Impact absorbing keyboard, contoured to the natural shape of the hand

An attachment to or a keyboard itself or other devices which require extending the fingers and hands so as to reach keys of the device. The invention includes at least one key pillow. The key pillow either replaces or fits over at least one key of a keyboard or other such device to advantageously alter the consistency, texture, shape, or height of the traditional key to which the key pillow corresponds. The key pillow is shaped so as to extend into the comfort zone of a user to thereby minimize the stretching and twisting required of the user's fingers, hands, wrists, and arms. The key pillow may be applied to a keyboard of a portable computer, where the at least one key pillow is inflatable. The at least one key pillow may also be applied to devices such as a computer mouse. The key pillow must extend into a comfort zone of the user. Also, a palm rest is designed so as to maintain the user's hands at a certain height above the lip of the keyboard, which may or may not include key pillows. The palm rests have a height which reduces the introduction of tension into the user's arms and upper body and thus, are suitable for reducing the occurrence of carpal tunnel syndrome and other RSIs. The palm rest may be formed in combination with the keyboard or totally separate therefrom.

BACKGROUND OF THE INVENTION
 1. Field of the Invention
 The present invention relates to keyboards and other devices which require
 manipulation via extension of the fingers, and in particular to a keyboard
 designed to minimize stress and injury related to carpal tunnel syndrome
 and other repetitive stress and strain injuries.
 2. Description of Related Art
 Incidents of Repetitive Strain Injuries (RSI), also known as Cumulative
 Trauma Disorder (CTD), such as Carpal Tunnel Syndrome (CTS) are increasing
 at an astronomical rate, affecting nearly two million workers annually and
 costing an estimated $20 billion per year in workers' compensation,
 medical benefits, and lost wages. RSI to the upper extremities results, in
 part, from the repetitive reaching, stretching, bending, flexing, and
 twisting of fingers. Maintaining the wrist in an awkward position during
 these repetitive motions increases the likelihood of injury. Holding the
 body and upper extremities in a static position (either sitting or
 standing) associated with keyboard use and data input also increases the
 likelihood of injury. Over time, these awkward repetitive motions can
 inflame soft tissue, creating pressure on various nerves and causing pain,
 numbness, and tingling sensations in the upper extremities. RSI may result
 in pain, numbness, weakness, or loss of dexterity or use of the hands and
 fingers.
 Computer keyboard operators such as secretaries, data entry personnel,
 computer programmers, and journalists are among the most frequent victims
 of RSI. From the standpoint of typing speed, keyboards have advantageously
 evolved to the point where pauses in typing required by typewriters for
 carriage returns, paper feeds, and manual error corrections are no longer
 required While disadvantageous from an efficiency standpoint, these typing
 pauses provided breaks in the repetitive motions associated with typing.
 Consequently, the occurrence of repetitive strain injuries was much lower
 than it is today.
 Despite the increased efficiency of the keyboard, the evolution of the
 keyboard from a health standpoint has been largely overlooked. With a
 conventional keyboard, the palms "float" in the air or rest on the desk or
 a conventional wrist rest located in front of and below the keyboard. With
 a conventional wrist rest, the wrist is forced to bend upwards to place
 the fingers on and depress the keys. Consequently, the muscle and tendons
 in the hands, arms, neck, and shoulders must continually support the
 fingers at this upward angle. Maintaining this position while typing for
 an extended period of time can strain the muscles and tendons of the
 hands, arms, neck, and shoulders and significantly contributes to
 repetitive strain injuries.
 Additionally, many keyboards today have a non-linear relationship between
 the force applied to a key relative to the downward distance a key travels
 during a key stroke. That is, many keyboards require a relatively large
 force to initiate a key stroke, but require a relatively small force on
 the keyboard key for the remainder of the stroke. The result is that often
 a greater force than necessary is applied to a key during the latter
 portion of the key stroke, and the abrupt beginning and end of the stroke
 results in an impact or shock and vibration on the fingers. While this
 effect is relatively insignificant in striking a single key, the
 cumulative effect of these forces, vibrations, and shocks from continuous
 typing can aggravate nerves and soft tissue in the upper extremities to
 the point that CTS and other repetitive strain injuries can occur.
 Commercially available keyboards that attempt to address some of these
 issues do so by changing the layout of the keys. These keyboards are
 intimidating and inhospitable to typists who are used to the traditional
 layout and have failed to gain popularity.
 Moreover, conventional wrist rests are available that support the fingers
 and hands of the user above the keys of the keyboard. Such conventional
 wrist rests also may be attached to the keyboard or sloped away therefrom.
 Known wrist rests may be formed of soft or hard material.
 SUMMARY OF THE INVENTION
 It is therefore an advantage of the present invention to provide a keyboard
 or an attachment thereto substantially alleviating many of the causes of
 CTS and other related repetitive strain injuries.
 It is a further advantage of the present invention to provide a keyboard or
 an attachment thereto including pads for elevating the palms and
 preventing an awkward, strained angle between the fingers and lower arm.
 It is another advantage of the present invention to provide soft key
 surfaces to alleviate much of the impact and shock and vibration occurring
 on the fingers during a keyboard stroke in conventional keyboards.
 It is still a further advantage of the present invention to provide a
 keyboard with key pillows that either adhere to or replace the keys of a
 keyboard. The key pillows are shaped so as to extend into a comfort zone
 of a user. The comfort zone is defined as the zone into which the fingers
 of a user extend as they travel comfortably between key pillows or
 conventional key tops. Travel through this comfort zone is defined as the
 natural movement of the fingers. Although some extension of the fingers
 will always be necessary to strike the key pillows, the fact that the key
 pillows extend into the user's comfort zone keeps such extension to a
 minimum. This minimum reaching of the fingers is also known as the natural
 movement of the fingers and hands. The shape of the key pillows is
 designed to minimize the reaching, stretching, and twisting that may
 result in strain.
 It is another advantage of the present invention to provide a comfortable,
 anti-skid key surface to reduce the force required to actuate a key. That
 is, the surface of the key pillows may provide a surface with a larger
 coefficient of friction than is found on a normal keyboard.
 It is a further advantage of the present invention to provide a solid,
 continuous layer over a keyboard to prevent dirt, dust, fluids and other
 particulates from entering between the keys of the keyboard.
 It is also an advantage of the present invention to redistribute or
 increase the surface area of the keys in order to allow the typist to vary
 his or her hand position, but still effectively strike the keys.
 These and other advantages are accomplished by the present invention, which
 in a preferred embodiment relates to an adaptation to a conventional
 keyboard, including a single keypad or a plurality of pads, or key
 pillows. The key pillows can replace or fit over the existing keys of a
 conventional or nonstandard keyboard to advantageously alter the
 consistency, texture and/or shape of the traditional keys. As noted above,
 the key pillows are formed of varying heights and shapes so as to extend
 into the comfort zone of a user. In alternative embodiments, the key
 pillows may be formed into a tablet to replace or fit over the keyboards.
 The invention further includes raised pads at the front of the keyboard on
 which the palms may rest during typing to reduce the bend or sag in the
 wrists, and to support the weight of the hand and arm. Such palm rests may
 be formed integrally with a keyboard or be separate from the keyboard.
 They may accompany a keyboard employing any key shape including key
 pillows and conventional keys.
 The key pillows elevate and reshape the keys including the space bar of a
 traditional keyboard into a sculpted form to better accommodate the
 varying lengths, strengths, and dexterities of the fingers. For example,
 the outer keys which are depressed by the shorter pinky and ring fingers
 are raised and shaped so as to extend toward the center of the keyboard,
 to thereby reduce twisting, and stretching of the fingers typically
 necessary to strike those keys. Further, the space bar may be elevated to
 reduce the motion required of the wrist and/or thumb in striking that bar.
 This puts the keys into the comfort zone of a user. That is, the user has
 to extend his or her fingers less than with conventional keys to reach the
 key pillows on the keyboard, thereby reducing stress on hands, fingers,
 and the upper extremities of a user, thereby reducing the likelihood of
 repetitive stress injury.
 The surfaces of each key pillow are preferably soft and shock absorbent to
 reduce shock to the fingers upon a keystroke, and are also preferably
 textured to reduce slippage and the force required to activate a
 particular key. Where each key pillow is part of a key pillow tablet, the
 entire tablet may be formed of a soft, shock absorbent, textured surface,
 or such soft, shock absorbent, textured surfaces may only be provided on
 the key pillows of the tablet. Alternatively, the key pillow tablet may be
 formed of a particular material, and a soft, shock absorbent, textured
 material may be provided on the top surfaces of the key pillows of the
 tablet.
 The present invention significantly reduces the risk of CTS and other
 repetitive strain injuries, is more comfortable to use than conventional
 keyboards, and is easy for a typist to learn to use. First, the raised
 palm rests support a typist's palms and reduce the muscle and tendon
 strain associated with typing with the wrist bent at an awkward angle. The
 raised palm rests also relieve strain and tension in a typist's hands by
 supporting the weight of the arms and shoulders during typing or resting.
 This additional support reduces the likelihood of nerve irritation and
 damage and reduces the risk of tendon and soft tissue inflammation within
 the wrists and throughout the upper extremities. Second, by varying the
 shape of the key pillows, the typical reaching, twisting, and stretching
 of the fingers to depress the keys of a conventional keyboard will be
 reduced, thereby further reducing the strain on the muscles and tendons in
 the upper extremity. Third, by providing the keys with a shock absorbent
 and textured upper surface, the shock and vibration to which the fingers
 are subjected on each keystroke is reduced.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EXEMPLARY EMBODIMENTS
 The invention will now be described with reference to FIGS. 1-4 and 6-7
 which in general depict a keyboard 20 having a length and width
 approximating that of a conventional full-sized keyboard (e.g.,
 approximately 20 inches by 8 inches). Other dimensions may be used in
 alternative embodiments such as that shown in FIGS. 5A and 5B, which
 depict a device intended for use with a portable computer or other device,
 such as medical or geological equipment, which require portability, and
 thus may require a smaller or thinner keyboard. The keyboard 20 shown in
 FIG. 1 may have a standard or non-standard keyboard layout of alphanumeric
 keys. The preferred embodiment includes a standard QWERTY layout. Common
 commercial adaptations of the standard layout include the AT keyboard
 layout, XT keyboard layout and APPLE MACINTOSH.RTM. keyboard layout.
 Non-standard keyboard layouts include for example splitting the standard
 layout into two halves, angled with respect to each other, such as for
 example the Natural Keyboard manufactured by MICROSOFT.RTM. Corporation.
 It is understood that the present invention may be adapted to work with
 any of the various known or future keyboards. Additionally, it is
 contemplated that the present invention may be used on other devices that
 use keys, including but not limited to, musical instruments, cash
 registers, calculators, adding machines, telephones, stenographic
 machines, and computer mice as shown in FIG. 8. Any device that could be
 the source of repetitive strain injury or would be made more comfortable
 by the addition of key pillows is a candidate for use with the present
 invention.
 Referring now to FIGS. 1-4, there is shown a keyboard 20 including an
 attachment 22 affixed thereon. Attachment 22 may include raised pads 24a
 and 24b for supporting the palms, and at least one key pillow 26 fitting
 over or replacing the respective key on the keyboard. A base material 28
 may surround and attach each of the key pillows 26 and pads 24a and 24b,
 so that the attachment 22 forms a continuous cover over the keyboard 20.
 The attachment may be formed with elastic straps to hold the attachment on
 the keyboard. Thus, the attachment may be easily removed, cleaned, and
 replaced. Other known fastening systems may alternatively be used. In a
 preferred embodiment of the invention, the lower surface of the attachment
 is formed with negative impressions of the keys of keyboard 20, to enable
 the attachment to fit over the keyboard keys. The upper surface of the
 attachment includes the key pillows 26 directly over the keys of the
 keyboard 20, which key pillow are formed to various heights and
 inclinations as explained hereinafter.
 In a preferred embodiment of the invention, the negative impression for
 each key on the underside of the attachment is formed such that the
 attachment extends partially over the keys of the keyboard, i.e., so that
 the attachment extends partially down along the vertical sides of each
 key. However, it is understood that the negative impression for each key
 on the underside of the attachment may be formed to a depth so that the
 attachment fits substantially entirely over the keys of keyboard 20.
 Moreover, in a further embodiment of the invention, the bottom surface of
 attachment 22 may be substantially flat, without any impressions. In this
 embodiment, the attachment may simply lie on top of each of the keys of
 keyboard 20. This latter embodiment may additionally have small brackets
 formed on the underside of the attachment, which brackets entirely or
 partially surround each key of the keyboard to assist in keeping the key
 pillows 26 aligned over their respective keys. Alternatively, this latter
 embodiment may be secured to the respective keys of keyboard 20 by an
 adhesive.
 The attachment has thus far been described as fitting over keys of a
 conventional keyboard. However, in a further embodiment of the invention
 as shown in FIG. 1, the invention may replace one or more of the keys of a
 keyboard. In this embodiment, an attachment with a negative impression or
 each post on the underside of the attachment may be formed to a depth so
 that the attachment may be fitted directly over the posts on which the
 keys are mounted in conventional keyboards. In any of the above-described
 keyboard and attachment embodiments, the attachment may simply rest over
 or on top of the keys or posts of the keyboard. Alternatively, an adhesive
 may be applied to the underside of the attachment so that the attachment
 is fixedly held in place over or on top of the keys or posts of the
 keyboard.
 As mentioned above, the keys of a conventional keyboard may be replaced by
 key pillows 26, with the key pillows 26 acting as the keys of the
 keyboard. Thus, when a key pillow 26 is pushed down, the respective key
 switch, i.e. the electrical connection, is actuated. The attachment is the
 keyboard, and thus, the present invention replaces a conventional
 keyboard.
 In a preferred embodiment, each of the key pillows 26 may be formed of a
 soft, shock absorbent material, such as, for example, silicone, rubber,
 latex, urethane, foam, molded and filled spandex, or any combination of
 these materials. It is understood that the key pillows 26 may be formed of
 other hard or soft materials in alternative embodiments of the invention.
 As explained in the Background of the Invention section, due in part to
 the larger force required to initiate a key stroke as compared to the
 remainder of the stroke, a greater force is applied downward on the keys
 by the fingers than the upward force of the keys during the latter portion
 of a keystroke. This results in an impact or shock as well as vibration to
 the fingers at the top and bottom of each key stroke. The shock absorbent
 material from which the key pillows 26 may be formed can greatly reduce
 the shock and vibration received by the fingers.
 The upper surfaces of key pillows 26 are preferably textured to reduce the
 likelihood of a finger slipping on a key, and to reduce the force
 necessary to depress a key. As would be appreciated by those skilled in
 the art, the key pillows may be textured in various configurations,
 including, for example, nubs, ridges, fine bristles, or the character(s)
 appearing on the key being raised relative to the key surface. In a
 preferred embodiment, a representative outline of the alphanumeric
 character or function associated with a particular key may be indicated on
 the upper surface of the key pillow located thereon. The upper surface of
 the key pads may additionally or alternatively be covered with or made of
 slip resistant material.
 As previously indicated, the height and shape of key pillows 26 on top of
 keyboard 20 vary with respect to each other. In one embodiment, the key
 pillows in the home row and row thereabove (i.e., the rows starting with
 "a" and "q", respectively) of a conventional QWERTY keyboard served by the
 pinky and ring finger (i.e., "q", "w", "tab", "caps lock", "shift",
 "control", "z", and "x" or "p", "o", "[", "]", """, "shift", ";", "enter",
 ",", ".", and "/") may extend higher and moreso than other keys on the
 keyboard as shown in FIG. 1, so as to be in the comfort zone of a user.
 The key pillows in the home row and row thereabove served by the pinky and
 ring fingers may additionally or alternatively have surfaces that are
 angled inward toward the center of the row or angled outward away from the
 center of the row. The keys in the row above the home row may additionally
 or alternatively have surfaces angled downward toward the home row (i.e.,
 the row beginning with "a") so as to physically position the keys closer
 to the shorter pinky and ring fingers. In a preferred embodiment of the
 invention, the key pillows in the home row and row thereabove served by,
 and farthest from, the pinky and ring finger may include the greatest
 angle of inclination inward toward the center or downward toward the home
 row or even away from the home row. Providing these key pillows with a
 greater extension into the comfort zone relative to other surrounding key
 pillows makes it easier to strike these keys by minimizing the repetitive
 stretching, twisting, and reaching of the shorter pinky and ring fingers.
 This, in turn, reduces the strain experienced by muscles and tendons in
 the lower arm, neck, and shoulder while typing.
 In a preferred embodiment, the surfaces of the remaining key pillows in the
 home row and row thereabove may also be extended downward toward the home
 row as shown in FIG. 1. Moreover, the key pillow covering the space bar
 may include one or more elevated sections, against which the thumb may
 strike. By providing one or more raised surfaces over the space bar, the
 amount by which the hand must rotate and/or the amount by which the thumb
 must extend to depress the space bar is reduced. Again, inclining or
 elevating the surfaces of the above described key pillows makes it easier
 to depress these keys by minimizing the repetitive stretching, twisting,
 and reaching of the fingers. This, in turn, reduces the strain experienced
 by muscles and tendons in the lower arm, fingers, hands, neck, and
 shoulder while typing. Although a preferred embodiment includes key
 pillows with elevated and inclined surfaces, it is contemplated that the
 key pillows have even and substantially parallel upper surfaces, used in
 conjunction with other inventive features of the present invention, in
 alternative embodiments. Additionally, it is contemplated that each key
 have the same shape, contour and inclination in an alternative embodiment
 of the invention. By surfaces of the key pillows as used above to define
 the shape of the key pillows, this language is intended to describe the
 three-dimensional surface of the key pillows, and not simply the upper
 surfaces of the key pillows. Thus, it could be said that the key pillows
 have a sculpted form that extends into the comfort zone of a user.
 The present invention further includes raised pads 24a and 24b shown in
 detail in FIG. 7. The pads are preferably formed integrally on attachment
 22, but may alternatively be affixed to attachment 22 after formation
 thereof. It is also possible that the pads 24a and 24b are simply
 manufactured separately from the attachment 22 and later connected thereto
 or placed proximate to the keyboard in a position comfortable to the user.
 The pads 24a and 24b are preferably slightly deformable so that the thenar
 eminence and hypothenar eminence of the hands may rest comfortably
 thereon, and may be formed of the same or different material as attachment
 22 or individual key pillows 26. In a preferred embodiment, the pads may
 have a height of approximately 0.5 inches to approximately 3 inches, and
 optimally about 1 inch to about 2 inches. That is, in the preferred
 embodiment, the pads have a varying height across their width. The heights
 listed above may vary in alternative embodiments of the invention so as to
 accommodate hands of different users, which vary in size. Alternatively,
 the pads may be uniform in height. The pads may be shaped so as to
 accommodate the contour of the hand or have a dip to avoid pressure on the
 carpal tunnel. Although a preferred embodiment of the invention includes
 two pads, it is understood that there may be one long pad along the front
 of keyboard 20, or a pad comprised of several segments. The pads function
 to elevate a typist's palms relative to the keyboard during typing or
 resting. That is, the pads 24a and 24b maintain the user's palms at a
 height above the lip of the keyboard. The pads additionally support the
 weight of a typist's hands, arms, and shoulders, thereby reducing strain
 at the neck and shoulders. The pads preferably suspend the palms so that
 the palms of the user are at a height greater than the lip of the
 keyboard. The lip of the keyboard is that portion of the keyboard between
 the front of the space bar and the front of the keyboard, with the front
 being the edge closest to the typist while maintaining a typing position.
 As indicated in the Background of the Invention section, extended typing
 with the wrists bent at an awkward angle is a significant contributor to
 CTS and other repetitive strain injuries. The height of the palm rests
 allows the user to comfortably manipulate the key pillows 26 or
 conventional keys and easily rest his/her hands while reducing awkward
 bending of the wrist. Although a preferred embodiment includes pads 24a
 and 24b, it is contemplated that the pads may be omitted from the
 invention in alternative embodiments. The pads 24a and 24b preferably have
 a groove 24a-1, 24b-1 formed therein to accommodate the thumb or thenar
 eminence of the user to allow the user to more easily access the space bar
 and keys or key pillows of the keyboard. Also, each palm rest may have a
 central dip 24b-2 located therein for support of the carpal tunnel.
 The invention has thus far been described as an attachment to a keyboard
 including a plurality of key pillows 26 and/or pads 24a and 24b provided
 on an attachment 22 to form a continuous sheet over the keyboard. However,
 in an alternative embodiment of the present invention, instead of forming
 a continuous attachment, each of the key pillows may be independent
 pieces, which may be added to select keys on keyboard 20 as desired. In
 this embodiment, each individual key pillow may include a lower surface
 having a negative impression fitting partially or completely over select
 keys, and maintained thereon by a pressure contact between the key pillow
 26 and key. Alternatively, the individual key pillows 26 may have a flat
 lower surface, and may be affixed to select keys by an adhesive. It is
 possible that only the keys farthest outside of the user's comfort zone
 will have key pillows affixed thereto. As a further alternative, selected
 keyboard keys may be omitted or removed, and the individual key pillows
 mounted over the key posts protruding from the keyboard. The individual
 key pillows according to this embodiment may be formed with the same
 materials, textures, elevations, shapes, or inclinations as the key
 pillows described above as part of attachment 22.
 In the embodiment described in the preceding paragraph, the pads 24a and
 24b may be affixed to the front edge of the keyboard by a pressure fit, an
 adhesive, or both. It is equally possible that the pads 24a and 24b are
 not fixed to the keyboard, but rather are simply used proximate the
 keyboard. It is also possible that only a single palm rest is used, rather
 than two palm rests. Such would be the case where the user is operating a
 mouse, such as that shown in FIG. 8, with a single hand.
 When the key pillows are attached to selected individual keys of the
 keyboard, the key pillows of the selected keys still extend into the
 comfort zone of a user. That is, the key pillows are shaped so as to be
 easily reached by the fingers and hands of a user without undue stretching
 or twisting of the fingers, hands, and wrists, thereby decreasing the
 user's chances of incurring a RSI such as Carpal Tunnel Syndrome.
 As an alternative embodiment, the keyboard may be formed as a attachment 22
 shown in FIG. 1. The key pillows 26 are formed thereon and replace the
 keys of the keyboard 20. As shown in this drawing, the palm rests 24a and
 24b are integral with the attachment 22, which acts as the keyboard 20.
 Also, the palm rests according to the present invention as shown in FIG. 7
 may be used with a conventional keyboard as shown in FIG. 7.
 In an alternative embodiment, the keyboard is formed to have only a single
 key pillow formed thereon. Such a device is shown in FIG. 6, where the key
 pillow 26 is formed only on the space bar. Although other keys might have
 the single key pillow 26 thereon, the key that includes the key pillow is
 usually one that is used often, such as the space bar, the shift key, or
 the enter button.
 The keys of the keyboard may be formed as shown in FIGS. 2-4. FIG. 2
 illustrates key pillows which extend into a comfort zone of a user and
 whose shape is that of a plurality of line segments 44 joined together to
 form a continuous semi-curved surface. Alternatively, as shown in FIG. 3,
 the key pillows could be formed as two blocks, 40 and 42, that intersect
 at an angle of up to 90.degree.. Alternatively, as shown in FIG. 4, the
 key pillows could be formed with a flat top surface 46 and an arcuate stem
 48. Regardless as to the method of key formation, every key will provide a
 striking surface 30 that may be pressed or struck to acuate the key. Any
 and all of these key pillows shown in FIGS. 2-4 could be incorporated into
 a single keyboard. As shown in FIG. 1, key pillows corresponding to those
 shown in FIG. 2 are labelled 26-2, those corresponding to FIG. 3 are
 labelled 26-3, and those corresponding to FIG. 4 are labelled 26-4.
 FIGS. 5A and 5B illustrate another embodiment of the present invention,
 which is particularly useful for portable computers 50 and other portable
 devices which incorporate CPU's and require some input through a keyboard.
 A laptop computer is depicted in FIG. 5A. The keyboard with the key
 pillows formed thereon is inflatable through an inlet 52. It is also
 possible to have the keyboard automatically inflate. Thus, the keyboard
 may be deflated as shown in FIG. 5A for easy carrying. When inflated, as
 shown in FIG. 5B, the key pillows 56 are shaped as shown in FIGS. 2-4 and
 the keyboard as in FIG. 1. When deflated, the keyboard packs away for easy
 storage.
 As noted above, the present invention may be utilized on devices other than
 keyboards. Computer mice are just such an example. Mice are getting more
 and more complicated and are being sold with several, i.e., three or more,
 keys thereon. Use of computer mice can also be a significant source of
 RSI. FIG. 8 illustrates the present invention as applied to computer mice.
 The mouse is shown with key pillow 86 formed thereon, with the key pillow
 extending into the comfort zone of a user.
 Although the invention has been described in detail herein, it should be
 understood that the invention is not limited to the embodiments herein
 disclosed. Various changes, substitutions and modifications may be made
 thereto by those skilled in the art without departing from the spirit or
 scope of the invention as described and defined by the appended claims.