Abstract:
An apparatus for holding a roll of paper having a mounting section with two arms extending outward therefrom. Each arm is hollow and includes an aperture on the inner surface of the arms. Pivoting members are mounted within the arms and are spring biased into a first position where the pivoting members support the roll of paper. The pivoting members includes cavity shields that prevent the entry of debris into the arms and the springs are secured to the pivoting members and the arms so as to inhibit the springs from being dislodged. The pivoting members are further biased such that the pivoting members can be retracted into a second position as a result of a user moving the roll of paper against the pivoting members in a first direction.

Description:
RELATED APPLICATIONS 
     This application is a continuation in part of U.S. patent application Ser. No. 09/436,177 which was filed on Nov. 8, 1999 and issued as U.S. Pat. No. 6,189,828 on Feb. 20, 2001. This application also claims the benefit of U.S. Provisional Patent No. 60/183,906 which was filed on Feb. 22, 2000. This application hereby incorporates by reference the above two applications. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to paper roll dispensers and, more specifically, concerns a more robust sanitary paper dispenser that inhibits the introduction of particle matter into the internal portion of the dispenser and provides a uniform and flat surface for easy cleaning. 
     2. Description of the Related Art 
     It has long been appreciated physically challenged persons have a difficult time installing paper rolls into conventional paper roll dispensers. Conventional dispensers often comprise a cylindrical shaft that fits into the hollow inner diameter of the paper roll, and the shaft often includes a smaller diameter knob at both ends. Usually, one knob is spring biased outward along the axis of the shaft and, when biased into a cavity in the wall, retains the cylinder along with the paper roll. This installation process requires the use of two hands and fine motor skills. In particular, one must hold onto the paper roll with one hand, insert the cylinder with the other hand, then gather the two components in one hand, bias the knob into the cylinder with the other hand, and then insert the knobs into the two receiving recesses in the wall. However, for many people, like the thousands of people suffering from arthritis, this procedure is too painful or difficult to perform. Hence, there is a need for a toilet paper roll dispenser allowing for quick and easy installation and removal of the paper roll. 
     It has also long been appreciated that germs can cause illness in humans. Germs are especially prevalent in restrooms on toilet paper dispensers, mainly because bodily waste products are within close proximity and because persons touching the dispensers often do so with unwashed hands. These germs can be passed on to the next person touching the dispenser and cause illness in the recipient. Also, dispenser designs often include recesses and other inaccessible features making cleaning very difficult. Hence, there is an on-going problem of paper dispensers that retain germs and are difficult to clean. 
     Various dispensers have been developed which retain the roll of paper with a pair of pivoting support members. These dispensers allow the user to install and remove the paper roll with one hand in one easy upward motion. For example, U.S. Pat. No. 4,553,710 discloses several types of paper roll dispensers which retain the roll of paper with a pair of pivoting support members. In particular, U.S. Pat. No. 4,553,710 discloses paper roll dispensers utilizing a pair of support members biased to pivot and enter the hollow section of the paper roll. Furthermore, the support members shown in U.S. Pat. No. 4,553,710 can retract into the main structure of the dispenser when either removing or inserting a roll of paper. In fact, products have become marketed, like those distributed by Rubbermaid, that include retractable support members similar to the members disclosed in U.S. Pat. No. 4,553,710. 
     While the dispensers disclosed in U.S. Pat. No. 4,553,710 and the Rubbermaid product have been particularly effective in reducing the time and effort needed to remove or insert a roll of paper, these dispensers are susceptible to the retention of germs and foreign particles. More specifically, when the support members are pivoted outward, the design leaves open apertures when the paper roll is installed. These apertures provide a path to the internal portion of the dispenser, and these are prime locations for germs and foreign particles to accumulate and potentially cause illness to all coming in contact with the dispenser. Also, the affected areas are difficult to clean because they are inaccessible inner surfaces. 
     The dispensers disclosed in U.S. Pat. No. 4,553,710 and the Rubbermaid product can also be difficult to assemble. For instance, the Rubbermaid product comprises two springs, two pivoting members, and two halves of a dispenser shell housing. Neither the springs nor the pivoting members can be rigidly attached to the shell housing during assembly. Instead, during assembly, the pivoting members swing freely on flanges extending from one half of the shell housing, and one end of the springs resides inside the hollow of the pivoting member. Then, the other half of the shell housing must be lowered onto the first half of the shell housing as the springs are bent and lined up with retainer posts on the lowered half. Hence, assembly of this Rubbermaid product can be time consuming and expensive. 
     Last, the Rubbermaid product is not a robust design because the pivoting members are prone to failure. More specifically, the springs bend from inside the pivoting members, around the base of the pivoting members, to the base of the dispenser shell housing. The bending of the spring results in a lateral offset of the spring, and this lateral offset actually biases the spring to eject out of the pivoting members where they can no longer bias the pivot members. If the springs bias out of the pivoting member, then the pivoting member will not bias and will not be able to support a paper roll. To account for this weakness, Rubbermaid designers have utilized overly long and overly stiff springs. Unfortunately, even these springs are still prone to bias out of the pivot members, and the overly stiff springs may actually impair the user&#39;s ability to install a roll of paper. Hence, the robustness of the Rubbermaid product could be significantly improved. 
     From the foregoing, it will be appreciated that there is a need for an improved paper roll dispenser that keeps germs from entering the dispenser assembly and is easy to clean. It will also be appreciated that there is a need for an improved paper roll dispenser that is easy and inexpensive to assemble. Last, it will be appreciated that there is a need for a more robust paper roll dispenser. 
     SUMMARY OF THE INVENTION 
     The aforementioned needs are satisfied by the paper roll dispenser of the present invention which, in one aspect, comprises a base member adapted to mount the apparatus onto a wall and a first and second arm having an inner and outer face wherein the first and second arms extend outward from the mounting plate so as to be spaced a first distance apart, the first distance being selected to be larger than the width of the roll of paper. The arms also have apertures formed on the outer surfaces of the first and second arm members. 
     This aspect of the present invention also includes a first and a second pivoting member each defining an outer perimeter and an apex where the first and second pivoting members are respectively mounted in the apertures in the first and second arms. The first and second pivoting members are biased inward into the space between the first and second arms in a first orientation such that the apex of the first and second pivoting arms are positioned a second distance apart that is less than the length of the roll of paper such that the roll of paper can be retained on the first and second pivoting members. The first and second pivoting members can be moved into a second orientation such that the apex of the first and second pivoting members are spaced a third distance apart that is greater than the length of the roll to permit removal of the roll. 
     This aspect of the present invention also includes a first and second cavity shield respectively mounted about the outer perimeter of the first and second pivoting members so as to extend outward therefrom a distance that is selected such that the first and second cavity shield contact the inner surface of the first and second arms when the first and second pivoting members are in the first orientation such that the first and second cavity shields substantially seal the first and second apertures. 
     In one embodiment, the first and second pivoting members are biased and have an angled surface that is angled such that positioning a roll of paper against the angled surface and exerting pressure against the roll of paper such that it exerts pressure against the first and second pivoting member results in the pivoting members moving from the first orientation to the second orientation to permit installation of the roll of paper. Similarly, to remove the roll of paper, the first and second pivoting members are biased such that moving the roll of paper away from the angled surface results in the first and second pivoting members moving into the second orientation. 
     In this way, installation and removal of the roll of paper is greatly simplified as the person simply has to grasp the roll of paper and push it against the pivoting members. For individuals with infirmities, this apparatus reduces the need for using both hands and compressing springs and the like to install the paper. Further, since the cavity shields extend outward from the outer perimeter of the first and second pivoting member, the entry of debris and particulate matter into the interior of the apparatus can be reduced thereby resulting in a more sanitary apparatus. 
     In another aspect, the present invention comprises a base member adapted to mount the apparatus onto a wall and a first and second arm having an inner and outer face wherein the first and second arms extend outward from the mounting plate so as to be spaced a first distance apart, the first distance being selected to be larger than the width of the roll of paper. The arms also have apertures formed on the outer surfaces of the first and second arm members. 
     This aspect of the present invention also includes a first and a second pivoting member each defining an outer perimeter and an apex where the first and second pivoting members are respectively mounted in the apertures in the first and second arms. The first and second pivoting members are biased inward into the space between the first and second arms in a first orientation such that the apex of the first and second pivoting arms are positioned a second distance apart that is less than the length of the roll of paper such that the roll of paper can be retained on the first and second pivoting members. The first and second pivoting members can be moved into a second orientation such that the apex of the first and second pivoting members are spaced a third distance apart that is greater than the length of the roll to permit removal of the roll. In this aspect, the first and second pivoting members are biased by springs that extend from an interior surface of the first and second arms respectively into the first and second pivoting members. Moreover, the springs are retained in contact with the interior surface and the interior of the pivoting member by retainers such that repeated operation of the pivoting members is less likely to result in the spring being dislodged. 
     In one specific embodiment, the first and second arms are hollow and the springs are mounted so as to extend laterally across the arms so as to be adjacent the pivoting members. In another embodiment, the springs extend from a bottom surface of the arms to a position adjacent the pivoting members. The use of the retainers in both embodiments results in a more easily assembled, more robust design. 
     Hence, the paper roll holder of the present invention is more sanitary, more robust and easier to assemble than similar dispensers of the prior art. These and other objects and advantages will be more apparent from the following description taken in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIGS. 1A and 1B are isometric views illustrating a paper roll dispenser assembly incorporating two pivoting retainer members with cavity shields; 
     FIG. 2 is an isometric view of a pivoting member included in the paper roll dispenser shown in FIGS. 1A and 1B; 
     FIGS. 3A and 3B are cross-sectional views of the paper roll dispenser assembly of FIG. 1B taken along the lines of  3 A— 3 A and  3 B— 3 B; 
     FIG. 4 is a front view of the paper roll dispenser assembly of FIG. 1B taken along the lines of  4 — 4 ; and 
     FIG. 5 is another cross-sectional view illustrating another embodiment of the paper roll dispenser of FIGS.  1 A and  1 B. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Reference will now be made to the drawings wherein like numerals refer to like parts throughout. Referring to FIGS. 1A and 1B, one embodiment of a paper roll dispenser assembly  100  is illustrated. As shown, the paper roll dispenser assembly  100  is generally a U-shaped shell  138  comprising a base member  104 , the portion that will attach onto a wall, and a first and second side arm  102   a ,  102   b . The first and second side arms  102   a ,  102   b  extend perpendicularly from the base member  104 . Also, the first and second side arms  102   a ,  102   b  are separated by a first distance  103 . Preferably, the arms define a space  101  having a width of the first distance  103 . The first distance  103  is wider than the paper roll  106  so that the paper roll  106  can fit in the space  101  between the first and second side arms  102   a ,  102   b  and be retained in a manner to be discussed in further detail below. 
     In the preferred embodiment, the shell  138  comprises an upper half shell  141  and a lower half shell  145 . When the upper half shell  141  and the lower half shell  145  are joined, the shell  138  is hollow, making room for a first and second pivot member  108   a ,  108   b  to protrude perpendicularly from an aperture  127  in the first and second side arms  102   a ,  102   b  and point toward the center of the space  101 . The pivot members  108   a ,  108   b  are assembled into the side arms  102   a ,  102   b  in a manner to be described below. The first and second pivot members  108   a ,  108   b  are spaced apart a second distance  105 . Preferably, the second distance  105  is less than the length of the paper roll  106  so that the paper roll can be held up by the pivoting members  108   a ,  108   b . More specifically, the pivoting members  108   a ,  108   b  will fit inside a cylindrical hollow core  107  around which the paper  109  of the paper roll  106  is wound. In this way, the first and second pivot members  108   a ,  108   b  support the paper roll  106 . 
     In one embodiment, the shell  138  and the pivot members  108   a ,  108   b  are made from a lightweight plastic known in the art. It will be appreciated that the overall form of the base member  104 , the first and second arms  102   a ,  102   b , and the pivot members  108   a ,  108   b  can take on a variety of shapes without departing from the spirit of the present invention. 
     FIG. 2 illustrates an isometric view of the first pivot member  108   a . It will be appreciated that the second pivot member  108   b  shares the same features with the first pivot member  108   a . In the embodiment shown, the pivot member  108   a  comprises various thin-walled surfaces. More specifically, the pivot member  108   a  comprises a top face  118  which provides a surface for a paper roll  106  to sit in a manner to be discussed in further detail below. A front face  120  extends at an acute angle from the top face  118  so as to provide a surface for the paper roll  106  to push on and bias the pivot member  108   a  to thereby induce the pivot member  108   a  to pivot in a manner to be discussed in further detail below. Also, a first side  114  perpendicularly connects both the top face  118  and the front face  120 . Similarly, a second side  116  perpendicularly connects the other side of the top face  118  and the front face  120 . 
     The pivot member  108   a  also includes a cavity shield  110  that extends ninety degrees from the top face  118  and from the first and second sides  114 ,  116 . This cavity shield  110  performs two functions, both of which will be discussed in further detail below. First, the cavity shield  110  prevents germs and foreign particles from entering the paper roll dispenser  100  through the aperture  127 . Second, the cavity shield limits the rotation of the pivoting member  108   a.    
     Also, connected to both the first and second sides  114 ,  116  is a half-circle protrusion  122 . Centered on the protrusion  122  is a cylinder  112 . As is illustrated in FIG. 2, the protrusion  122  is located at the bottom of the pivot member  108   a  adjacent the rear surface. In the preferred embodiment, the cylinder  112  is short—approximately twice the thickness of the protrusion  122 . The cylinder  112  provides a means of supporting the pivoting member  108   a  when installed into the paper roll dispenser  100  as will be described in greater detail below. 
     More specifically, FIGS. 3A and 3B illustrate the assembly of the first pivot member  108   a  into the first side arm  102   a , and also reveal inner features of the pivot member  108   a  and the side arm  102   a . It will be appreciated that the second pivot member  108   b  is assembled into the second side arm  102   b  in the same manner. 
     As shown in FIGS. 3A and 3B, a first support mount  130  is located inside a cavity  121  of the pivoting member  108   a  on the bottom interior wall of the first side arm  102   a . The first support mount  130  is a cylindrical outgrowth that defines a lip  131  and a recessed surface  139 . In the preferred embodiment, the end of the first support mount includes a collar  134 . The collar  134  is an extremely short cylinder of a slightly larger diameter than the first support mount  130 . The combination of the first support mount  130  and the collar  134  provide a mechanism of retaining a spring  128  in a manner to be discussed in greater detail below. 
     Also located on the bottom interior wall of the first side arm  102   a  is a support  124 . The support  124  is a thin, rectangular outgrowth that extends from the bottom surface  191  of the cavity  143  of the side arm  102  almost to the base of the aperture  127 . The support  124  supports the pivoting member  108   a . Specifically, the support  124  includes a pair of grooves  140  which are cut to a diameter greater than the diameter of the cylinders  112 . The grooves  140  provide a location to seat the cylinders  112  of the pivoting member  108   a  into the support  124 ; thus, the grooves  140  prevent the pivoting member  108   a  from dislocating from the support  124 . 
     FIGS. 3A and 3B illustrate a second support mount  132  located on the interior wall of the top face  118  of the pivot member  108   a . The second support mount  132  is a cylindrical outgrowth of the same diameter as the first support mount  130 . Likewise, the second support mount includes a collar  134  as described above. The combination of the second support mount  132  and the collar  134  provide a means of retaining the spring  128  in a manner to be discussed in greater detail below. 
     As shown in FIGS. 3A and 3B, the cylinders  112  of the pivot member  108   a  fit into the grooves  140  atop the supports  124  in a manner that supports the pivot member  108   a . The grooves  140  also permit the pivot member  108   a  to pivot around the axis of the cylinder  112 . As shown, the spring  128  further connects the pivot member  108   a  to the rest of the side arm  102   a . A first end  133  of the spring  128  attaches to the side arm  102   a  by way of the first support mount  130 . Preferably, the diameter of the first support mount  130  is larger than the inner diameter of the spring  128  so as to create an interference fit between the spring  128  and the support  130 . Similarly, a second end  135  of the spring  128  attaches to the second support mount  132  in the same manner. 
     It should be noted that the collars  134  on the support mounts  130 ,  132  further retain the spring  128 . This is because the diameter of the collar  134  is such that it creates a ridge that rides over and holds the ends  133 ,  135  of the spring  128  in the recesses  139  to either the pivot member  108   a  or the first side arm  102   a . Hence, the spring  128  is retained because of the interference force between the spring  128  and the first support mount  130 , and the spring  128  is further retained due to the hold down force that the collar  134  exerts on the spring  128 . 
     Advantageously, the force of the collar  134  on the spring  128  provides a rigid attachment for the spring  128  and prevents the spring  128  from shifting excessively when the pivot member  108   a  is biased. Thus, the paper roll dispenser  100  is robust because the spring  128  is more likely to stay in position and remain functional for the life of the paper roll dispenser  100 . The collar  134  also allows for easy assembly of the paper roll dispenser  100  because, during assembly, the ends  133 ,  135  of the spring  128  can be rigidly attached to the spring mounts  130 ,  132 , leaving the person assembling the paper roll free to manipulate other features of the paper roll dispenser  100 . 
     As shown in FIG. 3B, when force is applied to the front face  120  of the pivot member  108   a , the pivot member  108   a  pivots toward the inside of the side arm  102   a  thereby compressing the spring  128 . Then, once the force is removed, the spring  128  force biases the pivot member  108   a  outward from the side arm  102   a . The pivot member  108   a  rotates outward until the cavity shield  110  makes contact with the wall of the aperture  127 . Preferably, the position of the cavity shield  110  stops the pivot member  108   a  when the top face  118  of the pivot member  108   a  is perpendicular to the plane of the aperture  127 . 
     FIG. 4 illustrates the pivot member  108   a  assembled into the first side arm  102   a  from a vantage point looking directly into the aperture  127 . The pivot member  108   a  is shown rotated to a position where it is at rest. As shown, the pivot member  108   a  has come to rest because the cavity shield  110  has made contact with the walls of the aperture  127 . Also illustrated in FIG. 4 is the cavity shield  110  covering the open portion of the aperture  127  lying above the top face  118  of the pivot member  108   a . The cavity shield inhibits foreign particles from entering the side arm  102   a  through the aperture  127 . As is also illustrated in FIGS. 2 and 4, the cavity shield preferably includes portions  126  that extend outward along the side walls  114 ,  116  of each of the pivoting members  108   a ,  108   b  so as to inhibit the entry of foreign particles in the gap between the wall of the apertures  127  and the walls  114 ,  116  of the pivoting members  108   a ,  108   b . Advantageously, by sealing off the aperture  127 , the cavity shields prevent the growth and spread of germs inside the hollow side arm  102   a . Thus, the cavity shields reduce the accumulation of waste and germs. 
     Ordinarily, the pivot members  108   a ,  108   b  will be pivoted when the paper roll  106  is inserted and removed. To insert the paper roll  106 , the user can turn the paper roll  106  horizontally and raise the paper roll  106  into the first distance  103  between the two side arms  102   a ,  102   b . Then, as the paper roll  106  is raised, the paper roll  106  will make contact with the angled front face  120  of the pivot members  108   a ,  108   b . This urges the pivot members  108   a ,  108   b  to retract into the first and second side arms  102   a ,  102   b  and thereby compress the springs  128 . Once the paper roll  106  is centered in the paper roll assembly  100 , the pivot members  108   a ,  108   b  are then urged outward again by the springs  128  so as to be centered on the hollow core of the paper roll  106 . The springs  128  bias the pivot members  108   a ,  108   b  into the hollow core of the paper roll  106  such that the paper roll  106  is supported by the pivot members  108   a ,  108   b . Then, the paper roll  106  is free to turn along its axis and paper can be dispensed. 
     To remove a paper roll  106  from the paper roll dispenser  100 , the user grabs the paper roll  106  and moves it upwards normal to the top face  118  of the pivot members  108   a ,  108   b . As the paper roll  106  moves, the bottom of the paper roll  106  contacts the front face  120  of the pivot members  108   a ,  108   b , and the pivot members  108   a ,  108   b  pivot into the side arms  102   a ,  102   b  in the manner described above. Then, when the paper roll  106  clears the pivot members  108   a ,  108   b , the pivot members  108   a ,  108   b  are urged out toward the center of the paper roll dispenser  100  by the springs  128  until the cavity shields  110  make contact with the sides of the aperture  127  in the side arms  102   a ,  102   b . Advantageously, both the insertion and removal of the paper roll  106  can be achieved using only one hand. Hence, people can insert and remove paper rolls  106  easily and quickly, even if they are physically challenged. 
     FIG. 5 illustrates another embodiment of the paper roll dispenser  100 . As shown, a spring mount  230  with a collar  234  resides on an inner side wall  229  of the side arm  202   a  at a height above the bottom surface  241  of the cavity  243  that is approximately equal to the height of the pivot arm  108 . In this way, the spring  228  extends laterally across the cavity  243  such that the force of the spring in compression and extension is directly exerted against the pivoting member  108 . The use of the retaining spring mount  230  retains the spring in this orientation during operation of the apparatus. The spring  228  connects to the spring mount  230  in the same manner as described above in relation to spring mount  130 . Also shown is a pivot member  208   a  that is essentially the same as the pivot member  108   a  described above. As shown, an opposite end  235  of the spring  228  rests inside a cavity  221  of the pivot member  208   a . It should be noted that all features shown in FIG. 5 are the same structurally and perform the same function as the features described above. The only difference between the configuration shown in FIG.  5  and the configuration shown in FIGS. 3A and 3B is the location of the spring mount  230  and the absence of a spring mount inside the cavity  221  of the pivot member  208   a.    
     This configuration of the paper roll dispenser  100  is advantageous for several reasons. First, the location of the spring mount  230  allows the axis of the spring  228  to remain essentially straight, even when the pivot member  208   a  is biased into the side arm  202   a . Because the spring  228  remains straight, the forces in the spring  228  are primarily axial forces, and the amount of lateral forces on the spring  228  are minimal. This reduces the chances of the spring  228  dislodging from either the cavity  221  of the pivot member  208   a  or the spring mount  230 . Thus, this would be a more robust configuration. 
     It should be noted that the spring mount  230  or collar  234  may not be needed inside the cavity  221  for retaining the end  235  of the spring  228  in all implementations. Extra retention force may not be needed at the end  235  of the spring  228  because the spring  228  remains essentially straight and has little chance to dislodge from the cavity  221  of the pivoting member  208   a . Since no feature, like the spring mount  230  or collar  234 , is needed, the paper roll dispenser  100  is easy to assemble because the spring  228  can be inserted into the cavity  221  without having to retain it further. In this implementation, assembly is simplified through the lack of a retainer. Also, this configuration may allow a less stiff spring to be used; other designs, like the routing of the spring  128  described above, require an overly-stiff spring to prevent the spring from dislodging due to its offset. A less stiff spring means that the user will need less force to insert and remove a paper roll  206 . Another advantage is that a shorter spring  228  may be used because the spring mount  230  is closer to the hollow  221  as compared to the spring routing described above. A shorter spring  228  would be a less costly for the manufacturer. 
     The embodiment shown in FIG. 5 would be easier to assemble as well. This is because placing the spring mounts  230  in the position shown in FIG. 5 provides a more accessible location for mounting the spring as compared to the spring mount position described above. Assembly time is further reduced if the lower half shell  145  is shaped such that the entire periphery of the aperture  127  is encompassed by the lower half shell  145 . In this instance, assembly would involve the installation of the pivoting members  208   a ,  208   b  and their corresponding springs  228  into the lower half shell  145 . The springs  228  would be rigidly attached at this point, and the pivoting members  208   a ,  208   b  would remain in their first position, with the cavity shields making contact with the inside of the lower half shell  145 . Then, the upper half shell  141  would be attached to the lower half shell  145 . Thus, assembly time is reduced because the person assembling the dispenser would have an not have to hold the pivoting members  208   a ,  208   b  in a biased position while the upper half shell  141  is attached to the lower half shell  145 . 
     The use of the retainers in both implementations makes the apparatus significantly more robust as the springs are less likely to be dislodged from their desired orientations. Assembly is also simplified as the springs can be positioned on one of the retainers and retained in their desired orientation when the other components of the apparatus, such as the pivot arms, are assembled. The springs can then be positioned on the other retainer by simply forcing the spring end over the collar. The use of the retainers also allows for a less strong spring to be used as less biasing is required to prevent the spring from being inadvertently dislodged. The reduced spring bias allows for easier installation and removal of paper rolls particularly by physically challenged persons. 
     Although the illustrated embodiments of the present invention have shown, described, and pointed out the fundamental novel features of the invention, as applied to these embodiments, it will be understood that various omissions, substitutions and changes in the form of the detail of the device illustrated may be made by those skilled in the art without departing from the present invention. Consequently, the scope of the invention should not be limited to the foregoing description, but should be defined by the appended claims.