describe the container are meant to provide relative placement of one feature with respect to another feature and are not meant to designate absolute locations. As such, disposed in a bottom wall of the cartridge or the wall opposite the wall comprising the first slit, may be a second slit, slot, orifice or channel that also may serve to control access to the paper products held within. Desirably, the second slit is wholly contained by a bottom wall of the cartridge. However, it is contemplated that other locations may be used. 
     The second slit is sized so that only a portion of the face of a paper product is exposed to the user. By exposing only a portion of the paper product, the paper product will be caused to dispense one at a time. For example, if the paper products are in the form of folded paper napkins, the second slit may be sized to enable a user to grasp an exposed face of a single napkin, extract that napkin from the cartridge, leaving the next napkin in the stack exposed. 
     The cartridge may further define at least one other slot through one of the cartridge walls, the slot being visible from outside a dispenser housing when the cartridge is placed within the interior area of such a dispenser housing. An amount of paper products contained within the cartridge being determinable by visually inspecting the amount of paper products through the slot. 
     Desirably, other openings are provided in the cartridge for receiving protrusions situated in a dispenser housing. A first group of such protrusions is envisioned to include bumpers adapted to extend into an interior area of the carton to contact paper products and thereby oppose or slow the progression of the paper products in a dispensing direction. A second group of such protrusions is envisioned to include rib members adapted to extend into an interior area of the carton to contact paper products for spacing, slowing, aligning and supporting the paper products as they are moved in the dispensing direction. 
     It is also contemplated that the cartridge may have at least one additional opening corresponding to a key, rib, pin, or projection of some form located on an interior section of the dispenser housing. The key would permit the cartridge to be loaded properly into the dispenser housing. If a custodian were to attempt to incorrectly load the cartridge into the dispenser or attempt to load the cartridge in the wrong orientation, the key would not engage the opening in the cartridge thus preventing the cartridge from seating within the dispenser. 
     The above structure enables the cartridge, which has been preloaded with a stack of paper products, to be used with a dispenser adapted to dispense a controlled or limited number of paper products at each dispense or dispensing event. Alternatively the cartridge may be used with a dispenser adapted to dispense paper products one at a time, i.e., single dispensing. The dual use is accommodated desirably by flipping the cartridge end for end so that the front wall is placed in the rear and the rear wall is placed in the front, while switching the orientation of the top and bottom walls as well. As such this configuration would enable dispensing from each end of the stack of paper products. 
     Additional objects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through the practice of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will be more fully understood from the following detailed description, taken in conjunction with the accompanying drawings, wherein like reference numerals refer to like parts, and in which: 
     FIG. 1 is a perspective view of an exemplary cartridge for holding a plurality of paper products and dispensing the same therefrom. 
     FIG. 2 is a rear elevation view of the FIG. 1 cartridge, which has been rotated 180 degrees end to end about the x-axis. 
     FIG. 3 is a front elevation view of the FIG. 1 cartridge oriented as shown in FIG.  1 . 
     FIG. 4 is a top elevation view of the FIG. 1 cartridge depicting an exemplary slit adapted for the removal of a limited number of paper products in one dispensing event. 
     FIG. 5 is a bottom elevation view of the FIG. 1 cartridge depicting an exemplary slit adapted for the removal of a single paper product at a time. 
     FIG. 6 a  is a perspective view of the FIG. 1 cartridge inserted into one variant of an exemplary dispenser housing, specifically a dispenser housing adapted to dispense a limited number of paper products. 
     FIG. 6 b  is a front elevation view of the FIG. 1 cartridge inserted into another variant of an exemplary dispenser housing, specifically a dispenser housing adapted to dispense individual paper products or one-at-a-time dispensing. 
     FIG. 6 c  is a front elevation view of the FIG. 1 cartridge inserted into yet another variant of dispenser housing, specifically an alternative variant of an exemplary dispenser housing adapted to dispense individual paper products or one-at-a-time dispensing. 
     FIG. 7 a  is a perspective view of one exemplary form of dispenser housing for use with the FIG. 1 cartridge. 
     FIG. 7 b  is a perspective view of another exemplary form of dispenser housing for use with the FIG. 1 cartridge. 
     FIG. 8 is an enlarged cross-sectional view (not to scale) of the lower portion of a cartridge and dispenser housing assembly. 
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in more detail to the presently preferred embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention and not meant as a limitation of the invention. For example, features illustrated or described as part of one embodiment or figure can be used on another embodiment or figure to yield yet another embodiment. It is intended that the present invention include such modifications and variations. 
     As broadly embodied in FIGS. 1-5, one desirable embodiment of a cartridge  10  is disclosed in which paper products  12  are placed and from which paper products  12  are dispensed. The paper products  12  may be paper napkins, paper towels, toilet tissue, or any other similar material. The cartridge  10  comprises a plurality of cartridge walls  18  including a first wall, top wall, or end  24  and a corresponding second wall, bottom wall, or end  34 . It should be understood that the terms “top” and “bottom” are used only to describe the relative positions of each wall or end. During use in a dispenser housing, either end of the cartridge  10  may be located at a bottom or dispensing end of the dispenser housing. 
     As illustrated in FIGS. 6 a ,  6   b , and  6   c , the cartridge  10  is adapted to be inserted into the interior area of a dispenser housing  100 , the cartridge  10  is further adapted for holding or containing the paper products  12  to be dispensed. Looking to FIGS. 6 a ,  6   b , and  6   c  it can be seen that the cartridge  10  is sized to fit snugly within an interior area of the dispenser housing  100 . 
     Looking back to FIGS. 1-5, in general, the cartridge  10  may include a plurality of removable portions  14 , the removal of which creates openings  16  through the cartridge  10 . The removable portions  14  are disposed in outside walls  18  of the cartridge  10  so that, once the removable portions  14  are removed, the openings  16  encompass and receive protrusions from the dispenser housing  100  that may extend into the cartridge  10 . Thus, upon removal of the removable portions  14  and placement of the cartridge  10  into the appropriate dispenser housing  100 , portions of the dispenser housing  100  protrude through the openings  16  to contact the paper products  12  within cartridge  10 . 
     FIGS. 2 and 4 depict one desirable dispenser opening in the cartridge  10 . A slit, slot, orifice or channel, referred to hereafter as a dispensing throat  20  serves to control access to the paper products  12  contained within the cartridge  10 . The dispensing throat  20  is desirably configured to dispense a limited quantity of paper products at each dispense. 
     FIGS. 3 and 5 depict another desirable dispenser opening in the cartridge  10 . A different slit, slot, orifice or channel, referred to hereafter as a dispensing throat  32  serves to control access to the paper products  12  contained within the cartridge  10 . Unlike the dispensing throat  20 , the dispensing throat  32  is desirably configured to dispense a single paper product at each dispense. 
     In either case, the cartridge  10  can be provided such that each dispensing throat  20  and  32  is provided with removable portions  14 . This enables a user to select which dispensing throat the paper products  12  are to be dispensed from and to only access that throat. 
     Before discussing the cartridge  10  in greater detail, it is important to understand that the cartridge  10  includes both a first dispensing throat  20  and a second dispensing throat  32 . These throats may be located at opposite ends of the cartridge  10  or at least at different dispensing zones within the cartridge  10  as can be at least partially observed in FIG.  1 . This feature enables a single cartridge  10  to be used in different types of dispenser housings, for example, a dispenser housing adapted to dispense a controlled plurality of paper products as well as a dispenser housing adapted to dispense paper products singly, i.e., one-at-a-time. 
     It is also important to note that FIG. 2 depicts the dispensing throat  20  in dispensing zone  500  at a bottom portion of the cartridge  10 . Similarly, FIG. 3 also depicts the dispensing throat  32  in dispensing zone  600  at a bottom portion of the cartridge  10 . Since it is more desirable to dispense the paper products  12  from the bottom of the dispenser  100 , the cartridge  10  is made to be flipped  180  degrees end for end along the x-axis. Though not required, it is also contemplated that the container could be flipped end for end along the y-axis and/or the z-axis as well. The dispensing throats  20  and  32  could be relocated accordingly to accommodate numerous variations. In either case, the cartridge  10 , once flipped is capable of dispensing from either embodiment of the dispenser housing  100 . Positioning the cartridge  10  as shown in FIG. 2 such that paper products  12  are dispensed from the dispensing throat  20  allows the cartridge  10  to be used with a dispenser  100  similar to that shown in FIG. 6 a  or  6   c  whereas the FIG. 3 position using the dispensing throat  32  is adapted to be used with a dispenser  100  similar to that shown in FIG. 6 b.    
     To minimize any potential for confusion, all terms referring to the topographical features of the dispenser  10 , including the terms “front”, “rear” or “back”, “top”, and “bottom” are used only to refer to their respective positions as depicted in FIG.  1 . As such, looking more specifically at FIGS. 2 and 4, it can be seen that the dispensing throat  20  is defined by the cartridge rear wall  22  and top wall  24  of the cartridge. However, it is contemplated that other locations may be used. 
     The dispensing throat  20  is desirably sized so that it has a horizontal dimension “H” that is about the same as or slightly greater than the width of the paper products  12  within the cartridge  10  and a vertical dimension “V” that is large enough to permit the passage of a limited number of paper products  12 . For example, if the paper products  12  are in the form of folded paper napkins, the vertical dimension “V” of the dispensing throat may be sized so that a limited number of folded paper napkins may be extracted. This could be achieved by making the vertical dimension “V” some multiple of the thickness of an individual folded paper napkin (e.g., desirably greater than about 2 and less than about 10 thicknesses, even more desirably greater than about 2 and less than about 6 thicknesses). 
     Generally speaking, this first dispensing throat  20  provides for the reliable and trouble free dispensing of a corresponding amount of paper products in a single dispensing event. That is, the first dispensing throat  20  may be configured to allow from about 2 to about 10 paper products to dispense in one pull, i.e., dispensing event. 
     The paper product may be accessed by a thumb slot  26  and/or a finger slot  28 . Desirably, these slots are located on the top and rear walls of the cartridge and may be centered with respect to the dimensions of the cartridge  10  or the dimensions of the slot  20 . However, whether the thumb slot  26  is located on the rear wall or top wall is a matter of preference. The point to note is that the slot  20  is desirably expanded to include the thumb and/or finger slot(s). 
     Looking now more particularly to FIGS. 3 and 5, it can be seen that the dispensing throat  32  is defined by the cartridge bottom wall  34  of the cartridge. However, it is contemplated that other locations may be used. The dispensing throat  32  may have many shapes within the scope of the present invention, as long as the throat provides easy access for a user and delivery of paper products  12  for “one-at-a-time” or single product dispensing. 
     To permit visual inspection of the amount of paper products  12  remaining in the cartridge  10 , the cartridge  10  may define at least one additional slot  30  through one of the cartridge walls  18 . More desirably, at least one such slot  30  is visible from outside a dispenser housing  100  when the cartridge  10  is in the interior area of the dispenser housing  100 . Since the cartridge  10  can be loaded in more than one orientation, it is desirable to provide at least one such slot  30  on the rear wall  22  and at least one such slot  30  on the front wall  36 , an amount of paper products  12  disposed within the cartridge  10  being determinable by visually inspecting the amount of paper products  12  through the slot  30 . As shown in FIGS. 6 a  an  6   b , two slots  30  may be provided in the rear wall  22  and in the front wall  36  to provide a greater range of visual inspection. Note that FIGS. 1-3, and  6   c  reflect an embodiment having only one such slot  30  located in the rear wall  22  and in the front wall  36 . In fact, any number or arrangement of slots is possible within the scope of the invention. 
     Further in accordance with the invention, at least some of the openings  16  may have removable portions  14  corresponding to a first group of slots  38  and a second group of slots  40 . The first group of slots  38 , as shown in FIGS. 7 a  and  7   b , are adapted to receive at least one protrusion  102 , which is generally an attachment to or a part of the dispenser housing  100 . These protrusions  102  extend from the dispenser housing  100 , through the slot or slots  38  to contact the paper products  12 . By contacting the paper products  12 , the protrusions  102  impede, without actually prohibiting, the movement of the paper products  12  in a dispensing direction “D 1 ”, i.e., toward the dispensing zones  500  or  600  and the dispensing throats  20  or  32  depending upon the dispenser housing used to dispense the paper products  12 . 
     The second group of slots  40  may be provided in the cartridge walls  18  to adapt the cartridge  10  for use in dispenser housings wherein the dispenser housing  100  contains a rib or ribs  104  designed to protrude through the cartridge walls  18 , also to contact the paper products  12 . These second group of slots  40  are preferably disposed at least partly in the top wall  24  and/or the bottom wall  34  of the cartridge  10  and are adapted to receive the rib members  104  which are mounted or otherwise attached to the dispenser housing  100 . These slots  40  enable the rib members  104  to space, slow, align, and support the paper products  12  as they are moved in a dispensing direction “D”. 
     Some of these slots  40  can be of a different size than other of slots  40 . In fact, it may be desirable in at least the top wall  24 , to make the slots  40  smaller near a centerline of the dispenser  10  and larger near the outer edges of the dispenser  10  as depicted in FIG.  4 . This configuration is adapted to accommodate rib members  104  of differing heights. The rib members  104  closest to the centerline are shorter or protrude less distance into the cartridge  10  than do the outermost rib members  104 . This has the effect of bowing the center portions of the paper products toward the dispenser throat  20 . 
     Looking further to FIG. 4, it is also contemplated that the cartridge may have at least one additional opening  42 . This opening  42  corresponds to a key  44  located on the dispenser housing  10  as shown in FIG. 7 b . The key  44  would provide the cartridge  10  with a device minimizing the possibility that the cartridge could be improperly loaded into the dispenser housing  100 . It is desirable that the key  44  be associated with only one of the dispenser housing variations, i.e., either the configuration designed to dispense a limited quantity of paper products at each dispense or the configuration designed to dispense a single paper product at each dispense. In that way, in the event a custodian were to attempt to incorrectly load the cartridge  10  into a dispenser housing  100 , or alternatively attempt to load the cartridge  10  in the wrong orientation, the key  44  would not engage the opening  42  in the cartridge  10  thus preventing the cartridge  10  from seating within the dispenser housing  100 . 
     Generally speaking, removable portions  14  may either be removed or simply not formed in the cartridge walls  18  or ends  24  and/or  34  during manufacture of the cartridge  10 . Depending upon the circumstances desired, these removable portions  14  can be removed during installation of the cartridge  10  in the appropriate dispenser housing  10 . If the removable portions  14  are to be removed (or simply not formed) as part of the manufacturing process, the cartridge  10  may be shipped to the user wrapped, for example in a polyethylene bag, to prevent contamination and/or to preserve the sterility of the paper products  12  in the cartridge  10 . If the removable portions  14  are to be removed as part of the installation process, the edges of the removable portions  14  should be weakened, scored, etc. for easy removal. In one embodiment, it is desirable that the removable portions  14  are either not formed or are removed prior to shipment to the consumer. This minimizes the work necessary in loading the cartridge  10  into a dispenser. 
     Additional features which could be desirable, are that at least the top wall  24  and/or the bottom wall  34  of the cartridge  10  be disposed at an angle with respect to the front wall  36  and the rear wall  22  of the cartridge  10  as can be seen in FIGS. 3,  6   b , and  6   c . However, as depicted in FIGS.  1  and  6   a  it may be more desirable to have the top wall  24 , or that wall comprising the dispensing throat  20  to be perpendicular to its adjacent walls. In any case, it is desirable to dispense the paper products  12  from the dispensing throat  20  or  32  so that a face of the paper products  12  is parallel to the top wall  24  or bottom wall  34  from which the paper products  12  are being dispensed. 
     FIGS. 6 a  and  7   a  depict dispenser housings  100  adapted to work with a perpendicular wall embodiment whereas FIGS. 6 b ,  6   c , and  7   b  depict dispenser housings  100  adapted to work with an angled wall embodiment. Furthermore, the cartridge  10  is preferably made of heavy paper or cardboard, but may be made of any other suitable material within the scope of the invention. 
     FIG. 8 depicts an enlarged cross-sectional view (not to scale) of the lower portion of the cartridge  10  inserted into a dispenser  100  as embodied in FIG. 6 a . Though not necessary to practice the invention, the paper products  12  contained within the cartridge  10  are desirably interfolded or tab interfolded napkins to provide metered feeding of one or a number of such individual napkins at any one time. As explained above, and as can be seen in the enlarged and expanded view, the slot  950  has a vertical dimension “V” which is generally some multiple of the thickness of a single layer or ply or fold of the paper product  12 . A dispensing direction “D” is identified as generally perpendicular to the housing and cartridge assembly. If the paper product is, for example, an interfolded paper napkin or tissue, a leading flap or tail  960  can be seen extending out of the slot  950  for a user to grasp. Pulling the leading flap  960  will result in one-at-a-time dispensing of the product. 
     Whereas gripping the interfolded product between lower grip point  1000  and a first upper grip point  1002  engages two of the interfolded paper products (e.g., napkins, tissues, wipes, etc.) for dispensing. One of which has a visible tail  960  extending from the slot  950  (or dispensing throat  20 ) and the other still located inside the cartridge but accessible through the finger slot  954 . Pulling the product engaged at grip points  1000  and  1002  in the dispensing direction “D” will result in two of the interfolded paper products to be dispensed at a time. This result will be consistent provided the interfolding of the product is consistent and the grip areas  1000  and  1002  remain accessible. 
     Pulling the product engaged at grip points  1000  and  1004  in the dispensing direction “D” will result in four of the interfolded paper products to be dispensed at a time. This result will be consistent provided the interfolding of the product is consistent and the grip areas  1000  and  1004  remains accessible. 
     Pulling the product engaged at grip points  1000  and  1006  in the dispensing direction “D” will result in six of the interfolded paper products to be dispensed at a time. This result will be consistent provided the interfolding of the product is consistent and the grip areas  1000  and  1006  remains accessible. This can be described mathematically for interfolded products as N=F f ×2 where N=the number of products dispensed, F f =the number of forward folds (F f ) falling between the identified grip points and which are gripped by the user. The number of forward folds (F f ) available for gripping is generally limited only by the vertical dimension of the slot “V ” and the size of the finger and/or thumb slots. Generally speaking, the “stack” of product dispensed will be in a folded configuration except for the leading and trailing edge or flap. Of course, if the product is dispensed one-at-a-time, it will be in an unfolded configuration. 
     If a non-interfolded product is used in the cartridge, the dispensing direction “D” remains the same. However, there will be no leading flap as in the interfolded format. Generally speaking, the number of products dispensed will be the same as the number of forward folds gripped unless the product is double or triple folded. 
     Thus, it can be seen how the cartridge  10  may be used in dispenser housings  100  designed to dispense a controlled amount of paper products  12 . The cartridge  10  may also be used in dispenser housings  100  designed to dispense paper products singly, i.e., one at a time. This could be accomplished by providing access only to a portion of the face of the paper product  12 . For example, if the paper products are in the form of folded paper napkins, and only an exposed face of a single napkin is accessible to a user, extracting that napkin from the cartridge  10  leaves the next napkin in the stack exposed. 
     RELATED APPLICATIONS 
     This application is one of a group of commonly assigned patent applications which have been previously filed. This group includes application Ser. No. 09/991,669 filed on Dec. 15, 1997 by Paul Tramontina, application Ser. No. 09/156,230 filed on Sep. 18, 1998 by Paul Tramontina, and application Ser. No. 09/206,956 filed on Dec. 8, 1998 by Paul Tramontina et al. The subject matter of these applications is hereby incorporated herein by reference. 
     It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope and spirit of the invention. It is intended that the present invention include such modifications and variations as come within the scope of the appended claims and their equivalents.