PATENT DOCUMENT

Publication Number: US-11360258-B1
Application Number: US-201615170748-A
Country: US
Kind Code: B1

Title: Illuminated input devices

Abstract:
An electronic device may have input-output devices such as buttons formed from capacitive touch sensor electrodes. A transparent layer may be provided with opaque masking structures having a symbol-shaped opening aligned with a capacitive touch sensor electrode for a button or other input device. The symbol-shaped opening may be adjacent to the electrode and may be illuminated with light from a lighting system. The lighting system may include a light guide plate. The light guide plate may have edges that are oriented at non-zero angle with respect to each other. Light-emitting diodes of different colors may emit light into the edges. The light may be extracted from the light guide plate using bumps in a light extraction region. Light may be collimated using ribs formed on an opposing side of the light guide plate.

Claims:
What is claimed is: 
     
       1. An illuminated input device comprising: a transparent structure; an input device; opaque material on the transparent structure and having a symbol-shaped opening that forms a label for the input device; and an illumination system that provides illumination for the input device, wherein the illumination system has at least one light-emitting diode that emits light into a light guide plate, wherein the light guide plate comprises a light extraction region with light collimation structures and a mixing region without the light collimation structures, wherein the light extraction region is overlapped by the label and the mixing region is overlapped by the opaque material, wherein the light guide plate guides the light from the mixing region to the light extraction region via total internal reflection, and wherein the light exits the light guide plate via the light collimation structures and passes through the symbol-shaped opening and the transparent structure. 
     
     
       2. The illuminated input device defined in  claim 1  wherein the light guide plate has at least two edges that are oriented at a non-zero angle with respect to each other, wherein the at least one light-emitting diode includes first and second light emitting diodes, wherein the first light-emitting diode emits light into a first of the two edges of the light guide plate, and wherein the second light-emitting diode emits light into a second of the two edges of the light guide plate. 
     
     
       3. The illuminated input device defined in  claim 2  further comprising light extraction bumps on the light guide plate. 
     
     
       4. The illuminated input device defined in  claim 3  wherein the bumps are located in the light extraction region of the light guide plate. 
     
     
       5. The illuminated input device defined in  claim 4  wherein the light collimation structures comprise a plurality of parallel ribs on a first surface of the light guide plate and wherein the bumps protrude from an opposing second surface of the light guide plate. 
     
     
       6. The illuminated input device defined in  claim 1  further comprising a printed circuit to which the at least one light-emitting diode is soldered. 
     
     
       7. The illuminated input device defined in  claim 6  wherein the printed circuit has an opening through which the illumination passes. 
     
     
       8. The illuminated input device defined in  claim 7  further comprising adhesive that attaches the light guide plate to the printed circuit so that the light extraction region in the light guide plate overlaps the opening in the printed circuit. 
     
     
       9. The illuminated input device defined in  claim 1  wherein the opaque material comprises ink. 
     
     
       10. The illuminated input device defined in  claim 9  wherein the input device comprises at least one capacitive touch sensor electrode. 
     
     
       11. The illuminated input device defined in  claim 1  wherein the light guide plate has a wedge-shaped profile. 
     
     
       12. The illuminated input device defined in  claim 1  wherein the light guide plate has two edges that are oriented at a non-zero angle with respect to each other. 
     
     
       13. The illuminated input device defined in  claim 1  further comprising a printed circuit having a reflective layer, wherein the printed circuit with the reflective layer is attached to the light guide plate with adhesive and reflects light from the light guide plate back towards the light guide plate. 
     
     
       14. The illuminated input device defined in  claim 1  further comprising a diffuser interposed between the symbol-shaped opening and the light guide plate. 
     
     
       15. An illuminated input device comprising: an input device; an opaque layer on a transparent structure and having a symbol-shaped opening that forms a label for the input device; a light guide layer that overlaps the input device, wherein the light guide layer has a mixing region overlapping the opaque layer, a light extraction region with protrusions overlapping the symbol-shaped opening of the input device and first and second edges oriented at a non-zero angle with respect to each other; and first and second light-emitting diodes of different colors that emit light respectively into the first and second edges, wherein the first and second light-emitting diodes emit the light respectively along first and second paths that intersect at the light extraction region, and wherein the light guide layer guides the light from the mixing region to the light extraction region via total internal reflection such that the light is scattered out of the light guide layer by the protrusions in the light extraction region to pass through the symbol-shaped opening and the transparent structure. 
     
     
       16. The illuminated input device defined in  claim 15  further comprising parallel molded ridges on the light guide layer that collimate the light scattered by the protrusions. 
     
     
       17. The illuminated input device defined in  claim 16  wherein the light guide layer further comprises third and fourth edges that are oriented at a non-zero angle with respect to each other and wherein the third and fourth edges form a retroreflector that recycles light within the light guide layer. 
     
     
       18. An illuminated input device comprising:
 an opaque layer on a transparent structure and having a symbol-shaped opening; 
 at least one capacitive touch sensor electrode associated with the symbol-shaped opening, wherein the at least one capacitive touch sensor electrode forms an input device that is labeled by the symbol-shaped opening; 
 a light guide plate having a mixing region that overlaps the opaque layer and a light extraction region having protrusions that overlap with the symbol-shaped opening; and 
 a light source that emits light into the light guide plate, wherein the light is guided from the mixing region to the light extraction region via total internal reflection and is scattered out of the light guide plate by the protrusions in the light extraction region to pass through the symbol-shaped opening in the opaque layer and the transparent structure. 
 
     
     
       19. The illuminated input device defined in  claim 18  further comprising: a layer of ink that covers the transparent layer and that has a transmissivity of at least 1%, wherein the layer of ink is interposed between the opaque layer and the transparent layer. 
     
     
       20. The illuminated input device defined in  claim 18  wherein the light guide plate has a side with molded ribs that collimate the light scattered out of the light guide plate and wherein the protrusions are located on an opposing side of the light guide plate in the light extraction region.

Description:
FIELD 
     This relates generally to electronic devices and, more particularly, to electronic devices with illuminated input devices. 
     BACKGROUND 
     Electronic devices often include input devices such as buttons. It may be desirable to illuminate a button. For example, it may be desirable to illuminate a button so that a user may view the button clearly in low lighting conditions. 
     It can be challenging to light buttons in electronic devices. If care is not taken, illuminated buttons may be overly bulky or may be inadequately illuminated. 
     SUMMARY 
     An electronic device may be provided with a housing. The device may include control circuitry and input-output devices mounted in the housing. 
     The input-output devices may include input devices such as buttons. Buttons may be formed from capacitive touch sensor electrodes and other components that receive input from a user. An electronic device may have buttons, other input-output devices, and other structures that are provided with illuminated symbols. Illuminated symbols may serve as labels and may provide output such as status information to a user. 
     A portion of the housing of the electronic device or other structures in the device may include a transparent layer. The transparent layer may be provided with opaque masking structures having a symbol-shaped opening. The symbol-shaped opening may be illuminated to form the illuminated symbol. 
     The symbol-shaped opening may be aligned with a capacitive touch sensor electrode for a button or other input device. The symbol-shaped opening may be adjacent to the electrode and may be illuminated with light from a lighting system. The lighting system may include a light guide plate. 
     The light guide plate of the lighting system may have peripheral edges that are oriented at a non-zero angle with respect to each other. Light-emitting diodes of different colors may emit light into the edges. The light may be extracted from the light guide plate using bumps in a light extraction region. Light may be collimated using ribs formed on an opposing side of the light guide plate. 
     The light guide plate may have a light recycling retroreflector formed from a pair of angled peripheral edges. Light from the retroreflector may be reflected towards the light extraction region. 
     A printed circuit board may serve as a substrate for capacitive touch sensor electrodes. The light guide plate may scatter light through an opening in the printed circuit board. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a portion of an illustrative electronic device having an illuminated input device in accordance with an embodiment. 
         FIG. 2  is a schematic diagram of an illustrative electronic device of the type that may have one or more illuminated symbols for input-output devices or other structures in the electronic device in accordance with an embodiment. 
         FIGS. 3 and 4  are cross-sectional side views of illustrative illumination systems for input-output devices in accordance with an embodiment. 
         FIG. 5  is a graph showing how a light guide plate characteristic such as light-scattering feature density may vary as a function of distance across the light guide plate in accordance with an embodiment. 
         FIGS. 6, 7, and 8  are cross-sectional side views of illustrative prism-shaped ribs that may be used in forming a light collimator for a light guide plate in accordance with an embodiment. 
         FIG. 9  is a cross-sectional side view of an illustrative light guide plate with a wedge-shaped profile in accordance with an embodiment. 
         FIG. 10  is a top view of an illustrative light extraction region on a light guide plate and an associated illuminated symbol for an input-output device in accordance with an embodiment. 
         FIG. 11  is a top view of an illustrative backlight illumination system formed from a light-guide plate and associated light-emitting diodes in accordance with an embodiment. 
         FIG. 12  is a cross-sectional side view of an illustrative backlight illumination system formed using a light guide plate mounted on the underside of a printed circuit in alignment with an opening in the printed circuit in accordance with an embodiment. 
         FIG. 13  is a cross-sectional side view of an illustrative light guide plate with notches to accommodate adhesive and light guide plate in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Electronic devices may be provided with input-output devices. A perspective view of a portion of an electronic device with an input-output device is shown in  FIG. 1 . As shown in  FIG. 1 , device  10  may include a housing such as housing  12 . Housing  12 , which may sometimes be referred to as an enclosure or case, may be formed of plastic, glass, ceramics, fiber composites, metal (e.g., stainless steel, aluminum, etc.), other suitable materials, or a combination of any two or more of these materials. Housing  12  may be formed using a unibody configuration in which some or all of housing  12  is machined or molded as a single structure or may be formed using multiple structures (e.g., an internal frame structure, one or more structures that form exterior housing surfaces, etc.). 
     Electronic device  10  may be a laptop computer, a computer monitor containing an embedded computer, a tablet computer, a cellular telephone, a media player, or other handheld or portable electronic device, a smaller device such as a wrist-watch device, a pendant device, a headphone or earpiece device, a device embedded in eyeglasses or other equipment worn on a user&#39;s head, or other wearable or miniature device, a computer display that does not contain an embedded computer, speakers and other audio equipment, a computer display that includes an embedded computer, a gaming device, a navigation device, a television, an embedded system such as a system in which electronic equipment with a display is mounted in a kiosk or automobile, equipment that implements the functionality of two or more of these devices, or other electronic equipment. 
     Device  10  may have input-output devices. A microphone may gather voice input from a user and other audio input. Audio output may be provided to the user with speakers. Visual output may be provided using a display and/or status indicator lights. Buttons, keys, force sensors, touch sensors (e.g., capacitive touch sensors), proximity sensors, and other devices may gather user input (e.g., from a user&#39;s finger or other external object such as a stylus). Environmental sensors may be used to gather information on ambient light levels, temperature, humidity, magnetic fields, and other environmental parameters. Accelerometers may gather information on device movement and/or orientation. Device  10  may have input-output devices such these and/or may include any other suitable type of input-output components. 
     In the illustrative example of  FIG. 1 , the surface of device  10  that is shown in  FIG. 1  has a capacitive touch sensor button (button  22 ). Button  22  may receive input over a circular area (as shown by the circular dashed line of  FIG. 1 ), over a rectangular input area (see, e.g., the rectangular dashed lines surrounding button  22  of  FIG. 1 , or other suitable input area. An illuminated (backlit) symbol such as symbol  24  may serve as a label for button  22 , may serve as a label for other input devices in device  10 , may serve as a status indicator light (e.g., a power indicator, a charge status indicator, a wireless signal strength indicator, a wireless connectivity indicator, a mute indicator, a volume indicator, or other suitable status indicator), may have the shape of a trademark or other icon, or may provide other visual output functions for device  10 . Symbol  24  may contain an icon, text, a single alphanumeric character or set of characters, or other information that is associated with the function of button  22 , may have a pattern that serves as a label, or may have any other suitable pattern. The triangular pattern of symbol  24  that is shown on  FIG. 1  is merely illustrative. 
     Buttons such as button  22  of  FIG. 1  may be arranged in an array to form keys in a keyboard or key pad or may be used as stand-alone buttons (e.g., as power buttons, buttons for controlling media playback such as play, pause, forward, and rewind buttons, volume buttons, or as buttons for other functions). 
     Buttons such as button  22  may have switches that are controlled by applying pressure from a finger or other external object, may have force sensors that receive input, and/or may have other suitable input components for receiving user input. As an example, buttons such as button  22  may also be capacitive buttons (buttons that detect input from a user by processing capacitance measurements from capacitor electrode structures). In the illustrative configuration of  FIG. 1 , button  22  has a capacitive electrode that serves both as an individually controllable button that a user may press with the user&#39;s finger and that serves as an element in an array of capacitive touch sensor electrodes (i.e., electrodes  20 ). With this type of arrangement, a user may supply touch input to the surface of device  10  that contains the array of electrodes  20 . Touch sensor circuitry that is coupled to the array of electrodes may monitor the array for capacitance changes that are indicative of user touch input (e.g., taps, swipes, multi-touch gestures, etc.). When a user touches the electrode  20  that is associated by button  22 , the touch sensor circuitry can register a button press event (i.e., control circuitry in device  10  will detect that the user has pressed button  22 ). 
     In general, device  10  may use illuminated symbols such as illuminated symbol  24  for any suitable purpose (e.g., labeling a button, providing a user with information about the operation of other input devices, providing a user with visual feedback, informing a user about the proper operation of device  10 , etc. The use of symbol  24  as a label for a capacitive button that is located within an array of capacitive touch sensor electrodes is presented as an example. 
       FIG. 2  is a schematic diagram of device  10 . As shown in  FIG. 2 , electronic device  10  may have control circuitry  30 . Control circuitry  30  may include storage and processing circuitry for supporting the operation of device  10 . The storage and processing circuitry may include storage such as hard disk drive storage, nonvolatile memory (e.g., flash memory or other electrically-programmable-read-only memory configured to form a solid state drive), volatile memory (e.g., static or dynamic random-access-memory), etc. Processing circuitry in control circuitry  30  may be used to control the operation of device  10 . The processing circuitry may be based on one or more microprocessors, microcontrollers, digital signal processors, baseband processors, power management units, audio chips, application specific integrated circuits, etc. 
     Input-output circuitry in device  10  such as input-output devices  32  may be used to allow data to be supplied to device  10  and to allow data to be provided from device  10  to external devices. Input-output devices  32  may include illuminated input-output devices such as illustrative button  22  of  FIG. 1 , other buttons, joysticks, scrolling wheels, touch pads, key pads, keyboards, microphones, speakers, tone generators, vibrators, cameras, sensors (e.g., ambient light sensors, proximity sensors, orientation sensors, magnetic sensors, force sensors, touch sensors, etc.), light-emitting diodes and other status indicators, data ports, etc. A user can control the operation of device  10  by supplying commands through input-output devices  32  and may receive status information and other output from device  10  using the output resources of input-output devices  32 . Input-output devices  32  may include one or more displays and other components for providing visual information. Illuminated symbols such as illuminated symbol  24  of  FIG. 1  may be provided on devices  32 , may be provided adjacent to devices  32 , or may be provided elsewhere in device  10  (e.g., elsewhere on housing  12 ). 
     Control circuitry  30  may be used to run software on device  10  such as operating system code and applications. During operation of device  10 , the software running on control circuitry  30  may gather user input from buttons such as button  22  and other input-output devices  32 , may gather information from environmental sensors, and may gather other input and, may, in response, take appropriate action (e.g., device  10  may play media to a user, display information on a display or other visual output device, send messages electronically, retrieve information from the internet and present the retrieved information to a user visually and/or audibly, etc.). 
       FIGS. 3 and 4  are cross-sectional side views of illustrative illumination systems of the type that may be used to illuminate symbol  24  of  FIG. 1  or other suitable symbols or structures in device  10 . The illuminated symbols may be associated with input-output devices  32  or may be used for other labeling in device  10 . As an example, the illumination systems of  FIGS. 3 and 4  may be used for illuminating symbols  24  in buttons such as button  22 . 
     As shown in  FIG. 3 , a light source such as light source  34  may generate light  36 . Light source  34  may be formed from one or more light-emitting diodes or other components that generate light (e.g., lamps, laser diodes, etc.). Light-emitting diodes for source  34  may have one or more colors (e.g., red, green, blue, white, yellow, etc.). As an example, light source  34  may include a first light-emitting diode with of a first color and a second light-emitting diode of a second color that is different than the first color. During operation, control circuitry  30  may control the operations of the light-emitting diodes in source  34  (e.g., to control the color of backlight illumination that is produced by source  34 ). 
     Light  36  from light source  34  may be emitted into edge  38  of light guide  40 . Light guide  40  (sometimes referred to as a light guide layer) may be a transparent molded plastic light guide plate, may be formed form a flexible sheet of thin polymer (i.e., a light guide film), or may be formed form other transparent planar structures that guide light internally in accordance with the principle of total internal reflection. With one illustrative arrangement, light guide  40  is a light guide plate formed from a molded plastic such as polycarbonate or acrylic and has a thickness of 0.1 to 3 mm, more than 0.2 mm, more than 0.4 mm, more than 0.8 mm, more than 1.2 mm, less than 2 mm, less than 1 mm, or other suitable thickness. 
     Light  36  that has been emitted into light guide plate  40  travels laterally throughout light guide plate  40 . In mixing region  56 , light  38  becomes homogenized by reflecting repeatedly from the upper and lower surfaces of light guide plate  40 . To extract light out of light guide plate  40  to serve as backlight for symbol  24 , light guide plate  40  may have light extraction features in light extraction region  58 . The light extraction features (sometimes referred to as light scattering features or light extraction structures) may be pits, grooves, or other recesses, bumps, ridges, or other protrusions, and/or printed surface patterns on the upper and/or lower surfaces of light guide plate  40 . If desired, light extraction features may also be formed using internal light scattering structures such as embedded microspheres of material with an index of refraction that differs from the index of refraction of light guide plate  40 , voids, or other embedded structures. In the example of  FIG. 3 , light extraction features  42  are downwardly protruding bumps on the lower surface of light guide plate  40 . Other types of light extraction structures may be provided on light guide plate  40 , if desired. 
     Light that is scattered upwards from features  42  creates illumination (light)  44 . Light that is scattered downward may be reflected back in the upward direction by reflector  51 . Reflector  51  may be a layer of white plastic, a white polymer coating (e.g., a white ink) on a printed circuit or other substrate, a reflector formed from a stack of alternating high-index-of-refraction and low-index-of-refraction dielectrics (i.e., a dielectric stack mirror coating), metal, or other reflective structures. One or more optical films (see, e.g., illustrative layers  50 ) may be located above light guide plate  40 . Layers  50  may include, for example, a diffuser layer for diffusing illumination  44 , a light collimation film (e.g., a brightness enhancement film), a colored film that imparts a desired color to illumination  44 , or other suitable optical films. If desired, the functionality of one or more of these layers may be incorporated into light guide plate  24 . 
     Illumination  44  may serve as backlight for symbol  24  or other structures in device  10 . The shape of symbol  24  may be defined using an opening in a plastic or metal structure, using an opening in an opaque masking layer such as a layer of ink (white ink, black ink, gray ink, ink of other colors, etc.), or using any other suitable symbol-shaped structures. The ink in the opaque masking layer may include carbon black or other particles of pigment in a polymer binder (as an example). Masking layers based on colored dyes and other materials may also be used. 
     In the example of  FIG. 3 , opaque masking layer  46  has an opening (opening  48 ) with an outline (i.e., a footprint when viewed from the exterior of device  10  and housing  12 ) in the shape of symbol  24 . Light  44  that strikes layer  46  is blocked from view by a user of device  10 . Light  44  that strikes opening  48  passes through opening  48  as unblocked light  44 ′. Light  44 ′ has the shape of symbol  24  (i.e., light  44 ′ serves as illumination for symbol  24 ). If desired, structures may be provided above and below masking structures such as layer  46  (e.g., cover layers, supporting layers, etc.). In the example of  FIG. 3 , an array of capacitive touch sensor electrodes  20  have been formed under opaque masking layer  46 . Electrodes  20  may be formed from metal, transparent conductive material such as indium tin oxide, metal pads with openings (e.g., an opening aligned with opening  48 ), metal that is sufficiently thin to be transparent, and/or conductive electrode structures of other configurations. 
     If desired, light diffusing structures, light collimation structures, and/or structures for conditioning light  44  may be formed as part of light guide plate  40 . As shown in the illustrative configuration of  FIG. 4 , for example, the upper surface of light guide plate  40  may be provided with prism-shaped ridges  60  that serve as light collimation structures in light extraction region  58 . Ridges  60  may run parallel to each other into the page of  FIG. 4  (i.e., perpendicular to the propagation direction of light  36  from light source  34 ). If desired, light collimating protrusions such as ridges  60  may have other shapes and patterns. The configuration of  FIG. 4  in which light collimating protrusions on light guide plate  40  have triangular cross-sectional shapes is merely illustrative. 
     Light scattering features  42  and other structures in light guide plate  40  (e.g., light collimating structures  60 ) may be arranged on light guide plate  40  with a distribution that varies as a function of location across the surface of light guide plate  40 . Due to the light extraction process, the intensity of light  36  may tend to decrease with increasing distance from light source  34 . To counteract this decrease in the intensity of light  36  in light guide plate  40 , the density D of bumps  42  or other light extraction features on light guide plate  40  may be increased with increasing distance dm from light source  34 , as illustrated by the graph of  FIG. 5 . The density, shape, orientation, and/or other characteristics of light collimating features such as ridges  60  may also be varied as a function of location (e.g., distance dm) on light guide plate  40 . As an example, some of ridges  60  may have symmetrical shapes such as the symmetrical triangular profile of  FIG. 6 , whereas the ridges  60  at other locations in light guide plate may have different shapes such as the asymmetrical triangular profiles of  FIG. 7  and/or the asymmetrical triangular profile of  FIG. 8 . The shape of ridges  60  may, as an example, be progressively varied as a function of increasing distance dm from light source  34 . 
     Light guide plate  40  may have a thin planar shape with parallel opposing upper and lower planar surfaces as shown in  FIGS. 3 and 4 . If desired, light guide plate  40  and/or portions of light guide plate  40  may also have tapered shapes such as the light guide plate structure with the tapered profile shown in the cross-sectional side view of illustrative light guide plate  40  of  FIG. 9 . Tapered profiles such as the profile of  FIG. 9  may help enhance light extraction and may be characterized by non-zero angles BG between their upper and lower planar surfaces. 
     The shape of light extraction region  58  (i.e., the outline of region  58  when viewed from above) may be circular, rectangular, triangular, or may have other suitable shapes. The shape of light extraction region  58  may or may not match the shape of symbol  24 . For example, symbol  24  may have the shape of a letter character or set of characters, whereas light extraction region  58  may have a circular or rectangular shape. As another example, symbol  24  may form a cross and light extraction region  58  may form a rectangle or may have another suitable shape that is larger than the cross. In configurations such as these, illumination  44  that is blocked by opaque masking layer  46  may not contribute to the intensity of emitted illumination  44 ′. To enhance illumination efficiency, light-scattering features  42  may be distributed within an area  58  that has a shape that matches the overlapping shape of symbol  24  (see, e.g., the illustrative triangular shape of light extraction region  58  in  FIG. 10 , which matches the triangular shape of symbol  24  and that is slightly larger than symbol  24  to facilitate alignment between symbol  24  and region  58 ). 
     To accommodate multiple light-emitting diodes, it may be desirable to provide light guide plate  40  with multiple angled edge surfaces each of which is oriented so that a respective light-emitting diode may emit light towards the center of region  58 . An illustrative light guide plate with this type of configuration is shown in  FIG. 11 . As shown in  FIG. 11 , light guide plate  40  may be provided with light  36  from a pair of light-emitting diodes. First light-emitting diode  34 A may emit light  36  into first surface  38 A of light guide plate  40  and second light-emitting diode  34 B may emit light  36  into second surface  38 A of light guide plate  40 . Edges  38 A and  38 B are not parallel to each other (e.g., edges  38 A and  38 B extend along directions that are oriented at a non-zero angle AG of 155° or other suitable non-zero angle with respect to each other). The orientation of edge surface  38 A is configured so that light  36  from light-emitting diode  34  is directed along path  62 A toward center  64  of light extraction area  58 . The orientation of edge surface  38 B is similarly configured so that light  36  from light-emitting diode  34  is directed along path  62 B toward center  64  of light extraction area  58 . By aligning the directions of propagation of light  36  from the first and second light-emitting diodes toward light extraction area  58 , light  36  can be efficiently extracted from area  58  to serve as backlight illumination. 
     Light guide plate  40  may have straight sides such as edges  57  that run parallel to dimension Y (i.e., roughly parallel to the direction of propagation of light  36  exiting light-emitting diodes  34 A and  34 B). Light  36  that strikes edges  57  at a glancing angle will be reflected further along dimension Y. At the end of light guide plate  40  opposing the end of light guide plate  40  with light-emitting diodes  34 A and  34 B, edges  64  of light guide plate  40  may be oriented at 45° angles or other suitable angles to facilitate light recycling. Light  36  that is propagating in the −Y direction of  FIG. 11  and that is not extracted in region  58  may strike one of angled edges  64 . The 45° orientation of edges  64  with respect to light propagation dimension −Y causes light  36  that strikes a given edge  64  to reflect along the X dimension toward the other edge  64  and thereafter to reflect back in the +Y direction. The angled edges  64  at the lower end of light guide plate  40  of  FIG. 11  therefore serve as a retroreflector that helps recycle light  36  back into light guide plate for extraction by the light extraction features of region  58 . 
     In the example of  FIG. 11 , there are two different light-emitting diodes that provide light  36  to light guide plate  40 . If desired, there may be one or more, two or more, three or more, or four or more different light-emitting diodes that provide light to light guide plate  40 . The light-emitting diodes may all be of the same color or may each emit light with a different color. In configurations in which two or more of the light-emitting diodes emit light of different colors, the color of illumination  44  may be controlled by circuitry  30  by adjusting the relative proportion of light emitted by each of the diodes. 
     In addition to or instead of using a retroreflector structure to enhance light recycling, some or all of the edges of light guide plate  40  may be provided with a metal or plastic reflective coating that reflect light  36  back into plate  40  rather than allowing light  36  to escape from the edges of plate  40 . 
       FIG. 12  is a cross-sectional side view of an illustrative illumination system of the type that may be used to illuminate a symbol for a button such as button  22  or that may provide illumination elsewhere in device  10 . As shown in  FIG. 12 , light source  34  (e.g., one or more light-emitting diodes) may emit light  36  into light guide plate  40 . Light guide plate  40  may be mounted under printed circuit  84 . Printed circuit  84  may have an opening such as opening  86  (e.g., a circular opening, a rectangular opening, etc.) that overlaps light extraction region  58 . Opening  86  may, for example, be the same size as region  58  or may be larger than region  58 . 
     Light guide plate  40  may have light extraction features in light extraction region  58  that create illumination  44 . Illumination (light)  44  may travel upward in direction  81  through opening  86  in printed circuit  84 . Illumination  44  that is scattered out of region  58  in downward direction  83  may be reflected back in upward direction  81  by reflector  70 . 
     Reflector  70  may include a reflective layer such as layer  74  on a support structure such as substrate  72 . Substrate  72  may be formed from plastic, metal, or other suitable material. Reflector  70  may be formed from white polymer (white ink), a dielectric stack mirror coating, metal, or other reflective material. With one illustrative configuration, substrate  72  may be a layer of printed circuit material (e.g., a rigid printed circuit substrate or a flexible printed circuit substrate) and reflective layer  74  may be a white reflective layer (white coverlay) on the surface of the printed circuit substrate. 
     Adhesive  76  (e.g., a ring of adhesive that runs around the peripheral edge of reflector  70 ) may be used in attaching reflector  70  to the lower surface of light guide plate  40 . Light guide plate  40  may be attached to printed circuit  84  by a ring of adhesive such as adhesive  78 . Adhesive  78  may run along the periphery of opening  86  (i.e., adhesive  78  may have the shape of a ring that surrounds opening  86 ). If desired, reflector  70  may be attached to light guide plate (light guide layer)  40  using screws, clamps, or other attachment structures and light guide plate  40  may be attached to printed circuit  84  using screws, clamps, or other attachment structures. The use of adhesive  76  and  78  to attach light guide plate between reflector  70  and printed circuit  84  is illustrative. 
     Printed circuit  84  may be a rigid printed circuit board or other printed circuit with interconnects formed from metal traces  82 . Light-emitting diodes such as diode  34  of  FIG. 12  may be attached to traces  82  using solder  80 . If desired, metal traces or other conductive traces  82  on the upper surface of printed circuit  84  or elsewhere in printed circuit  84  may be used in forming an array of capacitive electrodes for a touch sensor (i.e., capacitive touch sensor electrodes  20 ). Electrodes  20  may have the shape of a grid of lines (e.g., drive lines that run across printed circuit  84  along one dimension and sense lines that run across printed circuit  84  along a perpendicular dimension), may have the shapes of strips of metal, or may form an array of pads or other touch sensor patterns. In the example of  FIG. 2 , touch sensor electrodes  20  have been formed on the upper surface of the same printed circuit substrate to which light-emitting diode  34  is mounted. This is merely illustrative. Touch sensor electrodes  20  may be formed on a separate substrate (e.g., a separate flexible printed circuit or rigid printed circuit, the underside of a cover layer, a molded plastic support, etc.) or elsewhere in device  10 . One or more of touch sensor electrodes  20  may be monitored for touch input and may therefore serve as an input device such as button  22  of  FIG. 1  that is aligned with symbol  24 . If desired, a button such as button  22  that is labeled with illuminated symbol  24  may have components for receiving user input without using an electrode  20  or in addition to using an electrode  20  (e.g., a collapsible dome switch or other switch that can be depressed by a user, a force sensor, a light-based proximity sensor, etc.), other input-output devices  32  or portions of housing  12  may be provided with illuminated symbols  24 , etc. 
     Cover layer  92  may form a part of housing  12 , may be part of a clear layer mounted within surrounding opaque structures (e.g., opaque metal or plastic housing structures), or may be any other suitable structure within device  10 . Layer  92  may be transparent or may have a region overlapping light guide plate  40  that is transparent (e.g., translucent, clear, or colored with sufficient transmissivity to allow light  44  to pass, etc.). Opaque masking materials such as opaque masking layer  46  or other light masking structures may be interposed between light guide plate  40  and cover layer  92  to pattern light  44 . 
     As shown in  FIG. 12 , layer  46  may have an opening such as opening  48 . The shape of opening  48  may be configured to pattern light  44  into the shape of a desired symbol (e.g., symbol  24  of  FIG. 1 , etc.). Layer  46  may be formed from a layer of black ink (e.g., a polymer with carbon black particles, a polymer with particles of other colors, etc.) or other opaque material that blocks visible light. The thickness of layer  46  may be 1-100 microns, more than 0.5 microns, or less than 50 microns (as examples). 
     To provide the exterior of device  10  with a desired appearance, it may be desirable to coat the underside of cover layer  92  with a thin layer of cosmetic ink such as cosmetic ink  88 . Ink  88  may be white ink (e.g., polymer containing titanium dioxide particles) or may be ink of other colors (black ink, gray ink, blue, red, or green ink, etc.). The thickness of ink  88  may be 0.1 to 100 microns, more than 1 micron, or less than 50 microns (as examples). Ink layer  88  may be configured so as to be sufficiently transparent to allow light  44  to escape from device  10  while being sufficiently opaque to block internal components in device  10  from view. With one illustrative configuration, the transmissivity of layer  88  may be 2-6%, may be more than 1%, may be less than 10%, etc. The transmissivity of layer  46  in this type of arrangement may be less than 1% or other amount less than the transmissivity of layer  88  (as an example). 
     If desired, layer  92  may form part of the outermost surface of housing  12  and device  10  (e.g., layer  92  may form part of housing  12 ). As another example, layer  92  may be an internal structure that is used as a support for patterned ink layers or other coating layers  90  (e.g., opaque layer  46  and cosmetic layer  88  or other coatings on layer  46 ). All of layer  92  may be transparent or the portions of layer  92  that overlap symbol  24  (i.e., opening  48 ) may be transparent. If desired, additional layer(s) of material that are sufficiently transparent to allow light  44  to exit device  10  may be stacked with layer  92  and/or the other layers of  FIG. 12 . 
       FIG. 13  is a cross-sectional side view of an illustrative illumination system in which light guide plate  40  has been provided with notches to receive adhesive  94 . Adhesive  94  may be used in attaching optical layer  50  over the surface of light guide plate  40  and may be used in attaching light guide plate  40  to printed circuit  84  in flush configurations. Optical layer  50  may be a diffuser, brightness enhancement film, and/or other optical layer. Light-emitting diode  34  may be attached to the surface of printed circuit  84  using solder  80 . 
     In the example of  FIG. 12 , light guide plate  40  is attached to the inner surface of printed circuit  84  and a touch sensor is formed from electrodes  20  on the opposing outer surface of printed circuit  84 . This type of configuration may sometimes be referred to as an underside mounting configuration or reverse mounting configuration. If desired, light guide plate  40  may be mounted to the outermost surface of a printed circuit or other support structure (i.e., in an topside mounting configuration). The example of  FIG. 12  is presented as an example. 
     The foregoing is merely illustrative and various modifications can be made by those skilled in the art. The foregoing embodiments may be implemented individually or in any combination.

Metadata:
Filing Date: 20160601
Publication Date: 20220614
Grant Date: 20220614
Priority Date: 20160601
Inventors: HUWE, ETHAN L.
TRAINER, GLENN K.
QI, JUN
LIU, RONG
YIN, VICTOR H.
Assignee: APPLE INC
CPC Classifications: [{"code": "G02B6/0068", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02B6/005", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02B6/0046", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B6/0038", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02B6/0036", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02B6/006", "inventive": true, "first": true, "tree": "[]"}, {"code": "F21V23/0485", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B6/0046", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B6/0036", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B6/0055", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B27/30", "inventive": true, "first": false, "tree": "[]"}, {"code": "F21V17/101", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B6/0051", "inventive": true, "first": false, "tree": "[]"}, {"code": "F21Y2101/00", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02B6/0055", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B6/0046", "inventive": true, "first": false, "tree": "[]"}, {"code": "F21Y2101/02", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02B6/0051", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B27/30", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B6/0036", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B6/006", "inventive": true, "first": true, "tree": "[]"}, {"code": "F21V23/0485", "inventive": true, "first": false, "tree": "[]"}, {"code": "F21V17/101", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 81944194