Patent Publication Number: US-8112841-B2

Title: Ultraviolet vacuum cleaner with safety mechanism

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority of and is a continuation-in-part of U.S. Ser. No. 11/360,045 filed Feb. 22, 2006, now U.S. Pat No. 7,444,711 and also co-pending U.S. Ser. No. 11/360,189 filed Feb. 22, 2006, which are incorporated by reference for all purposes. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     None 
     REFERENCE TO MICROFICHE APPENDIX 
     Not applicable 
     FIELD OF THE INVENTION 
     The invention generally relates to using ultraviolet radiation to disinfect various cleaning media. The invention more particularly relates to a combination vacuum cleaner and ultraviolet sanitizer, for disinfecting infestation agents within various cleaning media by using ultraviolet radiation, and safety mechanisms for preventing injury by the user. 
     BACKGROUND OF THE INVENTION 
     Many homes and businesses suffer from infestations of allergens and other undesirable organic and inorganic substances, such as molds, viruses, bacteria, and dust mites. Floor coverings such as carpeting in homes and hotels, for example, can contain a high concentration of organic or inorganic substances, which create a potentially unhealthy or harmful environmental condition. A common indoor allergen in carpeting and mattresses that can trigger allergy symptoms in humans is the dust mite, a microscopic insect related to spiders. It has been claimed that allergies developed in the early years of a child&#39;s life due to exposure to allergens can result in life-long allergic responses or more serious medical conditions such as asthma. Exposure to mold spores, for example, has been linked to certain types of respiratory illnesses. Long-term exposure to mold may cause asthma or other respiratory problems, even in individuals who are not naturally sensitive or allergic to mold. 
     Conventional cleaning methods do not effectively reduce populations of infestation agents present within carpeting. Standard vacuum cleaners do not sanitize or disinfect carpeting, and vacuuming alone usually removes only a fraction of allergens from carpeting. Typically, steam cleaning is cumbersome, expensive, and may involve the use of chemicals. Also, steam cleaning can leave a carpet and its carpet pad in a wet condition that can support the undesirable growth of molds, mildew, bacteria, or dust mites in or beneath the carpet. As another alternative, chemical powders or dry carpet cleaning powders comprised primarily of chemical pesticides and insecticides may be used to clean carpeting. The potential health and safety hazards associated with such chemical powders, however, often outweigh any benefits that might be obtained by using them. 
     Many experts have suggested that the only solution to dealing with infestation agents in carpeting is to remove existing carpeting altogether and to refrain from using carpeting as a floor covering. However, for many individuals who find carpeting desirable, and for many applications where carpeting is an optimum choice for a floor covering, this is not an acceptable solution. As a result of the inadequacy of conventional carpet cleaning methods, however, carpeting in homes and commercial establishments can become an ideal environment in which dust mites, germs, bacteria, viruses, molds and other pathogens or microorganisms can live, grow, and multiply. 
     In addition, mattresses and other like articles are often afflicted by infestation agents. By the nature of how a mattress is used for rest or sleep, it is frequently in close contact with humans or animals that may shed dead skin, for example, or discard other organic substances that are retained in the mattress. Insects such as dust mites can thrive on this organic matter and quickly develop into a significant population within the mattress. As described above for carpeting, conventional cleaning methods applied to a mattress cannot both safely and effectively reduce populations of infestation agents present within the mattress. 
     It has been discovered that ultraviolet (“UV”) light, particularly in the “C” spectrum (“UVC”), can deactivate the DNA of bacteria, viruses, germs, molds, and other pathogens and microorganisms, thus destroying their ability to reproduce and multiply. UVC light has been used effectively in various applications to disinfect and sanitize hospital rooms, medical clinics, food production facilities, and drinking water. However, existing products and processes have been unable to effectively and safely leverage the benefits of UV light to sanitize infestation agents in cleaning media such as carpeting and mattresses. 
     In view of the problems described above, safe and effective disinfecting devices are needed to address the deficiencies of conventional processes for sanitizing cleaning media such as carpeting and mattresses. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       The utility of the embodiments of the invention will be readily appreciated and understood from consideration of the following description of the embodiments of the invention when viewed in connection with the accompanying drawings. 
         FIG. 1  is an orthogonal view of an ultraviolet vacuum device according to one embodiment of the invention; 
         FIG. 2  is an orthogonal view of an exemplary handle assembly of the device; 
         FIG. 3  is an exploded view of the handle assembly; 
         FIGS. 4 and 5  are exploded views of a preferred embodiment of the lower housing of the device; 
         FIG. 6  is a exploded view of the lower housing from below; 
         FIGS. 7 and 8  are cross-sectional, partial views of the lower housing showing the wheel assembly and medium contact safety switch assembly in detail; 
         FIG. 9  is an exploded view of the UV light assembly of the lower housing; 
         FIG. 10  is a partial cross-sectional elevation view of the device; 
         FIG. 11  is a detail of  FIG. 10  showing the upper-housing in the in-use position with upper-housing position switch assembly disengaged; 
         FIG. 12  is a detail of  FIG. 10  showing the upper-housing in the storage position with upper-housing position switch assembly activated; 
         FIG. 13  a detail partial view of the storage-position locking assembly of the device; 
         FIG. 14  is a plan elevation view of the tilt safety switch shown in the disengaged position; 
         FIG. 15  is a plan elevation view of one embodiment of the tilt safety switch shown in the tilted, or activated, position; 
         FIG. 16  is a plan top view of the embodiment of the tilt safety switch; 
         FIG. 17  is a cross-sectional elevation view of another embodiment of a tilt switch assembly for use in the device; and 
         FIG. 18  is an electrical system block diagram of the device. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     The invention provides embodiments of cleaning and disinfecting devices, and features thereof, which offer various benefits: the devices maximize the disinfection capability of ultraviolet (“UV”) light by providing mechanisms for enhanced penetration of the UV light into a cleaning medium. The invention provides safety devices to protect the user from harmful exposure to UV light. 
     Incorporated herein by reference for all purposes are the co-pending U.S. applications: Ser. Nos. 11/360,045, 11/360,189, 11/360,046, and 11/360,044, all filed on Feb. 22, 2006, to Garcia, et al. 
     As applied herein, the term “cleaning medium” includes any area, region, substrate, surface, or other medium that can be acted upon by UV light. Examples of cleaning media include, without limitation, carpets, mattresses, furniture, drapery, or other surfaces or media (e.g., hardwood, linoleum, and ceramic tile). The cleaning medium can be horizontal, as in a typical floor or mattress top surface, or vertical or at any other angle, such as with drapery and furniture surfaces. 
     The term “infestation agent” may include any organism, microorganism, contagion, pathogen, germ, insect, and/or any other organic or inorganic substance which can be affected by application of ultraviolet radiation, or which can be present on or within a cleaning medium. Examples of infestation agents include, without limitation, viruses, bacteria, dust mites, molds, roaches, fleas, bed bugs, spiders, and other insects. 
       FIG. 1  generally shows an ultraviolet vacuum device  10  having a vacuum cleaner assembly and an ultraviolet disinfecting assembly. The device  10  has an upper housing  12  and a lower housing  14  which, in use, contacts the cleaning medium, such as a floor or other generally horizontal surface to be cleaned and disinfected. The upper housing  12  is rotatable or otherwise movable from a storage position  16 , as shown, to an in-use position  18  wherein the upper housing is rotated back for ease of use. The upper housing  12  includes a dust bag, an alternate hose extension, and a handle assembly  20 . The lower housing  14  can also include impeller cover  44 , shown in two parts, and the impeller housing  43 , described herein. The Figures and description are of preferred embodiments and are not intended to limit the claimed invention. 
       FIG. 2  is an orthogonal view of an exemplary handle assembly  20  of the device  10 .  FIG. 3  is an exploded view of the handle assembly  20 . The handle assembly  20  includes a handle  22 . At least one power switch  24 ,  26  are mounted on the handle assembly  20 . The power switches  24 ,  26  can be mounted anywhere on the device  10 . The power switches  24  and  26  are each movable between an on and off position and control power to the UV light source, the vacuum motor, and/or the brush bar motor. In one embodiment, the power switch  24  controls power supply to the UV light and vacuum motor while the power switch  26  controls power supply to the brush bar motor. Other arrangements may be employed. 
       FIG. 3  is an exploded view of the handle assembly of  FIG. 2 . The handle assembly  20  includes a safety switch assembly  28 . The safety switch assembly  28  includes an electrical switch  32 , which is activated by a depression-pad or trigger  32  which is contacted by the user. In use, the trigger  30  must be depressed by the user for the UV light to be supplied with power; that is, for the UV light to be “on,” the trigger must be depressed. The trigger  32  is biased by biasing spring  34  such that the switch is in an “off” position unless the trigger is activated. In such a manner, the device is provided with a deadman&#39;s safety switch. The UV light is off unless the user maintains pressure on the trigger switch. Should the user cease to actively depress the trigger, the UV light shuts off. The illustrated trigger switch is one type of deadman&#39;s switch which may be employed. The switch  30  is connected to the UV light through appropriate electrical circuitry. 
     As with all of the safety switches employed herein, the switch may be a normally closed or normally open switch. Further, the switches may be signal switches, or low-voltage switches, which open or close a signal circuit to provide a signal to a microprocessor or similar device and indicates that power may be provided or denied to the UV light. Alternately, the switches may be “live” current switches, or high-voltage switches, which are placed directly in the circuitry providing power to the UV light. In such a manner, the high-voltage switch directly operates to open or close the power circuit. The switches herein are exemplary only. For example, many of the switches, including the handle safety switch, are shown as contact switches. Alternate switch types may be employed where practicable, such as optical, proximity, electromagnetic, pressure, position switches, piezoelectric, force, vibration, acceleration, etc. The function of the switch (the action or condition that activates the switch) is of greater importance than the switch type. In the case of the handle assembly switch, the goal is to signal a microprocessor to prevent, or directly prevent, power supply to the UV light unless the handle trigger is constantly activated by the user. A contact switch is illustrated, but another switch type, such as a pressure or temperature switch, could be used. 
       FIGS. 4 and 5  are exploded views of a preferred embodiment of the lower housing  14  of the device  10 . The lower housing  14  is encased by a housing cover  38 , here shown in two portions. The lower housing  14  can house the vacuum assembly  40 , including impeller motor  41 , vacuum ducting  42 , and other parts of the vacuum assembly. The lower housing  14  can also house a beater bar or rotary brush assembly  46 , including the brush motor  47 , brush strap  48 , brush housing  49  and brush  50 . The lower housing  14  also includes the UV light assembly  110 , described herein and in related applications. The lower housing  14  is shown as including a pathway light assembly  51 , with a light source  52  and cover  53 . 
     In a preferred embodiment, the lower housing  14  also houses most of the electronic circuitry  60  of the device, including the ballast  61 , an electronic board  62 , wiring to connect the various electronic components, and a microprocessor  63  for controlling aspects of the circuitry. The lower housing also includes an AC power input such that the device may be powered from an electrical outlet such as in a home. The device includes transformers, rectifiers and other electric elements which will not be described in detail. 
     In a preferred embodiment, the lower housing  14  includes an indicator assembly  64 . The indicator assembly  64  provides a visible indication to the user, such as a light, as to whether the UV light is on or off. Here, the indicator assembly includes lights  65  and cover  66 . The indicator assembly may alternately be placed in the upper housing. 
     The lower housing may include a height adjustment assembly  68  for adjusting the height of the bottom of the lower housing above the cleaning medium. Adjustment knob assembly  69  is seen in  FIG. 5  in an exploded view. The height adjustment wheel assembly  70  is seen in  FIG. 6 . 
       FIG. 6  is an exploded view of the lower housing from below. The lower housing  14  includes wheel assembly  80  and medium contact safety switch assembly  100  which, in a preferred embodiment, act in concert. Wheel assembly  80  includes two wheel units  81  which each include a wheel  82 , wheel shaft  83 , swing arm  84 , wheel lock shaft  85 , biasing spring  86  and wheel hold cover  87 . Also seen in  FIG. 6  is lower housing bottom plate  88 . 
       FIGS. 7 and 8  are cross-sectional, partial views of the lower housing showing the wheel assembly  80  and medium contact safety switch assembly  100  in detail.  FIG. 7  shows the wheel assembly in an “up” position  93 ;  FIG. 8  shows the wheel assembly in a “down” position  94 . The wheel  82  is mounted for rotation about shaft  83  on the wheel-end  90  of swing arm  84 . The wheel-end  90  of the swing arm  84  is shaped like a horseshoe in a preferred embodiment to accommodate a secure mounting of the wheel. The swing arm  84  pivots about the lock shaft  85 . As the wheel-end  90  of the swing arm  84  moves upwards, the free-end  91  of the swing arm  84  moves downward. The free-end of the swing arm can include a non-metallic cover  92 . The spring  86  biases the wheel assembly into the “down” position  94 . 
     In use, the weight of the device, as the wheels  82  sit on the cleaning medium, force the wheels upward, and, consequently, the free-end  91  of the swing arm  84  downward. In the wheels “up” position  93 , as shown, the free-end of the swing arm does not activate the contact switch assembly  100 , as seen in  FIG. 7 . If the user lifts the lower housing away from the cleaning medium a predetermined distance, the wheels  82  drop downward and the free-end  91  of the swing arm moves into contact with, and activates, the medium contact safety switch assembly  100 , as seen in  FIG. 8 . 
     The medium contact safety switch assembly  100  includes switch  101  and lever arm  102 . When lever arm  102  is depressed by the swing arm  84 , as seen in  FIG. 8 , the switch is activated. The medium contact switch is exemplary. The “medium contact switch” is defined as any safety switch operable to sense or detect whether the lower housing is proximate to or in contact with the cleaning medium. The medium contact switch can be a contact switch which is activated by movement of some part of the lower housing, such as the wheel assembly, as shown. Alternately, the medium contact switch can be directly mounted to the bottom of the lower housing with an activator button directly contacting the cleaning medium, as shown in related patent applications. The medium contact switch can alternately be a proximity, pressure or other type of switch, and can employ an optical, piezoelectric or other type of sensor. 
     In a preferred embodiment, the device employs medium contact switch assemblies  100  in conjunction with both wheel assemblies  80 . If either of the medium contact switches  101  indicate that the lower housing is more than a prescribed distance from the cleaning medium, power is cut to the UV light assembly. As described above, the switch assembly  100  can be a normally open or closed switch, a signal or live switch, etc. 
       FIG. 9  is an exploded view of the UV light assembly  110  of the lower housing  14 . At least one UV light source  112 , such as a UV light bulb, is positioned to radiate UV light onto the cleaning medium when the device is in use. An embodiment of the UV light assembly is described in detail in related patent applications. UV bulbs  112  are removably mounted in sockets  113  with support provided by a rubber seating  114 . Socket  113  is mounted to the lower housing via socket bracket  115 . Side covers  111  are provided at the ends of the bulbs. Aluminum frame plates  116 , a rubber frame  117 , lens  118 , lens frame  119  and cover frame  120  are provided as shown. The UV light assembly radiates UV light through lens  118  onto the cleaning medium. The UV light assembly preferably includes a reflector  121 . The bulb assembly is mounted in the lower housing  14  in a recess  122 . A cooling system for the bulb assembly is described in the related patent applications. 
       FIG. 10  is a partial cross-sectional elevation view of the device  10 .  FIG. 11  is a detail of  FIG. 10  showing the upper-housing in the in-use position with upper-housing position switch assembly  132  disengaged.  FIG. 12  is a detail of  FIG. 10  showing the upper-housing in the storage position with upper-housing position switch assembly  132  activated. The upper housing  12  and lower housing  14  are connected such that the upper housing is movable in relation to the lower housing. The upper housing  12  is pivotally mounted to the lower housing and rotates about axis  130 . The upper housing  12  is movable between a storage position  16 , as seen in  FIGS. 1 and 12 , and an in-use position  18 , as seen in  FIGS. 10 and 11 . In the storage position  16 , the upper housing  12  is in a substantially upright or vertical orientation, or is rotated forward past the vertical.  FIGS. 1 and 12  shows a preferred embodiment wherein the upper housing in the storage position is rotated about five degrees forward, past the vertical. In the in-use position  18 , the upper housing is rotated back to an inclined position away from the vertical by at least a minimum amount. In  FIGS. 10 and 11 , the upper housing is rotated backward, past the vertical, by a minimum of about six degrees. The exact degrees of rotation are not critical. 
     The device includes an upper-housing position safety switch assembly  132 . The “upper-housing position safety switch assembly” is defined as any safety switch operable to sense or detect whether the upper housing is positioned in the storage position or the in-use position; the assembly  132  prevents power from being supplied to the UV light source when the upper housing is in the storage position. 
     The upper-housing position safety switch assembly  132  includes a switch  133  with a lever  136  for activating the switch. The assembly  132  includes an actuator  134  biased by a spring  135 . The impeller housing  43  of the upper housing  12  rotates with movement of the upper housing. When the upper housing is in the storage position, as shown in  FIG. 12 , a surface  138  of the impeller housing  43  contacts and depresses the actuator  134 . The actuator  134 , in turn, moves lever  136 , thereby activating the switch  133 . When the upper housing is rotated into the in-use position, the surface  138  of the impeller housing  43  moves away from the actuator  134 , allowing the actuator  134  to move upwards by force of the biasing spring  135 . As the actuator  134  moves upwardly, the switch  133  is disengaged as seen in  FIG. 11 . 
     The upper-housing position safety switch shown is exemplary. The upper-housing position safety switch can be a contact switch, as shown, which is activated by movement of some part of the upper housing. Alternately, the position safety switch  133  can be mounted to the upper housing and actuated as it moves in relation to some portion of the lower housing. The upper-housing position safety switch is shown as a contact switch but can alternately be a proximity, pressure or other type of switch, and can employ an optical, piezoelectric or other type of sensor. As described above, the switch assembly  132  can be a normally open or closed switch, a signal or live switch, etc. Multiple upper-housing safety switches  133  can be employed. 
       FIG. 13  is a detail partial view of the storage-position locking assembly  140  of the device. When the upper housing  12  is in the storage position  16 , it is locked in place by the locking assembly  140 . Locking assembly  140  includes lock plate  142 , biasing spring  144  and release pedal  146 . Biasing spring  144  biases the lock plate  142  in the locked position, as shown in  FIG. 13 . The lock plate  142  cooperates with an indentation  148  or in the upper housing to lock the upper housing in the storage position. Depression of the release pedal  146  operates to move the lock plate  142  out of the locked position and releases the upper housing to rotate into the in-use position. Note that the upper-housing position safety switch, or another switch, can cooperate with the locking assembly to prevent power supply to the UV light when the lock plate is in the locked position. 
     The device  10  also incorporates a tilt safety switch assembly  150  mounted in the lower housing  14 . The tilt safety switch assembly  150  includes a tilt switch  152 , as seen in  FIG. 5 . The tilt switch is operable to prevent the supply of power to the UV light source if the tilt switch is rotated or tilted more than a preselected degree. Since the tilt switch is mounted on the lower housing, if the lower housing is tilted from a generally horizontal position the tilt switch will cut power or turn off the UV light if the lower housing is tilted. The tilt switch assembly  150  is “invisible” to the user because it is enclosed within the lower housing  14 . 
       FIG. 14  is a plan elevation view of the tilt safety switch shown in the disengaged position.  FIG. 15  is a plan elevation view of one embodiment of the tilt safety switch shown in the tilted, or activated, position.  FIG. 16  is a plan top view of the tilt safety switch. 
       FIG. 14  show a conical surface  154  on which are mounted a plurality of ball switches  156 . Each ball switch  156  has a metallic ball  158  which is free to move, or roll, inside of tube  159 . At one end of tube  159  is a contact terminal  160 . When the ball  158  contacts the terminal  160 , the switch is activated. A ball switch is shown, however, any type of tilt switch can be employed, including mercury switches and the like. In  FIG. 14  the tilt switch assembly is generally horizontal and in a disengaged position; that is, the balls are not in contact with the terminals. In  FIG. 15 , the assembly is shown in an activated position, where at least one of the balls is in contact with its associated terminal. When the lower housing is generally horizontal, the tilt switch is disengaged; when the lower housing is tilted a preselected degree, at least one ball will contact its terminal and activate the switch. The switch prevents the supply of power to the UV light source. Preferably the tilt switch is a signal switch that provides the microprocessor with an indication that the tilt switch is activated. The microprocessor then cuts power to the UV light source. Any reasonable degree of tilt may be selected. In the Figures, the conical surface is approximately 20 degrees from the horizontal. 
       FIG. 16  is a plan top view of the embodiment of the tilt safety switch. Preferably six rolling ball tilt switches are mounted on the conical surface as indicated, spaced 60 degrees apart. In such a manner, regardless of the direction of tilt from the horizontal, at least one of the switches will activate. 
     A microprocessor or other logic device can be electronically attached to each of the ball switches and a logic routine performed prior to preventing power supply to the UV light source. In this manner “false positives,” due to motion or vibration of the lower housing, are prevented. For example, a time delay can be used, such that power is not cut to the UV light unless a ball contacts a terminal for more than a preselected amount of time, such as one-half second. Where a plurality of ball or tilt switches are in use, as in  FIG. 16 , the logic process can be employed so that power is cut to the UV light source only if a preselected number of switches have been activated. 
       FIGS. 14-16  are exemplary only. Another embodiment would employ a conical surface inverted from that shown. That is, the cone can be “upside down” with the ball switches mounted on the interior surface of the cone. Further, the conical surface can be replaced with any sloped surface regardless of its cross-sectional shape. For example, in the above example, six flat sloped surfaces can be used rather than a conical section. 
       FIG. 17  is a cross-sectional elevation view of another embodiment of a tilt switch assembly for use in the device. The tilt safety switch assembly  150  shown in  FIG. 17  also employs a conical surface  162  having an aperture  163  therein. An optical switch  167  is mounted in the assembly including an optical transmitter  168  and receiver  169 . The transmitter and receiver are interchangeable. An object  164 , shown as a disk-shaped ball, is placed at the apex of the conical surface and blocks transmission of the optical beam from the transmitter when the assembly is in a generally horizontal position. When the assembly is tilted or rotated a preselected degree, the object  164  moves away from the apex of the conical surface and the optical beam is unimpeded as it travels through the aperture  163  and hits receiver  169 . The switch assembly, when activated by tilting, prevents power supply to the UV source, as described above.  FIG. 17  is exemplary only. Those of skill in the art will recognize alternate designs with equivalent results.  FIG. 17  shows two tilt switches  161  to provide redundant operation. 
       FIG. 18  is an electrical system block diagram of the device. The Figure is self-explanatory and shows a block diagram of the electrical circuitry  60  of the device. The microprocessor  63  is shown along with the UV light source and vacuum motor power switch  24 , and brush motor power switch  26 , and UV light source  112 . The brush motor  47  and related circuitry are indicated. Similarly, the impeller motor  41  and related circuitry are shown. Transformer and regulators are indicated as well. The safety switch assemblies are also indicated: tilt switch assembly  150  (which can incorporate a plurality of tilt switches  152 ), handle safety switch  30 , medium contact switches  101  (also called drop wheel switches in a favored embodiment), and two upper-housing position switches  133 A and  133 B. Indicator light  65  is also indicated. 
     The safety switches are employed to prevent power supply to the UV light source when the switches are activated by the various preset conditions indicated herein. The safety switches can also be used to prevent power supply to the vacuum motor and/or brush motor. 
     The microprocessor  63  is capable of performing logic functions, as a computer, and to control power supply to the various components. For example, the microprocessor can sense whether power is being supplied to the UV lights and then turn on or off the indicator light to indicate to the user whether the UV lights are on. The microprocessor can be used to perform the tilt switch logic described above. The microprocessor can be used to “read” the condition of any of the various switches, such as upper-housing position switch  133 A, and then allow or prevent power supply to the UV light as desired. Some of the safety switches are arranged in series. For example, the medium contact switches  101 , the upper-housing position switch  133 B and the handle safety switch  30  are in series. The safety switches can be in the high voltage circuit, such as the medium contact switches (wheel drop switches)  101  and upper-housing position switch  133 B, and directly cut power to the UV light  112 . (Note the high voltage circuit indicated by “L” and “N.”) Other safety switches can be signal switches in a low voltage circuit, such as the handle safety switch  30  which is in series with switches  101  and  133 B through triac  172 . Obviously, if any of the safety switches arranged in series are activated by presence of the conditions described herein (such as movement of the lower housing away from the cleaning medium, thereby allowing the wheels to drop and activating the medium contact switch), the power to the UV light is prevented. 
     It is to be understood that the figures and descriptions of the present invention have been simplified to illustrate elements that are relevant for a clear understanding of the present invention, while eliminating, for purposes of clarity, other elements. Those of ordinary skill in the art will recognize, however, that these and other elements may be desirable. However, because such elements are well known in the art, and because they do not facilitate a better understanding of the present invention, a discussion of such elements is not provided herein. It should be appreciated that the figures are presented for illustrative purposes and not as construction drawings. Omitted details and modifications or alternative embodiments are within the purview of persons of ordinary skill in the art. 
     It can be appreciated that, in certain aspects of the present invention, a single component may be replaced by multiple components, and multiple components may be replaced by a single component, to provide an element or structure or to perform a given function or functions. Except where such substitution would not be operative to practice certain embodiments of the present invention, such substitution is considered within the scope of the present invention. 
     The examples presented herein are intended to illustrate potential and specific implementations of the present invention. It can be appreciated that the examples are intended primarily for purposes of illustration of the invention for those skilled in the art. The diagrams depicted herein are provided by way of example. There may be variations to these diagrams or the operations described herein without departing from the spirit of the invention. For instance, in certain cases, method steps or operations may be performed in differing order, or operations may be added, deleted or modified. 
     Furthermore, whereas particular embodiments of the invention have been described herein for the purpose of illustrating the invention and not for the purpose of limiting the same, it will be appreciated by those of ordinary skill in the art that numerous variations of the details, materials and arrangement of elements, steps, structures, and/or parts may be made within the principle and scope of the invention without departing from the invention as described in the following claims.