PATENT DOCUMENT

Publication Number: US-10984969-B1
Application Number: US-201816032876-A
Country: US
Kind Code: B1

Title: Uniform illumination of keys on a flexible substrate

Abstract:
Systems and methods for providing illumination to illuminable portions of keys associated with a keyboard are described. A key disposed on a flexible substrate includes a light guide positioned below a keycap. The light guide includes one or more light extraction features to produce a substantially uniform light distribution of light from a light emitting element at an illuminable portion of the key. In one embodiment, a light emitting element is positioned on the flexible substrate and is optically coupled to the light guide. In another embodiment, a light emitting element is positioned below the flexible substrate and is optically coupled to the light guide via an optical interface.

Claims:
What is claimed is: 
     
       1. An electronic device comprising:
 a keyboard comprising:
 a flexible substrate having a conductive trace; 
 a light emitting element on the flexible substrate and electrically coupled to the conductive trace; and 
 a set of keys, each key comprising:
 a keycap positioned over the flexible substrate and having an illuminable portion defining a symbol; 
 a light guide positioned between the keycap and the flexible substrate and configured to optically couple light from the light emitting element to the illuminable portion of the keycap; and 
 a switch assembly positioned below the flexible substrate. 
 
 
 
     
     
       2. The electronic device of  claim 1 , wherein:
 the flexible substrate is a fabric sheet; and 
 the conductive trace includes one or more conductive threads integrated into the fabric sheet. 
 
     
     
       3. The electronic device of  claim 1 , wherein the light emitting element is positioned above the flexible substrate and is configured to transmit light into a sidewall of the light guide. 
     
     
       4. The electronic device of  claim 1 , wherein the light guide defines light extraction features configured to direct the light to a lower surface of the keycap. 
     
     
       5. The electronic device of  claim 4 , wherein a spacing of the light extraction features varies in accordance with a distance from the light emitting element. 
     
     
       6. The electronic device of  claim 4 , wherein at least a portion of the light extraction features are positioned along a bottom surface of the light guide and the portion of the light extraction features are configured to reflect light toward the keycap. 
     
     
       7. The electronic device of  claim 4 , wherein at least a portion of the light extraction features are positioned along a top surface of the light guide and the portion of the light extraction features are configured to refract light toward the keycap. 
     
     
       8. The electronic device of  claim 1 , wherein the light guide is configured to produce a substantially uniform distribution of light along a lower surface of the keycap. 
     
     
       9. The electronic device of  claim 1 , wherein:
 the flexible substrate includes a folded perimeter feature; and 
 the folded perimeter feature is configured to facilitate movement of a localized region of the flexible substrate when the keycap is depressed. 
 
     
     
       10. A keyboard comprising:
 a flexible substrate; 
 a set of keycaps positioned over the flexible substrate, each keycap of the set of keycaps comprising a translucent portion and configured to depress in response to a press; 
 a set of light guides, each light guide of the set of light guides positioned above the flexible substrate and below a respective keycap of the set of keycaps; 
 a set of light emitting elements, each light emitting element of the set of light emitting elements optically coupled to a respective light guide of the set of light guides; 
 a set of switch assemblies positioned below the flexible substrate, each switch assembly of the set of switch assemblies comprising:
 a key mechanism configured to upwardly bias a corresponding keycap of the set of keycaps; and 
 a switch configured to actuate in response to the corresponding keycap being depressed; wherein:
 a movable portion of the flexible substrate associated with the corresponding keycap is configured to move in response to the keycap being depressed. 
 
 
 
     
     
       11. The keyboard of  claim 10 , wherein:
 the translucent portion of the keycap is a symbol defining a glyph; 
 the light guide comprises at least one light extraction feature configured to direct light to the symbol; and 
 the light emitting element is a light-emitting diode positioned in a corner of the light guide. 
 
     
     
       12. The keyboard of  claim 10 , wherein the flexible substrate includes a folded perimeter feature defining the movable portion of the flexible substrate. 
     
     
       13. The keyboard of  claim 10 , wherein the light emitting element is positioned below the flexible substrate. 
     
     
       14. The keyboard of  claim 10 , wherein:
 the light emitting element is disposed on the flexible substrate; 
 the flexible substrate comprises a conductive trace operably coupled to a power source; and 
 the light emitting element is electrically coupled to the power source via the conductive trace. 
 
     
     
       15. The keyboard of  claim 10 , wherein:
 the light emitting element is a first light emitting element; 
 the keyboard further comprises a second light emitting element optically coupled to the light guide; and 
 the first and second light emitting elements are positioned at different corners of the light guide. 
 
     
     
       16. The keyboard of  claim 10 , wherein:
 the light emitting element is positioned beneath the flexible substrate; and 
 the keyboard further comprises an optical interface configured to transmit light from the light emitting element to the light guide. 
 
     
     
       17. The keyboard of  claim 10 , further comprising a set of input members connected to the key mechanisms of the set of switch assemblies, the set of input members being connected to the flexible substrate opposite the set of light guides.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This claims priority to U.S. Provisional Patent Application No. 62/531,600, filed 12 Jul. 2017 and entitled, “UNIFORM ILLUMINATION OF KEYS ON A FLEXIBLE SUBSTRATE,” and the entire disclosure of which is hereby incorporated by reference. 
    
    
     FIELD 
     Embodiments described herein are directed to input devices for computing systems and, more particularly, to systems and methods for facilitating substantially uniform illumination of select features of such input devices. 
     BACKGROUND 
     Electronic devices can receive user input from a keyboard, some keys of which may be illuminable and thus visible to a user in dimly-lit environments. Using some traditional techniques, it may be difficult to produce a uniform or consistent illumination for symbols or glyphs, which may vary in size and shape for different keys. Furthermore, uniform illumination may be further complicated by the presence of various components within the keyboard including, key mechanisms, key webs, and other structural components. The embodiments described herein may be used to improve to quality and uniformity of illuminated keys for a keyboard. 
     SUMMARY 
     Certain embodiments described herein relate to, include, or take the form of an electronic device including a keyboard. The keyboard includes a flexible substrate having a conductive trace. The keyboard further includes a light emitting element on the flexible substrate and electrically coupled to the conductive trace. The keyboard further includes a set of keys. Each key includes a keycap positioned over the flexible substrate and having an illuminable portion defining a symbol. Each key further includes a light guide positioned between the keycap and the flexible substrate and configured to optically couple light from the light emitting element to the illuminable portion of the keycap. Each key further includes a switch assembly positioned below the flexible substrate. 
     Other embodiments described generally reference a keyboard that includes a flexible substrate. The keyboard further includes a set of keycaps positioned over the flexible substrate, each keycap of the set of keycaps comprising a translucent portion and configured to depress in response to a press. The keyboard further includes a set of light guides, each light guide of the set of light guides positioned above the flexible substrate and below a respective keycap of the set of keycaps. The keyboard further includes a set of light emitting elements, each light emitting element of the set of light emitting elements optically coupled to a respective light guide of the set of light guides. The keyboard further includes a set of switch assemblies positioned below the flexible substrate. Each switch assembly of the set of switch assemblies includes a key mechanism configured to upwardly bias a corresponding keycap of the set of keycaps and a switch configured to actuate in response to the corresponding keycap being depressed. A movable portion of the flexible substrate associated with the corresponding keycap is configured to move in response to the keycap being depressed. 
     Still further embodiments described herein generally reference an electronic device including a flexible substrate and a light emitting element positioned below the flexible substrate. The electronic device further includes a keycap positioned above the flexible substrate and defining an illuminable symbol. The electronic device further includes a light guide positioned between the flexible substrate and the keycap. The light guide is configured to receive light from the light emitting element to produce a substantially uniform distribution of light along a bottom surface of the keycap. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Reference will now be made to representative embodiments illustrated in the accompanying figures. It should be understood that the following descriptions are not intended to limit this disclosure to one preferred embodiment. To the contrary, the disclosure provided herein is intended to cover alternatives, modifications, and equivalents as may be included within the spirit and scope of the described embodiments, and as defined by the appended claims. 
         FIG. 1A  depicts an electronic device incorporating a keyboard with illuminable keys, according to an embodiment. 
         FIG. 1B  depicts a removed view of greater scale of the electronic device of  FIG. 1A . 
         FIG. 2A  depicts a schematic view of an example key stack that may be used with an illuminable key of the keyboard shown in  FIGS. 1A-1B , according to an embodiment. 
         FIG. 2B  illustrates a cross-section view of an example key stack, according to an embodiment. 
         FIG. 2C  illustrates a removed view of a flexible substrate identified by the enclosed circle B-B, shown in  FIG. 2B . 
         FIG. 2D  illustrates a removed view of a flexible substrate identified by the enclosed circle C-C, shown in  FIG. 2B . 
         FIG. 3A  illustrates an example light guide with a light emitting element, according to an embodiment. 
         FIG. 3B  illustrates an example cross-section of the light guide and light emitting element of  FIG. 3A . 
         FIG. 3C  illustrates a removed view of a light guide identified by the enclosed circle F-F, shown in  FIG. 3B . 
         FIG. 3D  illustrates a removed view of a light guide identified by the enclosed circle G-G, shown in  FIG. 3B . 
         FIG. 3E  illustrates an example cross-section of the light guide and light emitting element of  FIG. 3A . 
         FIG. 3F  illustrates a removed view of a light guide identified by the enclosed circle H-H, shown in  FIG. 3E . 
         FIG. 3G  illustrates a removed view of a light guide identified by the enclosed circle I-I, shown in  FIG. 3E . 
         FIG. 3H  illustrates an example cross-section of the light guide and light emitting element of in accordance with an additional configuration of the embodiment of  FIG. 3A . 
         FIG. 4A  illustrates an example light guide and light emitting elements, according to an embodiment. 
         FIG. 4B  illustrates an example cross-section of the light guide and light emitting elements of  FIG. 4A . 
         FIG. 5  illustrates an example light guide and light emitting element, according to an embodiment. 
         FIG. 6  illustrates an example light guide and light emitting elements, according to an embodiment. 
         FIG. 7A  depicts a schematic view of an example key stack that may be used with an illuminable key of a keyboard, according to an embodiment. 
         FIG. 7B  is a cross-section of an example key stack including an optical interface, according to an embodiment. 
         FIGS. 8-12  illustrate cross-sections of an example key stacks including an optical interface. 
         FIG. 13A  depicts a schematic view of an example key stack that may be used with an illuminable key of a keyboard, according to an embodiment. 
         FIG. 13B  is a cross-section of an example key stack, according to an embodiment. 
         FIG. 13C  is a cross-section of the example key stack of  FIG. 13B  in a depressed position, according to an embodiment. 
         FIG. 13D  depicts a schematic view of an example keyboard incorporating key stacks, according to an embodiment. 
         FIG. 14  shows a keyboard with illuminable keys for use with an electronic device, as described herein. 
     
    
    
     The use of the same or similar reference numerals in different figures indicates similar, related, or identical items. 
     Additionally, it should be understood that the proportions and dimensions (either relative or absolute) of the various features and elements (and collections and groupings thereof) and the boundaries, separations, and positional relationships presented therebetween, are provided in the accompanying figures merely to facilitate an understanding of the various embodiments described herein and, accordingly, may not necessarily be presented or illustrated to scale, and are not intended to indicate any preference or requirement for an illustrated embodiment to the exclusion of embodiments described with reference thereto. 
     DETAILED DESCRIPTION 
     Reference will now be made in detail to representative embodiments illustrated in the accompanying drawings. It should be understood that the following descriptions are not intended to limit the embodiments to one preferred embodiment. To the contrary, it is intended to cover alternatives, modifications, and equivalents as can be included within the spirit and scope of the described embodiments as defined by the appended claims. 
     Embodiments described herein are directed to systems and techniques for improving the uniformity of illumination of illuminated keys of a keyboard. In particular, the embodiments are directed to keys having a light guide positioned below a keycap. The light guide may include features for producing a uniform backlight for the keycap of the key. The optical features of the light guide may be tailored to produce a desired light effect or distribution for a specific key symbol or glyph. The optical features may also be optimized to provide substantially uniform distribution of light so that a variety of symbols or glyphs produce a consistent and uniform level of illumination. 
     Some embodiments described herein are directed to a keyboard having a flexible substrate or membrane that may provide a protective covering for the internal components of a keyboard or electronic device having a keyboard. The flexible substrate or membrane may include a cloth, fabric, or other pliable material that provides a barrier to contaminants and may also improve the visual appearance and tactile quality of the keyboard or device. In various embodiments, the flexible substrate is configured to move in response to the keycap being depressed, for example in response to a press. 
     As described in more detail here, the light guide may be positioned between the keycap and the flexible substrate or membrane to more efficiently couple or transmit light to the keycap. A light-emitting diode (LED) may be positioned between the keycap and the flexible substrate and may be powered using conductive traces or elements integrated with the flexible substrate. In some embodiments, the LED is positioned below the flexible substrate and is configured to couple light into the light guide using one or more optical coupling techniques, some examples of which are provided herein. 
     As noted above, the light emitting element optically couples to illuminable portions of a key via a light guide. In some implementations, the light guide includes various light extraction features. As used herein, the phrase “light extraction feature” may be used to refer to a feature that is contained within, or formed on, a body or structure of the light guide that facilitates the extraction or reflection of light from the light emitting element to cause the light to illuminate portions of the key. The light extraction features may be operative to direct light out of a top surface of the light guide to illuminate the illuminable portion(s) of the key. The light extraction features may include various prisms, serrations, scallops, lenticular features, or other such shapes that reflect light into a center portion of the light guide to illuminate the illuminable portion(s). As explained in more detail below, the light extraction features may be configured and arranged to produce a substantially uniform light distribution for illuminating a symbol or glyph. The light extraction features may be positioned on or along a top surface of the light guide, on or along a bottom surface of the light guide, within the light guide, or some combination thereof. In other embodiments, a light guide, or portions of the light guide, can form a structural portion of the key in addition to directing light. 
     In one embodiment, the light emitting element is disposed above the flexible substrate and is positioned to transmit light into the light guide. In another embodiment, the light emitting element is disposed below the flexible substrate and is optically coupled to the light guide via an optical interface. 
     The optical interface is configured to optically couple or transmit light from the light emitting element(s) to the light guide. In various embodiments, the optical interface directs light from the light emitting element. Directing light may include shaping light (e.g., focusing, collimating, dispersing, and so on), reflecting light, changing direction of light, and so on. The optical interface may include one or more components or features for directing light, including reflective elements, refractive elements, lenses, collimators, prisms, serrations, scallops, and so on. The optical interface may further include reflective coatings and/or masking of components of the key stack. The optical interface may be positioned above the flexible substrate, below the flexible substrate, within the flexible substrate, or some combination thereof. 
     As used herein, the phrase “illuminable portion of a key” may be used to refer to a portion of a key that is configured to emit light. For example, the illuminable portion of a key may be a symbol or glyph of a keycap. The illuminable portion of a key may also include any or all areas of (or adjacent to) a keycap or other input surface that are intended to be illuminated such that the location, size, and/or functionality of that portion of the key is visually emphasized. 
     A symbol or glyph can be formed in an outer surface of a key from a translucent or transparent material to define an alphanumeric character, symbol, word, phrase, abbreviation, or any other linguistic, scientific, numeric, or pictographic symbol or set of symbols. In one example, the symbol itself illuminates upon activation of the light emitting element. In other examples, other portions of the key associated with the symbol illuminate upon activation of the light emitting element such as a glyph border, a glyph underline, a glyph outline, and so on. All are examples of illuminable portions of a key. 
     Another example of an illuminable portion of a key are geometric or structural features of the keycap. In one example, the light emitting element illuminates a keycap perimeter. In other examples, other portions of the keycap are illuminated, such as an external surface, a sidewall, a corner, and so on. In further examples, the light emitting element can illuminate spaces between one or more keys and the adjacent structure of a keyboard. For example, an aperture in which a key is disposed illuminates upon activation of the light emitting element, thereby generating a halo around a base of the key. 
     These and other embodiments are discussed below with reference to  FIGS. 1A-14 . However, those skilled in the art will readily appreciate that the detailed description given herein with respect to these Figures is for explanatory purposes only and should not be construed as limiting. 
       FIG. 1A  depicts an electronic device  100  incorporating a keyboard  101  with illuminable keys, such as the illuminable key  102  depicted in a removed view of greater scale identified by the enclosed circle A-A, shown in  FIGS. 1A-1B . 
     The electronic device  100  includes a housing  106  and a flexible substrate  110  along a surface of the housing  106 . The illuminable key  102  may be located on a surface of the housing  106  such as a surface defined by the flexible substrate  110 . The illuminable key  102  may depress when a user presses the illuminable key  102 . In one example, a top surface of the illuminable key  102  is flush with a top surface of the housing  106  when the illuminable key  102  is fully pressed. 
     A structure associated with the illuminable key  102  is disposed partially above and partially below the flexible substrate  110 . The structure associated with the illuminable key  102  may be referred to as a “key stack,” and can include a key assembly disposed above the flexible substrate  110  and a switch assembly (not shown in  FIGS. 1A-1B ) disposed below the flexible substrate  110 . In various embodiments, the key assembly includes a keycap that defines at least one illuminable portion, depicted in  FIG. 1A  as a glyph  108 . 
     The flexible substrate  110  may be a sheet, film, or other pliable or flexible material. Examples include fabric, polymer, leather, rubber, and so on. The flexible substrate  110  may extend over the switch assembly of the key thus forming an external surface of the housing  106  upon which the key assembly is disposed. In various embodiments, the flexible substrate  110  provides a barrier to contaminants and may also improve the visual appearance and tactile quality of the keyboard. The flexible substrate  110  may be bonded to the housing  106  and/or the key assembly and switch assembly of the keys. In one embodiment, the flexible substrate  110  includes one or more conductive traces configured to transmit signals between the illuminable key  102  and other components of the electronic device  100  such as a power source for illuminating the illuminable key  102 . 
     As shown, the electronic device is a laptop computer, though it can be any suitable electronic device, including, for example, a desktop computer, a smart phone, an accessory, or a gaming device. Moreover, while the keyboard in  FIG. 1A  is incorporated with the electronic device  100 , the keyboard may be separate from an electronic device. For example, the keyboard  101  may be a standalone device that is connected (via a cable or wirelessly) to a separate electronic device as a peripheral input device. The keyboard may also be integrated into another product, component, or device, such as a cover or case for a tablet computer. In such cases, the housing  106  may refer to a housing of any product, component, or device in which the keyboard is integrated or otherwise positioned. 
     The electronic device  100  may also include a display  116  within the housing  106 . For example, the display  116  may be within or otherwise coupled to a first portion  112  of the housing  104  that is pivotally coupled to a second portion  114  of the housing  106 . The keyboard  101  may be within or otherwise coupled to or incorporated with second portion  114  of the housing  106 . The electronic device may include one or more input devices, including the keyboard, a trackpad  118 , buttons, switches, and so on. The trackpad  118  may form an input surface on a surface of the housing  106 . The trackpad  118  may be within or otherwise coupled to or incorporated with the second portion  114  of the housing  106 . 
     While the instant application describes components of an illuminable key of a keyboard, the concepts and components described herein apply to other depressible input mechanisms as well, including buttons, standalone keys, switches, or the like. Moreover, such keys, buttons, or switches may be incorporated into other devices, including smart phones, tablet computers, or the like. 
     The electronic device  100  may include one or more components that interface or interoperate, either directly or indirectly, with the illuminable key  102  which are not depicted in  FIGS. 1A-1B . For example, the electronic device  100  may include a processor coupled to or in communication with a memory, a power supply, one or more sensors, one or more communication interfaces, and one or more input/output devices such as a display, a speaker, a rotary input device, a microphone, an on/off button, a mute button, a biometric sensor, a camera, a force and/or touch sensitive trackpad, and so on. 
     Producing consistent, uniform illumination for symbols or glyphs in traditional keyboards may be difficult because of the varying shapes, sizes, and positions of symbols or glyphs for different keys. Key mechanisms, key webs, and other structural components further complicate illumination by reflecting, absorbing, redirecting, or otherwise interfering with light traveling from a light emitting element to a keycap. 
     Key stacks including illuminable portions described herein include various optical features for producing a uniform backlight for the keycap. The optical features of the light guide may be tailored to produce a desired light effect for a specific key symbol or glyph. The optical 4823-2383-1148 \  1  features may also be optimized to provide substantially uniform distribution of light so that a variety of symbols or glyphs produce a consistent and uniform level of illumination. 
       FIG. 2A  depicts a schematic view of an example key stack  200  that may be used with an illuminable key of the keyboard shown in  FIGS. 1A-1B . The key stack  200  includes a key assembly  220  disposed above a flexible substrate  210  and a switch assembly  230  disposed on a base plate  260  below the flexible substrate  210 . The key assembly  220  includes a keycap  222  disposed above a light guide  224  and a light emitting element  226 . 
     The keycap  222  defines an exterior surface of the key stack  200 . The keycap  222  includes one or more illuminable portions  208  (e.g., glyphs  208 A and  208 B) formed of a translucent material. The illuminable portions  208  are configured to be illuminated by the light emitting element  226 . The light guide  224  is configured to transmit or direct light from the light emitting element  226  to the illuminable portions  208 . 
     The light emitting element  226  may be positioned between the keycap  222  and the flexible substrate  210  and configured to emit light into the light guide  224 . The light guide  224  optically couples the light emitting element  226  and the illuminable portions  208  of the keycap  222 . The light guide  224  may be positioned between the flexible substrate  210  and the keycap  222 . The flexible substrate  210  may include one or more conductive traces operably coupled to a power source of the electronic device. The conductive traces may electrically couple the light emitting element  226  to the power source. 
     In various embodiments, the light guide  224  includes light extraction features for directing and/or reflecting light to the illuminable portions  208  of the keycap  222 . The light extraction features may produce a substantially uniform distribution of light along a bottom surface of the keycap  222  and/or a top surface of the light guide  224 . As noted above, the light extraction features are features contained within, or formed on, a body or structure of the light guide that direct light from the light emitting element  226  out of the light guide  224 . The light extraction features may include various prisms, serrations, scallops or other such shapes. The light extraction features may be positioned on or along an upper surface of the light guide  224 , on or along a lower surface of the light guide  224 , within the light guide  224 , or some combination thereof. In one embodiment, the light extraction features are indentations in the light guide  224 . In another embodiment, the light extraction features are protrusions from the light guide  224 . 
     The light guide  224  may be formed from an optically translucent or transparent material such as acrylic, plastic, glass, doped plastic or glass, sapphire, zirconia, composite material, glass fiber epoxy laminate (e.g., FR4), or the like. In many examples, the light guide  224  is insert-molded into a structural body configured to contain the light guide. In other embodiments, the light guide  224  and the keycap  222  are a single part. Thus, in some embodiments, the keycap  222  is formed from acrylic, plastic, glass, doped plastic or glass, sapphire, zirconia, composite material, glass fiber epoxy laminate (e.g., FR4), or the like. The light guide  224  may be co-molded with the keycap  222 . In still further examples, the light guide  224  is molded into a light guide cavity that is defined within the keycap  222 . The light extraction features may be formed using a variety of techniques, including molding, laser etching, lithography, and so on. 
     Different keys of the keyboard may have different illuminable portions  208 . For example, different keys may have illuminable portions  208  having different positions on the key, different shapes, and so on. The example key of  FIG. 2A  has two illuminable portions  208 A and  208 B, but different embodiments may have more or fewer illuminable portions. The light guide features for a particular key may be based on the illuminable portions  208  of that key so that the features direct light to the illuminable portions more effectively. 
     The light emitting element  226  may be positioned near, adjacent to, or within the light guide  224 . In one embodiment, the light emitting element  226  is positioned in an opening in the light guide  224 . In another embodiment, the light emitting element  226  is integrated with the light guide  224 . The light emitting element may be positioned in a support structure within the light guide  224 . 
     The light emitting element  226  may include one or more light-emitting diodes. The light-emitting diodes emit light of a particular color and at a particular brightness. In some embodiments, the light emitting element  226  provides light of a variable color and/or a variable brightness. In one example, the light emitting element  226  emits white light having a cool color temperature, although this is not required. The light emitting element  226  may be configured to emit light in one or more particular directions, such as toward the center of the light guide  224 . The light emitted by the light emitting element may be a focused beam, a dispersed beam, a collimated beam, and so on. 
     The light guide  224  may be directly or indirectly coupled to the light emitting element and/or the illuminable portions  208 . The light guide  224  can take a square shape, a rectangular shape, a grid shape, or any other shape or combination of shapes. In still further examples, the light guide  224  is formed as a segmented shape, such as a segmented ring. The light guide  224  may define an interior volume and perimeter surfaces. The light guide features may be located at or near the perimeter surfaces and/or within the interior volume. 
       FIGS. 3A-6  illustrate example configurations of light guides and light emitting elements such as those described herein.  FIG. 3A  illustrates an example light guide  324  with a single light emitting element  326  located near a corner of the light guide. The light emitting element  326  may be partially or entirely surrounded by the light guide  324  or it may be disposed on top of or below a layer defined by the light guide. The light emitting element  326  may emit light in a particular direction, such as downward and to the right (with respect to  FIG. 3A ) toward the center of the light guide  324 . 
     The light guide  324  may include light extraction features  350  such as those discussed above with respect to  FIG. 2A . In various embodiments, the light extraction features  350  have characteristics to produce a uniform illumination of the keycap. Characteristics of the light extraction features may include position, arrangement, size, shape, spacing, and so on. For example, the light extraction features  350  may be arranged based on the position of the light emitting element  326  and the illuminable portion(s) (not shown). In the example of  FIG. 3A , the light extraction features  350  are arranged in curved lines that form a ripple pattern emanating from the position of the light emitting element  326 . The spacing and/or size of the light extraction features  350  may change based on a position within the light guide  324  (e.g., based on a distance from the light emitting element  326 ) as shown in  FIG. 3A  to optimize the delivery of light to the illuminable portion(s). A space between adjacent light extraction features may vary based on a distance between the light extraction features and the light emitting element. For example, as shown in  FIG. 3A , the features closer to the light emitting element  326  may be spaced farther apart than the features farther from the light emitting element  326 . This may result in more effective light distribution by allowing more light to be transmitted or directed to the portions of the keycap that are farther from the light emitting element  326 . 
       FIGS. 3B and 3E  illustrate example cross-sections of the light guide  324  taken through section line D-D of  FIG. 3A .  FIG. 3B  depicts light extraction features  350 B disposed on or near a bottom surface of the light guide  324 . The light extraction features  350 B of  FIG. 3B  are serrated features (e.g., grooves with an iscosceles- or other type of triangular cross-section) configured to direct or transmit light to the illuminable portions of the keycap. For example, the light extraction features  350 B may reflect light upward toward the keycap or an upper surface of the light guide  324 . 
       FIG. 3E  depicts light extraction features  350 C disposed on or near a top surface of the light guide  324 . The light extraction features  350 C of  FIG. 3E  are lenticular features (e.g., rounded features) configured to direct or transmit light to the illuminable portions of the keycap. For example, the light extraction features  350 C may refract light upward toward the keycap or an upper surface of the light guide  324 . 
     As illustrated in  FIGS. 3B and 3E , the spacing and/or size of the light extraction features  350  may vary within the light guide  324 . In the example of  FIG. 3B , the light extraction features  350 B are spaced farther apart as the distance from the light emitting element  326  increases, as depicted in a removed view of greater scale identified by the enclosed circles F-F and G-G, shown in  FIGS. 3C-3D . The greater spacing between the features closer to the light emitting element causes less light to be directed by the features closer to the light emitting element and allows the light extraction features to produce a uniform illumination of an upper surface of the light guide  324 , the keycap (not pictured), and/or an illuminable portion of the keycap. 
     In the example of  FIG. 3E , the light extraction features  350 C change size and spacing as the distance from the light emitting element changes, as depicted in a removed view of greater scale identified by the enclosed circles H-H and I-I, shown in  FIGS. 3F-3G . In various embodiments, the light extraction features may vary in size, shape, spacing, and other characteristics to maximize delivery of light to the illuminable portion(s) of the keycap. Variations in size, shape, spacing, and/or other characteristics may be based on a position within the light guide  324 , a distance from the light emitting element  326 , a position of the illuminable portion(s) of the keycap, and/or other characteristics of the key stack. 
     As noted above, the light extraction features  350  may be formed using a variety of techniques, including molding, laser etching, lithography, and so on. In one embodiment, the light extraction features are indentations in the light guide  324 . In another embodiment, the light extraction features are protrusions from the light guide  324 . As shown in  FIGS. 3B-3C , the light extraction features  350  may be extrusions in a surface of the light guide  324  and/or protrusions from a surface of the light guide  324 . 
       FIG. 3H  shows a cross-section of the light guide  324  of  FIG. 3A  in accordance with another embodiment of the disclosure. In this configuration, the light extraction features  350 D can include grooves with right-triangular or “sawtooth” profiles, wherein a first side of the triangle profile is oriented perpendicular to the outer surface of the light guide  324  (or perpendicular to the direction of light emitted from the light emitting element  326 —referred to as the vertical sidewall), and a second side of the triangle profile slopes from the innermost end of the first side to the outer surface (referred to as the angled sidewall). In this embodiment, the vertical sidewall of the profile is closer to the light emitting element  326  than the angled sidewall, but in other embodiments, the angled sidewall of the profile can be positioned closer to the light emitting element  326  than the vertical sidewall. As compared to the embodiment of  FIG. 3B , the configuration of  FIG. 3H  can direct light from the light emitting element  326  more towards the top right corner of the light guide  324 . Thus, this configuration can increase the amount of light distributed to the areas of the light guide positioned farthest from the light emitting element  326 . 
       FIG. 4A  illustrates an example light guide  424  with two light emitting elements  426  disposed at opposite corners of the light guide. The light emitting elements  426  may emit light in one or more directions, and may emit light in different directions from one another. In one embodiment, each of the light emitting elements  426  emits light toward the center of the light guide  324 . 
     In the embodiment of  FIG. 4A , the light emitting elements  426  are positioned near a side of the light guide  424  and configured to direct or transmit light into the light guide  424  (e.g., into a sidewall of the light guide  424 ). A light transmission feature  420  may be positioned between the light emitting element  426  and the light guide  424  to facilitate or maximize the transmission of light into the light guide  424 . In one embodiment, the light transmission feature  420  is a lens or other optical element configured to maximize the transmission of light into the light guide  424 . The light guide  424  includes feature regions  425 A and  425 B having different light extraction features, for example to maximize the light delivered to the illuminable portion(s) of the key. In one embodiment, the region  425 A does not include light extraction features. In another embodiment, the region  425 A includes light extraction features such as a reflective coating. Region  425 B includes features  450  configured to direct or transmit light to an illuminable portion (e.g., above the region  425 B). 
     In various embodiments, the light guide  424  may include feature regions having different light extraction features, arrangements, sizes, spacing, and so on. The shapes and positions of the feature regions may vary from the example regions of  FIG. 4A  based on characteristics of the illuminable portion(s) and other considerations. For example, in one embodiment, a feature region with light extraction features has a shape that corresponds to a shape of the illuminable portion(s) of the keycap. Feature regions may be located directly beneath the illuminable portions, or at different positions within the light guide and at different positions relative to the illuminable portion(s). Further, some regions may not include light extraction features. In one embodiment, the light guide does not include distinct feature regions. 
       FIG. 4B  illustrates a cross-section of the light guide  424  taken through section line E-E of  FIG. 4A .  FIG. 4B  illustrates light extraction features  450 A on a top surface of the light guide  424  and light extraction features  450 B on a bottom surface of the light guide. As shown in  FIGS. 4A-4B , the light extraction features  450 A- 450 B are oriented perpendicular to a path between the light emitting elements and the light extraction features to maximize the transmission of light to the illuminable portion. In various embodiments, the light extraction features may be positioned in different positions and/or orientations to maximize light transmission. 
     In some embodiments, the light extraction features  450 A- 450 B can be configured with right-triangular profiles similar to the light extraction features  350 D shown in  FIG. 3H . A first portion of the light extraction features  450 A- 450 B can have cross-sectional profiles wherein the vertical sidewall of the right-triangular profile shape is closer to the light-emitting element  426  of one corner of the light guide  424 , and a second portion of the light extraction features  450 A- 450 B can have cross-sectional profiles that have the vertical sidewall closer to the light-emitting element  426  at the opposite corner of the light guide  424 . In this way, the two portions of the light extraction features  450 A- 450 B can direct light toward the centerline of the light guide  424  between the light-emitting elements  426 . 
       FIG. 5  illustrates an example light guide  524  with a light emitting element  526  disposed near a center of the light guide. Light extraction features  550  are arranged as concentric circles centered around the light emitting element  526 . The light emitting element  526  may emit light in any direction or directions. For example, the light emitting element  526  may emit light outward in multiple directions along the plane defined by the light guide  524  as well as directions not along the plane (e.g., in and out of the page with respect to  FIG. 5 ). 
       FIG. 6  illustrates an example light guide  624  with an array of light emitting elements  626  disposed below, or within the light guide. In one embodiment, the light emitting elements  626  are configured to direct or transmit light through the light guide (e.g., out of the page). In various embodiments, the light emitting elements  626  may be configured to emit light in any direction. The light emitting elements  626  may be separately controllable or drivable to direct light to illuminable portions of the key. The light guide  624  may include light extraction features disposed around, above, and/or below the light emitting elements  626  to direct light to illuminable portions of the key. 
     Returning now to  FIG. 2A , the flexible substrate  210  is disposed between the key assembly and the switch assembly of the key stack  200 . As noted above, the flexible substrate  210  may be a sheet or film such as a fabric, polymer, or leather sheet, thermoplastic polyurethane (TPU), silicone, thermoplastic elastomer (e.g., HYTREL® from DUPONT®), or any other appropriate deformable or flexible substrate or sheet. In one embodiment, the flexible substrate  210  includes one or more folded perimeter features to facilitate movement of a movable portion of the flexible substrate relative to the rest of the flexible substrate when the key assembly is depressed. Folded perimeter features are discussed in more detail below with respect to  FIG. 13A . In another embodiment, the flexible substrate  210  does not include the folded perimeter features and deforms or flexes when the key is depressed. 
     As noted above, the flexible substrate  210  includes one or more conductive traces that may electrically couple the light emitting element  226  and/or other components of the key stack to a power source of the electronic device. In one embodiment, the conductive trace is integrated into the flexible substrate. The conductive traces may be included in the flexible substrate  210  using a variety of methods or techniques, including weaving the conductive threads into the flexible substrate, painting a conductive material onto the flexible substrate, and so on. 
       FIG. 2B  illustrates a cross-section view of an example key stack (e.g., key stack  200 ).  FIG. 2C  illustrates a removed view of the flexible substrate  210  at greater scale identified by the enclosed circle B-B, shown in  FIG. 2B . As shown in  FIG. 2C , the flexible substrate may include a first layer  214 , a second layer  216 , and a conductive trace  218 . The first and second layers  214 ,  216  may be formed of different materials and/or have different characteristics. In one embodiment, the first layer  214  includes cosmetic features such as a particular finish or feel because it may be located on an exterior surface of the electronic device. The conductive traces can comprise a conductive metallic or nonmetallic material such as, for example, copper, silver, aluminum, graphite, a conductive polymer, and related materials. 
     In the embodiment of  FIG. 2C , the conductive trace  218  is located between two layers  214 ,  216 , but in various embodiments, the flexible substrate  210  may include more or fewer layers, and the conductive trace  218  may be located above and/or below one or more layers at any suitable location. 
       FIG. 2D  illustrates a removed view of the flexible substrate  210  at greater scale identified by the enclosed circle C-C, shown in  FIG. 2B .  FIG. 2D  illustrates the light emitting element  226  coupled to the flexible substrate  210 . The flexible substrate  210  includes an opening  215  ( FIG. 2A ) in the layer  214  that allows the conductive trace  218  to be coupled to the light emitting element  226 . In one embodiment, the light emitting element  226  is disposed in the opening such that a portion of the light emitting element  226  is below the top surface of the flexible substrate  210  and contacting the conductive trace  218 . In another embodiment, the light emitting element  226  is above the flexible substrate  210  and a connector electrically couples the light emitting element  226  to the conductive trace  218 . The connector may include a conductive material capable of electrically coupling the conductive trace  218  and the light emitting element  226 . The connector may be integrated as part of the light emitting element  226  and/or the flexible substrate  210 , for example as an electrical contact. 
     Returning to  FIG. 2A , the key stack  200  may include a switch assembly  230  for facilitating movement of the key assembly  220  and detecting inputs in response to forces applied at the keycap  222 . The switch assembly  230  upwardly biases an input member (e.g., the keycap  222 , light guide  224 , and/or flexible substrate  210 ). The switch assembly  230  is configured to actuate a switch (not pictured) in response to the input member translating. In particular, the input member is configured to transmit a force applied to the keycap  222  to the switch, thereby actuating the switch. This, in turn, causes an input to be registered by the electronic device. 
     The switch assembly  230  may generally bias the input member upward (with respect to the view of  FIG. 2B ), thereby keeping the input member in a default or rest position in the absence of external force. Likewise, when force is removed from the input member after the input member translates, the switch assembly  230  returns to its default configuration as shown in  FIG. 2B , thereby moving the input member from a depressed to rest position. 
     As noted above, in one embodiment, the input member is the key assembly  220  and/or the flexible substrate  210 . In another embodiment, a separate input member is positioned below the flexible substrate  210 , for example as shown below with respect to  FIG. 13A . 
     In the depicted example, the switch assembly  230  is a collapsible dome disposed on the base plate  260 . The input member may be configured to transmit a force from the keycap  222  to the collapsible dome, thereby collapsing the dome and actuating a switch. This, in turn, causes an input to be registered by the electronic device. In addition, the collapsible dome may generally bias the input member upward (with respect to the view of  FIG. 2B ), thereby keeping the key mechanism in a default or rest position in the absence of external force. Likewise, when force is removed from the input member after the dome collapses, the dome (or other switch) returns to its default configuration, thereby moving the input member from a depressed to a rest position. 
     The switch assembly  230  of  FIGS. 2A-2B  is merely one example of a switch assembly  230 . In one embodiment, the switch assembly includes multiple components, such as a key mechanism, a switch, and/or a switch housing, as discussed in more detail with respect to  FIGS. 13A-13B . 
     The base plate  260  may provide a rigid support structure for the various components forming the key stack  200  and other components of the keyboard assembly. The base plate  260  can be a printed circuit board (PCB). The base plate  260  may include a plurality of electrical traces (not shown) formed therein that may be in electrical communication with distinct components or layers of the key stack  200 . The traces may subsequently provide an electrical signal (e.g., input) to the electronic device when an input is received at the key stack  200 , as discussed herein. 
     The embodiments described with respect to  FIGS. 2A-6  are generally directed to key stacks that include a light emitting element disposed above a flexible substrate. Other embodiments may include one or more light emitting elements positioned below or within a flexible substrate. A key stack with a light emitting element positioned below a flexible substrate may require an optical interface for transmitting or directing light from the light emitting element to a light guide and/or keycap positioned above the flexible substrate. 
       FIG. 7A  depicts a schematic view of an example key stack  700  that may be used with an illuminable key of a keyboard. The key stack  700  is similar to the key stack  200 , and includes a key assembly  720  disposed over a flexible substrate  710  and a switch assembly  730  disposed below the flexible substrate  710 . 
     The key stack  700  includes a light emitting element  726  positioned below the flexible substrate  710  and operative to illuminate an illuminable portion  708  of a keycap  722 . The light emitting element  726  is optically coupled to the illuminable portion  708  via an optical interface  750  and a light guide  724 . In one embodiment, the flexible substrate  710  includes a passage  740  that allows light to pass from the light emitting element  726  through the flexible substrate  710  to the key assembly  720 . 
     In one embodiment, the optical interface  750  optically couples the light emitting element  726  with the light guide  724  and is configured to direct or transmit light from the light emitting element  726  to the light guide  724 . In the embodiment of  FIG. 7A , the optical interface  750  may include a reflector configured to reflect light into the light guide  724  and a lens configured to disperse light evenly into the light guide. In various embodiments, the optical interface  750  may include one or more components or features for directing light, including reflective elements, refractive elements, lenses, collimators, prisms, serrations, scallops, and so on, as described below with respect to  FIGS. 8-12 . Directing light may include shaping light (e.g., focusing, collimating, dispersing, and so on), reflecting light, changing direction of light, and so on. The optical interface  750  may further include reflective coatings and/or masking of components of the key stack  700 . The optical interface  750  is positioned such that light emitted by the light emitting element  726  passes through the optical interface  750  and into the light guide  724 . 
       FIG. 7B  is a cross-section of an example key stack including an optical interface (e.g., key stack  700 ) with example light rays  742  passing from the light emitting element  726 , through the passage  740  and optical interface  750  and into the light guide  724 . The light guide  724  directs light to the illuminable portion  708  of the keycap  722  as discussed above with respect to  FIGS. 2A-6 . As shown in  FIG. 7B , the optical interface  750  changes the direction of travel of the light emitted from the light emitting element from upward to rightward (with respect to  FIG. 7B ). In some embodiments, the light guide  724  can include serrations or sawtooth grooves in its surface such as the light extraction features  350 ,  450  of the embodiments of  FIG. 3B .  3 E,  3 H, or  4 A. In embodiments with light extraction features having right-triangular profile shapes, the vertical sidewalls of the profile shapes can be positioned closer to the optical interface  750  than to the opposite side of the light guide  724 . Light extraction features can also be implemented in the light guides of  FIGS. 8-13C . 
     In one embodiment, elements of the optical interface  750  are positioned in a layer defined by the light guide  724  as shown in  FIGS. 7A-7B . In other embodiments, elements of the optical interface  750  may be positioned at various positions in the key stack  700 , including above the flexible substrate  710 , below the flexible substrate  710 , within the flexible substrate  710 , extending through the passage  740  of the flexible substrate  710 , or some combination thereof. In one embodiment, the optical interface  750  includes multiple components and/or features disposed at different positions in the key stack  700 . 
     The optical interface  750  may include one or more components or features (e.g., reflectors, prisms, lenses, and so on) disposed beneath, within, and/or above the flexible substrate  710 . In one embodiment, a lens (e.g., an optical collimating lens) is positioned above or otherwise near the light emitting element  726  and is configured to direct light (e.g., as a collimated beam) through the passage  740  to other components of the optical interface  750  and/or the light guide  724 . 
     The elements of the optical interface  750  may partially or entirely integrated with one or more components of the key stack  700 , including the keycap  722 , the light guide  724 , the flexible substrate  710 , the switch assembly  730 , and so on. In one embodiment, the optical interface includes one or more structural components that provide structural support for the key stack  700  in addition to directing light. For example, the optical interface may include a collapsible element (e.g., a light tube) that directs light, and serves as a key mechanism and/or switch as discussed below with respect to  FIG. 9 . 
     The optical interface  750  may include optical coatings on various surfaces of the key stack  700 , including layers of metal (e.g., aluminum, silver), dielectrics (e.g., magnesium fluoride, calcium fluoride, and so on), and the like. For example, surfaces  790 A,  790 B, and  790 C may include reflective coatings to direct light through the passage  740  and avoid light loss. 
     The light emitting element  726  is similar to the light emitting element  226  of  FIGS. 2A-2B , and may include one or more light-emitting diodes. The light emitting element  726  may be disposed on the base plate  760  as shown in  FIGS. 7A-7B . In other embodiments, the light emitting element  726  may be disposed at any position below the flexible substrate  710 . The light emitting element  726  may be disposed on, in or integrated with a switch housing, a key mechanism, and/or a switch. The embodiment shown in  FIG. 7A  includes one light emitting element  726 , but in various embodiments, multiple light emitting elements  726  may be used. 
     In one embodiment, the light emitting element  726  is electrically coupled to a power source via conductive traces in the flexible substrate  710 . In another embodiment, the light emitting element is electrically coupled to a power source via conductive traces in the base plate  760  and/or the switch assembly  730 . 
       FIG. 8  illustrates a cross-section of an example key stack  800  including an optical interface, as described herein. The key stack  800  is similar to the key stack  700  described above with respect to  FIGS. 7A-7B . The key stack  800  includes a light emitting element  826  disposed on a base plate  860 . 
     The key stack  800  may include a lens  850 B optically coupled to the light emitting element  826  and configured to direct light upward with respect to  FIG. 8  and through the passage  840 . In one embodiment, the lens is a collimator configured to collimate the light from the light emitting element  826 . 
     The key stack  800  may include a reflective element  850 A such as a mirror or other object with a reflective surface optically coupled to the light emitting element  826 . The reflective element  850 A is configured to direct light passing through the passage  840  in the fabric layer  810  and into the light guide  824 . In one embodiment, the reflective element redirects light traveling generally upward (with respect to  FIG. 8 ) to travel generally rightward (with respect to  FIG. 8 ). Depending on characteristics of the key stack  800 , such as the location of the illuminable portion  808 , the reflective element  850 A may be configured to reflect a portion of incident light and transmit a portion of incident light. For example, the reflective element may allow between 5% and 20% of light to pass through while reflecting the remaining light. 
       FIG. 9  illustrates a cross-section of an example key stack  900  including an optical interface, as described herein. The key stack  900  is similar to the key stack  700  described above with respect to  FIGS. 7A-7B . The key stack  900  includes a light emitting element  926  disposed on a base plate  960 . 
     The key stack  900  may include a lens  950  optically coupled to the light emitting element and the light guide  924  and configured to collect light from the light emitting element and/or direct light into the light guide. In one embodiment, the lens  950  is disposed entirely or partially within the passage  940  in the flexible substrate  910 . In another embodiment, the lens  950  is disposed above or below the flexible substrate  910 . In one embodiment, the lens  950  is a diverging lens such that light passing through the lens diverges. In another embodiment, the lens  950  is a converging lens such that light passing through the lens converges. 
       FIG. 10  illustrates a cross-section of an example key stack  1000  including an optical interface, as described herein. The key stack  1000  is similar to the key stack  700  described above with respect to  FIGS. 7A-7B . The key stack  1000  includes a light emitting element  1026  disposed at least partially in a passage  1040  in a flexible substrate  1010 . 
     The key stack  1000  may include a prism  1050  optically coupled to the light emitting element and the light guide  1024  and configured to direct light into the light guide. In one embodiment, the prism is 1050 is disposed entirely or partially within the passage  1040  in the flexible substrate  1010 . In another embodiment, the prism  1050  is disposed above or below the flexible substrate  1010 . In one embodiment, the prism  1050  is a deflecting prism configured to deflect (e.g., redirect) the light emitted by the light emitting element  1026 . 
       FIG. 11  illustrates a cross-section of an example key stack  1100  including an optical interface, as described herein. The key stack  1100  is similar to the key stack  700  described above with respect to  FIGS. 7A-7B . The key stack  1100  includes a light emitting element  1126  disposed beneath a flexible substrate  1110  (e.g., on a base plate  1160 ). 
     The key stack  1100  may include a light tube  1150 A optically coupled to the light emitting element  1126  and configured to direct light through the flexible substrate  1110  to a light guide  1124 . In one embodiment, the light tube  1150 A extends through a passage  1140  in the flexible substrate  1110 . The light tube  1150 A may be optically coupled to one or more optical elements  1150 B (e.g., the reflective element  850 A, the lens  950 , the prism  1050 , and so on) to transport light to the light guide  1124 . 
     The light tube  1150 A may be a hollow structure that includes a reflective lining to minimize light loss. In one embodiment, the light tube  1150 A is coupled to the key assembly  1120  and the switch assembly  1130 . The light tube may be capable of buckling, compressing, collapsing, or otherwise deforming when the key assembly  1120  moves relative to the switch assembly  1130  (e.g., when the key is pressed). 
       FIG. 12  illustrates a cross-section of an example key stack  1200  including an optical interface, as described herein. The key stack  1200  is similar to the key stack  700  described above with respect to  FIGS. 7A-7B . The key stack  1200  includes a light emitting element  1226  disposed beneath a flexible substrate  1210 . 
     The key stack  1200  includes a switch assembly  1230  for facilitating movement of the key assembly  1220  and detecting inputs in response to forces applied at the keycap  1222 . The switch assembly  1230  includes a key mechanism  1250 A that movably supports the key assembly  1220  relative to the switch assembly  1230 , similar to the key mechanism discussed above with respect to  FIGS. 2A-2B . 
     In one embodiment, the key mechanism  1250 A is disposed above the light emitting element  1226  (with respect to  FIG. 12 ). The key mechanism  1250 A may be configured to transport light from the light emitting element  1226  through the flexible substrate  1210 . For example, the key mechanism  1250 A may be an element capable of buckling, compressing, collapsing, or otherwise deforming such as a dome or a tube. The key mechanism  1250 A may have a hollow or translucent portion with reflective coating that is optically coupled to the light emitting element  1226  and configured to transport light in a similar manner as the light tube  1150 A of  FIG. 11 . In one embodiment, the key mechanism  1250 A extends through a passage  1240  in the flexible substrate  1210  and is optically coupled to the light guide  1224 . The key mechanism  1250 A may be optically coupled to one or more optical elements  1250 B (e.g., the reflective element  850 A, the lens  950 , the prism  1050 , and so on) to transport light to the light guide  1224 . 
     In one embodiment, the key mechanism  1250 A is further configured to detect inputs. For example, the key mechanism  1250 A may be a collapsible dome as discussed above with respect to  FIG. 2B . In another embodiment, the switch assembly  1230  includes a switch to detect inputs. 
       FIGS. 2A-12  illustrate example embodiments of key stacks for directing light from a light emitting element to an illuminable portion of a key using a light guide and/or an optical interface. The embodiments described with respect to  FIGS. 2A-12  are example embodiments, and the components and/or the arrangement of components may differ in alternate embodiments. For example, the switch assembly may be a different type of switch mechanism.  FIG. 13A  illustrates a schematic view of an example key stack  1300  that may be used with an illuminable key of a keyboard. The key stack  1300  is similar to and may include one or more components of the key stacks discussed herein (e.g., key stack  200 , key stack  700 , and so on). 
     The key stack  1300  includes a flexible substrate  1310  disposed between the key assembly  1320  and the switch assembly  1330  of the key stack  1300 . As noted above, the flexible substrate  1310  may be a sheet or film such as a fabric, polymer, or leather sheet, or any other appropriate deformable or flexible substrate or sheet. In one embodiment, the flexible substrate  1310  includes one or more folded perimeter features  1312  to facilitate movement of a localized region (e.g., the movable portion  1313 ) of the flexible substrate relative to the rest of the flexible substrate when the key assembly is depressed.  FIG. 13B  illustrates a cross-section of an example key stack. As shown in  FIG. 13B , the folded perimeter feature  1312  is a U-shaped bend of the flexible substrate  1310 . The shape of the folded perimeter feature  1312  allows the movable portion  1313  of the flexible substrate  1310  to move relative to the rest of the flexible substrate (e.g., up and down with respect to  FIG. 13B ). In various embodiments, the folded perimeter feature  1312  may have different shapes and/or forms (e.g., S-shaped, embossed, and so on). 
     As shown in  FIGS. 13A-13B , the key stack  1300  includes a switch assembly  1330  disposed below the flexible substrate  1310 . Similar to the switch assemblies described herein, the switch assembly  1330  is configured to facilitate movement of the key assembly  220  and to detect inputs in response to forces applied at a keycap  1322 . In the embodiment of  FIG. 13A , the switch assembly  1330  is a butterfly switch mechanism. The butterfly switch mechanism includes a key mechanism  1332  and a switch  1334 . The switch assembly  1330  may further include a switch housing  1336  for performing various mechanical and/or electrical functions of the key stack  1300 , such as housing and supporting the switch  1334 , coupling the switch assembly to a base plate  1360  or other substrate of the electronic device, providing mounting and/or coupling features for the key mechanism  1332 , and the like. 
       FIG. 13B  is a cross section of an example key stack (e.g., key stack  1300 ), according to an embodiment. The input member  1338  is configured to actuate the switch  1334  in response to the keycap being depressed, for example in response to the key being pressed. In particular, the input member is configured to transmit a force applied to the keycap  1322  to the switch  1334 , thereby actuating the switch. This, in turn, causes an input to be registered by the electronic device.  FIG. 13C  illustrates the example key stack of  FIG. 13B  in a depressed position, according to an embodiment. 
     The key mechanism  1332  may generally bias the input member  1338  upward (with respect to the view of  FIG. 13B ), thereby keeping the input member in a default or rest position in the absence of external force. Likewise, when force is removed from the input member  1338  after the input member translates, the key mechanism  1332  returns to its default configuration as shown in  FIG. 13B , thereby moving the input member from a depressed to a rest position. In some embodiments, the key assembly  1320  can include the input member  1338 . The keycap  1322  and light guide  1324  can be a first portion of the key assembly  1320 , and the input member  1338  can be a second portion of the key assembly  1320 , wherein a first portion of the key assembly (including the keycap  1322  and light guide  1324 ) are positioned on a first, outer side of the flexible substrate  1310 , and a second portion of the key assembly (including the input member  1338 ) is positioned on a second, inner side of the flexible substrate  1310 . In some cases, the keycap  1322  and light guide  1324  can be a single, integral, monolithic structure. Alternatively, the keycap  1322  can be positioned on the first, outer side of the flexible substrate  1310 , and the light guide  1324  and input member  1338  (or an integral, monolithic combination thereof) can be positioned on the second, inner side of the flexible substrate  1310 . 
     The input member  1338  can be connected to the key mechanism  1332  using hooks, clamps, interlocking parts, and related devices. The input member  1338  can be attached to the underside of the flexible substrate  1310  opposite the light guide  1324  and can have an outer perimeter similar to the outer perimeter of the light guide  1324  or keycap  1322 . In some embodiments, the light guide  1324  comprises a light-transmissive material such as one of the light-transmissive materials described elsewhere herein. 
     As depicted in  FIG. 13C , the folded perimeter features  1312  allow the movable portion of the flexible substrate to move relative to the rest of the flexible substrate when the key assembly is depressed. 
     In the depicted example, the key mechanism  1332  is a butterfly hinge. However, this is merely one example of a key mechanism that may be used in a switch assembly  1330 , and other key mechanism may be used instead of the butterfly hinge in any given key, including scissor mechanisms, hinge mechanisms, or any other mechanism that movably supports a keycap relative to a switch. 
     In the depicted example, the switch  1334  is a dome switch. However, this merely one example of a switch that may be used in a switch assembly  1330 , and other switches may be used instead of the collapsible dome in any given key, including membrane switches, scissor switches, mechanical switches, buckling springs, optical switches, and so on. 
       FIG. 13D  depicts a schematic view of an example keyboard incorporating key stacks (e.g., key stacks  200 ,  700 ,  1300 , and so on), according to an embodiment. The keyboard includes a key web  1370  that supports the key assembly  1320  and the flexible substrate  1310 . In various embodiments, the key web  1370  is formed of a rigid material such as aluminum, titanium, plastic, or the like. The key web  1370  includes an opening that allows the movable portion  1313  of the flexible substrate  1310  to depress relative to the rest of the flexible substrate when the keycap is depressed. 
     Although many embodiments described and depicted herein reference light guides for illuminable keys of a keyboard, it should be appreciated that other implementations can take other form factors. Thus, the various embodiments described herein, as well as functionality, operation, components, and capabilities thereof may be combined with other elements as necessary, and so any physical, functional, or operational discussion of any element or feature is not intended to be limited solely to a particular embodiment to the exclusion of others. 
     For example, although the electronic device  100  is shown in  FIGS. 1A-1B  as a laptop computer, it may be appreciated that other electronic devices are contemplated. For example, the electronic device  100  can be implemented as a peripheral input device, a desktop electronic device, a handheld input device, a tablet electronic device, a cellular phone, a wearable device, and so on. 
       FIG. 14  shows a keyboard  1400  with illuminable keys for use with an electronic device  1401 , as described herein. The electronic device  1401  is depicted as a tablet computer that includes a housing  1403  and a display  1405  (which may be a touch-sensitive display). As shown, the keyboard  1400  is a peripheral input device for the electronic device  1401 , and is incorporated into a cover or case for the electronic device  1401 , which may be removable or detachable from the electronic device  1401 . The keyboard  1400  includes a keyboard housing  1404  and illuminable keys  1402 , similar to the illuminable key  102  described herein. 
     In other embodiments, a keyboard such as described herein may be incorporated within a housing of an electronic device (rather than in its own separate housing), or it may be housed in a different housing or structure than that shown in  FIGS. 1A and 14 . For example, in some embodiments, the keyboard may be a standalone keyboard (e.g., it need not be incorporated into a cover or case of a separate electronic device). 
     It may be appreciated that the electronic devices (e.g., electronic devices  100  and  1401 ) can include one or more components that interface or interoperate, either directly or indirectly, with the illuminable keys which, for simplicity of illustration are not depicted herein. For example, the electronic device may include a processor coupled to or in communication with a memory, a power supply, one or more sensors, one or more communication interfaces, and one or more input/output devices such as a display, a speaker, a rotary input device, a microphone, an on/off button, a mute button, a biometric sensor, a camera, a force and/or touch sensitive trackpad, and so on. 
     In some embodiments, the communication interfaces provide electronic communications between the electronic device and an external communication network, device or platform. The communication interfaces can be implemented as wireless interfaces, Bluetooth interfaces, universal serial bus interfaces, Wi-Fi interfaces, TCP/IP interfaces, network communications interfaces, or any conventional communication interfaces. The electronic device may provide information related to externally connected or communicating devices and/or software executing on such devices, messages, video, operating commands, and so forth (and may receive any of the foregoing from an external device), in addition to communications. As noted above, for simplicity of illustration, the electronic devices herein are illustrated without many of these elements, each of which may be included, partially, optionally, or entirely, within a housing. 
     In some embodiments, the housing can be configured to, at least partially, surround a display. In many examples, the display may incorporate an input device configured to receive touch input, force input, and the like and/or may be configured to output information to a user. The display can be implemented with any suitable technology, including, but not limited to, a multi-touch or multi-force sensing touchscreen that uses liquid crystal display (LCD) technology, light-emitting diode (LED) technology, organic light-emitting display (OLED) technology, organic electroluminescence (OEL) technology, or another type of display technology. 
     The housing can form an outer surface or partial outer surface and protective case for the internal components of the electronic device. In the illustrated embodiment, the housing is formed in a substantially rectangular shape, although this configuration is not required. The housing can be formed of one or more components that are operably connected, such as a front piece and a back piece or a top portion and a bottom portion. Alternatively, the housing can be formed of a single piece (e.g., uniform body or unibody). 
     Various embodiments described herein can be incorporated with other systems or apparatuses and may not, in all cases, be directly associated with an input device configured for use with an electronic device such as depicted herein. For example, a light guide as described herein can be incorporated into an independent electronic switch such as a button (e.g., light switch, automotive button, doorbell, and so on). In other examples, a light guide as described herein can be incorporated into a different portion of an electronic device, such as a display element of an electronic device. In such an example, a light guide incorporating prismatic or scalloped sidewalls can be used as a backlight diffuser within a display stackup. 
     Additionally, it may be appreciated, that for illuminable key embodiments, the various structures and mechanisms described herein are not intended to limit the disclosure to a particular favored or required geometry or form factor. For example, an illuminable key can include a butterfly mechanism, a scissor mechanism, or any other suitable type of key mechanism. An illuminable key can include a keycap that is formed to have a substantially flat top surface or, in other embodiments, to have a partially curved top surface. An electronic switch associated with the illuminable key can be implemented as a single throw switch, a multi-throw switch, a capacitive switch, and so on. A tactile feedback structure associated with the illuminable key can be implemented as an elastomeric dome, a spring, an elastomer deposit, a metal dome, or any combination thereof. 
     Furthermore, one may appreciate that although many embodiments are disclosed above, that the operations and steps presented with respect to methods and techniques described herein are meant as exemplary and accordingly are not exhaustive. One may further appreciate that an alternate step order or fewer or additional steps may be implemented in particular embodiments. 
     Although the disclosure above is described in terms of various exemplary embodiments and implementations, it should be understood that the various features, aspects and functionality described in one or more of the individual embodiments are not limited in their applicability to the particular embodiment with which they are described, but instead can be applied, alone or in various combinations, to one or more of the some embodiments of the invention, whether or not such embodiments are described and whether or not such features are presented as being a part of a described embodiment. Thus, the breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments but is instead defined by the claims herein presented.

Metadata:
Filing Date: 20180711
Publication Date: 20210420
Grant Date: 20210420
Priority Date: 20170712
Inventors: WANG, PAUL X.
ZIMMERMAN, AIDAN N.
Assignee: APPLE INC
CPC Classifications: [{"code": "H01H2223/003", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01H2219/066", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01H2219/056", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01H2219/048", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01H2219/046", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01H2219/044", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01H3/122", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01H2219/062", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01H2219/06", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01H13/83", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0202", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F1/1662", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01H3/125", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F1/1662", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01H13/83", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01H2219/06", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/0202", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01H2003/007", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01H2219/036", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01H2003/007", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F1/1662", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01H2219/036", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01H13/83", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01H2219/06", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01H3/125", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0202", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 75495332