Abstract:
A keyboard assembly is provided. The keyboard assembly includes a keyboard having at least one input key assembly positioned within the housing and an infection controllable apparatus attached thereto.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS  
       [0001]     This application claims the benefit of U.S. Provisional Patent Application No. 60/654,527, filed Feb. 17, 2005; U.S. Provisional Patent Application No. 60/691,374, filed Jun. 17, 2005; and U.S. Provisional Patent Application No. 60/748,886, filed Dec. 8, 2005, the disclosures of which are all hereby expressly incorporated by reference. 
     
    
     TECHNICAL FIELD  
       [0002]     The presently claimed subject matter relates generally to data input or signal generating devices and more specifically to data input or signal generating devices such as keyboard assemblies, having a cleanable top surface.  
       BACKGROUND  
       [0003]     Generally described, a wide variety of keyboards are utilized for signal generating functions, generating data entry terminals, and remote control terminals. Typically, each key of each key assembly of the keyboard corresponds to a particular alphanumeric, such as a specific numeral, character, letter, or operation. Often the key assemblies are complex in construction and operate not only to make switch contact, but to provide an operator with a tactile sensation or feedback. Such key assemblies employ a wide variety of structures ranging from spring loaded switches to dome-type switches to provide this tactile feedback signal.  
         [0004]     Although the above-described keyboards are effective for data entry, they offer a distinct disadvantage in that they are a source susceptible to the spreading of infectious agents, resulting in the contamination or infection of the user. Moreover, the keyboards include numerous crevices where grime and infectious agents can reside. Further, these crevices, such as the area between adjacent keys, make the keyboard hard and/or impractical to clean, since a cleaning cloth or tool may be difficult or impossible to operate between adjacent keys and any cleaning solvent used may pass between adjacent keys and contact the electronics of the keyboard, thus damaging the keyboard.  
         [0005]     Keyboards are frequently used in work areas in the presence of infectious germs and other hazardous materials. Keyboards and other equipment in these environments often must be cleaned at regular intervals to reduce the risk of spreading disease and infection. These cleaning intervals can be set to a variety of conditions, including a predetermined period of time or a defined amount of equipment usage.  
         [0006]     To facilitate cleaning, membrane keyboards have been developed that incorporate a substantially smooth top. Although previously developed membrane keyboards help reduce the spread of infectious diseases by providing a cleanable top surface, they are not without their problems. For instance, currently available membrane keyboards generally include key assemblies of a high actuation force and low travel length type. More specifically, actuation force is the force required to transition a key of the key assemblies from a normally raised position to a depressed position in which a signal is generated. Actuation forces are typically divided into two classifications: low actuation forces and high actuation forces. A low actuation force is generally characterized as less than about 0.3 lbf. Conversely, a high actuation force is generally characterized to be more than about 0.3 lbf.  
         [0007]     The term “travel length” refers to the distance that the key is moved between the raised position and the depressed position. Travel lengths are typically divided into three classifications: low travel; medium travel; and full travel. Low travel is for keys which travel less than about 0.02 inches between their raised position and their depressed position. Medium travel is for keys which travel between about 0.02 inches to about 0.06 inches between their raised position and their depressed position. Full travel is for keys which travel more than about 0.06 inches between their raised position and their depressed position.  
         [0008]     As previously developed cleanable keyboards do not have a way to alert users that the keyboard requires cleaning, the burden is on the user to keep track of the scheduled cleaning intervals. Furthermore, because the previously developed cleanable membrane style keyboards having key assemblies of the high actuation force and low travel length type, they are not suitable for touch typing (i.e., typing performed on a keyboard having key assemblies of a low actuation force and medium-to-full travel type such that a user can type with relatively no fatigue and with positive feedback of switch contact), which is preferred in most data entry terminals. Since previously developed cleanable membrane style keyboards are not t ouch-type keyboards, a user is unable to type for long periods of time without looking at the keyboard and/or without experiencing fatigue in his or her hands.  
       SUMMARY  
       [0009]     A combination keyboard and cover assembly constructed in accordance with one embodiment of the present invention is provided. Such a keyboard and cover assembly includes a keyboard having at least one input key assembly positioned within the housing and a cover. The cover is sized and configured to substantially incase the keyboard and has a substantially flat top surface to resist wrinkling during use. The cover also includes a predetermined flexibility to substantially mechanically isolate one input key assembly from a second input key assembly during a key stroke input travel distance of at least 0.05 inches.  
         [0010]     This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. 
     
    
     DRAWINGS  
       [0011]     The foregoing aspects and many of the attendant advantages of the presently claimed subject matter will become better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein:  
         [0012]      FIG. 1  is a partially exploded perspective view of a keyboard assembly formed in accordance with one embodiment of the presently claimed subject matter showing a keyboard cover removed from a keyboard;  
         [0013]      FIG. 2  is a top planar view of the keyboard assembly of  FIG. 1  showing the keyboard cover disposed over the keyboard, the keyboard cover being sufficiently translucent to permit a user to view the keyboard disposed below the keyboard cover;  
         [0014]      FIG. 3  is a cross-sectional view of the keyboard assembly of  FIG. 2 , the cross-sectional cut taken substantially through Section  3 - 3  of  FIG. 2 ;  
         [0015]      FIG. 4  is a partial cross-sectional planar view of a portion of the keyboard assembly of  FIG. 3  showing one key assembly of the keyboard assembly in a raised position;  
         [0016]      FIG. 5  is a partial cross-sectional view of the key assembly of  FIG. 4  showing the key assembly in a depressed position;  
         [0017]      FIG. 6  is a partial cross-sectional view of a portion of the keyboard assembly of  FIG. 3  showing a touch pad of the keyboard assembly;  
         [0018]      FIG. 7  is a partially exploded perspective view of a keyboard assembly formed in accordance with another embodiment of the presently claimed subject matter showing a keyboard cover removed from a keyboard, the keyboard having an actuation layer, a switch layer, and a base layer, wherein each layer is shown spaced from the others for clarity;  
         [0019]      FIG. 8  is a partial cross-sectional view of a key assembly of the keyboard assembly of  FIG. 7 ;  
         [0020]      FIG. 9  is a perspective view of a top of an alternate embodiment of a keyboard assembly formed in accordance with the presently claimed subject matter;  
         [0021]      FIG. 10  is a perspective view of a bottom of the keyboard assembly of  FIG. 9 ;  
         [0022]      FIG. 11  is a cross-sectional view of the keyboard assembly of  FIG. 9 , the cross-sectional cut taken substantially through Section  11 - 11  of  FIG. 9 ;  
         [0023]      FIG. 12  is a partial cross-sectional view of a homing indicia of the keyboard assembly of  FIG. 11 ;  
         [0024]      FIG. 13  is a partial cross-sectional view of a leading edge of the keyboard assembly of  FIG. 11 ;  
         [0025]      FIG. 14  is a partial cross-sectional view of a trailing edge of the keyboard assembly of  FIG. 11 ;  
         [0026]      FIG. 15A  is a partial cross-sectional view of a portion of a sensor assembly of the keyboard assembly of  FIG. 9 ;  
         [0027]      FIG. 15B  is a partial cross-sectional view of a portion of an alternate sensor assembly of the keyboard assembly of  FIG. 9 ;  
         [0028]      FIG. 16  is a cross-sectional view of a keyboard position adjustment assembly of the keyboard assembly of  FIG. 10 , the cross-sectional cut taken substantially through Section  16 - 16  of  FIG. 10 , the keyboard position adjustment assembly shown in a retracted position;  
         [0029]      FIG. 17  is a view of the keyboard position adjustment assembly of  FIG. 16 , the keyboard position adjustment assembly shown in an extended position;  
         [0030]      FIG. 18  is a cross-sectional view of a key assembly suitable for use with the above described embodiments;  
         [0031]      FIG. 19  is an perspective view of a light guide assembly suitable for use with the key assembly of  FIG. 18 ;  
         [0032]      FIG. 20  is a block diagram of a user interface system for managing the operation of the keyboard and exchanging data with the user;  
         [0033]      FIG. 21  is a graphical user interface for managing the operation of the keyboard and exchanging data with the user; and  
         [0034]      FIGS. 22A and 22B  are functional flow diagrams indicating operation of the keyboard assembly of  FIG. 9 . 
     
    
     DETAILED DESCRIPTION  
       [0035]     The presently claimed subject matter is described herein with reference to the accompanying illustrations where like numerals correspond to like elements. One suitable embodiment of a keyboard assembly  100 , constructed in accordance with the presently claimed subject matter is illustrated in  FIGS. 1-6 . The keyboard assembly  100  includes a plurality of input key assemblies  108  disposed within a housing to form a keyboard  104 . Such a keyboard assembly  100  can be used in combination with any conventional system, such as a computer, word processor, calculator, data entry terminal, control panel and the like, to generate signals and/or to enter data into the system.  
         [0036]     For clarity in the following description, directional terms such as vertical, horizontal, downwardly, upwardly, etc., have been used to describe one suitable embodiment of the keyboard assembly  100 , wherein the key assemblies  108  are mounted on a horizontal plane and extend away from the plane in an upward manner. However, it will be appreciated that the keyboard assembly  100  may be mounted in any orientation, and thus, the directional terms will change accordingly. Therefore, such terms should be viewed as merely descriptive and non-limiting.  
         [0037]     The keyboard assembly  100  includes a cover  102  removably coupled to the keyboard  104 . The cover  102  has a substantially smooth top surface  106 , which is substantially free of crevices so as to be amenable to cleaning. In one embodiment, the cover  102  is substantially free of features on the top surface  106  which exceed a selected depth or height from the top surface  106 , such as about 0.02 inches, 0.015 inches, 0.010 inches, or 0.005 inches. Preferably, these features are subtle and localized features either convex or concave in shape so as to have smooth transitions amenable to cleaning, for example, by wiping with a cloth. In another embodiment, the cover  102  is substantially free of crevices such that a cloth can pick up foreign material, such as germs, with a simple wiping action.  
         [0038]     When assembled, the cover  102  is disposed over, or encases, the key assemblies  108 . To actuate the key assemblies  108  underlying the cover  102 , a user types upon the cover  102 . The key assemblies  108  are preferably medium-to-full travel key assemblies requiring low actuation forces to permit a user to use the keyboard assembly  100  in a touch-type manner. The cover  102  may be removed and cleaned, or alternately, cleaned when disposed over or encasing the key assemblies  108 , to reduce the spread of infectious diseases.  
         [0039]     In light of the above general description of the keyboard assembly  100 , the components of the keyboard assembly  100  will now be described in greater detail. The keyboard  104 , as stated above, includes a plurality of key assemblies  108 . The key assemblies  108  are of any suitable design that is currently known or to be developed in the future, a few suitable examples being elastomeric tactile style key assemblies, metal dome style key assemblies, elastomeric dome style key assemblies as shown and described, or spring loaded style key assemblies. For the purposes of this detailed description, the term “dome” refers to domes having a semi-spherical shape as well as domes of any other geometric shape.  
         [0040]     Referring to  FIG. 4 , while only one of the key assemblies  108  will be described in detail for the sake of brevity, those skilled in the art will appreciate that the description of the single key assembly  108  pertains equally well to the other key assemblies  108  of the keyboard assembly  100 . In that regard, the key assembly  108  of  FIG. 4  includes a moveable key  110 , a plunger  112 , a key support structure  114 , an actuation layer  116 , and a switch contact  118 . The key assembly  108  is disposed above a switch layer  120  having a switch layer contact  122 .  
         [0041]     During use, when a user applies a downward force on the moveable key  110  equaling or exceeding the actuation force of the key assembly  108 , the moveable key  110  moves from its raised position (as shown in  FIG. 4 ) toward the switch layer  120  to a depressed position (as shown in  FIG. 5 ). This depressed position results in switch closure. Specifically, the switch contact  118  of the moveable key  110  electrically contacts the electrical contact of the switch layer contact  122 , as shown in  FIG. 5 . Such switch closure results in the generation of a signal, and optionally, an associated data entry.  
         [0042]     During movement of the moveable key  110 , the key support structure  114  supports the moveable key  110  and guides the moveable key  110  along a vertical axis of the key assembly  108 . After the actuation force is removed from the moveable key  110 , the actuation layer  116  returns the moveable key  110  to the raised position shown in  FIG. 4 .  
         [0043]     Still referring to  FIG. 4 , each individual element of the key assembly  108  will now be described in detail, beginning with the key support structure  114 . The key support structure  114  is adapted to support and guide the moveable key  110  when the moveable key  110  is pressed and released. In the embodiment shown, the key support structure  114  is constructed in the form of a bezel housing that includes a base plate  124  having upwardly extending side walls  126 . The side walls  126  extend from the base plate  124  to form a hollow key silo  128 .  
         [0044]     At least partially disposed in the hollow key silo  128  is the plunger  112 . The plunger  112  includes a vertically disposed bore  130  extending therethrough. The bore  130  forms a socket for receiving a shaft of the moveable key  110  to couple the moveable key  110  to the plunger  112 , for example, in an interference fit relationship. While the moveable key  110  is described above and illustrated as being a separable part from the plunger  112 , it will be readily evident that the moveable key  110  and the plunger  112  may alternately be integrally formed as a unitary member.  
         [0045]     The plunger  112  is disposed in sliding arrangement within the side walls  126  of the key support structure  114 . In one embodiment, the plunger  112  is preferably keyed to the key support structure  114  so that the moveable key  110  is impeded from rotating relative to the key support structure  114 . The key support structure  114  may be of a unitary construction, preferably made from a semi-rigid, or rigid material, one suitable example being a polycarbonate material.  
         [0046]     The actuation layer  116  is constructed out of an elastomeric material, such as silicon rubber, and is disposed directly below the key support structure  114  and substantially parallel to the base plate  124 . The actuation layer  116  may be of a unitary construction integrally formed with a depressible dome  132 , the dome  132  being associated with the moveable key  110 .  
         [0047]     In the embodiment shown, the depressible dome  132  is generally circular in cross-section and of a suitable size such that the dome  132  provides a generally uniform upward force and uniform support for its associated moveable key  110  across the entire bottom surface of the moveable key  110 .  
         [0048]     The upward force, or biasing force, which the depressible dome  132  applies to the moveable key  110  maintains the moveable key  110  in the raised position until a user applies an actuation force which overcomes the biasing force, resulting in the downward movement of the moveable key  110  to the depressed position. In the illustrated embodiment, the force of actuation required to transition the moveable key  110  from the raised position to the depressed position is selected such that the key assembly  108  is suitable for touch-typing. For instance, in one embodiment, the key assembly  108  is a low actuation force key assembly  108 , having an actuation force less than any one of the following forces: about 0.3 lbf, 0.2 lbf, 0.1 lbf, 0.08 lbf, or 0.06 lbf. Preferably, the actuation force of the key assemblies  108  is between about 0.1 lbf and about 0.2 lbf.  
         [0049]     When the moveable key  110  is depressed, the bottom surface of the moveable key  110  presses downwardly, equally and symmetrically, on the depressible dome  132  so that the dome  132  flexes or deforms downwardly and uniformly around its entire cross-section as shown in  FIG. 5 . The depressible dome  132  includes an electrically conductive contact  118  mounted on the bottom surface of an extension  113  of the dome  132 , facing the switch layer  120 .  
         [0050]     In the embodiment shown, the electrically conductive contact  118  is a unitary member extending the entire width of the bottom of the extension  113 . Alternatively, the contact  118  can be made up of a plurality of smaller dimensioned contacts disposed around the perimeter of the bottom surface of the extension  113 . In operation, the contact  118  contacts an associated electrical contact  122  on the switch layer  120  when the depressible dome  132  is sufficiently depressed by the moveable key  110  to produce the desired switching effect and associated data entry.  
         [0051]     In the illustrated embodiment, the length of travel  134  of the moveable key  110  from its raised position to its depressed position is selected such that the key assembly  108  is suitable for touch-typing. For instance, in one embodiment, the key assembly  108  is a medium travel or a full travel key assembly  108 , having a length of travel  134  greater than any one of the following: about 0.05 inches, about 0.06 inches, about 0.08 inches, about 0.10 inches, about 0.12 inches, about 0.14 inches, about 0.16 inches, about 0.18 inches, about 0.20 inches, or about 0.22 inches. Preferably, the travel length  134  of the key assemblies  108  is between about 0.06 inches and about 0.16 inches.  
         [0052]     Still referring to  FIG. 4 , the key assembly  108  further includes the switch layer  120 , a spacer layer  135 , and a base layer  136 , all of which are parallel to and disposed directly below the actuation layer  116 . The switch layer  120  may be a well-known printed circuit board and may be carbon coated to prevent corrosion. In addition, the switch layer may be formed by any conventional method, such as a copper cladding process or a printed silver ink process. The spacer layer  135  suspends the switch layer  120  above the base  136 , the base  136  forming a bottom of a housing of the keyboard  104 .  
         [0053]     Referring to  FIG. 6 , the keyboard  104  may also include a well-known touchpad  140 . The touchpad  140  detects and tracks finger motion above the touchpad  140 . To move a cursor associated with the user&#39;s finger disposed above the touchpad  140 , the user lightly slides his or her finger over the portion of the cover  102  disposed above the touchpad  140  surface. The touchpad  140  translates the finger&#39;s location above the touchpad  140  into cursor movement.  
         [0054]     Referring to  FIG. 1 , the cover  102  will now be described in greater detail. The cover  102  includes a substantially smooth top surface  106  which is substantially free of crevices so as to be amenable to cleaning, as mentioned briefly above. Extending perpendicular downward about a perimeter of the top surface  106  is a sidewall  142 . The sidewall  102  is adapted to fit about a shoulder  144  of the keyboard  104 , preferably in an interference fit relationship, thereby removably coupling the cover  102  to the keyboard  104 . Although the cover  102  is illustrated and described as being removably coupled to the keyboard  104 , it should be appreciated by those skilled in the art that the cover  102  may also be integrally formed or permanently attached to the keyboard  104 .  
         [0055]     The cover  102  is made from a flexible material such that the cover  102  may deform when pressure is applied to it to reciprocate the moveable key between its normally raised position and the depressed position. The cover  102  is formed from a material that is able to deflect or stretch like a trampoline during use so that the key assembly  108  disposed below the cover  102  can actuate with very little to no extra resistance caused by the cover  102 . For instance, the cover  102  may be made from a flexible material that increases the actuation force of a low actuation force, medium-to-full travel key assembly by less than any one of the following values: about 50%, 40%, 30%, 20%, 10%, or 5%. In a preferred embodiment, the flexible material increases the actuation force of the key assembly by less than 25%.  
         [0056]     The cover  102  is preferably made from a flexible material with a predetermined flexibility to substantially mechanically isolate one key assembly  108  from the other key assemblies  108  during use. In that regard, the flexibility of the material permits a user to press the cover  102  in one location to activate a selected key assembly  108  without activating any adjacent key assemblies  108 .  
         [0057]     Although the cover  102  has a predetermined flexibility to substantially mechanically isolate one key assembly  108  from the other key assemblies  108  during use, it should be appreciated that some compression of adjacent key assemblies  108  may occur when one key assembly  108  is sufficiently depressed by an actuation force to be actuated, thus resulting in a desired switching effect and associated data entry. However, such adjacent compression is generally insufficient to actuate the adjacent key assemblies  108  (i.e., to produce a desired switching effect and associated data entry by the adjacent key assemblies  108 ).  
         [0058]     In one embodiment, the material of the cover  102  is of a selected flexibility permitting low actuation force, medium-to-full travel key assemblies of a standard keyboard, for example, located on a ¾″ center to center spacing, to be individually actuated from the raised position to the depressed position without causing adjacent key assemblies to also be actuated. In another embodiment, a top layer of the cover  102  has a thickness substantially between about 0.01 inches and about 0.2 inches. In another embodiment, the top layer has a thickness substantially between about 0.02 inches and about 0.08 inches, with a preferred value of about 0.031 inches.  
         [0059]     One suitable material for constructing the cover  102  is an elastomer that resists wrinkling when coupled to the keyboard, such as a silicone elastomer. In one embodiment, the cover  102  is made of an elastomer having a durometer rating substantially between about 20 and about 40, with a preferred rating of about 30. In another embodiment, the cover  102  is formed from a soft urethane material or any other material that can be stretched and which is then able to return to its original configuration.  
         [0060]     The cover  102  may include one or more protective coatings added to the top surface  106  to resist contaminants from being absorbed into the elastomer and resist degradation of the elastomer by an adverse chemical reaction. The cover  102  may also include protective coatings added to impede the growth of infectious material upon the cover  102 , such as antibacterial based coatings. The cover  102  may be formed from a translucent, transparent, or opaque material, or any combination thereof, to permit the key assemblies  108  to be visible through the cover with substantial clarity.  
         [0061]     The cover  102  may further include indicia  138  disposed on the cover  102  to indicate to a user the alphanumeric associated with the key assemblies  108  disposed below the indicia. The indicia  138  may be visual or physical in nature, such as text printed on the cover  102 , an outline of an outer perimeter of the key assemblies  108  disposed below the indicia, a change in the texture of the cover  102 , slight indentation(s) on the cover  102 , and/or raised structure(s) on the cover  102 .  
         [0062]     Such indentations or raised structures may be convex or concave in shape so as to be free of crevices, and such indentations or raised structures may or may not resemble the alphanumerics associated with the key assemblies  108 . It should be appreciated that printed indicia may be negatively illuminated (the indicia is opaque and the surrounding area is transparent or translucent) or positively illuminated (the indicia is transparent or translucent and the surrounding area opaque).  
         [0063]     In the illustrated embodiment, one suitable indicia  138  is shown as the letters “ESC” printed, indented, or raised upon the cover  102  and disposed over the key assembly  108  associated with an escape operation of a computer (not shown) coupled to the keyboard  104 . Although only a single indicia  138  is shown in the illustrated embodiment for purposes of clarity, it should be appreciated by those skilled in the art that the cover  102  may include multiple indicia  138 , such as one for every key assembly  108 , or a lesser number, such as indicia  138  disposed above selected reference keys, such as above the keys associated with characters “F” and “J” in a standard English (or QWERTY) keyboard.  
         [0064]     In light of the above description of the components of the keyboard assembly  100 , the operation of the keyboard assembly  100  will now be described. Referring to  FIG. 1 , the cover  102  is removably coupled to the keyboard  104  such that the cover  102  completely covers or encases the underlying keyboard  104 , including the key assemblies  108 . Referring to  FIG. 2 , a user views the underlying key assemblies  108  through the translucent cover  102 , and places his or her fingers in a typing position, aided by indicia  138  disposed on the cover  102 . Alternatively, the user locates his or her fingers by printing on the cover  102 , the printing being located in the vicinity of the corresponding keys. A user then performs touch-type typing.  
         [0065]     Referring to  FIG. 5 , as the user&#39;s finger  146  contacts the cover  102  disposed above a key assembly  108  and presses downward with a force equaling or exceeding the actuation force of the key assembly  108  (which is preferably a low actuation force of about 0.3 lbf or less), the moveable key  110  underlying the cover  102  moves downward an amount equal to a medium-to-full travel length. As the moveable key  110  moves downward, the switch contact  118  associated with the moveable key  110  contacts the contact  122  associated with the switch layer  120 , resulting in a desired switching effect and associated data entry.  
         [0066]     The cover  102  is of sufficient flexibility such that when one key assembly  108  is fully actuated, adjacent key assemblies  108  are not inadvertently actuated. Further, the cover  102  is of sufficient flexibility such that the actuation force of the key assembly  108  is not appreciably increased by the force required to deflect the cover  102 . Specifically, even with the cover  102  in place over the keyboard  104 , the actuation force of the key assembly  108  is still a low actuation force for allowing a user to perform touch typing without significant fatigue.  
         [0067]     Referring to  FIGS. 7 and 8 , a keyboard assembly  200  constructed in accordance with another embodiment of the present disclosure is illustrated. The keyboard assembly  200  is substantially similar in structure and operation to the keyboard assembly  100  illustrated and described above in relation to  FIGS. 1-6  with the following exceptions. The keyboard assembly  200  is an elastomer style version of the above described keyboard, and as such, is constructed without the moveable key  110 , plunger  112 , and key support structure  114  illustrated and described with regard to  FIG. 4 . Inasmuch as the two embodiments are substantially similar, for the sake of brevity, the following paragraphs focus generally on the aspects of the keyboard assembly  200  that deviate from the previously described embodiment.  
         [0068]     The keyboard assembly  200  includes a cover  202  and a keyboard  204 . The keyboard generally includes three layers, namely, from top to bottom, an actuation layer  210 , a switch layer  206 , and a base layer  208 . The cover  202  and the three layers ( 210 ,  206 , and  208 ) making up the keyboard  204  are substantially similar in construction and operation to the components of the above described embodiment bearing the same names, and therefore will not be described in detail.  
         [0069]     The cover  202  wraps around the keyboard  204 . A top surface  212  of the cover  202  is substantially flat and contains substantially no key-top features. Because the key-top features are substantially or entirely eliminated, the accumulation of contaminates on the keyboard assembly  200  are reduced. As a result, the keyboard assembly  200  can be easily cleaned.  
         [0070]     The cover  202  suitably includes indicia  214  (see  FIG. 7 ) indicating the function of the key, such as a letter of the alphabet that will be entered when the key is depressed, or a function, such as the letters “ESC” (signifying the “escape” function). The cover  202  may include support webs  222  (see  FIG. 8 ) which extend downward from the top surface  212  of the cover  202  to engage the actuation layer  200  between adjacent key assemblies  216  to aid in the support and suspension of the cover  202  above the key assemblies  216 .  
         [0071]     The key assemblies  216  are generally of a low actuation force, medium-to-full travel variety. Each key assembly  216  includes a biasing member in the form of a depressible dome  218  which normally biases a contact pad  220  in an upward, non-contact, raised position, as shown in  FIG. 8 .  
         [0072]     When the user presses downward on the cover  202  above the contact pad  220 , the depressible dome  218  exerts an upward resistant force on the key assembly  216  that is being depressed. Thus, the user must overcome the upward resistant force to sufficiently depress the key assembly  216  to obtain switch closure and associated data entry. After the user releases his or her downward force on the key assembly  216 , the upward force exerted by the depressible dome  218  returns the contact pad  220  to its raised position.  
         [0073]     A keyboard assembly  300  constructed in accordance with another embodiment of the present disclosure may be best understood by referring to  FIGS. 9-21 . The keyboard assembly  300  is substantially similar in construction and operation to the keyboard assembly embodiment described with reference to  FIGS. 1-8 . Therefore, the following paragraphs generally focus only on aspects of the keyboard assembly  300  different from the embodiments described above.  
         [0074]     The keyboard assembly  300  of  FIGS. 9-19  the keyboard assembly  300  includes homing indicia  360  for helping a user to properly locate his or her fingers upon the keyboard assembly  300 , a wraparound cover  302  for enhanced cleanability and aesthetics, and sensor assemblies  370  and  372  for detecting keyboard assembly  300  cleaning. The keyboard assembly  300  also includes a keyboard position adjustment assembly  380  (see  FIG. 10 ); and a user interface system  450  (see  FIG. 20 ) for managing the operation of the keyboard assembly  300 .  
         [0075]     Referring to  FIGS. 9 and 12 , homing indicia  360  are disposed on the cover  302  to indicate to a user a desirable hand or finger location on the keyboard assembly  300 . The homing indicia  360  may be visual or physical in nature. As non-limiting examples, homing indicia  360  within the scope of the present disclosure includes text or images printed on the cover  302 ; an outline of an outer perimeter of the key assemblies  308  disposed below the homing indicia  360  on the cover  302 ; a change in the texture of the cover  302 ; slight indentation(s) on the cover  302 ; and/or raised structure(s) on the cover  302 . As best seen in  FIG. 12 , the homing indicia  360  are in the form of convex bumps which are free of crevices and thus easily cleanable.  
         [0076]     The homing indicia  360  of the illustrated embodiment may be disposed in one or more predetermined locations upon the cover  302  to aid a user in locating their hands/fingers in a preselected position upon the cover  302 . In one embodiment, the homing indicia  360  are located on the cover  302  over the key assemblies  308  associated with selected reference keys, such as above the keys associated with characters “F” and “J” in a standard English keyboard and upon the “5” key of the numerical pad, to help a user properly locate their hands and fingers upon the keyboard assembly  300  in a standard position.  
         [0077]     As discussed briefly above, the cover  302  may be of a wrap-around design. For example, referring to  FIG. 11 , the cover  302  wraps around a top surface  362  and side wall  364  of the keyboard  304 , and couples to a bottom surface  366  of the keyboard  304 . This “wrap-around” feature of the cover  302  may provide an aesthetically pleasing look to the keyboard assembly  300 , as the ends of the cover  302  are substantially hidden from view. As configured, the ends of the cover  302  are located underneath the keyboard  304 .  
         [0078]     Further, because the cover  302  substantially covers, and preferably completely covers, the top surface  362  and the sides  364  of the keyboard  304 , the top surface  362  and sides  364  are encased by an easily cleanable and substantially crevice-free material. Such encasement impedes the accumulation of dirt and infectious substances upon the keyboard  304 , and provides a keyboard assembly  300  having both top  362  and side surfaces  364  that are easily cleanable.  
         [0079]     Referring to  FIGS. 13 and 14 , the cover  302  of the illustrated embodiment is suitably coupled to the keyboard  304  by a coupling assembly  390 . In the illustrated embodiment, the coupling assembly  390  includes a tongue  392  and groove  394  arrangement. More specifically, the ends of the cover  302  terminate in lips or tongues  392 . The tongues  392  are sized and shaped to be cooperatively received within grooves  394  disposed slightly inward of an outer perimeter of the bottom surface  366  of the keyboard  304 .  
         [0080]     The cover  302  couples to the bottom surface  366  of the keyboard  304  such that the outer surface of the cover  302  and the bottom surface  366  are substantially coplanar. Such coplanar configuration provides an easily cleanable surface as it does not include any substantial crevices, abrupt changes in height or contour, or protrusions formed at the interface between the cover  302  and the bottom surface  366  of the keyboard  302 .  
         [0081]     In one embodiment, the tongue  392  is sized and shaped to sealingly engage the groove  394  to impede fluid ingress at the interface cover  302  and bottom surface  366 . Although a specific coupling assembly  390  is illustrated and described, it is noted to those skilled in the art that other coupling assemblies  390  are suitable for use with and are within the spirit and scope of the presently claimed subject matter. As non-limiting examples, the cover  302  may be retained by many other coupling assemblies, such as fasteners, a few suitable examples being snaps, hook and loop fasteners, adhesives, clamps, etc.  
         [0082]     Further, although a specific coupling assembly  390  is illustrated and described for coupling the cover  302  to the keyboard  304 , it should be noted that the coupling assembly  390  is optional and may be eliminated. For example, the cover  302  may be sized and configured to be stretched over the keyboard  304 , with the resiliency and elasticity of the cover  302  retaining the cover  302  to the keyboard  304  after the stretching force is removed. Additionally, although the cover  302  of the presently claimed subject matter is illustrated as only covering a portion of the bottom surface  366  of the keyboard  304 , it should be appreciated by those skilled in the art that the cover  302  may alternately completely or substantially encompass the keyboard  304 .  
         [0083]     Referring to  FIG. 9 , the sensor assemblies  370  and  372  will now be described in greater detail. The sensor assemblies  370  and  372  are adapted to detect or sense user input. As a non-limiting example, a user input may be a cleaning of the keyboard assembly  300  with a cleaning fluid, such as water or alcohol. Inasmuch as the first and second sensor assemblies  370  and  372  are identical in construction and operation, only the first assembly  370  will be described for the sake of brevity.  
         [0084]     Referring to  FIGS. 9 and 15 A, the first sensor assembly  370  is a suitable conductive sensor assembly, including a first electrode or element  374   a  and a second electrode or element  374   b.  As the user wipes or applies a cleaning fluid  378  (optionally, with a cloth or towel) to the cover  302  during cleaning, the fluid  378  forms an electrical bridge between the first and second electrodes  374   a  and  374   b.  As a result, the electrodes  374   a  and  374   b  become electrically connected with one another, and the resistance between electrodes  374   a  and  374   b  is reduced.  
         [0085]     After the cleaning fluid  378  has sufficiently bridged electrodes  374   a  and  374   b  together (i.e., the resistance between electrodes  374   a  and  374   b  has been reduced to a predetermined amount by the cleaning fluid  378 ), the first sensor assembly  370  sends a signal to a controller  454  ( FIG. 20 ) indicating that the first sensor assembly  370  has detected the presence or application of a cleaning fluid  378  to the keyboard assembly  300 . The controller  454  includes a well-known sensor controller (not shown) and a keyboard controller (not shown). Likewise, as the cleaning fluid  378  is applied to the keyboard assembly  300 , first and second electrodes  376   a  and  376   b  of the second sensor assembly  372  become electrically connected with one another.  
         [0086]     After the cleaning fluid  378  has sufficiently bridged electrodes  376   a  and  376   b  together, the second sensor assembly  372  sends a signal to the sensor controller  454  indicating that the second sensor assembly  372  has detected the presence of a cleaning fluid  378 . Although two sensor assemblies  370  and  372  are described in the illustrated embodiment, it should be appreciated that more or less than two sensor assemblies are within the scope of the present disclosure.  
         [0087]     One sensor controller suitable for use in the present embodiment is manufactured and sold by Cypress Semiconductor Corporation of 198 Champion Ct., San Jose, Calif. 95134 under the model number CY8C21534-24PVXI. One keyboard controller suitable for use in the present embodiment is manufactured and sold by Cypress Semiconductor Corporation of 198 Champion Ct., San Jose, Calif. 95134 under the model number CY8C24794-24LFXI.  
         [0088]     The controller  454  is suitably programmed to monitor the duration of time between receipt of the signals indicating the presence of a cleaning fluid from each of the sensor assemblies  370  and  372 . If the duration of time is within a certain range of time, then the controller  454  will acknowledge an input, e.g., a “successful cleaning” of the keyboard assembly  300 . In another embodiment, the controller  454  may be programmed such that all sensor assemblies  370  and  372  must send their signals indicating the presence of a cleaning fluid  378  within a predetermined amount of time of each other before an input, e.g., a “successful cleaning” of the keyboard assembly  300 , is acknowledged by the controller  454 .  
         [0089]     The sensor assemblies  370  and  372  are configured to be in communication with a warning assembly  456 , as described in greater detail below. In such a configuration, after an input (e.g., a “successful cleaning” of the keyboard assembly  300 ) has been acknowledged by the sensor controller  454 , a predetermined condition used to determine the state of the warning assembly  456 , such as a predetermined interval, is reset to the beginning of the interval (such as “zero”).  
         [0090]     As a non-limiting example, the predetermined condition or interval may be a predetermined time period. In such a case, the predetermined time interval (monitored by, for example, a timer) is reset to time equal to zero. If this predetermined time interval passes before a new successful cleaning of the keyboard assembly  300  is acknowledged by the sensor controller  454 , then the user will be notified by a warning signal issued by a warning assembly  456 .  
         [0091]     Thus, the warning assembly is at least partially operatively coupled to the keyboard assembly, and includes at least a first state and a second state. The first state of the warning assembly  456  indicates the expiration of a predetermined interval, such as a time interval. When in the first state, the warning assembly  456  provides a warning signal. Some non-limiting, but suitable examples of an warning signal include: a visual signal, such as a flashing light associated with the keyboard or a text message appearing on a display screen associated with the keyboard; an audible signal, such as a beep or voice message; a functional signal, such as locking of the keyboard such that the keyboard will not function until a successful cleaning has been logged; and/or a physical signal, such as the vibrating of the keyboard. The signal may be selectable changeable by the user. In one embodiment, a graphical user interface is operably connected to the keyboard assembly  300  to permit a user to selectively change the signal (see  FIG. 21 ).  
         [0092]     The second state of the warning assembly  456  indicates the duration of a predetermined interval, such as a time interval. When in the second state, the warning assembly  456  does not provide a warning signal and also indicates that a predetermined cleaning condition has been met.  
         [0093]     Although the illustrated embodiment of the warning assembly  456  is described as indicating the passage of a predetermined time interval (i.e., a predetermined amount of time since a “successful cleaning”), it should be appreciated that any number of parameters could be used to set the predetermined cleaning interval. Such parameters include a predetermined number of keystrokes, after the computer is powered off or on a predetermined number of times, login by a new user, or any other interval for determining or monitoring usage of the key board. Each of the foregoing may also be referred to as “warning trigger sources,” as described below with respect to  FIGS. 22A and 22B .  
         [0094]     The parameters of the predetermined interval are selectably changeably by the user. In one embodiment, a graphical user interface is operably connected to the keyboard assembly  300  to permit a user to selectively change the parameters of the predetermined interval (see  FIG. 21 ).  
         [0095]     Referring to  FIG. 15B , an alternate embodiment is shown in which a single capacitance proximity sensor  396  is used in place of each sensor group  370 . Capacitance proximity sensors  396  are well-known in the art and readily available. Therefore, for the sake of brevity, their function will not be described in detail herein.  
         [0096]     In the illustrated embodiment, the capacitance proximity sensor  396  is disposed under the cover  302  and the top surface  362  of the keyboard  304 , although it should be readily appreciated that other placements are also possible. In use, the capacity proximity sensors  396  detect a change in capacitance when an object is placed within its electric field. Different objects create different changes in capacitance, thereby allowing the capacitance proximity sensors  396  to differentiate between.  
         [0097]     For example, the capacitance proximity sensor  396  can differentiate between the user&#39;s hand, the user&#39;s hand holding a dry cloth  398 , and the user&#39;s hand holding a cloth  398  wetted with cleaning fluid  378 . For that reason, as a non-limiting example, the capacitance proximity sensor  396  may be tuned so that the above conditions are distinguishable from each other.  
         [0098]     Of note, although the illustrated embodiments are illustrated and described as having either a pair of sensor assemblies (whether of the conductive or capacitance type), it should be appreciated by those skilled in the art that any number of sensor assemblies in any number of locations may be used without departing from the spirit and scope of the presently claimed subject matter. Multiple sensors help ensure that the entire keyboard assembly is cleaned during cleaning, opposed to just one area of the keyboard assembly. Further, sensors may be substantially visually isolated within the keyboard assembly. In this regard, the sensors may be located inconspicuously within the keyboard assembly to help ensure that the user cleans the entire keyboard assembly rather than just around the known locations of the sensors.  
         [0099]     It should also be noted that although specific sensor types are illustrated and described for use with the presently claimed subject matter, other types of sensors for detecting whether or not a successful cleaning evolution has occurred are within the present disclosure. As a non-limiting example, another type of sensor is actuation of a “cleaning complete” switch on the keyboard by a user after they have cleaned the keyboard. Another non-limiting example, another type of sensor is an optical liquid sensor able to detect the presence of a certain chemical or component of a cleaning fluid.  
         [0100]     As may be best understood by referring back to  FIG. 9 , the keyboard assembly  300  may also include a clean mode system (lock-out assembly) to minimize the risk of inadvertent keyboard activation during cleaning. The clean mode system includes an activation button  600 , a status light  602 , and a warning light  604 . The activation button  600  is a standard on/off switch coupled to the keyboard.  
         [0101]     When cleaning of the keyboard is desired or required, the operator presses the activation button  600 . This action will turn on the status light  602  to indicate to the operator that the keyboard is in a “CLEAN-MODE.” Pressing the activation button  600  simultaneously deactivates the keyboard, such that in the event that keys are inadvertently pressed during cleaning, no data is sent to the host. This allows the operator to safely clean the keyboard.  
         [0102]     After the keyboard is cleaned, the operator again presses the activation button  600 . This causes the status light  602  to turn off, thereby indicating that the keyboard is no longer in CLEAN-MODE. The keyboard is simultaneously reactivated so that data can again be sent to the host.  
         [0103]     If the keyboard is in CLEAN-MODE and a period of time elapses without the operator pressing the activation button  600 , the CLEAN MODE will be automatically turned-off. As such, the status light  602  is turned-off and the keyboard is reactivated. A typical period of time for this automatic reactivation could be about 15-120 seconds, with 30 seconds being preferred. The actual period of time can be set by a systems administrator and according to use.  
         [0104]     Still referring to  FIG. 9 , operation of the clean mode system will now be described in greater detail. In a typical protocol of operation, the warning light  604  will start to flash to indicated that cleaning is required. This functions as a signal to notify an operator that cleaning is required. The operator must then put the keyboard into clean mode by pressing the activation button  600  so that the keyboard can be safely cleaned. This, in turn, causes the status light  602  to be activated. Proper cleaning of the keyboard by a wipe-down protocol will cause the warning light  604  to go off. The operator will then press the activation button  600  a second time to reactivate the keyboard.  
         [0105]     Although the use of the warning light  604  is preferred, other embodiments are within the scope of the present disclosure. As a non-limiting example, the clean mode system can be put into CLEAN-MODE without the warning light  604  being activated. Therefore, such embodiments are within the scope of the present disclosure.  
         [0106]     Referring now to  FIGS. 10 and 11 , the keyboard position adjustment assembly  380  of the keyboard assembly  300  will now be described in greater detail. The keyboard position adjustment assembly  380  permits an inclination and/or height of the keyboard assembly  300  relative to a support surface  384  to be adjusted, thereby allowing a user to select a proper ergonomic position for the keyboard assembly  300  during use.  
         [0107]     The keyboard position adjustment assembly  380  includes one or more supports  382   a,    382   b,    382   c,  and  382   d.  The supports  382  are adapted to rest upon the support surface  384  and support the keyboard at a selected height and inclination above the support surface  384 . One or more of the supports  382  may be adjustable in height such that a user may selectively adjust the height and/or inclination of the keyboard.  
         [0108]     Turning to  FIGS. 16 and 17 , the right rear support  382   b  is shown. The right rear support  382   b  includes a cover  386  and a height adjustment mechanism  388 . The cover  386  may be coupled to the bottom surface or enclosure  366  of the keyboard assembly  300  and at least partially house the adjustment mechanism  388  therein. The cover  386  is preferably coupled to the bottom enclosure in manner that does not result in the formation of crevices, such that the cover  386  provides an easily cleanable surface. Moreover, the cover  386  is coupled to the bottom enclosure  366  such that the transition between the cover  386  and the bottom enclosure  366  is substantially free of abrupt changes in contour, height, angle, etc., such that the outer surface of the cover  386  provides a smooth transition to the outer surface of the bottom enclosure  366 .  
         [0109]     The adjustment mechanism  388  may be a push button style adjustment mechanism, such that pressing the adjustment mechanism  388  causes the adjustment mechanism  388  to toggle between two or more positions, such as a retracted position as shown in  FIG. 16  and an extended position as shown in  FIG. 17 . For instance, pressing on the adjustment mechanism  388  causes the adjustment mechanism to toggle from the retracted position to the extended position. Pressing the adjustment mechanism again causes the adjustment mechanism  388  to toggle back to the retracted position.  
         [0110]     The adjustment mechanisms  388  associated with the rear supports  382   a  and  382   b  travel between the retracted and extended positions approximately between about 0.2 inches and 1 inch, with a preferred travel distance  383  of about 0.6 inches. However, it should be noted that other travel distances, either more or less than the distances recited herein, are suitable for use with and within the spirit and scope of the presently claimed subject matter.  
         [0111]     The pressing force used to actuate the adjustment mechanism  388  between the retracted and extended positions is preferably large enough to prevent inadvertent closing by pressing on the keyboard assembly  300 . A locking mechanism (not shown) may also be used to lock the adjustment mechanism  388  in a selected position to impede inadvertent actuation or change in height. Although the adjustment mechanism  388  is illustrated and described as a push button style adjustment mechanism, those skilled in the art will appreciate that the adjustment mechanism may take any suitable form that permits the support  382 B to be adjusted in length, without departing from the spirit and scope of the presently claimed subject matter.  
         [0112]     Any combination of adjustable and non-adjustable supports may be used. For instance, in one embodiment, only the rear supports  382   a  and  382   b  are adjustable in height. In another embodiment, all four supports  382   a,    382   b,    382   c,  and  382   d  are adjustable in height. In yet another embodiment, only the front supports  382   c  and  382   d  are adjustable in height. In still yet another embodiment, none of the supports are adjustable in height. Although the illustrated embodiment is illustrated and described as having four supports, it should be noted that any number of supports are suitable for use with and are within the spirit and scope of the presently claimed subject matter, including one, two, three, four, or five or more. Also, the supports may be eliminated all together.  
         [0113]     Referring to  FIG. 18 , the components forming the keyboard assembly  300  will be described in greater detail on a layer by layer basis. The top layer of the keyboard assembly  300  is the cover  302 . As discussed in detail above, the cover  302  may be a flexible, easily cleanable, translucent material, which is substantially free of crevices.  
         [0114]     The key assemblies  308  are disposed directly below the cover  302 . The key assemblies  308  of the illustrated embodiment of  FIG. 18  are of a well-known scissor type key assembly arrangement, although any well-known or to be developed key assembly may be used without departing from the spirit and scope of the presently claimed subject matter.  
         [0115]     As discussed in detail above, the key assemblies  308  are preferably medium-to-full travel key assemblies requiring low actuation forces to permit a user to use the keyboard assembly in a touch-type manner. Each key assembly  308  may be formed from transparent or translucent materials or is at least substantially formed from transparent or translucent material to permit a high percentage of light striking the key assembly to pass therethrough.  
         [0116]     A key assembly support layer  400  may be disposed below the key assemblies  308 . The key assembly support layer  400  may be used to provide a rigid or semi-rigid frame or base for supporting the key assemblies  308  during operation and to provide a substrate for mounting the key assemblies  308  thereto. The key assembly support layer  400  includes a plurality of apertures  402 , the apertures  402  selectively located to be disposed below the key assemblies  308 . The apertures  402  are sized and located to permit the energy director  404  to pass through the aperture  402  when a user depresses the key assembly  308  during typing such that the energy director  404  contacts a circuit board  406  disposed below the key assembly support layer  400 .  
         [0117]     The circuit board  406  of the illustrated embodiment includes three layers: a top contact layer  408 , a spacer layer  410 , and a bottom contact layer  412 . The top contact layer  408  may be a flexible layer having a plurality of contacts (not shown) printed on the bottom surface of the top contact layer  408 . The bottom contact layer  412  may be a rigid or flexible layer having a plurality of contacts (not shown) printed on the top surface of the bottom contact layer  412 .  
         [0118]     The spacer layer  410  is sandwiched between the top and bottom contact layers  408  and  412 , thereby separating the top contact layer  408  from the bottom contact layer  412  under normal conditions. The spacer layer  410  includes a plurality of apertures  414 . The apertures  414  are selectively sized and located as to be disposed below the energy director  404  of the key assemblies  308 .  
         [0119]     As the energy director  404  is actuated downward, the top contact layer  408  is deformed downward through one of the apertures  414  in the spacer layer  410  such that a contact disposed on the bottom surface of the top contact layer  408  is pressed into electrical communication with a contact disposed on a top surface of the bottom contact layer  412 , thereby completing a circuit.  
         [0120]     Completion of the circuit may result in a signal being sent to a computer or other device attached to the keyboard, instructing the computer or device to take a specific action. The circuit board  406  is preferably transparent or translucent to permit a substantial portion of the light hitting at least the bottom surface of the circuit board  406  to pass through the circuit board  406 .  
         [0121]     Disposed below the circuit board  406  may be a backer layer  416 . The backer layer  416  may be a rigid or semi-rigid layer and may be used to increase the rigidity of the keyboard assembly  300 . The backer layer  416  may be transparent or translucent to permit a substantial portion of the light hitting at least the bottom surface of the backer layer  416  to pass through the backer layer  416 .  
         [0122]     A light guide assembly  418  may be disposed below the backer layer  416  and may be used to back-light the cover  302 . More specifically, the light guide assembly  418  includes a light guide  420  and a light emission assembly  422 . Generally stated, the light emission assembly  422  directs light into the light guide  420 , which redirects the light upward toward the cover  302 . The light guide  420  is preferably able to redirect the light to the top surface of the cover  302  so as to illuminate substantially the entire top surface of the cover  302 .  
         [0123]     As a result of the transparent/translucent nature of the components disposed above the light guide  420 , the light guide assembly  418  is preferably able to light substantially all of the top surface of the cover  302 , although other percentages of illumination of the cover  302  are within the spirit and scope of the presently claimed subject matter, such as percentages greater than about 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, or 90%.  
         [0124]     Referring to  FIG. 19 , the light guide assembly  418  of  FIG. 18  will be described in further detail. The light guide assembly  418  includes one or more light emitters  424  and the light guide  420 . The light emitters  424  may be any suitable light generating source, a few examples being LEDs as illustrated, incandescent lights, etc. The light guide  420  may be made of any transparent or translucent material able to transmit light, a few suitable examples being acrylic and polycarbonate materials.  
         [0125]     The light guide  420  may include one or more light redirectors  426 . The light redirectors  426  are positioned and shaped to redirect light emitted from the light emitters  424  toward a top surface of the light guide  420  so as to be directed toward a top surface of the keyboard. In the illustrated embodiment, the light emitters  424  emit light in a horizontal direction. After the emitted light  428  hits the light redirectors  426 , the light redirectors  426  redirect the light from anywhere between 0 to 180 degrees, and preferably 90 degrees, from the original path of the emitted light, such that the emitted light is directed toward the top surface of the keyboard.  
         [0126]     In the illustrated embodiment, the light redirectors  426  are in the form of hemispherically-shaped recesses located in an array on the bottom surface of the light guide  420 . Although a specific shape of the light redirectors  426  is illustrated and described, it should be appreciated by those skilled in the art that alternately shaped light redirector geometries  426  are suitable for use with and are within the spirit and scope of the presently claimed subject matter.  
         [0127]     The light guide  420  may also include a series of light reflectors  430  disposed about the outer surface of the light guide  420 . The light reflectors  430  increase the efficiency of the light guide  420  by impeding the emitted light  428  from passing out of the light guide  420  except through a predetermined area, one suitable example being the top surface of the light guide  420 .  
         [0128]     In the illustrated embodiment, the light reflectors  430  are formed from reflective material attached to the sides (except the side in which the light emitters  424  direct the emitted light toward to enter the light guide) and the bottom surface of the light guide  420 . The reflective material includes a reflective surface which reflects any emitted light hitting the reflective surface back into the light guide  420  for redirection toward the top surface of the light guide  420 . A diffusing film may also be employed on the top surface.  
         [0129]     Turning to  FIG. 20 , a user interface system  450  for permitting data exchange with a user will be illustrated and described. The user interface system  450  places the above described keyboard assembly  300  and its associated subcomponents, such as the sensor assemblies  370  and  372  and the warning assembly  456 , in communication with another. Further, the user interface system  450  places the keyboard assembly  300  and its associated subcomponents in communication with a computer  452 .  
         [0130]     The computer may be a well-known computer  452  adapted to send and/or receive data from the keyboard assembly  300 , and therefore will not be described further herein for the sake of brevity. The controller  454  is adapted to send and/or receive signals from the keyboard assembly  300 , its associated subcomponents, and/or a user, and control the operation of the keyboard assembly  300  and sensor assemblies  370  and  372  in accordance with the information received. For instance, a user may select and enter a predetermined threshold sensor value, i.e., the level at which the sensor assemblies will indicate detection of a cleaning fluid.  
         [0131]     The user may select and enter a predetermined time value in which the first sensor assembly  370  detects a cleaning fluid, the second sensor assembly  372  must detect a cleaning fluid or a failed cleaning evolution will be indicated. The user may also select and enter predetermined times or events in which cleaning will be required, such as upon boot up of a computer associated with the keyboard, upon a change in users, a predetermined duration after a logged successful cleaning, a certain time of the day/week/month/year, etc.  
         [0132]     The user may also select the manner in which data is sent to the user, i.e., via audio alarm, visual alarms and or messages, functional (locking out of keyboard), physical alarms (vibration), data reports, etc. The user may also select the parameters or format of the data sent to the user (a few suitable examples being the volume of audible alarms, the frequency and pattern of beeps, etc.), the characteristics of the visual alarms (a few suitable examples being selecting an image to be displayed, frequency and pattern of flashes of light, etc.)  
         [0133]     The user may also select and enter if a message (and what message) should be sent to the computer for display to the user related to cleaning of the keyboard. A few suitable examples would be indicating that cleaning is required, that cleaning has been completed, when the next scheduled cleaning is to take place, instructions for cleaning, etc.  
         [0134]      FIG. 21  illustrates one embodiment in which the user interface system  450  has a graphical user interface  460  through which the user can enter data to control the operation of the keyboard assembly  300 . The illustrated graphical user interface  460  is a software program that can be installed on the computer, embedded in the keyboard hardware, or otherwise operably connected to the computer. Graphical user interfaces are well-known in the art and therefore will not be described further herein for the sake of brevity. It should be appreciated by those skilled in the art that a graphical user interface could be modified to allow a user to send and/or receive a wide variety of signals and data as dictated by the user&#39;s needs.  
         [0135]     The operation of the controller  454  in controlling the sensor assemblies  370  and  372  will now be described. A predetermined threshold sensor value may be entered through the graphical user interface  460  via the keyboard assembly  300  or any other suitable means. The controller  454  then records the predetermined threshold sensor value.  
         [0136]     After a signal is received from the sensor assembly  370  from one of the sensor groups indicating a potential sensing of a cleaning fluid, the controller  454  analyzes the signal received relative to the predetermined threshold sensor value to determine if the signal received exceeds the predetermined threshold sensor value. If the value of the signal received exceeds the predetermined threshold sensor value then a “cleaning fluid detected” or “sensor has been wiped” at the right sensor group is recorded.  
         [0137]     If the value of the signal received does not reach the predetermined threshold sensor value, then a “failed cleaning fluid detection” is recorded. This process is repeated for the left sensor group. After a cleaning fluid detected signal is received by both the left and right sensor groups by the controller, the controller  454  compares the duration of time between receipt of the cleaning fluid detected signals. If this value is less than a predetermined time cycle value entered by the user, then a successful cleaning action is indicated by the controller via the warning assembly  456 . If this value is more than the predetermined time cycle valve entered by the user, then a failed cleaning action is acknowledged by the controller  454  and no change in cleaning state or operation of the keyboard is initiated.  
         [0138]     Although the controller  454  is depicted as a separate component from the keyboard assembly  300  in the illustrated embodiment, it should be noted that the controller  454  may be located in any suitable location. For instance, the controller  454  may be an integral component or group of components of the keyboard assembly  300 , or may be a software program running on the computer.  
         [0139]     Operation of the key board assembly  300  is further understood by reference to  FIGS. 22A and 22B . A user will power on the keyboard, indicated by the start block  500 . This initiates the warning trigger sources described above and referred to by the block  502 . The user may optionally turn on the back-lit key board feature, indicated by the decision block  504 . If the user activates the back-lit key feature, the intensity of the lighting level may be adjusted, indicated by the block  506 .  
         [0140]     The keyboard is scanned to determine whether or not it is in the “clean mode,” indicated by the decision block  508 . If the keyboard is not in the “clean mode,” the user may press the activation button  600  ( FIG. 9 ) and indicated by the decision block  510 . If the activation button  600  is pressed by the user, then the clean mode indicator light or status light  602  is activated and indicated by the block  512 . This also starts the clean mode time out timer, designated by the block  514 .  
         [0141]     As described above, the clean mode system is operational for only a predetermined period of time and decision block  516  assess whether or not this time has expired. If the time has not expired, then the keyboard remains in the clean mode until the user represses the activation button  600 , indicated by the block  518 . If the user has pressed the activation button  600 , then the clean mode indicator or status light  602  is turned off, indicated by the block  520 .  
         [0142]     The operational flow diagram continues to the decision block  522  to determine whether any one of the triggering events has occurred. If the triggering event has occurred, then the warning indicator, such as the warning light  604 , is activated, as set forth in the block  524 . Also, an optional data warning report may be trigger, indicated by the block  526 .  
         [0143]     Referring to  FIG. 22B , if the trigger event has occurred and the warning for cleaning is activated, the sensors are monitored to determine whether or not they have been wiped, indicated by the decision block  528 . If the sensor has been wiped, then the sensor interval timer, indicated by the block  530  is initiated. As set forth in the decision block  532 , the interval is monitored to determine whether the interval period has expired. The timer may be set for any range of time, such as between one second up to three minutes or more, with a preferred range being about 20 seconds. As noted above, this represents the period of time in which (if the keyboard includes more than one sensor) all sensors must be wiped for a satisfactory cleaning.  
         [0144]     If the timer has expired, then the sensor interval timer is reset, as indicated by the block  530 . In the event that the sensor interval timer has not expired, the sensor is monitored to determine whether or not it meets the threshold condition (i.e., has been wiped), indicated by the block  534 . If the second sensor has not been wiped, the sensor interval timer is reevaluated to determine whether or not the interval timer has expired.  
         [0145]     It should be noted that this portion of the flow diagram is repeated for the number of sensors embedded in the keyboard. As a non-limiting example, if the keyboard assembly includes five sensors, then each sensor must be evaluated within the allotted time to determine whether all sensors have been wiped clean.  
         [0146]     Still referring to  FIG. 22B , if the sensor, indicated in block  534 , meets the threshold, then the warning indicator is turned off, indicated by the block  536 . The warning triggers are reset, indicated by the block  538 , and finally a cleaning date report may be generated, indicated by the block  540 .  
         [0147]     While illustrative embodiments have been illustrated and described, it will be appreciated that various changes can be made therein without departing from the spirit and scope of the presently claimed subject matter.