PATENT DOCUMENT

Publication Number: US-8319128-B2
Application Number: US-15136308-A
Country: US
Kind Code: B2

Title: System and methods for electronic device keyboard illumination

Abstract:
A keyboard may be generally illuminated while also providing for key-specific illumination of one or more particular keys. The keyboard may be generally illuminated using any configuration of any number of suitable illumination sources. The keyboard may selectively illuminate any key or keys together with or apart from the general illumination of other keys. The keyboard may also variably illuminate certain keys to aid the user in navigating the keyboard.

Claims:
1. A keyboard comprising:
 a plurality of keys; and 
 a flexible circuitry layer positioned under the plurality of keys, wherein the flexible circuitry layer includes a plurality of illumination sources, wherein at least a first one of the illumination sources is adapted to illuminate only a first key of the plurality of keys, wherein at least a second one of the illumination sources is adapted to generally illuminate at least two keys of the plurality of keys, and wherein one of the at least two keys is the first key. 
 
     
     
       2. The keyboard of  claim 1 , wherein at least one of the illumination sources is larger than at least one other of the illumination sources, and wherein at least some of the light emitted by the at least one of the illumination sources travels beyond the position of the at least one other of the illumination sources. 
     
     
       3. The keyboard of  claim 1 , further comprising at least one reflective surface for reflecting light emitted by at least one of the illumination sources. 
     
     
       4. The keyboard of  claim 3 , further comprising a base layer positioned under the flexible circuitry layer, wherein the base layer includes the at least one reflective surface. 
     
     
       5. The keyboard of  claim 1 , further comprising a transparent layer positioned between the plurality of keys and the flexible circuitry layer, wherein the transparent layer includes at least one hole for passing at least one of the illumination sources at least partially through the transparent layer. 
     
     
       6. The keyboard of  claim 1 , further comprising a transparent layer positioned between the plurality of keys and the flexible circuitry layer, wherein the transparent layer contains at least one slot for at least one of reflecting the light emitted by at least one of the illumination sources and preventing the light emitted by at least one of the illumination sources from diffusing beyond the slot. 
     
     
       7. A keyboard comprising:
 a plurality of keys; 
 a keyboard membrane layer positioned under the plurality of keys; and 
 a transparent layer positioned under the keyboard membrane layer, wherein the keyboard membrane layer includes at least a first keyboard membrane illumination source configured to emit light into the transparent layer. 
 
     
     
       8. The keyboard of  claim 7 , wherein the first keyboard membrane illumination source is adapted to one of illuminate a specific portion of the plurality of keys and generally illuminate the plurality of keys. 
     
     
       9. The keyboard of  claim 7  further comprising at least one reflective surface to reflect the light emitted by the first keyboard membrane illumination source. 
     
     
       10. The keyboard of  claim 9 , further comprising a base layer, wherein the transparent layer is positioned between the keyboard membrane layer and the base layer, and wherein the base layer includes the at least one reflective surface. 
     
     
       11. The keyboard of  claim 7 , further comprising a flexible circuitry layer positioned under the transparent layer, wherein the flexible circuitry layer includes at least a first flexible circuitry layer illumination source configured to emit light into the transparent layer. 
     
     
       12. The keyboard of  claim 11 , wherein the first keyboard membrane illumination source is adapted to illuminate at least one specific portion of the plurality of keys, and wherein the first flexible circuitry layer illumination source is adapted to generally illuminate the plurality of keys. 
     
     
       13. The keyboard of  claim 11 , wherein the first keyboard membrane illumination source is adapted to generally illuminate the plurality of keys, and wherein the first flexible circuitry layer illumination source is adapted to illuminate at least one specific portion of the plurality of keys. 
     
     
       14. The keyboard of  claim 7 , wherein the transparent layer includes at least one slot for at least one of reflecting the light emitted by the first keyboard membrane illumination source and preventing the light emitted by the first keyboard membrane illumination source from diffusing beyond the slot. 
     
     
       15. A keyboard comprising:
 a plurality of keys; 
 at least a first source reflective surface; and 
 a flexible circuitry layer positioned under the plurality of keys, wherein the flexible circuitry layer includes at least a first illumination source, wherein the first illumination source primarily emits light in a first direction along a first plane substantially parallel to the flexible circuitry layer, and wherein the first source reflective surface primarily reflects the emitted light in a second direction along the first plane.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This claims the benefit of U.S. Provisional Application No. 61/009,961, filed Jan. 4, 2008, which is hereby incorporated by reference herein in its entirety. 
    
    
     FIELD OF THE INVENTION 
     This invention can relate to systems and methods for improved keyboard illumination. 
     BACKGROUND OF THE DISCLOSURE 
     Currently, there are a wide variety of known electronic devices that include a keyboard as a user interface component (e.g., cellular telephones and personal computers). The keyboard of many of these devices can be illuminated such that a user may be able to see and use the keyboard when provided with little or no ambient light. For example, some known devices include a light source, such as a light emitting diode (“LED”), underneath each of a plurality of the keys of the keyboard. Alternatively, some known devices include only a few light sources, but diffuse the light in such a way that each of the keys of the keyboard are illuminated. 
     However, these light sources can add an undesirable additional weight to the electronic device which can undesirably increase the thickness of the electronic devices. Therefore, it would be beneficial to provide systems and methods for improving the illumination of an electronic device keyboard while reducing the thickness and weight. 
     SUMMARY OF THE DISCLOSURE 
     Improved systems and methods for electronic device keyboard illumination are provided. In one embodiment, a keyboard includes a plurality of keys and a flexible circuitry layer positioned under the plurality of keys. The flexible circuitry layer includes a plurality of illumination sources for generally illuminating the plurality of keys, wherein each one of the illumination sources is positioned to emit light in the plane of the keyboard, and wherein at least a first one of the illumination sources is positioned to primarily emit light in any direction other than a direction that is directly opposite to the direction of light primarily emitted by each of the other ones of the illumination sources. 
     In one embodiment, a keyboard includes a plurality of keys and a flexible circuitry layer positioned under the plurality of keys, wherein the flexible circuitry layer includes at least a first illumination source and at least a first source reflective surface, wherein the first illumination source primarily emits light in a first direction, and wherein the first source reflective surface is positioned at a first angle with respect to the flexible circuitry layer to reflect at least a portion of the emitted light in a second direction that is different than the first direction. 
     In one embodiment, a keyboard includes a plurality of keys and a flexible circuitry layer positioned under the plurality of keys, wherein the flexible circuitry layer includes a plurality of illumination sources, wherein at least a first one of the illumination sources is adapted to illuminate at least one specific portion of the plurality of keys, and wherein at least a second one of the illumination sources is adapted to generally illuminate the plurality of keys. 
     In one embodiment, a keyboard includes a plurality of keys, a keyboard membrane layer positioned under the plurality of keys, and a transparent layer positioned under the keyboard membrane layer. The keyboard membrane layer includes at least one illumination source configured to primarily emit light into the transparent layer. 
     In one embodiment, a method for varying the illumination of a keyboard having at least one illumination source includes presenting information with an electronic device, generating an instruction with the electronic device based on the information, transmitting the instruction to the keyboard, and altering the state of the at least one illumination source in response to the keyboard receiving the instruction. 
     In one embodiment, a system for varying the illumination of a keyboard includes a keyboard having at least one illumination source and a plurality of keys. The system also includes a processing device, wherein the processing device is configured to transmit an instruction, and wherein the keyboard is configured to alter the state of the at least one illumination source in response to receiving the instruction. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other aspects and advantages of the invention will become more apparent upon consideration of the following detailed description, taken in conjunction with the accompanying drawings, in which like reference characters refer to like parts throughout, and in which: 
         FIG. 1  shows an exploded perspective view of a keyboard assembly in accordance with some embodiments of the invention; 
         FIG. 2  shows a cross-sectional view of a portion of the keyboard assembly of  FIG. 1  in accordance with some embodiments of the invention; 
         FIG. 3  shows an exploded perspective view of a keyboard assembly in accordance with some embodiments of the invention; 
         FIG. 4  shows a cross-sectional view of a portion of the keyboard assembly of  FIG. 3  in accordance with some embodiments of the invention; 
         FIG. 5  shows a vertical cross-sectional view of a distribution of illumination sources in a portion of a keyboard assembly in accordance with some embodiments of the invention; 
         FIG. 5A  shows a cross-sectional view of a portion of the keyboard assembly of  FIG. 5  in accordance with some embodiments of the invention; 
         FIG. 6  shows a vertical cross-sectional view of a distribution of illumination sources in a portion of a keyboard assembly in accordance with some embodiments of the invention; 
         FIG. 7  shows a vertical cross-sectional view of a distribution of illumination sources in a portion of a keyboard assembly in accordance with some embodiments of the invention; 
         FIG. 8  shows a vertical cross-sectional view of a distribution of illumination sources in a portion of a keyboard assembly in accordance with some embodiments of the invention; 
         FIG. 9  shows a vertical cross-sectional view of a distribution of illumination sources in a portion of a keyboard assembly in accordance with some embodiments of the invention; 
         FIG. 10  shows a top view of a distribution of illumination sources in a portion of a keyboard assembly in accordance with some embodiments of the invention; 
         FIG. 11  shows a vertical cross-sectional view of the portion of the assembly of  FIG. 10 , but with a portion removed, in accordance with some embodiments of the invention; 
         FIG. 12  shows a perspective view of the portion of the keyboard assembly of  FIGS. 10-11  in accordance with some embodiments of the invention; 
         FIG. 13  shows a flowchart of an illustrative process for illuminating one or more keys of a keyboard assembly in accordance with some embodiments of the invention; and 
         FIG. 14  shows a simplified schematic diagram of a system including a keyboard assembly in accordance with some embodiments of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE DISCLOSURE 
     In some embodiments of the invention, general illumination of a keyboard may be provided. The keys of the keyboard assembly may be made of any suitable material, such as plastic, and one or more of the keys may have a transparent legend, a transparent face, or may be entirely transparent. The general illumination may be provided by positioning under the array of keys any number of illumination sources in any suitable arrangement, such that the light emitted by the illumination sources may diffuse under the keys and may illuminate some or all of the keys. Any number of illumination sources, including only one illumination source, may be used, and the angle or angles at which two or more illumination sources are positioned relative to one another may be any suitable size. The illumination sources may be placed anywhere within the keyboard assembly, such as directly underneath the keys on a keyboard membrane, within a light guide pipe, or on a flexible circuit but protruding into a light guide pipe. Each illumination source may be any suitable element able to emit light, such as an LED or an organic LED. In addition to illuminating a keyboard when the device is provided with little or no ambient light, the general illumination of the invention may be provided under any other suitable condition (e.g., when the keyboard is providing instructions to a particular application being run by the electronic device, or when it is determined that the keyboard is being used by a user with a visual disability, for example, in response to a user input). 
     In some embodiments of the invention, the selective illumination of certain keys of a keyboard assembly may be provided. The selective illumination may occur when any suitable number of illumination sources of the keyboard assembly are instructed to emit light in response to any suitable input, such as an electrical signal received from a computing device coupled to the keyboard assembly, a mechanical input received by the keyboard (e.g., by a keystroke), or any other suitable input. The selective illumination may include placing any suitable number of illumination sources within a keyboard assembly to illuminate one or more particular keys of interest, such as the “CAPS LOCK” key, or the “NUM LOCK” key, or any other suitable key or keys. The one or more illumination sources used to selectively illuminate particular keys may be of the same illumination source type or may even be the one or more illumination sources used to generally illuminate the keyboard. The one or more selective illumination sources may be positioned on or within any suitable layer of the keyboard assembly (e.g., on a keyboard membrane or a flexible circuit but protruding into a light guide pipe). The selective illumination may occur simultaneously with the general illumination of the keyboard. In one embodiment, the keyboard may be generally illuminated with one color while certain keys may be illuminated with one or more other colors. In another embodiment, all of the keys may be constantly illuminated with one color of a certain brightness, while certain keys may be constantly illuminated with the same color but with a greater intensity or in a different manner, such as by blinking. The selective illumination also may occur independently from the general illumination, thereby allowing particular keys on the keyboard to be illuminated at any one time while other keys remain unilluminated. 
     In some embodiments of the invention, the variable illumination of certain keys of a keyboard assembly may be provided to aid a user in navigating the keyboard. Similarly to the selective illumination, the variable illumination may occur in response to any suitable input, such as an electrical signal received from a computing device coupled to the keyboard assembly, a mechanical input received by the keyboard (e.g., by a keystroke), or any other suitable input. In response to receiving such an input, one or more illumination sources may be instructed to emit light, to stop emitting light, to change color, to blink, or to illuminate one or more keys using any suitable approach. A user may be guided in using the keyboard because the variable illumination of different keys may increase the user&#39;s efficiency in navigating the keyboard. In some embodiments, the keyboard may be generally illuminated using one color, while certain keys may be variably illuminated using one or more different colors to guide the user in choosing amongst available menu options. As another alternative, the keyboard may be generally illuminated, and certain keys may be variably illuminated using any other suitable approach (e.g., certain keys that may be useful in choosing amongst available menu options may blink, or certain keys may be more intensely illuminated than other keys illuminated on the keyboard). 
     In some embodiments of the invention, a user may be presented with a list of menu options on a display screen of an electronic device associated with a keyboard. The electronic device, which may be coupled to the keyboard, may provide electrical inputs to the keyboard. Each electrical input may contain instructions to illuminate certain keys corresponding to the list of available menu options presented on the display screen. In response to such an input, the keyboard may instruct one or more certain illumination sources to emit light such that one or more keys, or all of the keys, may be illuminated to represent available menu options to the user. The inputs from the electronic device may change in real time and the illumination of certain keys may also vary in real time. Certain other keys may not be illuminated, including those that may have been previously variably illuminated, to represent to the user that striking those keys may not result, or may no longer result, in the selection of an available menu option. 
     In some embodiments of the invention, a user may be presented with a form on a display screen of an electronic device associated with a keyboard, such as an electronic tax form. The variable illumination of one or more different keys on the keyboard may increase the user&#39;s efficiency in completing the form using the keyboard. The form may require the user to enter one or more numbers in order to complete the form and may require the user to move or “tab” between entries on the form, or perform mathematical operations with the “+,” “−,” and “.” keys. The electronic device, which may be coupled to the keyboard, may provide a device input to the keyboard instructing that the numerical keys (e.g., the number pad provided on the right side of some keyboards), the “TAB” key, and the “+,” “−,” and “.” keys on the keyboard may be illuminated. In response to such a device input, the keyboard may instruct one or more certain illumination sources to emit light to illuminate these keys such that the user may be guided in completing the form on the display screen. The remainder of the keys on the keyboard may be illuminated in any suitable manner (e.g., the remainder of the keys may be generally illuminated in another color, they may be less intensely illuminated than the keys of interest, or they may not be illuminated at all). 
     In some embodiments of the invention, different keys of a keyboard assembly may be variably illuminated using any suitable approach to help guide the user of the keyboard through any suitable task. For example, a spelling software program being run by an electronic device associated with the keyboard may instruct the keyboard to variably illuminate those keys needed to properly finish spelling a word once the user has started to type the word. As another example, a variably illuminated keyboard may illuminate the one or more keys that match the first letter of one or more filenames in a directory presented on a display screen associated with the keyboard, thereby guiding a user in selecting from available filenames. As a further example, all of the keys of the keyboard may be variably illuminated in one color associated with a particular application shown on the display screen. If a user minimizes one application associated with a particular color, and maximizes another application instead on the display screen, then the color associated with the second application may be used to illuminate the keys. 
     It is to be understood that an illumination source may emit light in many directions simultaneously. Reference herein to an illumination source emitting light in a particular direction is to be understood to mean that the illumination source may emit the majority of its light primarily in the referenced direction. A portion of the light emitted by the illumination source may diffuse in directions other than the one referenced herein. 
     It is also to be understood that the present invention may be employed with any digit-driven user input device. For example, reference herein to a “keyboard” may be understood to include a keyboard coupled to a desktop computer, a keyboard included within a laptop computer or other portable computing device, or any user input interface (e.g., a touch-screen for inputs) for any portable or wired electronic device, such as a pocket-sized personal computer such as an iPAQ Pocket PC available by Hewlett Packard Inc. of Palo Alto, Calif., a personal digital assistant (“PDA”), a personal e-mail or messaging device with audio and/or video capabilities (e.g., a Blackberry® or a Sidekick®), an iPhone™ or an iTouch™ available by Apple Inc., or any other suitable cellular telephone device. 
     Improved systems and methods for electronic device keyboard illumination are provided and described with reference to  FIGS. 1-14 . 
       FIG. 1  shows an exploded perspective view of a keyboard assembly in accordance with some embodiments of the invention. Keyboard assembly  100  may include base layer  110 , flex layer  120 , reflector sheet layer  125 , light guide pipe layer  130 , mask layer  140 , keyboard membrane layer  150 , keypad layer  160 , or any other suitable layer. Keyboard assembly  100  may also include one or more illumination sources, reflecting plates, and slots in one or more of its layers. Keyboard assembly  100  may also include one or more flex circuits and voltage sources. 
     Base layer  110  may at least partially be made of any suitable material for providing structural support to keyboard assembly  100 . For example, base layer  110  may be made of a plastic sheet or a metal sheet, such as a piece of aluminum or stainless steel, that may be shiny or dull. Although base layer  110  may be positioned beneath the other layers of keyboard assembly  100 , base layer  110  may not be exposed to the user. For example, if keyboard assembly  100  is part of a laptop computer, then base layer  110  may still be contained within the outer casing of the laptop. Base layer  110  may also include any suitable material that may be bent up through an opening in light guide pipe layer  130  to provide an additional reflecting surface to redirect light that may be diffusing through light guide pipe layer  130 . 
     Flex layer  120  may at least partially be made of any suitable material operative to provide support for and/or power to other layers of keyboard assembly  100 . Flex layer  120  may be of any suitable thickness and any suitable flexibility. One or more illumination sources may be positioned on flex layer  120 , but an illumination source may not need to be positioned on flex layer  120  in order to receive power from flex layer  120 . An illumination source may be positioned within light guide pipe layer  130  (described in more detail below), but may still receive power through flex layer  120 . Flex layer  120  may also include any suitable logic circuitry to process input signals received by keyboard assembly  100 . In some embodiments, flex layer  120  may provide power and support to the illumination sources of keyboard assembly  100 , while an additional flex circuit (not shown) may contain any suitable logic circuitry for processing input signals received by keyboard assembly  100 . The additional flex circuit may form any suitable layer within keyboard assembly  100 . 
     In some embodiments, flex layer  120  may contain one or more illumination sources  121 , such as sources  121   a ,  121   d ,  121   f ,  121   k ,  121   n , and  121   s  to provide general illumination to keypad layer  160  using any suitable approach.  FIG. 1  illustrates one spatial arrangement of multiple illumination sources  121  within flex layer  120 . Each illumination source  121  may be the same type of illumination source as or a different type of illumination source from another illumination source  121 . Each illumination source  121  may be positioned on flex layer  120 , but there may be a corresponding hole  127  in reflector sheet layer  125  and a corresponding hole  131  in light guide pipe layer  130  to allow each illumination source  121  to fit through the corresponding holes and emit light from the optical portion of each illumination source  121  through light guide pipe layer  130 . For example, illumination source  121   a  may fit through hole  127   a  in reflector sheet layer  125  and hole  131   a  in light guide pipe layer  130  so that the light emitted by illumination source  121   a  may diffuse through light guide pipe layer  130  (i.e. at least in the X-Y plane of light guide pipe layer  130 ) while illumination source  121   a  is physically mounted upon flex layer  120 . 
     Each illumination source  121  may be positioned anywhere within flex layer  120 , such that each illumination source  121  may emit light primarily along an axis that may form any suitable angle with an edge  132  of light guide pipe layer  130  (within the X-Y plane of light guide pipe layer  130 ). For example, an illumination source  121  may emit light primarily along an axis that is parallel with edge  132 . Although, in some embodiments, some light may be emitted upwardly towards mask layer  140  and downwardly towards reflector sheet layer  125  because an illumination source  121  may emit light in three dimensions (e.g., in X, Y, and Z directions of  FIG. 1 ). Light that may be diffused through light guide pipe layer  130  by an illumination source  121  may also diffuse upwardly through one or more openings in mask layer  140 , such as an unmasked portion  145 , and through keyboard membrane layer  150  to illuminate one or more keys  105  on keypad layer  160 . 
     Each one of illumination sources  121   a ,  121   d ,  121   f ,  121   k ,  121   n , and  121   s  may be positioned on flex layer  120  to emit light into light guide pipe layer  130  primarily along an axis parallel to edge  132  as shown. However, in some embodiments, the position of each illumination source  121  relative to another illumination source  121  may not be along a single axis parallel to edge  132 . For example, illumination sources  121   a  and  121   k  may each emit light primarily along an axis parallel to edge  132  and directed away from the middle portion of light guide pipe layer  130 , and may be positioned anywhere between illumination sources  121   d  and  121   f  and illumination sources  121   n  and  121   s , respectively. 
     Illumination sources  121   n ,  121   s ,  121   d  and  121   f  may each emit light primarily along an axis parallel to edge  132 , directed toward the middle portion of light guide pipe layer  130 , but may be positioned anywhere within flex layer  120 . As shown in  FIG. 1 , for example, illumination sources  121   n  and  121   s  may be positioned on either side of illumination source  121   k  with respect to edge  132 . But the position of illumination sources  121   n  and  121   s , relative to illumination source  121   k , may form any suitable angle with respect to edge  132 , although the light emitted by illumination sources  121   n  and  121   s  may be parallel to edge  132 . 
     In other embodiments, flex layer  120  may include any illumination source for generally illuminating keyboard assembly  100 . For example, flex layer  120  may include a sheet at least partially made of or coated with an organic LED or an electroluminescent material, such as that described in commonly assigned U.S. Pat. No. 6,987,466, which is hereby incorporated by reference herein in its entirety, or any other material that may emit light if a voltage source is applied across it. Alternative arrangements of illumination sources positioned on flex layer  120  to emit light through light guide pipe layer  130  are described herein with respect to  FIGS. 5-9 . 
     Reflector sheet layer  125  may at least partially be made of any suitable material for reflecting light emitted within keyboard assembly  100  towards keypad layer  160 . For example, reflector sheet layer  125  may at least partially be made of a white plastic sheet or a sheet of any other suitable material, and may include a reflective coating on its upper face  126  closest to light guide pipe layer  130 . Alternatively, reflector sheet layer  125  may be a sheet that is reflective on its upper face  126  and lower face (not shown), or may be a sheet composed entirely of reflective material. If light guide pipe layer  130  is transparent, and if flex layer  120  includes one or more illumination sources  121 , then some light emitted from one or more of the illumination sources  121  through light guide pipe layer  130  may diffuse downwardly towards reflector sheet layer  125  (e.g., downwardly at least partially in the Z direction of  FIG. 1 ). Reflector sheet layer  125  may redirect at least some of the diffused light upwardly towards keypad layer  160  to help ensure that keypad layer  160  may be illuminated efficiently without requiring additional illumination sources. Reflector sheet layer  125  may include any suitable number of holes  127 , such as holes  127   a ,  127   d ,  127   f ,  127   k ,  127   n , and  127   s  that may traverse the depth of reflector sheet layer  125  to allow any illumination sources  121  of flex layer  120  to traverse reflector sheet layer  125  and to emit light into light guide pipe layer  130 . In other embodiments, keyboard assembly  100  may not include reflector sheet layer  125 , and flex layer  120  may be positioned between base layer  110  and light guide pipe layer  130 . If reflector sheet layer  125  is not present, then base layer  110  may be at least partially made of any suitable material that is operative to reflect light emitted by one or more illumination sources  121  of flex layer  120  upwardly towards keypad layer  160 . 
     Light guide pipe layer  130  may be at least partially made of any suitable material for diffusing light emitted within keyboard assembly  100 . For example, light guide pipe layer  130  may include a transparent material, such as a flexible clear plastic sheet, that may allow light to travel along its length (i.e. in its X-Y plane). Light guide pipe layer  130  may also allow light to be reflected through it along any suitable path toward keypad layer  160  (e.g., in the Z-direction), the reflection of which may be aided by reflector sheet layer  125 . 
     Light guide pipe layer  130  may include one or more holes  131 , such as holes  131   a ,  131   b ,  131   d ,  131   f ,  131   j ,  131   k ,  131   n ,  131   q ,  131   s , and  131   y  that may not traverse the full depth of light guide pipe layer  130 , but may allow any illumination sources to traverse at least a portion of light guide pipe layer  130  to emit light into light guide pipe layer  130 . Light guide pipe layer  130  may also contain one or more balancing slots (not shown) positioned within light guide pipe layer  130  that may be operative to balance the illumination between different regions of light guide pipe layer  130 , such that keypad layer  160  may appear evenly illuminated. 
     Light guide pipe layer  130  may also contain one or more slots  153 . Slots  153  may be formed using any suitable approach and may include any suitable configuration in order to keep light from diffusing beyond the slots. Slots  153  may reflect the light emitted by one or more illumination sources and may also deflect the light from diffusing in one or more undesired directions. For example, slot  153   z  may be an opening formed in light guide pipe layer  130  that may reflect the light emitted by an illumination source  151   y  of keyboard membrane layer  150  (described in more detail below) back towards illumination source  151   y  via total internal reflection. In some embodiments, slots  153  may be at least partially filled with any suitable opaque and/or reflective material. In some embodiments, slots  153  may traverse the depth of light guide pipe layer  130 . Alternatively, in some embodiments, slots  153  may be embedded within light guide pipe layer  130  and may not contact any edge of light guide pipe layer  130 . 
     Slot  153   z  may also deflect the light emitted by illumination source  151   y  from illuminating other keys  105  of keypad layer  160  other than the specific key or keys  105  desired to be illuminated. In addition, slot  153   z  may create a bounded area within light guide pipe layer  130 , in which the light emitted by illumination source  151   y  may be contained and may continue to be reflected for enhancing the key-or-keys-specific illumination provided by illumination source  151   y . In some embodiments, slots  153  may also be a reflecting plate (described in more detail below). 
     Similarly, illumination source  151   j  of keyboard membrane layer  150  (described in more detail below) may provide key-specific illumination to a specific key  105  of keypad layer  160  (e.g., the “ESCAPE” key  105   b ). Slot  153   r , which may be the same as or different from other slots  153 , and which may include some or all of the features of slot  153   z , may prevent at least some of the light emitted by illumination source  151   j  from diffusing into undesired portions of light guide pipe layer  130  while reflecting at least some of the light back towards illumination source  151   j  to enhance the illumination of the specific key (e.g., “ESCAPE” key  105   b ). 
     Mask layer  140  may at least partially be made of any suitable material for directing light through one or more unmasked portions  145  provided through mask layer  140  for illuminating keypad layer  160 . For example, mask layer  140  may be made of any opaque material, such as black plastic, for allowing some light to pass (through one or more unmasked portions  145 ) from illumination sources below mask layer  140  upwardly while blocking (e.g., reflecting) other light that may be attempting to pass through any other portion of mask layer  140  that may not be an unmasked portion  145 . Mask layer  140  may include any number of unmasked portions  145 , and each unmasked portion  145  may be of any suitable size and shape. One unmasked portion  145  is shown in  FIG. 1  for the sake of simplicity and clarity. Unmasked portion  145  may be a hollow opening in mask layer  140  or a transparent material covering an opening in mask layer  140  to allow light to pass upwardly through unmasked portion  145  towards keypad layer  160 . Mask layer  140  may also include any suitable number of holes  147 , such as holes  147   b ,  147   j ,  147   q , and  147   y  to allow any illumination sources positioned above mask layer  140 , such as illumination sources  151   b ,  151   j ,  151   q , and  151   y , to pass through mask layer  140  and to emit light into light guide pipe layer  130 . 
     In some embodiments, the location of unmasked portions  145  of mask layer  140  may correspond to the position of each of the keys  105  on keypad layer  160  (described in more detail below). In other embodiments, mask layer  140  may include a small number of unmasked portions  145 , and unmasked portions  145  may be positioned to only allow illumination of one or more certain keys  105 , or one unmasked portion may span several keys  105  on keypad layer  160 , to allow light emitted from one or more illumination sources to illuminate more than one key on keypad layer  160 . In other embodiments, keyboard assembly  100  may not contain mask layer  140 , and light guide pipe layer  130  may include some or all of the features of mask layer  140 . For example, light guide pipe layer  130  may include a pattern of openings, such as a dot pattern, that can focus the light diffusing through light guide pipe layer  130  such that the light may be at least partially diffused upwardly through the openings towards keypad layer  160  in a specific pattern to improve the illumination of the keys. One example of a dot pattern may include one dot for each key on keypad layer  160 . 
     Keyboard membrane layer  150  may include any suitable mechanism for receiving any suitable inputs related to keyboard assembly  100  and transmitting any suitable information to any other suitable device. For example, keyboard membrane layer  150  may contain flex circuitry. Keyboard membrane layer  150  may convert an input from a user that may be received through keypad layer  160  into a signal that may be transmitted to any suitable device, such as the processing circuitry of a desktop computer or any other suitable electronic device. Keyboard membrane layer  150  may be of any suitable thickness, and may be compressible in response to receiving an input from a user on keypad layer  160 . Keyboard membrane layer  150  may also be transparent to allow light emitted from lower layers within keyboard assembly  100  to travel through keyboard membrane layer  150  towards keypad layer  160 . 
     Keyboard membrane layer  150  may also include one or more illumination sources  151  in any suitable position to provide illumination to keypad layer  160 . For example, keyboard membrane layer  150  may include illumination sources  151   b ,  151   j ,  151   q , and  151   y  to provide illumination to keypad layer  160 . Illumination source  151   j  may be physically mounted to the underside of keyboard membrane layer  150 , but illumination source  151   j  may also fit through hole  147   j  in mask layer  140  and hole  131   j  in light guide pipe layer  130  to allow illumination source  151   j  to emit light through light guide pipe layer  130 . 
     In one embodiment, the user may wish to selectively illuminate a specific key  105   a  on keypad layer  160  (e.g., the “ENTER” key). Upon receiving any suitable input (e.g., from a processor of a computer associated with keyboard assembly  100 ), illumination source  151   b  may emit light away from the middle portion of light guide pipe layer  130  and generally toward edges  155 ,  157 , and  159  (in the X-Y plane of light guide pipe layer  130 ). 
     The light emitted by illumination source  151   b  may diffuse through light guide pipe layer  130  under key  105   a  toward slots  153   e ,  153   m , and  153   x.    
     Slots  153   e ,  153   m , and  153   x , which may be the same as or different from other slots  153 , and may include some or all of the features of slot  153   z , may reflect at least some of the light emitted by illumination source  151   b  back towards illumination source  151   b  (in the X-Y plane of light guide pipe layer  130 ). Illumination source  151   b  and slots  153   e ,  153   m , and  153   x  may also block at least some of the light from diffusing along light guide pipe layer  130  past slots  153   e ,  153   m , and  153   x  to prevent the light from illuminating keys other than key  105   a . Slots  153   e ,  153   m ,  153   x , and any other slots within light guide pipe layer  130  may be positioned such that they do not overlap with the unmasked portions  145  of mask layer  140  and may prevent light emitted into light guide pipe layer  130  from traveling through an unmasked portion  145  of mask layer  140  upwardly towards keypad layer  160 . 
     In some embodiments, any illumination source within keyboard assembly  100  may provide variable illumination to keypad layer  160 . Keyboard assembly  100  may form a part of a device (e.g., a laptop computer) or may be externally coupled to another device wirelessly or through a cable  190  (e.g., a desktop computer with a display screen). The display screen of the electronic device may present an image that may request input from a user. In response to this image being presented, keyboard assembly  100  may receive input from the device that instructs keyboard assembly  100  to illuminate one or more keys to guide the user in providing responsive input. Keyboard assembly  100  may then signal the appropriate illumination source or sources to emit light. If the input received by keyboard assembly  100  from the device changes (e.g., the laptop or desktop computer sends a new input to keyboard assembly  100  in a real-time fashion), then keyboard assembly  100  may continue to signal the same or different illumination sources to emit light as appropriate to guide the user. 
     For example, the user may be presented with an image on a display screen that requires the user to “tab” through the image. The device may transmit a device input to keyboard assembly  100  that instructs keyboard assembly  100  to signal illumination source  151   q  to emit light. Illumination source  151   q  may emit light in response to a device signal from keyboard assembly  100 , and the light may diffuse through light guide pipe layer  130 , away from illumination source  151   q  and underneath the “TAB” key  105   c  on keypad layer  160 , thereby illuminating the key of interest to the user. Light emitted by illumination source  151   q  may be reflected toward the “TAB” key  105   c  on keypad layer  160  using reflector sheet layer  125 . Slots  153   a  and  153   b , which may be the same as or different from other slots  153 , and may include some or all of the features of slot  153   z , may also prevent light emitted by illumination source  151   q  from illuminating other keys  105  on keypad layer  160 . If the “TAB” key is no longer helpful to the user in navigating an image on a display screen, then the device may send a device input to keyboard assembly  100  to signal illumination source  151   q  to stop emitting light. Thus, the “TAB” key  105   c  may not be illuminated and the user may thereby realize that the “TAB” key  105   c  is no longer needed. 
     Keypad layer  160  may include any suitable mechanism for receiving user inputs to keyboard assembly  100 . Keypad layer  160  may be at least partially made of any suitable material, such as plastic or metal. Keypad layer  160  may include any suitable arrangement of keys  105  for presentation to a user, and may include any suitable legend scheme in any suitable arrangement to denote each key  105  on keypad layer  160 . For example, keypad layer  160  may include a legend scheme representing letters or characters of a particular language. Alternatively, keypad layer  160  may include a legend scheme representing symbols or operations. As a further alternative, keypad layer  160  may include both characters and symbols. 
       FIG. 2  shows a cross-sectional view of a portion of keyboard assembly  100  of  FIG. 1  that includes individual key  105   a  in accordance with some embodiments of the invention. Key  105   a  may form a part of keypad layer  160 , and may be mounted above base layer  110 , flex layer  120 , reflector sheet layer  125 , light guide pipe layer  130 , mask layer  140 , and keyboard membrane layer  150 . Key  105   a  may include a striking surface  180 , keycap  170 , key mount  175 , conducting plates  152  and  154 , and any other suitable features. Other keys  105  on keypad layer  160  may be the same as or different from key  105   a , and may include some or all of the features of key  105   a . The shape of keycap  170  may take any shape suitable, and striking surface  180  may be of any size or shape suitable, relative to keycap  170 , to present a legend to and receive a user input from a user. Key mount  175  may be coupled to the top surface of keyboard membrane layer  150  and to the underside of keycap  170 . 
     Keyboard membrane layer  150  may include conducting plates  152  and  154 . Conducting plate  152  may be coupled to the top of keyboard membrane layer  150 , underneath key  105   a , and conducting plate  154  may be coupled to the bottom of keyboard membrane layer  150 . The plates may include or may be coated with any material capable of conducting electricity. When placed in contact with one another, conducting plates  152  and  154  may complete an electrical circuit. For example, if a user strikes key  105   a  on striking surface  180 , key mount  175  may move downward, causing keyboard membrane layer  150  to compress and thereby moving conducting plate  152  downwardly. Conducting plate  152  may contact conducting plate  154  as a result of the compression and an electrical circuit may be completed by the contact. The completion of the electrical circuit may generate an electrical keyboard input that keyboard membrane layer  150  may transmit to any suitable device, such as the processor of a desktop computer or a laptop computer associated with keyboard assembly  100 , to process the keyboard input. 
     In one embodiment, key  105   a  may be generally illuminated using any suitable approach. For example, illumination source  121   a  may be mounted on flex layer  120  and may pass through holes  127   a  and  131   a  to emit light generally in the direction  122  through a portion of light guide pipe layer  130  lying underneath key  105   a . Light that diffuses in the direction of arrows  122  under unmasked portion  145  in mask layer  140  may pass through mask layer  140  to keypad layer  160  and may illuminate key  105   a  using any suitable approach. For example, light from illumination source  121   a  may illuminate all of keycap  170  if keycap  170  is transparent. Alternatively, the legend (not shown) on striking surface  180  may be transparent while keycap  170  may be opaque, and light from illumination source  121   a  may illuminate only the legend. As another alternative, there may be a hole or window (not shown) near the legend on striking surface  180 , and light from illumination source  121   a  may illuminate only the hole. As shown, for example, light emitted by illumination source  121   a  and diffused in direction  122  may not be reflected back by slot  153   m  because slot  153   m  may not span the height of light guide pipe layer  130  and may not impede the diffusion of light in direction  122 . 
     In some embodiments, key  105   a  may also be selectively illuminated using any suitable approach. For example, illumination source  151   b  may be coupled to the underside of keyboard membrane layer  150 , but may be inserted through holes  147   b  and  131   b  to emit light generally in the direction of arrow  155  and underneath key  105   a . A portion of the light that diffuses under key  105   a  along direction  155  may diffuse upwardly through unmasked portion  145  of mask layer  140  and keyboard membrane layer  150  to illuminate key  105   a , but another portion of the light may also reach slot  153   m , slot  153   e  (not shown in  FIG. 2 ), and slot  153   x  (not shown in  FIG. 2 ). Slots  153   m ,  153   e , and  153   x , which may not be overlapping with openings like unmasked portion  145  in mask layer  140 , may reflect the light emitted by illumination source  151   b  in the direction of arrow  156  back towards illumination source  151   b . The location of slots  153   m ,  153   e , and  153   x , along with the lack of alignment between the slots in light guide pipe layer  130  and the unmasked portion  145  in mask layer  140 , may prevent illumination source  151   b  from selectively illuminating keys other than key  105   a.    
     In some embodiments, key  105   a  may be variably illuminated. For example, keyboard assembly  100  may form a part of or may be coupled to an electronic device, such as a desktop computer or a laptop computer. Keyboard assembly  100  may receive a device input from the device instructing the keyboard to illuminate key  105   a  and may thereby signal illumination source  151   b  to emit light (e.g., the user may be presented with an image on a display screen of the device that requires the user to hit the “ENTER” key  105   a  to advance to the next image on the display screen). Illumination source  151   b  may emit light in response to a signal from keyboard assembly  100  or in response to the device input instruction itself, and the light may diffuse away from illumination source  151   b  and underneath key  105   a , thereby illuminating the key of interest to the user. If the device input changes (e.g., key  105   a  is no longer necessary to navigate the display screen), then the device may instruct keyboard assembly  100  to signal illumination source  151   b  to stop emitting light. 
     The lack of illumination of key  105   a  may inform the user that key  105   a  is no longer needed. 
     Illumination source  151   b  may emit light to distinguish key  105   a  from other keys that may be illuminated using any suitable approach of the invention. For example, illumination source  151   b  may emit light of a different color than that emitted by illumination source  121   a . Alternatively, illumination source  151   b  may emit a blinking light while illumination source  121   a  may emit a constant light signal. Alternatively, illumination source  151   b  may emit light of the same color as that emitted by illumination source  121   a , but with a stronger intensity. 
       FIG. 3  shows an exploded perspective view of a keyboard assembly in accordance with some embodiments of the invention. Keyboard assembly  300  may include base layer  310 , flex layer  320 , reflector sheet layer  325 , light guide pipe layer  330 , mask layer  340 , keyboard membrane layer  350 , and keypad layer  360 , each of which may be the same as or different from, and may include some or all of the features of, base layer  110 , flex layer  120 , reflector sheet layer  125 , light guide pipe layer  130 , mask layer  140 , keyboard membrane layer  150 , and keypad layer  160 , respectively (of  FIGS. 1 and 2 ). Keyboard assembly  300  may also include one or more illumination sources, which may be positioned anywhere within keyboard assembly  300 . Each illumination source may be the same as, or different from, other illumination sources. Keyboard assembly  300  may also include one or more flex circuits, one or more slots in one or more layers, and one or more voltage sources. 
     In some embodiments, one or more illumination sources  321  may be located in a layer within keyboard assembly  300  to illuminate keyboard assembly  300 . For example, illumination sources  321   a ,  321   d ,  321   f ,  321   k ,  321   n , and  321   s , which may be the same as or different from illumination sources  121   a ,  121   d ,  121   f ,  121   k ,  121   n , and  121   s  ( FIG. 1 ), may provide general illumination to keyboard assembly  300  using any suitable approach. Each of these illumination sources  321  may be positioned anywhere on flex layer  320 , and each illumination source may pass through holes  327   a ,  327   d ,  327   f ,  327   k ,  327   n , and  327   s , respectively, in reflector sheet layer  325  and through holes  331   a ,  331   d ,  331   f ,  331   k ,  331   n , and  331   s , respectively, in light guide pipe layer  330 . In some embodiments, reflector sheet layer  325  may not be present, and flex layer  320  may be positioned between base layer  310  and light guide pipe layer  330 . If reflector sheet layer  325  is not present in keyboard assembly  300 , then base layer  310  may be made of any suitable material that is operative to reflect light emitted by flex layer  320  upwardly towards keypad layer  360 . Base layer  310  may also be made of any suitable material that may be bent up through an opening in light guide pipe layer  330  to provide an additional reflecting surface for light diffusing through light guide pipe layer  330  (e.g., in the X-Y plane). 
     Each of illumination sources  321   a ,  321   d ,  321   f ,  321   k ,  321   n , and  321   s  may emit light into light guide pipe layer  330  along an axis that may form any suitable angle with edge  332  within the X-Y plane of light guide pipe layer  330 . In addition, the position of each general illumination source relative to another general illumination source may create any suitable angle (e.g., illumination sources  321   a ,  321   d ,  321   f ,  321   k ,  321   n , and  321   s  may be positioned to emit light primarily along an axis parallel to edge  332 , but the position of each of these illumination sources relative to each other may not be along the same axis). Light that may be emitted by any of these illumination sources  321  may be diffused through light guide pipe layer  330  generally in the X-Y plane, may be reflected upwardly through unmasked portions of mask layer  340  (e.g., unmasked portion  345 ) through keyboard membrane layer  350  (generally in the Z-axis), and may illuminate keys on keypad layer  360 . 
     In some embodiments, illumination sources  321   a  and  321   k  may each emit light in opposite directions along the X-Y plane, but each primarily along an axis parallel to edge  332 , and directed away from the middle portion of light guide pipe layer  330 . Illumination sources  321   n ,  321   s ,  321   d , and  321   f  may each emit light along an axis parallel to edge  332 , directed generally toward the middle portion of light guide pipe layer  330 , but may be positioned anywhere within flex layer  320 . In  FIG. 3 , for example, illumination sources  321   n  and  321   s  may be positioned on either side of illumination source  321   k . But the position of illumination sources  321   n  and  321   s , relative to illumination source  321   k  with respect to edge  332 , may form any suitable angle with edge  332 , although the light emitted by illumination sources  321   n  and  321   s  may be parallel to edge  332 . 
     Flex layer  320  also may contain one or more illumination sources to provide selective or variable illumination of keypad layer  360  using any suitable approach. For example, flex layer  320  may contain one or more illumination sources, such as illumination sources  321   b ,  321   j ,  321   q , and  321   y , positioned anywhere within flex layer  320  to provide key-specific illumination to particular keys  305  of keyboard assembly  300 . By positioning these illumination sources on flex layer  320 , keyboard membrane layer  350  may not include any illumination sources. As a result, more space may exist on keyboard membrane layer  350  to make conducting plates  352  and  354  (see, e.g.,  FIG. 4 ) larger, which may enhance the sensitivity of keyboard membrane layer  350  to user inputs on keys  305  of keypad layer  360 . 
     Each of illumination sources  321   b ,  321   j ,  321   q , and  321   y  may be positioned anywhere on flex layer  320 , and each illumination source may pass through holes  327   b ,  327   j ,  327   q , and  327   y  in reflector sheet layer  325  and through holes  331   b ,  331   j ,  331   q , and  331   y , in light guide pipe layer  330  respectively, in order to emit light into light guide pipe layer  330 . Light guide pipe layer  330  may also contain balancing slots (not shown) that may be operative to balance the illumination between different regions of light guide pipe layer  330 , such that keypad layer  360  may appear evenly illuminated. 
     In some embodiments, a user of keyboard assembly  300  may wish to selectively illuminate a key  305   a  on keypad layer  360  (e.g., the “ENTER” key). Upon receiving any suitable input, illumination source  321   b  may emit light away from the middle portion of light guide pipe layer  330  (e.g., away from illumination source  321   a ). When the light emitted by illumination source  321   b  diffuses through light guide pipe layer  330  under key  305   a , the light may also reach slots  333   e ,  333   m , and  333   x . Slots  333   e ,  333   m , and  333   x , each of which may be the same as or different from, and may include some or all of the features of slots  153   e ,  153   m , and  153   x  ( FIG. 1 ), may reflect the light emitted by illumination source  321   b  back towards illumination source  321   b  while also deflecting the diffused light away from other portions of light guide pipe layer  330  beyond slots  333   e ,  333   m , and  333   x  to prevent the light from illuminating keys other than key  305   a . Because slots  333   e ,  333   m , and  333   x  may diffuse at least some of the light from illumination source  321   b  downwardly onto reflector sheet layer  325 , reflector sheet layer  325  may reflect the diffused light back upwardly towards light guide pipe layer  330 . If slots  333   e ,  333   m ,  333   x , and any other slots within light guide pipe layer  330  are positioned such that they do not overlap with any of the unmasked portions  345  within mask layer  340 , then light reflected back through any slots within light guide pipe layer  330  by reflector sheet layer  325  may be blocked from diffusing further through mask layer  340 . 
     In some embodiments, any illumination source emitting light into light guide pipe layer  330  may provide variable illumination to keypad layer  360  to aid a user. Keyboard assembly  300  may form a part of a device (e.g., a laptop computer) or may be externally coupled to another device through a cable  390  (e.g., a desktop computer with a display screen). Keyboard assembly  300  may also communicate wirelessly with another device without using cable  390 . The display screen of the laptop or desktop computer may present an image that may request input from a user. In response to this image being presented, keyboard assembly  300  may receive a device input from the device that instructs keyboard assembly  300  to illuminate one or more keys  305  (e.g., “ENTER” key  305   y ) to guide the user in providing one or more responsive inputs in response to the image of the display screens. Keyboard assembly  300  may signal the appropriate illumination source or sources to emit light (e.g., illumination source  321   y ) and to alert the user that one or more particular keys may be used to navigate the display screen (e.g., “ENTER” key  305   y  of the number pad). If the input from the device changes such that the specific key or keys no longer need to be illuminated, then keyboard assembly  300  may signal illumination source  321   y  to stop emitting light, thereby indicating to the user that that key may no longer be needed to navigate the display screen. 
       FIG. 4  shows a cross-sectional view of a portion of the keyboard assembly of  FIG. 3  in accordance with some embodiments of the invention. Key  305   a  may be a part of keypad layer  360 , and may be mounted above base layer  310 , flex layer  320 , reflector sheet layer  325 , light guide pipe layer  330 , mask layer  340 , and keyboard membrane layer  350  ( FIG. 3 ). Key  305   a  may include striking surface  380 , keycap  370 , key mount  375 , and conducting plates  352  and  354 , each of which may be the same as or different from, and may include some or all of the features of, striking surface  180 , keycap  170 , key mount  175 , and conducting plates  152  and  154 , respectively (see, e.g.,  FIGS. 1 and 2 ). Other keys  305  on keypad layer  360  may be the same as or different from, and may include some or all of the features of, key  305   a . The shape of keycap  370  may take any suitable shape, and striking surface  380  may be of any suitable size or shape, relative to keycap  370 , to present a legend to and to receive an input from a user. 
     In some embodiments, key  305   a  may be generally illuminated using any suitable approach. For example, illumination source  321   a  may be mounted on flex layer  320  and may fit through holes  327   a  and  331   a  to emit light generally in the direction of arrow  322  through a portion of light guide pipe layer  330  underneath key  305   a . Light that diffuses in direction  322  under unmasked portion  345  of mask layer  340  may pass upwardly through mask layer  340  to keypad layer  360  and may illuminate key  305   a  using any suitable approach. For example, light from illumination source  321   a  may illuminate all of keycap  370  if keycap  370  is transparent. Alternatively, a legend (not pictured) on striking surface  380  may be transparent while keycap  370  may be opaque, and light from illumination source  321   a  may illuminate only the legend. As another alternative, there may be a hole or window (not shown) near a legend on striking surface  380 , and light from illumination source  321   a  may illuminate only the hole. At least some of the light emitted by illumination source  321   a  and diffusing in the direction of arrow  322  may not be reflected back by slot  333   m  because slot  333   m  may not span the height of light guide pipe layer  330  and may not impede the diffusion of at least some of the light emitted in direction  322  by illumination source  321   a.    
     In some embodiments, key  305   a  also may be selectively illuminated using any suitable approach. For example, illumination source  321   b  may be mounted on flex layer  320  and may fit through holes  327   b  and  331   b  to emit light generally in the direction of arrow  324  through a portion of light guide pipe layer  330  underneath key  305   a . Light that diffuses under key  305   a  along direction  324  may illuminate key  305   a , but the light may also reach slot  333   m , slot  333   e  (not shown), and slot  333   x  (see, e.g.,  FIG. 3 ). Slots  333   m ,  333   e , and  333   x , which may not be overlapping with unmasked portions  345  of mask layer  340 , may reflect at least some of the light emitted by illumination source  321   b  in the direction of arrow  324 ′ back towards illumination source  321   b . The location of slots  333   m ,  333   e , and  333   x , coupled with the lack of alignment between the slots in light guide pipe layer  330  and the unmasked portions  345  of mask layer  340  may prevent illumination source  321   b  from selectively illuminating keys other than key  305   a.    
     In some embodiments, although illumination sources  321   a  and  321   b  may be in the same layer within keyboard assembly  300  and may be emitting at least some light in the same direction within light guide pipe layer  330 , all of the light emitted by illumination source  321   a  may not be obstructed by illumination source  321   b . For example, illumination source  321   b  may not protrude into light guide pipe layer  330  as far as illumination source  321   a  (e.g., illumination source  321   a  may be larger than illumination source  321   b ), thereby allowing at least some of the light emitted by illumination source  321   a  to diffuse in direction  322  over illumination source  321   b  and upwardly through unmasked portion  345 . Alternatively, illumination source  321   b  may emit light at a lesser intensity, relative to the intensity of the light that may be emitted by illumination source  321   a , to allow the more intense light from illumination source  321   a  to illuminate key  305   a  even if illumination source  321   b  obstructs some of the diffusion of the light from illumination source  321   a  through light guide pipe layer  330 . As another alternative, one illumination source may be positioned at the bottom of light guide pipe layer  330 , while the other illumination source may be positioned at the top of light guide pipe layer  330 , so that each illumination source may emit light without obstructing the emission of the other illumination source. For example, if illumination source  321   b  were to be mounted from keyboard membrane layer  350  and powered by keyboard membrane layer  350 , while emitting light into the body of light guide pipe layer  330 , then slots  333   m ,  333   e , and  333   x  may be moved correspondingly to the top of light guide pipe layer  330 . 
     In some embodiments, key  305   a  may be variably illuminated to aid a user. Keyboard assembly  300  may form a part of or may be coupled to a device such as a desktop computer or a laptop. Keyboard assembly  300  may receive a device instruction from the device to illuminate key  305   a  and may signal illumination source  321   b  to emit light in response thereto (e.g., the user may be presented with an image on a display screen of a computer that requires the user to hit the “ENTER” key to advance to the next image on the display screen). Illumination source  321   b  may emit light in response to a signal from keyboard assembly  300 , and the light may diffuse away from illumination source  321   b  in direction  324  and underneath key  305   a , thereby illuminating the key of interest to the user. If the device input changes (e.g., key  305   a  is no longer necessary to navigate the display screen of the device), then the device may instruct keyboard assembly  300  to signal illumination source  321   b  to stop emitting light. The lack of illumination of key  305  may inform the user that key  305   a  is no longer needed. 
     Illumination source  321   b  may emit light to distinguish key  305   a  from other keys that may be illuminated using any suitable approach. For example, illumination source  321   b  may emit light of a different color than that emitted by illumination source  321   a . Alternatively, illumination source  321   b  may emit a blinking light while illumination source  321   a  may emit a constant light signal or illumination source  321   b  may emit light of the same color as that emitted by illumination source  321   a , but of a different intensity. 
     A keyboard may be generally, selectively, or variably illuminated using one or more illumination sources positioned in any suitable manner.  FIGS. 5 ,  6 ,  7 ,  8 , and  9  each shows a top view of a distribution of illumination sources in a portion of a keyboard assembly in accordance with some embodiments of the invention. The keyboard layer portrayed within each of  FIGS. 5 ,  6 ,  7 ,  8 , and  9  may be the same as or different from, and may include some or all of the features of, the other keyboard layers portrayed within  FIGS. 5 ,  6 ,  7 ,  8 , and  9 . In each of  FIGS. 5 ,  6 ,  7 ,  8 , and  9 , the layer shown may be a light guide pipe. Each light guide pipe may be the same as or different from, and may include some or all of the features of, light guide pipe layer  130  ( FIGS. 1 and 2 ) or light guide pipe layer  330  ( FIGS. 3 and 4 ). For example, each light guide pipe pictured in  FIGS. 5 ,  6 ,  7 ,  8 , and  9  may also contain reflecting plates or slots to reflect or channel light, holes to permit illumination sources to emit light into the light guide pipe (not shown), or any other suitable feature. 
     Each light guide pipe may employ any suitable number of illumination sources to provide general, selective, or variable illumination to a keyboard. For example,  FIGS. 5 ,  6 ,  7 ,  8 , and  9  present different embodiments that may include an odd number or an even number of illumination sources, such as LEDs, to illuminate a keyboard. Each illumination source may be the same as, or different from, all other illumination sources within each light guide pipe. Each illumination source may be powered using any suitable approach, such as through a connection to a flex layer like flex layer  120  or keyboard membrane layer  150  ( FIG. 1 ). Each illumination source may be physically mounted to any suitable layer, such as flex layer  120  or keyboard membrane layer  150 , but in some embodiments, the optical portion of each illumination source may extend into the light guide pipe to emit light into the light guide pipe. Each illumination source that may be accompanied by a reflecting plate (described in more detail below) may emit light upwardly into its respective light guide pipe generally perpendicular to the X-Y plane, or it may emit light sideways along its respective light guide pipe generally along the X-Y plane. Alternatively, each illumination source that may be accompanied by a reflecting plate may emit light at any suitable angle with respect to the X-Y plane of its respective light guide pipe. In  FIGS. 5 ,  6 ,  7 ,  8 , and  9 , each illumination source may be an LED for simplicity in describing the invention, although any other type of illumination source may be used. 
       FIG. 5  is a vertical cross-sectional view of a distribution of illumination sources in accordance with some embodiments of the invention. Light guide pipe  500  may provide any suitable arrangement of illumination sources to provide general illumination to a keyboard. For example, LED  502 , LED  504 , and LED  506  may be positioned on a flex layer (e.g., flex layer  120  of  FIG. 1 ) so that each may emit light along an axis parallel to longitudinal axis  550  toward the middle portion of light guide pipe  500 . LED  507  and LED  509  may also be positioned on a flex layer so that each may emit light along an axis parallel to longitudinal axis  550  toward the middle portion of light guide pipe  500 . More LEDs may emit light toward the right side of light guide pipe  500  because the right side of the keyboard above light guide pipe  500  may contain more keys than the left side. 
     LEDs  502 ,  504 , and  506  may generally emit light parallel to but opposite to the light emitted from LEDs  507  and  509 . LED  507  may be positioned anywhere suitable between LED  502  and LED  504  so as to emit light in a direction opposite to, but without overlapping entirely, the light emitted by LED  502  and LED  504  (e.g., LED  507  may be at least partially offset along the X-axis and/or the Y-axis of light guide pipe  500  with respect to LED  502  and LED  504 ). Similarly, LED  509  may be positioned anywhere suitable between LED  504  and LED  506  so as to emit light in a direction opposite to, but without overlapping entirely, the light emitted by LEDs  504  and  506  (e.g., LED  509  may be at least partially offset along the X-axis and/or the Y-axis of light guide pipe  500  with respect to LED  504  and LED  506 ). At least some of the light emitted by LED  507  may pass between LEDs  502  and  504 , and at least some of the light emitted by LED  509  may pass between LEDs  504  and  506 , to allow light to illuminate the left side of light guide pipe  500 . The light emitted by these five LEDs may diffuse across the length of light guide pipe  500  to generally illuminate a keyboard. Diffused light may be redirected toward the keyboard using any suitable method. In one embodiment, a reflector sheet may be positioned underneath light guide pipe  500  to direct the diffused light upwardly through light guide pipe  500 , and a mask layer may be positioned above light guide pipe  500  to channel the diffused light upwardly through unmasked portions toward the keypad (e.g., reflector sheet layer  125  and unmasked portions  145  of mask layer  140  of  FIGS. 1 and 2 ). 
     In addition or as an alternative to the general illumination that may be provided by LEDs  502 ,  504 ,  506 ,  507 , and  509 , light guide pipe  500  may contain any suitable number of illumination sources to selectively or variably illuminate a keyboard using any suitable approach. For example, light guide pipe  500  may include one or more illumination sources accompanied by one or more reflective surfaces for redirecting emitted light towards particular keys of interest. In  FIG. 5 , LED  515  and LED  517  may be provided within light guide pipe  500  near reflecting plates  516  and  518 , respectively. 
     Reflecting plates  516  and  518  may include any suitable configuration for reflecting light. In some embodiments, reflecting plates  516  and  518  may include mirrors mounted within light guide pipe  500 . In other embodiments, reflecting plates  516  and  518  may include flat, curved, or V-shaped plates coated with a reflective substance. In further embodiments, reflecting plates  516  and  518  may include a reflective material, such as metal, provided by another layer (e.g., material from base layer  110  of  FIGS. 1 and 2 ) that may be bent or otherwise formed into light guide pipe  500  to provide a reflecting surface. In some further embodiments, reflecting plates  516  and  518  may include edges positioned within a layer that may be plated with a reflective substance or that may be placed at a high angle within the layer in order to spread light emitted by an illumination source via total internal reflection. Reflecting plates  516  and  518 , while allowing light from illumination sources to be reflected in any suitable direction within light guide pipe  500 , may also permit at least some light to diffuse through them. Reflecting plates  516  and  518  may be positioned anywhere within light guide pipe  500  to aid LEDs  515  and  517  in selectively or variably illuminating particular keys of interest. In some embodiments, reflecting plates  516  and  518  may be angled to face in any suitable direction other than what is pictured in  FIG. 5  to provide illumination to different keys. 
     LEDs  515  and  517  may be used with reflecting plates  516  and  518 , respectively, to selectively or variably illuminate particular keys of interest using any suitable approach. For example, LED  515  may illuminate the arrow keys on a standard keyboard (e.g., arrow keys  105   w  of keyboard assembly  100  of  FIG. 1 ). LED  515  may be mounted to a flex layer above or below light guide pipe  500 , such as flex layer  120  or keyboard membrane layer  150  of  FIGS. 1 and 2  to obtain power, but LED  515  may emit light upwardly into or sideways along light guide pipe  500 . For simplicity, LED  515  is described with respect to  FIG. 5  as being mounted below light guide pipe  500 . Upon receiving an appropriate input, LED  515  may emit light upwardly into or sideways along light guide pipe  500  and reflecting plate  516  may reflect the emitted light generally towards the right edge  501   r  of light guide pipe  500 , in a direction generally parallel with longitudinal axis  550 , and underneath the specifically desired key or keys. The emitted and reflected light may diffuse upwardly towards the particular key or keys of interest to illuminate them. The light may diffuse through one or more suitable layers before illuminating the key or keys, such as a mask layer and a keyboard membrane layer. 
     The light that may be emitted by LED  515  and reflected toward the keys of interest by reflecting plate  516  may be prevented from diffusing toward undesired portions of light guide pipe  500  using any suitable approach. For example, there may be perforations provided in light guide pipe  500 , such as slots  540   a - 540   c , which may be the same as or different from, and may include some or all of the features of the slots described in  FIGS. 1-4 . Slots  540   a - 540   c  may channel light emitted by LED  515  away from light guide pipe  500  while also reflecting light back towards LED  515 . Slots  540   a - 540   c  may be positioned anywhere suitable in light guide pipe  500  to aid LED  515  and reflecting plate  516  in illuminating only the key or keys of interest. In  FIG. 5 , slot  540   a  may be positioned to prevent the light emitted by LED  515  and reflected by reflecting plate  516  from diffusing into a portion of light guide pipe  500  underneath other keys. Similarly, slot  540   b  may be positioned to prevent the same light from diffusing further along light guide pipe  500  towards right edge  501   r . Light guide pipe  500  may also include a third slot  540   c  parallel to slot  540   a  and positioned to the right of LED  515  to prevent light from diffusing out along bottom edge  501   b  of light guide pipe  500 . Slots  540   a - 540   c  may also reflect light back into the area of light guide pipe  500  bounded by the slots and reflecting plate  516  to enhance the particular illumination of the key or keys of interest. 
     LED  517  may also be used to illuminate a particular key or keys of interest, such as the number keys along the top edge of a standard keyboard (e.g., number keys  105   n  of  FIG. 1 ), using any suitable approach. For simplicity, LED  517 , like LED  515 , is described with respect to  FIG. 5  as being mounted below light guide pipe  500 . The position of LED  517  relative to reflecting plate  518  within light guide pipe  500  is described in more detail with respect to  FIG. 5A  below. Upon receiving an appropriate input, LED  517  may emit light upwardly into or sideways along light guide pipe  500  and reflecting plate  518  may reflect the emitted light generally towards the right edge  501   r  of light guide pipe  500 , in a direction generally parallel with axis  550 , and underneath the keys of interest. The emitted and reflected light may diffuse upwardly toward the particular keys of interest to illuminate them. The light may diffuse through one or more suitable layers before illuminating the number keys, such as a mask layer and a keyboard membrane layer. 
     The light that may be emitted by LED  517  and reflected toward the keys of interest by reflecting plate  518  may be prevented from diffusing towards undesired portions of light guide pipe  500  using any suitable approach. For example, there may be slots  530   a - 530   c , which may be the same as or different from, and may possess some or all of the features of slots  540   a - 540   c , that may channel light emitted by LED  517  away from light guide pipe  500  while also reflecting light back towards LED  517 . Slots  530   a - 530   c  may be positioned anywhere suitable in light guide pipe  500  to aid LED  517  and reflecting plate  518  in illuminating only the keys of interest. In  FIG. 5 , slot  530   a  may be positioned to prevent the light emitted by LED  517  and reflected by reflecting plate  518  from diffusing toward a portion of light guide pipe  500  underneath LEDs  502 ,  504 ,  506 ,  507 , and  509 , for example. Similarly, slot  530   b  may be positioned to prevent the same light from diffusing further along light guide pipe  500  towards right edge  501   r . Light guide pipe  500  may also include a third slot  530   c  parallel to slot  530   a  to prevent light from diffusing out along top edge  501   t  of light guide pipe  500 . Slots  530   a - 530   c  may also reflect light back into the area of light guide pipe  500  bounded by the slots and reflecting plate  518  to enhance the particular illumination of the keys of interest. 
     Light guide pipe  500  may also provide for the selective or variable illumination of particular keys, without the help of a reflective surface, in any suitable manner. For example, light guide pipe  500  may include LED  511  and LED  512 , for emitting light anywhere suitable within light guide pipe  500 , to provide key-specific illumination without the aid of a reflecting plate. 
     LEDs  511  and  512  may be employed to selectively or variably illuminate particular keys of interest using any suitable approach. For example, LED  512  may illuminate the “CAPS LOCK” key on a standard keyboard (e.g., “CAPS LOCK” key  105   d  of keyboard assembly  100  of  FIG. 1 ). LED  512  may be mounted to a flex layer above or below light guide pipe  500 , such as flex layer  120  or keyboard membrane layer  150  of  FIG. 1 , but LED  512  may emit light into light guide pipe  500 . For simplicity, LED  512  is described with respect to  FIG. 5  as being mounted below light guide pipe  500 . Upon receiving an appropriate input, LED  512  may emit light into light guide pipe  500  and toward left edge  501   l  of light guide pipe  500 , in a direction generally parallel with axis  550 , and underneath the “CAPS LOCK ” key. The light emitted by LED  512  may be prevented from diffusing toward undesired portions of light guide pipe  500  using any suitable approach, such as slots  535   a - 535   c , which may be the same as or different from, and may possess some or all of the features of slots  540   a - 540   c . Slot  535   a  may be positioned to prevent the light emitted by LED  512  from diffusing toward the portion of light guide pipe  500  with LED  517 , for example. Similarly, slot  535   b  may be positioned to prevent the same light from diffusing toward a portion of light guide pipe  500  closer to bottom edge  501   b  of light guide pipe  500 . Light guide pipe  500  may also include a third slot  535   c  to prevent light from diffusing out along left edge  501   l  of light guide pipe  500 . Slots  535   a - 535   c  may also reflect light back into the area of light guide pipe  500  bounded by the slots to enhance the particular illumination of the key or keys of interest. 
     Similarly, LED  511  may be mounted to a flex layer above or below light guide pipe  500 , such as flex layer  120  or keyboard membrane layer  150  of  FIG. 1 , but LED  511  may emit light into light guide pipe  500  to illuminate keys of interest, such as the function keys on a standard keyboard (e.g., function keys  105   f  of  FIG. 1 ). For simplicity, LED  511  is described with respect to  FIG. 5  as being mounted below light guide pipe  500 . Upon receiving an appropriate input, LED  511  may emit light into light guide pipe  500 , toward the bottom edge  501   b  and right edge  501   r  of light guide pipe  500 , and underneath the keys of interest. Light emitted by LED  511  may diffuse in a direction that forms any suitable angle with axis  550  in the X-Y plane of light guide pipe  500 . The light emitted by LED  511  may be prevented from diffusing toward undesired portions of light guide pipe  500  using any suitable approach, such as slots  525   a - 525   d , which may be the same as or different from, and may possess some or all of the features of slots  540   a - 540   c . Slot  525   a  may be positioned to prevent the light emitted by LED  511  from diffusing to a portion of light guide pipe  500  closer to left edge  501   l . Similarly, slot  525   b  may be positioned to prevent the same light from diffusing to a portion of light guide pipe  500  closer to right edge  501   r . Light guide pipe  500  may also include a third slot, slot  525   c , that may prevent light from diffusing along light guide pipe  500  toward a portion closer to bottom edge  501   b , while a fourth slot  525   d  may prevent light from diffusing out of light guide pipe  500  along top edge  501   t . Slots  525   a - 525   d  may also reflect light back into the area of light guide pipe  500  bounded by the slots to enhance the particular illumination of the key or keys of interest. 
     In some embodiments, the slots of  FIG. 5  may be shaped differently to prevent light from diffusing toward other keys not meant to be selectively or variably illuminated. For example, slots  530   a  and  530   b  may be merged to form one L-shaped slot. Alternatively, slots  525   a - 525   c  may be merged and reshaped to form a U-shaped slot around LED  511 . 
     In some embodiments, the reflecting plates of  FIG. 5  may include material from another layer of the keyboard assembly, such as a base layer (e.g., base layer  110  of  FIGS. 1 and 2  or base layer  310  of  FIGS. 3 and 4 ) that may be bent or otherwise formed into light guide pipe  500  to provide a reflecting surface.  FIG. 5A  shows a cross-sectional view of a portion of the keyboard assembly including the light guide pipe  500  of  FIG. 5 . As shown, an illumination source may be reflected using material from a base layer in accordance with some embodiments of the invention. Light guide pipe  500  may be positioned above any suitable layer or layers in a keyboard assembly, such as a reflector sheet  570  and a base layer  560 , which may be the same as or different from, and may include some or all of the features of reflector sheet layer  125  and base layer  110 , respectively, of  FIGS. 1 and 2 . For example, reflecting plate  518  may form part of base layer  560  and may include the same material as base layer  560 . Reflecting plate  518  may be bent into light guide pipe  500  to provide a reflecting surface for light emitted by LED  517  ( FIG. 5 ). 
     Reflecting plate  518  may aid LED  517  in providing key-specific illumination using any suitable approach. For example, LED  517  may emit light upwardly into light guide pipe  500  in the direction of arrow  585  towards a top portion  519  of reflecting plate  518 . 
     The light may be reflected by reflecting plate  518  in the direction of arrow  590  towards slot  530   b , thereby diffusing under the key or keys of interest (e.g., number keys  105   n  of  FIG. 1 ). 
     The reflected light may reach slot  530   b  and may be reflected back in the direction of arrow  591  towards reflecting plate  518  to enhance the key-specific illumination provided by LED  517 . Slot  530   b  may also prevent the light emitted by LED  517  from diffusing to other portions of light guide pipe  500  beyond slot  530   b  (e.g., in the direction of arrow  592 ). 
     In some embodiments, instead of emitting light upwardly in the direction of arrow  585  into light guide pipe  500  (e.g., substantially along the Z-axis), LED  517  may emit light sideways along light guide pipe  500  in any direction in the X-Y plane. Reflecting plate  518  may be positioned anywhere suitable within light guide pipe  500  to reflect the light emitted by LED  517  along the X-Y plane. 
     At least some of the light emitted by LED  517  may be reflected by the side portion  520  of reflecting plate  518  in the direction of arrow  587  towards slot  530   b , thereby diffusing under the key or keys of interest (e.g., number keys  105   n  of  FIG. 1 ). 
     The reflected light may reach slot  530   b  and may be reflected back in the direction of arrow  594  towards side portion  520  of reflecting plate  518  to enhance the key-specific illumination provided by LED  517 . Slot  530   b  may also prevent the light emitted by LED  517  from diffusing to other portions of light guide pipe  500  beyond slot  530   b  (e.g., in the direction of arrow  592 ). 
     In some embodiments, LED  517  may emit light upwardly in the direction of arrow  585  (e.g., generally along the Z-axis) while also emitting light sideways along light guide pipe  500  in any direction along the X-Y plane. At least some of the light emitted by LED  517  may be reflected by top portion  519  and at least some of the light emitted by LED  517  may be reflected by side portion  520  of reflecting plate  518  in the direction of arrow  590  and arrow  587 , respectively, towards slot  530   b . The reflected light may reach slot  530   b  and may be reflected back in the direction of arrow  591  and arrow  594 , respectively, towards top portion  519  and side portion  520  of reflecting plate  518  to enhance the key-specific illumination provided by LED  517 . 
       FIG. 6  is a vertical cross-sectional view of a distribution of illumination sources in accordance with some embodiments of the invention. Light guide pipe  600  may provide any suitable arrangement of illumination sources, which may be the same as or different from, and may possess some or all of the features of the illumination sources in  FIG. 5 , to provide illumination to a keyboard assembly. For example, LED  602  and LED  604  may be positioned on a flex layer (e.g., flex layer  120  of  FIG. 1 ) so that each may emit light towards the middle portion of light guide pipe  600  along an axis that is not parallel to longitudinal axis  650  of light guide pipe  600 . LED  607  may be positioned on a flex layer (e.g., flex layer  120  of  FIG. 1 ) so that it may emit light away from the middle portion of light guide pipe  600  along an axis parallel to axis  650 . More LEDs may emit light toward the right edge  601   r  of light guide pipe  600  than toward the left edge  601   l  because the right side of the keyboard assembly above light guide pipe  600  may contain more keys than the left side of the keyboard assembly. The close proximity of LEDs  602 ,  604 , and  607  to one another in  FIG. 6  may allow a smaller flex layer to be used, thereby lowering the cost and weight of the keyboard assembly. Other LEDs may be mounted to a keyboard membrane, such as keyboard membrane layer  150  of  FIGS. 1 and 2 , to allow the keyboard assembly to provide key-specific illumination while minimizing the space required for a flex layer to support LEDs  602 ,  604 , and  607 . 
     LEDs  602  and  604  may not face LED  607 , and the relative position of each of LEDs  602 ,  604 , and  607 , as illustrated by reference line  625 , may form an angle β of any suitable value in the X-Y plane of light guide pipe  600 . LED  607  may be positioned anywhere suitable between LED  602  and LED  604  with respect to the X-axis so as to emit light in a direction substantially opposite to LEDs  602  and  604 , with respect to the Y-axis. The light emitted by the three LEDs may diffuse across the length of light guide pipe  600  to generally illuminate a keyboard. Diffused light may be redirected upwardly towards the keyboard using any suitable method, such as a reflector sheet layer (e.g., reflector sheet layer  125  of  FIGS. 1 and 2 ) underneath light guide pipe  600  to direct the diffused light upwardly through light guide pipe  600 , and a mask layer (e.g., mask layer  140  of  FIGS. 1 and 2 ) to channel the diffused light through unmasked portions toward the keys (e.g., through unmasked portions  145  towards keys  105  of  FIGS. 1 and 2 ). 
     In addition to or as an alternative to the general illumination that may be provided by LEDs  602 ,  604 , and  607 , light guide pipe  600  may contain any suitable number of illumination sources to selectively or variably illuminate a keyboard using any suitable approach. For example, light guide pipe  600  may include one or more illumination sources accompanied by a reflective surface for redirecting emitted light towards particular keys of interest. For example, as shown in  FIG. 6 , LED  618  and LED  620  may be positioned near reflective surfaces, such as reflecting plate  619  and reflecting plate  621 , respectively. Reflecting plates  619  and  621  may be the same as or different from, and may include some or all of the features of, reflecting plates  516  and  518  of  FIG. 5 . Reflecting plates  619  and  621  may be positioned anywhere within light guide pipe  600  to aid LEDs  618  and  620  in selectively or variably illuminating particular keys of interest. In some embodiments, reflecting plates  619  and  621  may be angled to face in any suitable direction other than what is pictured in  FIG. 6  to provide illumination to different keys. 
     LEDs  618  and  620  may be provided with reflecting plates  619  and  621 , respectively, to selectively or variably illuminate particular keys of interest using any suitable approach. For example, LEDs  618  and  620  may illuminate the keys that create the number pad of a standard keyboard (e.g., number pad keys  105   p  of keyboard assembly  100  of  FIG. 1 ). LEDs  618  and  620  may be coupled to a flex layer above or below light guide pipe  600 , such as flex layer  120  or keyboard membrane layer  150  of  FIG. 1 , but LEDs  618  and  620  may emit light upwardly into or sideways along light guide pipe  600 . For simplicity, LEDs  618  and  620  are described with respect to  FIG. 6  as being mounted below light guide pipe  600 . Upon receiving an appropriate input, LED  618  may emit light upwardly into or sideways along light guide pipe  600 , and reflecting plate  619  may reflect the emitted light towards the bottom edge  601   b  and right edge  601   r  of light guide pipe  600 . Likewise, LED  620  may emit light upwardly into or sideways along light guide pipe  600 , and reflecting plate  621  may reflect the emitted light toward the top edge  601   t  and left edge  601   l  of light guide pipe  600 . The light emitted by LEDs  618  and  620  and reflected by reflecting plates  619  and  621  may diffuse upwardly toward the key or keys of interest (e.g., number pad keys  105   p ) to illuminate them. The light may diffuse through one or more suitable layers, such as a mask layer and a keyboard membrane layer (e.g., mask layer  140  and keyboard membrane layer  150  of  FIG. 1 ), before illuminating the key or keys of interest. 
     The light that may be emitted by LEDs  618  and  620  and reflected by reflecting plates  619  and  621  may be prevented from diffusing through undesired portions of light guide pipe  600  using any suitable approach. For example, slots  630   a - 630   b , which may be the same as or different from, and may include some or all of the features of slots  540   a - 540   c  of  FIG. 5 , may be positioned to prevent the light reflected by reflecting plates  619  and  621  from diffusing beyond the portion of light guide pipe  600  underneath the key or keys of interest. Light guide pipe  600  may also include two additional slots  630   c  and  630   d , which may be the same as or different from, and may include some or all of the features of slots  540   a - 540   c  of  FIG. 5 , positioned along the right edge  601   r  and the bottom edge  601   b  of light guide pipe  600 , to prevent light from diffusing out beyond light guide pipe  600 . Slots  630   a - 630   d  may also reflect light back into the area of light guide pipe  600  bounded by the slots to enhance the particular illumination of the key or keys of interest. 
     Light guide pipe  600  may also provide for the selective or variable illumination of particular keys, without the help of a reflective surface, in any suitable manner. For example, light guide pipe  600  may include LED  612  and LED  615  for emitting light anywhere suitable within light guide pipe  600 , to provide key-specific illumination without the use of a reflecting plate. 
     LEDs  612  and  615  may be used to selectively or variably illuminate particular keys of interest using any suitable approach. For example, LED  612  may illuminate the “ESCAPE” key on a standard keyboard (e.g., “ESCAPE” key  105   b  of keyboard assembly  100  of  FIG. 1 ). LED  612  may be mounted to a flex layer above or below light guide pipe  600 , such as flex layer  120  or keyboard membrane layer  150  of  FIG. 1 , but LED  612  may emit light into light guide pipe  600 . For simplicity, LED  612  is described with respect to  FIG. 6  as being mounted below light guide pipe  600 . Upon receiving an appropriate input, LED  612  may emit light into light guide pipe  600  toward the right edge  601   r  of light guide pipe  600 , in a direction generally parallel with axis  650 , and underneath the key of interest. The light emitted by LED  612  may be prevented from diffusing towards undesired portions of light guide pipe  600  using any suitable approach, such as slots  614   a - 614   c , which may be the same as or different from, and may possess some or all of the features of, slots  540   a - 540   c  of  FIG. 5 . Slot  614   a  may be positioned to prevent light from diffusing through a portion of light guide pipe  600  closer to bottom edge  601   b . Similarly, slot  614   b  may be positioned to prevent the same light from diffusing through a portion of light guide pipe  600  closer to right edge  601   r . Light guide pipe  600  may also include a third slot  614   c  parallel to slot  614   a  to prevent light from diffusing out along top edge  601   t  of light guide pipe  600 . Slots  614   a - 614   c  may also reflect light back into the area of light guide pipe  600  bounded by the slots to enhance the particular illumination of the key or keys of interest. 
     Similarly, LED  615  may be mounted to a flex layer above or below light guide pipe  600 , such as flex layer  120  or keyboard membrane layer  150  of  FIGS. 1 and 2 , but LED  615  may emit light into light guide pipe  600  to illuminate the “ALT” or “COMMAND” key on a standard keyboard, such as “COMMAND” key  105   r  of keyboard assembly  100  of  FIG. 1 . For simplicity, LED  615  is described with respect to  FIG. 6  as being mounted below light guide pipe  600 . Upon receiving an appropriate input, LED  615  may emit light into light guide pipe  600  and towards right edge  601   r  of light guide pipe  600 , in a direction generally parallel with axis  650 , and underneath the key of interest. The light that may be emitted by LED  615  may be prevented from diffusing through undesired portions of light guide pipe  600  using any suitable approach, such as slots  616   a - 616   c , which may be the same as or different from, and may possess some or all of the features of, slots  540   a - 540   c  of  FIG. 5 . Slot  616   a  may be positioned to prevent light from diffusing to a portion of light guide pipe  600  closer to top edge  601   t . Similarly, slot  616   b  may be positioned to prevent the same light from diffusing to the portion of light guide pipe  600  closer to right edge  601   r . Light guide pipe  600  may also include a third slot  616   c  parallel to slot  616   a  to prevent light from diffusing out along bottom edge  601   b  of light guide pipe  600 . Slots  616   a - 616   c  may also reflect light back into the area of light guide pipe  600  bounded by the slots to enhance the particular illumination of the one or more keys of interest. 
       FIG. 7  is a vertical cross-sectional view of a distribution of illumination sources in accordance with some embodiments of the invention. Light guide pipe  700  may provide for any suitable arrangement of illumination sources, which may be the same as or different from, and may include some or all of the features of, the illumination sources in  FIG. 5 , to illuminate a keyboard. 
     For example, LEDs  702 ,  706 ,  709 , and  711  may each be positioned on a flex layer (e.g., flex layer  120  of  FIG. 1 ) so that each may emit light towards the middle portion of light guide pipe  700  but along an axis that is not parallel to longitudinal axis  750 . LEDs  705  and  708  may be positioned on a flex layer so that each may emit light away from the middle portion of light guide pipe  700  along an axis parallel to axis  750 . 
     Although there may be an even number of general illumination sources, the illumination sources may not be facing one another, nor may they be facing all in the same direction. The relative position of each of LEDs  702 ,  705 , and  706 , as shown by reference line  730 , may form an angle β′ of any suitable value that may be equal to, less than, or greater than an angle β″ formed by the relative position of each of LEDs  709 ,  708 , and  711 , as shown by reference line  735 . LED  705  may be positioned anywhere suitable between LED  702  and LED  706  with respect to the X-axis so as to emit light in a direction generally opposite to LEDs  702  and  706  with respect to the Y-axis and that may serve to illuminate the left portion of a keyboard. Similarly, LED  708  may be positioned anywhere suitable between LED  709  and LED  711  with respect to the X-axis so as to emit light in a direction generally opposite to LEDs  709  and  711  with respect to the Y-axis and that may serve to illuminate the right portion of a keyboard. The light emitted by these six LEDs may diffuse across the length of light guide pipe  700  (in the X-Y plane) to generally illuminate a keyboard. Diffused light may be redirected upwardly towards the keyboard using any suitable method, such as a reflector sheet layer (e.g., reflector sheet layer  125  of  FIGS. 1 and 2 ) underneath light guide pipe  700  to direct the diffused light upwardly through light guide pipe  700  and a mask layer (e.g., mask layer  140  of  FIGS. 1 and 2 ) to channel the diffused light towards the keys (e.g., keys  105  of  FIGS. 1 and 2 ). 
     In addition to or as an alternative to the general illumination that may be provided by LEDs  702 ,  705 ,  706 ,  708 ,  709 , and  711 , light guide pipe  700  may contain any suitable number of illumination sources to selectively or variably illuminate a keyboard using any suitable approach. For example, light guide pipe  700  may include one or more illumination sources accompanied by a reflective surface for redirecting emitted light towards a particular key or keys of interest. For example, as shown in  FIG. 7 , LED  739  and LED  749  may be provided within light guide pipe  700  near reflecting plate  740  and reflecting plate  760 , respectively. Reflecting plates  740  and  760  may be the same as or different from, and may include some or all of the features of, reflecting plates  516  and  518  of  FIG. 5 . Reflecting plates  740  and  760  may be positioned anywhere within light guide pipe  700  to aid LEDs  739  and  749  in selectively or variably illuminating particular keys of interest. In some embodiments, reflecting plates  740  and  760  may be angled to face in any suitable direction other than what is pictured in  FIG. 7  to provide illumination to different keys. 
     LEDs  739  and  749  may be employed with reflecting plates  740  and  760 , respectively, to selectively or variably illuminate particular keys of interest using any suitable approach. For example, LED  739  may illuminate the “function” keys in the lower left corner (e.g., the “CAPS LOCK” key, the “SHIFT” key, the “CTRL” key, etc.) of a standard keyboard, such as keys  105   d ,  105   t ,  105   m  and  105   r  of keyboard assembly  100  of  FIG. 1 . LED  739  may be coupled to a flex layer above or below light guide pipe  700 , such as flex layer  120  or keyboard membrane layer  150  of  FIG. 1 , but LED  739  may emit light upwardly into or sideways along light guide pipe  700 . For simplicity, LED  739  is described with respect to  FIG. 7  as being mounted below light guide pipe  700 . Upon receiving an appropriate input, LED  739  may emit light upwardly into or sideways along light guide pipe  700  and reflecting plate  740  may reflect the emitted light toward the top edge  701   t  and right edge  701   r  of light guide pipe  700  and underneath the key or keys of interest. 
     Likewise, LED  749  may illuminate a row of number keys on a standard keyboard, such as number keys  105   n  of keyboard assembly  100  of  FIG. 1 . LED  749  may be mounted below light guide pipe  700 , similar to LED  739 . For simplicity, LED  749  is described with respect to  FIG. 7  as being mounted below light guide pipe  700 . 
     Upon receiving an appropriate input, LED  749  may emit light upwardly into or sideways along light guide pipe  700 , and reflecting plate  760  may reflect the emitted light generally towards left edge  7011  of light guide pipe  700 , in a direction generally parallel with longitudinal axis  750 , and underneath the row of number keys  105   n.    
     The emitted and reflected light from these LEDs may diffuse upwardly towards the particular keys of interest to illuminate them. The light of LEDs  739  and  749  may diffuse through one or more suitable layers before illuminating the keys of interest, such as a mask layer and a keyboard membrane layer (e.g., mask layer  140  and keyboard membrane layer  150  of  FIG. 1 ). 
     The light that may be reflected by reflecting plates  740  and  760  may be prevented from diffusing through undesired portions of light guide pipe  700  using any suitable approach. For example, slots  741   a  and  751   a  may be the same as or different from, and may include some or all of the features of, slots  540   a - 540   c  of  FIG. 5 . Slots  741   a  and  751   a  may each be positioned in light guide pipe  700  to prevent the light reflected by reflecting plates  740  and  760  from diffusing into the portion of light guide pipe  700  underneath keys that are not of interest. Light guide pipe  700  may also include additional slots (not shown) positioned along left edge  701   l  and bottom edge  701   b  of light guide pipe  700  to prevent light from LEDs  739  from diffusing out beyond those edges, for example. Slots  741   a  and  751   a  may each reflect light back into the area of light guide pipe  700  bounded by the respective slots to enhance the particular illumination of the keys of interest. 
     Light guide pipe  700  may also provide for the selective or variable illumination of particular keys, without the help of a reflective surface, in any suitable manner. For example, light guide pipe  700  may include LED  715  and LED  720 , emitting light anywhere suitable within light guide pipe  700 , to provide key-specific illumination without the aid of a reflecting plate. 
     LEDs  715  and  720  may be employed to selectively or variably illuminate particular keys of interest using any suitable approach. For example, LED  715  may illuminate the number pad on a standard keyboard, such as number pad keys  105   p  of keyboard assembly  100  of  FIG. 1 . LED  715  may be mounted to a flex layer above or below light guide pipe  700 , such as flex layer  120  or keyboard membrane layer  150  of  FIG. 1 , but LED  715  may emit light into light guide pipe  700 . For simplicity, LED  715  is described with respect to  FIG. 7  as being mounted below light guide pipe  700 . 
     Upon receiving an appropriate input, LED  715  may emit light into light guide pipe  700  and toward top edge  701   t  of light guide pipe  700 , in a direction generally perpendicular to axis  750 , and underneath the keys of interest. 
     The light emitted by LED  715  may be prevented from diffusing through undesired portions of light guide pipe  700  using any suitable approach, such as slots  716   a - 716   c , which may be the same as or different from, and may possess some or all of the features of slots  540   a - 540   c  of  FIG. 5 . Slots  716   a  and  716   b  may be positioned to prevent light from diffusing beyond the portion of light guide pipe  700  underneath the keys of interest (e.g., number pad keys  105   p  of  FIG. 1 ). Slot  716   c  may be parallel to slot  716   b  and may prevent light from diffusing out along right edge  701   r  of light guide pipe  700 , for example. Slots  716   a - 716   c  may also reflect light back into the area of light guide pipe  700  bounded by these slots and bottom edge  701   b  of light guide pipe  700  to enhance the particular illumination of the keys of interest. 
     Similarly, LED  720  may be mounted to a flex layer above or below light guide pipe  700 , such as flex layer  120  or keyboard membrane layer  150  of  FIGS. 1 and 2 , but LED  720  may emit light through light guide pipe  700  to illuminate the “SPACEBAR” key on a standard keyboard, such as the “SPACEBAR” key  105   s  of keyboard assembly  100  of  FIG. 1 . For simplicity, LED  720  is described with respect to  FIG. 7  as being mounted below light guide pipe  700 . 
     Upon receiving an appropriate input, LED  720  may emit light into light guide pipe  700  and towards bottom edge  701   b  of light guide pipe  700 , in a direction generally perpendicular to axis  750 , and underneath the keys of interest (e.g., key  105   s ). 
     The light that may be emitted by LED  720  may be prevented from diffusing through undesired portions of light guide pipe  700  using any suitable approach, such as slots  723   a - 723   d , which may be the same as or different from, and may possess some or all of the features of, slots  540   a - 540   c  of  FIG. 5 . Each of the slots may be positioned to prevent light from diffusing beyond the portion of light guide pipe  700  underneath the key of interest. Light guide pipe  700  may also include a fifth slot (not shown) to prevent light from diffusing out along bottom edge  701   b  of light guide pipe  700 . Slots  723   a - 723   d  may also reflect light back into the area of light guide pipe  700  bounded by the slots and bottom edge  701   b  of light guide pipe  700  to enhance the particular illumination of the key of interest (e.g., “SPACEBAR” key  105   s  of  FIG. 1 ). 
       FIG. 8  is a vertical cross-sectional view of a distribution of illumination sources in accordance with some embodiments of the invention. Light guide pipe  800  may provide for any suitable arrangement of illumination sources, which may be the same as or different from, and may include some or all of the features of the illumination sources in  FIG. 5 , to illuminate a keyboard. For example, each of LEDs  802 ,  804 ,  806 ,  808 , and  810  may be positioned on a flex layer (e.g., flex layer  120  of  FIGS. 1 and 2 ) so that each may emit light in the same direction as each of the other LEDs upwardly into or sideways along light guide pipe  800  along an axis that may form any suitable angle with longitudinal axis  850 . 
     The light emitted by each of LEDs  802 ,  804 ,  806 ,  808 , and  810  may be redirected to generally illuminate a keyboard using any suitable approach. For example, LEDs  802 ,  804 ,  806 ,  808 , and  810  may each be positioned on a flex layer (e.g., flex layer  120  of  FIG. 1 ) to emit light upwardly into or sideways along light guide pipe  800  toward reflecting plates  802   a ,  804   a ,  806   a ,  808   a , and  810   a , respectively. Reflecting plates  802   a ,  804   a ,  806   a ,  808   a , and  810   a  may be the same as or different from, and may include some or all of the features of reflecting plates  516  and  518  of  FIG. 5 , for example. Light emitted from LEDs  808  and  810  may be reflected toward the middle portion of light guide pipe  800  using reflective plates  808   a  and  810   a , respectively, while the light emitted by LEDs  802 ,  804 , and  806  may be reflected by reflecting plates  802   a ,  804   a , and  806   a  towards the middle portion of light guide pipe  800 . However the light reflected by reflective plates  808   a  and  810   a  may diffuse in a direction generally opposite that of the light reflected by reflective plates  802   a ,  804   a , and  806   a.    
     None of these LEDs may directly face another LED in some embodiments. Reflecting plate  808   a  may be positioned anywhere suitable between reflecting plates  802   a  and  804   a  with respect to the X-axis so as to redirect light in a direction opposite to, but without overlapping entirely, the light reflected by reflecting plates  802   a  and  804   a , respectively, with respect to the Y-axis. Similarly, reflecting plate  810   a  may be positioned anywhere suitable between reflecting plates  804   a  and  806   a  with respect to the X-axis so as to redirect light in a direction opposite to, but without overlapping entirely, the light reflected by reflecting plates  804   a  and  806   a , respectively, with respect to the Y-axis. Because the diffused light may not substantially overlap, light reflected by these reflecting plates may diffuse uniformly across the X-Y plane of light guide pipe  800  to generally illuminate a keyboard. Diffused light may be redirected upwardly towards the keyboard using any suitable method, such as a reflector sheet layer (e.g., reflector sheet layer  125  of  FIGS. 1 and 2 ) underneath light guide pipe  800  to direct the emitted light up through light guide pipe  800  and a mask layer (e.g., mask layer  140  of  FIGS. 1 and 2 ) to channel the diffused light toward the keys (e.g. keys  105  of  FIG. 1 ). 
     In addition to or as an alternative to the general illumination that may be provided by LEDs  802 ,  804 ,  806 ,  808 , and  810 , light guide pipe  800  may contain any suitable number of illumination sources to selectively or variably illuminate a keyboard using any suitable approach. For example, light guide pipe  800  may include additional illumination sources accompanied by a reflective surface for redirecting emitted light towards particular keys of interest. In  FIG. 8 , LED  820  and LED  822  may be provided within light guide pipe  800  near reflecting plate  820   a  and reflecting plate  822   a , respectively. Reflecting plates  820   a  and  822   a  may be the same as or different from, and may include some or all of the features of, reflecting plates  516  and  518  of  FIG. 5 , for example. Reflecting plates  820   a  and  822   a  may be positioned anywhere within light guide pipe  800  to aid LEDs  820  and  822  in selectively or variably illuminating particular keys of interest. In some embodiments, reflecting plates  820   a  and  822   a  may be angled to face in any suitable direction other than what is pictured in  FIG. 8  to provide illumination to different keys. 
     LEDs  820  and  822  may be used with reflecting plates  820   a  and  822   a , respectively, to selectively or variably illuminate particular keys of interest using any suitable approach. For example, similar to LEDs  802 ,  804 ,  806 ,  808  and  810 , both LEDs  820  and  822  may be positioned on a flex layer (e.g., flex layer  120  of  FIGS. 1 and 2 ). LED  820  may illuminate the arrow keys of a standard keyboard, such as arrow keys  105   w  of keyboard assembly  100  of  FIG. 1 . Upon receiving an appropriate input, LED  820  may emit light upwardly into or sideways along light guide pipe  800  and reflecting plate  820   a  may reflect the emitted light in a direction generally parallel with longitudinal axis  850  towards left edge  801   l  of light guide pipe  800 , and under the key or keys of interest (e.g., arrow keys  105   w  of  FIG. 1 ). 
     Likewise, LED  822  may illuminate the “ZERO” number key on a standard keyboard, such as “ZERO” key  105   z  of keyboard assembly  100  of  FIG. 1 , for example. Upon receiving an appropriate input, LED  822  may emit light upwardly into or sideways along light guide pipe  800 , and reflecting plate  822   a  may reflect the emitted light in a direction generally parallel with axis  850  toward left edge  801   l  of light guide pipe  800 , and under the key of interest (e.g., “ZERO” key  105   z ). The emitted and reflected light from LEDs  820  and  822  may diffuse upwardly towards the particular keys of interest to illuminate them. The light of LEDs  820  and  822  may diffuse through one or more suitable layers of the keyboard assembly before illuminating the keys of interest, such as a mask layer and a keyboard membrane layer (e.g., mask layer  140  and keyboard membrane layer  150  of  FIGS. 1 and 2 ). 
     The light that may be reflected by reflecting plates  820   a  and  822   a  may be prevented from diffusing through undesired portions of light guide pipe  800  using any suitable approach. For example, slots  821   a ,  821   b ,  823   a , and  823   b  may be the same as or different from, and may include some or all of the features of, slots  540   a - 540   c  of  FIG. 5 . Slots  821   a  and  821   b  may be positioned in light guide pipe  800  to prevent the light reflected by reflecting plate  820   a  from diffusing beyond the portion of light guide pipe  800  underneath the keys of interest (e.g., arrow keys  105   w ). Slots  823   a  and  823   b  may be positioned in light guide pipe  800  to prevent the light reflected by reflecting plate  822   a  from diffusing beyond the portion of light guide pipe  800  underneath the key of interest (e.g., “ZERO” key  105   z ). Light guide pipe  800  may also include additional slots (not shown) positioned along bottom edge  801   b  and top edge  801   t  of light guide pipe  800  to prevent light from LEDs  820  and  822 , respectively, from diffusing out beyond those edges. Slots  821   a ,  821   b ,  823   a , and  823   b  may each reflect light back into the area of light guide pipe  800  bounded by the respective slots to enhance the particular illumination of keys of interest. 
     In some embodiments, it may be desirable to selectively or variably illuminate one half of a keyboard (e.g., for using the left letter keys to control a video game on an externally coupled computer). LEDs  820  and  822  may not be accompanied by any slots to channel away light, because the emitted light may be desirable under numerous keys and not just the mentioned keys of interest. 
     Light guide pipe  800  may also provide for the selective or variable illumination of particular keys, without the help of a reflective surface, in any suitable manner. For example, light guide pipe  800  may include LED  816  and LED  817 , for emitting light anywhere suitable within light guide pipe  800 , to provide key-specific illumination without the aid of a reflecting plate. 
     LEDs  816  and  817  may be used to selectively or variably illuminate particular keys of interest using any suitable approach. For example, LED  816  may illuminate the “TAB” key on a standard keyboard, such as “TAB” key  105   c  of keyboard assembly  100  of  FIG. 1 . LED  816  may be mounted to a flex layer above or below light guide pipe  800 , such as flex layer  120  or keyboard membrane layer  150  of  FIG. 1 , but LED  816  may emit light into light guide pipe  800 . For simplicity, LED  816  is described with respect to  FIG. 8  as being mounted below light guide pipe  800 . Upon receiving an appropriate input, LED  816  may emit light into light guide pipe  800  and toward left edge  801   l  of light guide pipe  800 , in a direction generally parallel with axis  850 , and underneath the key of interest (e.g., “TAB” key  105   c ). The light emitted by LED  816  may be prevented from diffusing through undesired portions of light guide pipe  800  using any suitable approach, such as slots  815   a  and  815   b , which may be the same as or different from, and may possess some or all of the features of, slots  540   a - 540   c  of  FIG. 5 . Slots  815   a  and  815   b  may be positioned to prevent light from diffusing beyond the portion of light guide pipe  800  underneath the key of interest. Light guide pipe  800  may also include a third slot (not shown) perpendicular to slots  815   a  and  815   b  to prevent light from diffusing out along left edge  801   l  of light guide pipe  800 . Slots  815   a  and  815   b  may also reflect light back into the area of light guide pipe  800  bounded by the two slots and left edge  801   l  of light guide pipe  800  to enhance the particular illumination of the key of interest (e.g., “TAB” key  105   c ). 
     Similarly, LED  817  may emit light into light guide pipe  800  to illuminate the “CAPS LOCK” key on a standard keyboard, such as “CAPS LOCK” key  105   d  of keyboard assembly  100  of  FIG. 1 . For simplicity, LED  817  is described with respect to  FIG. 8  as being mounted below light guide pipe  800 . Slot  815   b  and slot  815   c , which may be the same as, or different from, and may include some or all of the features of, slots  535   a - 535   c  of  FIG. 5 , may be positioned to prevent light from diffusing beyond the portion of light guide pipe  800  underneath the key of interest. Light guide pipe  800  may also include a third slot (not shown) perpendicular to slots  815   b  and  815   c  to prevent light from diffusing out along left edge  801   l  of light guide pipe  800 . Slots  815   b  and  815   c  may also reflect light back into the area of light guide pipe  800  bounded by the slots and left edge  801   l  to enhance the particular illumination of the key of interest (e.g., “CAPS LOCK” key  105   d ). 
       FIG. 9  is a vertical cross-sectional view of a distribution of illumination sources in accordance with some embodiments of the invention. Light guide pipe  900  may provide for any suitable arrangement of illumination sources, which may be the same as or different from, and may include some or all of the features of, the illumination sources in  FIG. 5 , to illuminate a keyboard. For example, each of LEDs  902 ,  903 ,  904 ,  905 ,  906 ,  907 ,  908 , and  909  may be positioned on any suitable layer, such as flex layer  120  or keyboard membrane layer  150  of  FIG. 1 , to receive power while emitting light through light guide pipe  900 . For simplicity, each of LEDs  902 ,  903 ,  904 ,  905 ,  906 ,  907 ,  908  and  909  is described with respect to  FIG. 9  as being mounted below light guide pipe  900 . The light emitted by each of these LEDs, when reflected toward the middle portion of light guide pipe  900 , may form any suitable angle of intersection with longitudinal axis  950 . 
     The light emitted by each LED may be redirected toward the middle portion of light guide pipe  900  to generally illuminate a keyboard using any suitable approach. For example, LEDs  902 ,  903 ,  904 ,  905 ,  906 ,  907 ,  908 , and  909  each may emit light upwardly into light guide pipe  900  (e.g., upwardly out of the drawing sheet containing  FIG. 9  along the Z-axis (not shown)), or each may emit light sideways along light guide pipe  900  generally along the X-Y plane. The light emitted by each of these LEDs may diffuse toward its respective reflecting surface  902   a ,  903   a ,  904   a ,  905   a ,  906   a ,  907   a ,  908   a , and  909   a . Reflecting plates  902   a ,  903   a ,  904   a ,  905   a ,  906   a ,  907   a ,  908   a , and  909   a  may be the same as or different from, and may include some or all of the features of, reflecting plates  516  and  518  of  FIGS. 5 and 5A . For example, if light is emitted from LED  904  upwardly into light guide pipe  900 , or emitted sideways along light guide pipe  900 , then the light may be reflected by reflecting surface  904   a  toward the middle portion of light guide pipe  900  along a path  960 , which may form any suitable angle Ψ with axis  950 . Similarly, light that may be emitted from LED  905  upwardly into light guide pipe  900  or emitted sideways along light guide pipe  900  may be reflected by reflecting surface  905   a  toward the middle portion of light guide pipe  900  along a path  970 , which may form any suitable angle Ψ′ with axis  950 . 
     Light emitted from LEDs  902 ,  904 ,  906 , and  908  may be reflected toward the middle portion of light guide pipe  900 . The reflected light may intersect with light emitted from LEDs  903 ,  905 ,  907 , and  909 , the intersection of which may form an angle of any suitable value. For example, the light emitted by LED  904  and reflected by reflecting plate  904   a  may intersect the light emitted by LED  905  and reflected by reflecting plate  905   a  at an angle (180°-Ψ-Ψ′). None of the LEDs may face another LED in some embodiments. The light emitted by these LEDs may diffuse across the X-Y plane of light guide pipe  900  to generally illuminate a keyboard. Diffused light may be redirected upwardly towards the keyboard using any suitable method, such as a reflector sheet layer (e.g., reflector sheet layer  125  of  FIGS. 1 and 2 ) underneath light guide pipe  900  to direct the diffused light up through light guide pipe  900  and a mask layer (e.g., mask layer  140  of  FIGS. 1 and 2 ) to channel the diffused light through unmasked portions (e.g., unmasked portions  145  of  FIG. 1 ) toward the keys (e.g., keys  105  of  FIG. 1 ). 
     In addition to or as an alternative to the general illumination that may be provided by LEDs  902 ,  903 ,  904 ,  905 ,  906 ,  907 ,  908 , and  909 , light guide pipe  900  may include any suitable number of illumination sources to selectively or variably illuminate a keyboard using any suitable approach. For example, light guide pipe  900  may include one or more illumination sources accompanied by a reflective surface for redirecting emitted light towards only a particular key or keys of interest. In  FIG. 9 , LED  930  and LED  932  may be provided within light guide pipe  900  near reflecting plate  931  and reflecting plate  933 , respectively. Reflecting plates  931  and  933  may be the same as or different from, and may include some or all of the features of, reflecting plates  516  and  518  of  FIGS. 5 and 5A , for example. Reflecting plates  931  and  933  may be positioned anywhere within light guide pipe  900  to aid LEDs  930  and  932  in selectively or variably illuminating particular keys of interest. In some embodiments, reflecting plates  931  and  933  may be angled to face in any suitable direction other than what is shown in  FIG. 9  to provide illumination to different keys. 
     LEDs  930  and  932  may be employed with reflecting plates  931  and  933 , respectively, to selectively or variably illuminate particular keys of interest using any suitable approach. For example, LEDs  930  and  932  may illuminate the bottom row of keys of a standard keyboard, such as the bottom row of keys  105  of keyboard assembly  100  of  FIG. 1 . LEDs  930  and  932  may be coupled to a flex layer above or below light guide pipe  900 , such as flex layer  120  or keyboard membrane layer  150  of  FIG. 1 , but LEDs  930  and  932  may emit light upwardly into or sideways along light guide pipe  900 . For simplicity, LEDs  930  and  932  are described with respect to  FIG. 9  as being mounted below light guide pipe  900 . Upon receiving an appropriate input, LED  930  may emit light upwardly into or sideways along light guide pipe  900  and reflecting plate  931  may reflect the emitted light in a direction generally parallel with axis  950  and toward left edge  901   l  of light guide pipe  900 . Likewise, LED  932  may emit light upwardly into or sideways along light guide pipe  900  and reflecting plate  933  may reflect the emitted light in a direction generally parallel with axis  950  and toward right edge  901   r  of light guide pipe  900 . The light may diffuse through one or more suitable layers of the keyboard assembly before illuminating the keys of interest, such as a mask layer and a keyboard membrane layer (e.g., mask layer  140  and keyboard membrane layer  150  of  FIGS. 1 and 2 ). 
     The light that may be reflected by reflecting plates  931  and  933  may be prevented from diffusing through undesired portions of light guide pipe  900  using any suitable approach. For example, slot  934   a , which may be the same as or different from, and may include some or all of the features of, slot  540   a  of  FIG. 5 , may be positioned to prevent the light reflected by reflecting plates  931  and  933  from diffusing into a portion of light guide pipe  900  closer to top edge  901   t  of light guide pipe  900 . Light guide pipe  900  may also include an additional slot (not shown) positioned along bottom edge  901   b  of light guide pipe  900  to prevent light from diffusing out beyond that edge of light guide pipe  900 . Slot  934   a  may also reflect light back into the area of light guide pipe  900  bounded by it and bottom edge  901   b  of light guide pipe  900  to enhance the particular illumination of the keys of interest (e.g., bottom row of keys  105   o  of  FIG. 1 ). 
     Light guide pipe  900  may also provide for the selective or variable illumination of particular keys, without the help of a reflective surface, in any suitable manner. For example, light guide pipe  900  may include LED  921  and LED  923 , for emitting light anywhere suitable within light guide pipe  900 , to provide key-specific illumination without the aid of a reflecting plate. 
     LEDs  921  and  923  may be used to selectively or variably illuminate particular keys of interest using any suitable approach. For example, LEDs  921  and  923  may illuminate the number keys along the top edge of a standard keyboard, such as number keys  105   n  of keyboard assembly  100  of  FIG. 1 . LEDs  921  and  923  may be mounted to a flex layer above or below light guide pipe  900 , such as flex layer  120  or keyboard membrane layer  150  of  FIG. 1 , but LEDs  921  and  923  may emit light through light guide pipe  900 . For simplicity, LEDs  921  and  923  are described with respect to  FIG. 9  as being mounted below light guide pipe  900 . Upon receiving an appropriate input, LEDs  921  and  923  may each emit light into light guide pipe  900  and toward bottom edge  901   b  of light guide pipe  900 , in a direction generally perpendicular to axis  950 , and underneath the keys of interest. The light emitted by LEDs  921  and  923  may be prevented from diffusing through undesired portions of light guide pipe  900  using any suitable approach, such as slots  925   a  and  925   b , which may be the same as or different from, and may possess some or all of the features of, slots  530   a  and  530   b  of  FIG. 5 , for example. Slot  925   a  may be positioned to prevent the light emitted by LEDs  921  and  923  from diffusing through a portion of light guide pipe  900  closer to right edge  901   r  of light guide pipe  900 . Similarly, slot  925   b  may be positioned to prevent the same light from diffusing through a portion of light guide pipe  900  closer to bottom edge  901   b . Light guide pipe  900  may also include a third slot (not shown) perpendicular to and to the left of slot  925   b  to prevent light from diffusing out along left edge  901   l  of light guide pipe  900 . Slots  925   a  and  925   b  may also reflect light back into the area of light guide pipe  900  bounded by the slots and left edge  901   l  of light guide pipe  900  to enhance the particular illumination of the keys of interest (e.g., number keys  105   n  of  FIG. 1 ). 
     In some embodiments, light guide pipe  900  may generally illuminate a keyboard by positioning LEDs only along one edge of light guide pipe  900  (e.g., LEDs  902 ,  904 ,  906  and  908  may be retained along left edge  901   l  and LEDs  903 ,  905 ,  907 , or  909  may be removed from right edge  901   r ). Alternatively, LEDs  902 ,  903 ,  904 ,  905 ,  906 ,  907 ,  908 , and/or  909  may be moved closer to the middle portion of a flex layer (e.g., flex layer  120  of  FIG. 1 ) so that they emit light closer to the middle portion of light guide pipe  900 . In some embodiments, any suitable coating, such as a reflective paint or an opaque but internally bright coating, may be applied to light guide pipe  900  in those regions of light guide pipe  900  where light emitted by the LEDs is not as bright. Application of the coating may improve the uniformity of general illumination provided by the LEDs. 
     A layer within a keyboard, such as a light guide pipe, may permit the diffusion of light to provide key-specific illumination to any suitable number of keys.  FIG. 10  shows a top view of an illumination of one key of a keyboard assembly in accordance with some embodiments of the invention. Layer  1000  may be a light guide pipe that may be the same as or different from, and may contain some or all of the features of, light guide pipe layer  130  of  FIG. 1  or light guide pipe layer  330  of  FIG. 3 , for example. 
     Light guide pipe  1000  may include any suitable number of slots, such as slots  1050   a - 1050   c , which may be the same as, or different from, and may include some or all of the features of, slots  540   a - 540   c  of  FIG. 5 , for example. Light guide pipe  1000  may also include any suitable number of holes, such as hole  1035  (which may be the same as, and may contain some or all of the features of holes  131   a ,  131   d ,  131   f ,  131   k ,  131   n  and  131   s  of  FIG. 1 ) to permit illumination sources coupled to other layers within a keyboard assembly to at least partially traverse those layers and to emit light into light guide pipe  1000 . For example, illumination source  1030 , which may be the same as or different from, and may include some or all of the features of, the illumination sources described in  FIGS. 5-9 , may be mounted to any suitable layer, such as a flex layer or a keyboard membrane layer (e.g. flex layer  120  or keyboard membrane layer  150  of  FIG. 1 ). For simplicity, illumination source  1030  may be described in  FIGS. 10-12  as being mounted to a keyboard membrane such as keyboard membrane layer  150 , while emerging into light guide pipe  1000  through hole  1035  to emit key-specific light. Also positioned in any suitable layer above light guide pipe  1000  may be a layer including any suitable number of keys, such as key  1020  with an unique legend  1025 . Key  1020  may be the same as or different from, and may include some or all of the features of, keys  105  of  FIG. 1  or keys  305  of  FIG. 3 , for example. Key  1020  may include an opaque keycap or a transparent keycap. Legend  1025  may be transparent if key  1020  is opaque and legend  1025  may be opaque if key  1020  is transparent, for example. Alternatively, both key  1020  and legend  1025  may be transparent, but may include different materials to provide a visual contrast in the perceived illumination. 
     Key  1020  may be selectively or variably illuminated using any suitable approach. For example, key  1020  may be selectively illuminated to aid a user in capitalizing letters. Upon receiving any suitable input, illumination source  1030  may emit light into light guide pipe  1000  and generally underneath key  1020 . The light may diffuse upwardly from light guide pipe  1000  to illuminate key  1020 , or legend  1025 , or both. The light emitted by illumination source  1030  may be prevented from diffusing through undesired portions of light guide pipe  1000  using any suitable approach, such as slots  1050 . Slots  1050   a - 1050   c  may be positioned to prevent the light emitted by illumination source  1030  from diffusing beyond the portion of light guide pipe  1000  underneath key  1020 . Slots  1050  may also reflect light back into the area of light guide pipe  1000  bounded by the slots to enhance the particular illumination of key  1020 . Because slots  1050  may diffuse the light from illumination source  1030  onto a reflector sheet, such as reflector sheet layer  125  of  FIG. 1 , the reflector sheet may reflect the diffused light back up through light guide pipe  1030  toward key  1020 . In some embodiments, if slots  1050  are positioned such that they do not overlap with any unmasked portions within a mask layer above light guide pipe  1000 , such as unmasked portions  145  within mask layer  140  of  FIG. 1 , then light reflected back through slots  1050  by a reflector sheet may be blocked from diffusing further through a mask layer. 
     In some embodiments, key  1020  may also be variably illuminated using any suitable approach. For example, light guide pipe  1000  may form a part of a keyboard within a device, such as a laptop, or may be coupled to another device, such as a desktop computer, with a display screen. The display screen may present an image that may request input from a user. As a result of the image being presented, a keyboard may receive a device input from the device instructing the keyboard to illuminate one or more keys to guide the user in providing input in response to the display screen (e.g., the keyboard may receive an instruction to illuminate the “CAPS LOCK” key). The keyboard may signal illumination source  1030  to emit light in response to the device input. The illumination may alert the user that the illuminated key may be useful in navigating the display screen. If the input from the device changes such that the “CAPS LOCK” key no longer needs to be illuminated, then the keyboard may receive an input from the device to instruct illumination source  1030  to stop emitting light, thereby indicating to the user that the “Caps Lock” key may no longer be needed to navigate the display screen. 
       FIG. 11  is a vertical cross-sectional view of the portion of the assembly of  FIG. 10 , but with key  1020  removed, in accordance with some embodiments of the invention. In response to any suitable input, illumination source  1030  may pass through hole  1035  and may emit light into light guide pipe  1000  generally in the direction of arrow  1040 . Slots  1050  may channel away from light guide pipe  1000  any light emitted by illumination source  1030  that may have diffused toward slots  1050   a - 1050   c.    
       FIG. 12  is a perspective view of the portion of the assembly of  FIG. 10  in accordance with some embodiments of the invention. Key  1020  may be positioned in any suitable layer above light guide pipe  1000 . Light that may be emitted by illumination source  1030  in the direction of arrow  1040  may diffuse through light guide pipe  1000  and underneath key  1020 . The light may diffuse upwardly away from light guide pipe  1000  and toward key  1020 . Light guide pipe  1000  may also permit any other suitable illumination sources to emit light into light guide pipe  1000  for the purpose of generally illuminating key  1020 . 
       FIG. 13  shows a flowchart of an illustrative process for illuminating one or more keys of a keyboard assembly in accordance with some embodiments of the invention. Process  1300  may begin at step  1302 . At step  1304 , the keyboard may determine whether it has received an input from a device coupled to the keyboard. For example, the keyboard may be embedded within a laptop device that contains a display screen, or the keyboard may be coupled via a cable (e.g., cable  190  of  FIG. 1 ) with a computer having a processor and a display screen. The device may send an input to the keyboard as a result of what is displayed on the display screen. If the keyboard has not received an input from the device, then process  1300  may return to step  1304  to continue sampling for an input from the device. If the keyboard has received an input, then process  1300  may move to step  1310 . 
     At step  1310 , the keyboard may determine whether the input received from the device is an instruction to alter the state of one or more illumination sources. For example, the display screen may display a menu of choices. To navigate the menu using the keyboard, the device may send an input to the keyboard that instructs the keyboard to alter the state of one or more illumination sources within the keyboard that would be beneficial to the user in navigating the menu. This input may instruct the keyboard to provide any suitable selective or variable illumination to the keyboard (e.g., using LED  720  or LED  749  of  FIG. 7 ), to provide any suitable general illumination to the keyboard (e.g., using LEDs  602 ,  604 , and  607  of  FIG. 6 ), or to provide any suitable combination of general, selective, or variable illumination to the keyboard (e.g., using LEDs  502 ,  504 ,  506 ,  507 ,  509 ,  511  and  517  of  FIG. 5 ) to illuminate the desired key or keys. The illumination that may result from the instruction may aid a user in navigating the menu. As another example, the keyboard may receive an input that instructs the keyboard to illuminate one or more currently dark illumination sources because the device has sensed that there is little or no light surrounding the keyboard, making it difficult for a user to use the keyboard. 
     If the input sent from the device is not an instruction to alter the current state of one or more illumination sources, then process  1300  may move to step  1312 . At step  1312 , the keyboard may maintain the current state of the illumination source or sources in the keyboard affected by the instruction and the keyboard may also maintain, by default, the current state of the illumination source or sources not affected by the instruction received from the device. 
     Process  1300  may then move to step  1320 , where the keyboard may determine whether an input has been received from a user of the keyboard in response to maintaining the state of one or more illumination sources. 
     For example, a user may provide an input to the keyboard by striking one or more keycaps on the keyboard (e.g., keycap  170  of key  105   a  of  FIG. 2 ). 
     If an input has not been received from a user, then process  1300  may return to step  1304  to continue sampling for an input from the device. If the keyboard receives an input from a user in response to maintaining the current state of one or more illumination sources, then process  1300  may move to step  1330 . At step  1330 , the keyboard may transmit the user&#39;s input to the device. The user&#39;s input may affect what the device displays next on the display screen, for example. As a result of an alteration in what is displayed on the screen, the device may send new input to the keyboard. Process  1300  may return to step  1304  to continue sampling for an input from the device. 
     If, at step  1310 , the device has sent an instruction to alter the current state of one or more illumination sources (e.g., to illuminate or “turn on” one or more illumination sources that are currently unilluminated or “turned off,” or vice versa), then process  1300  may move to step  1316 . At step  1316 , the keyboard may signal the appropriate illumination source or sources to alter its current state in response to the instruction received from the device. For example, the keyboard may have received an instruction from the device to begin illuminating the number pad, the “SPACEBAR” key, and/or the letters positioned on the left side of the keyboard (e.g., using LEDs  705 ,  715 , and  720  of  FIG. 7 ). Process  1300  may then move to step  1320 , described above. Process  1300  may eventually return to step  1304 , to continue sampling for an input from the device. The processes discussed above are intended to be illustrative and not limiting. Persons skilled in the art will appreciate that steps of the processes discussed herein may be omitted, modified, combined, and/or rearranged, and any additional steps can be performed without departing from the scope of the invention. 
       FIG. 14  shows a simplified schematic diagram of a system including a keyboard assembly in accordance with some embodiments of the invention. System  1400  may include a processing device  1430  that can initiate an outgoing instruction and network  1410 , which processing device  1430  may use to transmit instructions to other devices within network  1410 . For example, system  1400  may include a keyboard  1420  that can receive instructions from processing device  1430 . Although system  1400  may include several processing devices  1430  and keyboards  1420 , only one of each is shown in  FIG. 14  for the sake of simplicity and clarity. Keyboard  1420  may include one or more illumination sources  1450 , only one of which is shown in  FIG. 14  for simplicity and clarity. Illumination source  1450  may be the same as or different from, and may include some or all of the features of, other illumination sources (e.g., illumination sources  121  in  FIG. 1  or illumination sources  321  in  FIG. 3 ). Illumination source  1450  may be illuminated by keyboard  1420  in response to instructions received from processing device  1430 . 
     Any suitable circuitry, device, system, or combination thereof (e.g., a wireless communications infrastructure including communications towers and telecommunications servers) operative to create a network may be used to create network  1410 . Network  1410  may be capable of providing instructions using any suitable protocol. In some embodiments, network  1410  may support, for example, Wi-Fi (e.g., a 802.11 protocol), Bluetooth™, high frequency systems (e.g., 900 MHz, 2.4 GHz, and 5.6 GHz systems), infrared, other relatively localized wireless protocols, or any combination thereof. Processing device  1430  and keyboard  1420 , when located in network  1410 , may communicate over a path, such as path  1440 . Both processing device  1430  and keyboard  1420  may be capable of sending an input to the other and receiving an input from the other. 
     Processing device  1430  may include any suitable device for transmitting and receiving inputs. For example, processing device  1430  may include a desktop computer, a laptop computer, a device capable of communicating wirelessly (with or without the aid of a wireless enabling accessory system) or via wired pathways (e.g., using traditional electrical wires), a pocket-sized personal computer such as an iPAQ Pocket PC available by Hewlett Packard Inc. of Palo Alto, Calif., a personal digital assistant (“PDA”), a personal e-mail or messaging device with audio and/or video capabilities (e.g., a Blackberry® or a Sidekick®), an iPod™ available by Apple Inc. of Cupertino, Calif., or an iPhone™ available by Apple Inc. The input may include any suitable form of instruction, including for example, voice instruction, data instruction, an instruction from a program installed in processing device  1430  (e.g., a spelling software tool), an instruction based upon an environmental condition (e.g., a signal related to the amount of ambient light measured in the vicinity of processing device  1430  or keyboard  1420 ), or combinations thereof. 
     While there have been described systems and methods for improving the keyboard illumination, it is to be understood that many changes may be made therein without departing from the spirit and scope of the present invention. It will also be understood that various directional and orientational terms such as “up” and “down,” “left” and “right,” “top” and “bottom,” “side” and “edge” and “corner,” “height” and “width” and “depth,” “horizontal” and “vertical,” and the like are used herein only for convenience, and that no fixed or absolute directional or orientational limitations are intended by the use of these words. For example, keyboards and illumination sources of this invention can have any desired orientation. If reoriented, different directional or orientational terms may need to be used in their description, but that will not alter their fundamental nature as within the scope of the invention. Those skilled in the art will appreciate that the invention can be practiced by other than the described embodiments, which are presented for purposes of illustration rather than of limitation, and the invention is limited only by the claims which follow.

Metadata:
Filing Date: 20080505
Publication Date: 20121127
Grant Date: 20121127
Priority Date: 20080104
Inventors: BRONSTEIN CHAD A.
MAHOWALD PETER H.
Assignee: APPLE INC
CPC Classifications: [{"code": "H01H2219/062", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01H2219/044", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01H2219/06", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01H2219/039", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01H2219/039", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01H2219/044", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01H2219/06", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01H2219/062", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01H2221/07", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01H2221/07", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01H13/83", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01H13/83", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05B47/165", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01H13/023", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05B47/165", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 40843705