PATENT DOCUMENT

Publication Number: US-10694607-B1
Application Number: US-201916450813-A
Country: US
Kind Code: B1

Title: Electronic devices with light sensor waveguides

Abstract:
An electronic device may have a housing with a display. A transparent portion of the housing may serve as a display cover layer and may overlap an array of pixels in the display. The array of pixels may form an active area of the display for displaying images for a user. An ambient light sensor window may be formed in an inactive area of the display that does not overlap pixels. An ambient light sensor may be mounted in an interior region of the housing. A metal-coated light guide may have a first end aligned with the ambient light sensor window to receive ambient light from an exterior region surrounding the device and may have a second end at which the ambient light is provided to the ambient light sensor.

Claims:
What is claimed is: 
     
       1. An electronic device, comprising:
 a housing; 
 an ambient light sensor window; 
 an ambient light sensor in the housing; and 
 a light guide in the housing between the ambient light sensor window and the ambient light sensor, wherein the light guide has a core, a metal coating, and a dielectric layer between the metal coating and the core, and wherein the dielectric layer comprises a thin-film interference filter formed from a stack of multiple thin-film coatings. 
 
     
     
       2. The electronic device defined in  claim 1  wherein the stack of multiple thin-film coatings is configured to reflect light traveling through the core. 
     
     
       3. The electronic device defined in  claim 2  wherein the metal coating comprises a metal coating layer selected from the group consisting of: an aluminum coating layer, a silver coating layer, and a gold coating layer. 
     
     
       4. The electronic device defined in  claim 3  wherein the core comprises a core selected from the group consisting of: a glass core and a polymer core, and wherein the stack of multiple thin-film coatings comprises an innermost layer on an exterior surface of the core that is formed from silicon oxide. 
     
     
       5. The electronic device defined in  claim 3  wherein the metal coating layer is an aluminum coating layer and wherein the stack of multiple thin-film coating layers comprises an outermost layer adjacent to the aluminum coating layer that is formed from aluminum oxide. 
     
     
       6. The electronic device defined in  claim 2  further comprising light-scattering structures in the core. 
     
     
       7. The electronic device defined in  claim 1  further comprising an additional dielectric layer on an outer surface of the metal coating. 
     
     
       8. The electronic device defined in  claim 7  further comprising a polymer coating on the additional dielectric layer. 
     
     
       9. The electronic device defined in  claim 8  wherein the additional dielectric layer comprises an aluminum oxide layer and a silicon oxide layer. 
     
     
       10. The electronic device defined in  claim 1  wherein the ambient light sensor comprises a color ambient light sensor that is configured to measure ambient light color and ambient light intensity. 
     
     
       11. The electronic device defined in  claim 10  further comprising:
 pixels that are configured to display an image; and 
 control circuitry configured to adjust image color and intensity for the image based on the measured ambient light color and ambient light intensity. 
 
     
     
       12. An electronic device comprising:
 a transparent display cover layer; 
 a light guide having an entrance configured to receive ambient light that has passed through the display cover layer, wherein the light guide has a core and has coating layers including a metal coating layer, a first dielectric layer between the metal coating layer and the core, and a second dielectric layer on an exterior surface of the metal coating layer; 
 a color ambient light sensor configured to receive the ambient light after the ambient light has reflected from the coating layers while passing through the core; 
 pixels; and 
 control circuitry configured to adjust the pixels using a measurement from the color ambient light sensor. 
 
     
     
       13. The electronic device defined in  claim 12  wherein the coating layers comprise a stack of multiple thin-film dielectric layers between the metal coating layer and the core. 
     
     
       14. The electronic device defined in  claim 13  further comprising a polymer coating layer on the second dielectric layer. 
     
     
       15. The electronic device defined in  claim 12  further comprising light-scattering structures embedded in the core. 
     
     
       16. An electronic device comprising:
 a housing configured to separate an interior region from an exterior region surrounding the housing; 
 an optical component window in the housing; 
 a light guide having first and second ends, wherein the first end is aligned with the optical component window, wherein the light guide has a core with a metal coating, and wherein the light guide comprises multiple thin-film dielectric layers between the metal coating and the core; and 
 an optical component aligned with the second end. 
 
     
     
       17. The electronic device defined in  claim 16  wherein the core has light-scattering structures, and wherein the optical component comprises an ambient light sensor.

Description:
FIELD 
     This relates generally to electronic devices, and, more particularly, to electronic devices with optical components such as light sensors. 
     BACKGROUND 
     Electronic devices may have optical components such as light sensors. For example, electronic devices may have ambient light sensors for measuring ambient light levels. During operation of an electronic device with an ambient light sensor, display brightness can be adjusted based on measured ambient light levels. In devices with color ambient light sensors, display color cast can be adjusted based on measured ambient light color. 
     It can be challenging to incorporate an ambient light sensor into an electronic device. If care is not taken, the presence of an ambient light sensor may adversely affect a device&#39;s appearance or an ambient light sensor may not gather ambient light readings accurately. 
     SUMMARY 
     An electronic device may have a housing with a display. A transparent portion of the housing may serve as a display cover layer and may overlap an array of pixels in the display. The array of pixels may form an active area of the display for displaying images for a user. An ambient light sensor window may be formed in an inactive area of the display that does not overlap pixels or other portion of the electronic device. An ambient light sensor may be mounted in an interior region of the housing. A metal-coated light guide may have a first end aligned with the ambient light sensor window to receive ambient light from an exterior region surrounding the device and may have a second end at which the ambient light is provided to the ambient light sensor. 
     The light guide may have a first set of one or more dielectric layers on an exterior surface of a transparent light guide core. The light guide core may be formed from polymer or glass and may include optional light-scattering structures. 
     The first set of layers may include a layer of material that adheres to the light guide core. The first set of layers may also include a layer that exhibits satisfactory adhesion to a metal coating layer. Multiple thin-film dielectric layers in the first let of layers may be configured to form a thin-film interference filter mirror structure that exhibits high reflectivity for rays of light traveling down the light guide core and reflecting from the coatings on the light guide core. The inclusion of the thin-film interference filter mirror structure may help enhance light guide transmission. 
     The light guide may also have a second set of one or more dielectric layers on an exterior surface of the metal reflective layer. These layers may include a layer that exhibits satisfactory adhesion to the metal coating layer and another layer that exhibits satisfactory adhesion to a black ink layer or other polymer coating layer. The inclusion of the second dielectric layers may help enhance adhesion of the polymer coating layer. 
     The light guide may be assembled with other components for an ambient light sensor such as an ambient light sensor die, diffusers, and other optical components such as infrared-light-blocking-and-visible-light-transmitting filters. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cross-sectional side view of an illustrative electronic device with an optical component such as an ambient light sensor in accordance with an embodiment. 
         FIG. 2  is a cross-sectional side view of a portion of an illustrative ambient light sensor assembly in accordance with an embodiment. 
         FIG. 3  is a cross-sectional side view of an illustrative coated light guide in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     An electronic device may have optical components. The optical components may operate through transparent portions of a device that serve as optical component windows and that allow light to pass between the exterior and interior of the device. The optical components may include, for example, light sensors such as ambient light sensors and other components that detect and/or emit light. 
     Ambient light sensors may be used to gather measurements of ambient light intensity and color. During operation of an electronic device, display adjustments may be made and other actions may be taken based on ambient light sensor measurements. For example, display brightness may be adjusted based on measurements of ambient light intensity and display color cast may be adjusted based on measurements of ambient light color. 
     Optical component windows are sufficiently transparent to allow light to pass from the interior of the electronic device to the exterior of the electronic device and to allow light to pass from the exterior of the electronic device to the interior. For example, an ambient light sensor window is sufficiently transparent to allow visible light from the exterior of an electronic device to pass to an ambient light sensor in the interior that is aligned with the ambient light sensor window. 
     To accommodate an optical component such as an ambient light sensor within the interior of an electronic device, the optical component may be provided with a light guide. As an example, a light guide may be coupled between an ambient light sensor window and an ambient light sensor. During operation, the light guide guides light from the ambient light sensor window to the ambient light sensor, so that the ambient light sensor may make ambient light measurements. 
     In general, light guides may be used to convey light to or from any optical component that receives and/or emits light (e.g., proximity sensors, camera flash devices, time-of-flight sensors, status indicator lights, etc.). Configurations in which light guides are used to convey light to ambient light sensors are sometimes described herein as examples. 
     A cross-sectional side view of an illustrative electronic device with a waveguide-based ambient light sensor assembly is shown in  FIG. 1 . Electronic device  10  may have a display such as display  14  mounted in a housing such as housing  12 . Device  10  of  FIG. 1  is a portable device such as a cellular telephone, wristwatch device, or tablet computer. Other types of electronic devices may be provided with ambient light sensors if desired. Electronic device  10  may be, for example, a computing device such as a laptop computer, a media player, a pendant device, a display, a gaming device, a head-mounted device, a desktop computer with an integrated display, an embedded system such as a system mounted in a kiosk or automobile, or other electronic equipment. 
     Housing  12  may be formed from polymer, metal, glass, crystalline material such as sapphire, ceramic, fabric, fibers, fiber composite material, natural materials such as wood and cotton, other materials, and/or combinations of such materials. Housing  12  may be configured to form housing walls. The housing walls may enclose an interior region such as interior region  30  within device  10  and may separate interior region  30  from an exterior region such as exterior region  32  surrounding device  10 . The housing walls may include a rear wall on rear side R of device  10 , sidewalls on edges W of device  10 , and a transparent housing wall that serves as a display cover layer on front side F of device  10 . Front side F opposes rear side R of device  10  in the illustrative configuration of  FIG. 1 . Other arrangements may be used for forming housing  12  in device  10 , if desired. 
     Display  14  may be a liquid crystal display, an organic light-emitting diode display, or other suitable display. Display  14  may have an array of pixels P. The portion of housing  12  that overlaps display  14  may sometimes be referred to as a display cover layer. The display cover layer (e.g., display cover layer  12 F in the example of  FIG. 1 ) may be formed from glass, crystalline material such as sapphire, clear polymer, other transparent materials, and/or combinations of these materials. The display cover layer may be coupled to metal housing walls or other housing structures in housing  12  and may sometimes be referred to as forming transparent housing structures or a transparent housing wall. 
     Display cover layer  12 F may overlap active area AA of display  14  on front side F of device  10 . During operation, pixels P of active area AA may display an image for viewing by a user of device  10 . One or more portions of display cover layer  12 F may also overlap inactive display areas such as inactive area IA. Inactive area IA may contain display driver circuitry and other components, but does not include pixels and does not display images. Inactive area IA may, as an example, form a notch at one end of device  10 . Configurations in which inactive area IA forms a border that runs along one or more peripheral edges of device  10  or in which inactive area IA forms an isolated island surrounded by pixels P in active area AA may also be used. 
     Opaque material may be formed as a coating on an inner surface of the display cover layer in inactive area IA, as shown by opaque coating layer  34 . This opaque coating layer, which may sometimes be referred to as an opaque masking layer, ink layer, opaque ink layer, etc., may be black (e.g., black ink formed from black dye and/or black pigment in a polymer), may be white, gray, silver, or other neutral colors, or may have a non-neutral color (e.g., red, blue, yellow, etc.). In some configurations, the opaque coating layer may be formed from multiple sublayers. The opaque coating layer may be visible from the exterior of device  10  (e.g., through peripheral portions of the display cover layer. Due to the presence of the opaque coating layer in inactive area IA, display driver circuitry and other components in inactive area IA may be hidden from view from the exterior of device  10 . 
     Optical components may be mounted within device  10 . For example, an ambient light sensor may be mounted within interior  30  and may make ambient light measurements on ambient light received through display cover layer  12 F. In some configurations, ambient light may be received through transparent portions of active area AA. In the example of  FIG. 1 , ambient light sensor assembly  36  is mounted under inactive area IA and is configured to receive light through a portion of inactive area IA. 
     The portion of device  10  through which ambient light sensor assembly  36  receives ambient light from exterior region  32  may sometimes be referred to as an ambient light sensor window. An ambient light sensor window may be formed in any suitable portion of housing  12 . For example, an ambient light sensor window may be formed within an opaque portion of housing  12  (e.g., in a wall on an edge W or rear side R). If desired, an ambient light sensor window may, as shown in the example of  FIG. 1 , be formed within a portion of layer  34 . In this type of configuration, a portion of layer  34  may be provided with perforations or other openings, locally thinned opaque material (sufficiently thin to allow light to pass), selectively altered coating materials (e.g., ambient light sensor window ink that is at least partly transparent and/or has desired spectral properties), thin-film interference filter coating structures, other suitable window structures, and/or combinations of these structures. 
     Ambient light sensor windows may be provided with sufficient transparency to allow ambient light to pass from exterior  32  to components in interior  30  such as ambient light sensor assembly  36 . This allows ambient light sensor readings to be taken during the operation of device  10 . 
     As shown in  FIG. 1 , electrical components  22  may be mounted in interior  30  of device  10  (e.g., on a substrate such as printed circuit  24  located between display cover layer  12 F on front side F and an opposing rear housing wall on rear side R). Components  22  may include integrated circuits, discrete components, light-emitting components, sensors, and/or other circuits. Electrical components  22  may include control circuitry. The control circuitry 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 the control circuitry may be used to control the operation of device  10 . For example, the processing circuitry may use sensors and other input-output circuitry to gather input and to provide output, to transmit signals to external equipment, to adjust display  14  (e.g., to adjust display brightness and/or color cast to control the brightness and/or color cast of images on display  14  in response to measurements from a color ambient light sensor such as ambient light color and/or ambient light intensity), and/or to perform other tasks. 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. The control circuitry may include wired and/or wireless communications circuitry (e.g., antennas and associated radio-frequency transceiver circuitry such as cellular telephone communications circuitry, wireless local area network communications circuitry, etc.). The communications circuitry of the control circuitry may allow device  10  to communicate with other electronic devices. For example, the control circuitry (e.g., communications circuitry in the control circuitry) may be used to allow wired and/or wireless control commands and other communications to be conveyed between devices such as cellular telephones, tablet computers, laptop computers, desktop computers, head-mounted devices, handheld controllers, wristwatch devices, other wearable devices, keyboards, computer mice, remote controls, speakers, accessory displays, accessory cameras, and/or other electronic devices. Wireless communications circuitry may, for example, wirelessly transmit control signals and other information to external equipment in response to receiving user input or other input from sensors or other devices in components  22 . 
     Input-output circuitry in components  22  of device  10  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. The input-output circuitry may include input devices that gather user input and other input and may include output devices that supply visual output, audible output, or other output. 
     Output may be provided using light-emitting diodes (e.g., crystalline semiconductor light-emitting diodes for status indicators and/or displays, organic light-emitting diodes in displays and other components), lasers, and other light-emitting devices, audio output devices (e.g., tone generators and/or speakers), haptic output devices (e.g., vibrators, electromagnetic actuators, piezoelectric actuators, and/or other equipment that supplies a user with haptic output), and other output devices. 
     The input-output circuitry of device  10  (e.g., the input-output circuitry of components  22 ) may include sensors. Sensors for device  10  may include force sensors (e.g., strain gauges, capacitive force sensors, resistive force sensors, etc.), audio sensors such as microphones, touch and/or proximity sensors such as capacitive sensors (e.g., a two-dimensional capacitive touch sensor integrated into a display, a two-dimensional capacitive touch sensor and/or a two-dimensional force sensor overlapping a display, and/or a touch sensor or force sensor that forms a button, trackpad, or other input device not associated with a display), and other sensors. Touch sensors for a display or for other touch components may be based on an array of capacitive touch sensor electrodes, acoustic touch sensor structures, resistive touch components, force-based touch sensor structures, a light-based touch sensor, or other suitable touch sensor arrangements. If desired, a display may have a force sensor for gathering force input (e.g., a two-dimensional force sensor may be used in gathering force input on a display). 
     If desired, the sensors may include optical sensors such as optical sensors that emit and detect light, ultrasonic sensors, optical touch sensors, optical proximity sensors, and/or other touch sensors and/or proximity sensors, monochromatic and color ambient light sensors in an assembly such as ambient light sensor assembly  36 , image sensors, fingerprint sensors, temperature sensors, sensors for measuring three-dimensional non-contact gestures (“air gestures”), pressure sensors, sensors for detecting position, orientation, and/or motion (e.g., accelerometers, magnetic sensors such as compass sensors, gyroscopes, and/or inertial measurement units that contain some or all of these sensors), health sensors, radio-frequency sensors (e.g., sensors that gather position information, three-dimensional radio-frequency images, and/or other information using radar principals or other radio-frequency sensing), depth sensors (e.g., structured light sensors and/or depth sensors based on stereo imaging devices), optical sensors such as self-mixing sensors and light detection and ranging (lidar) sensors that gather time-of-flight measurements, humidity sensors, moisture sensors, gaze tracking sensors, three-dimensional sensors (e.g., time-of-flight image sensors, pairs of two-dimensional image sensors that gather three-dimensional images using binocular vision, three-dimensional structured light sensors that emit an array of infrared light beams or other structured light using arrays of lasers or other light emitters and associated optical components and that capture images of the spots created as the beams illuminate target objects, and/or other three-dimensional image sensors), facial recognition sensors based on three-dimensional image sensors, and/or other sensors. 
     In some configurations, components  22  may include mechanical devices for gathering input (e.g., buttons, joysticks, scrolling wheels, key pads with movable keys, keyboards with movable keys, and other devices for gathering user input). During operation, device  10  may use sensors and/or other input-output devices in components  22  to gather user input (e.g., buttons may be used to gather button press input, touch and/or force sensors overlapping displays can be used for gathering user touch screen input and/or force input, touch pads and/or force sensors may be used in gathering touch and/or force input, microphones may be used for gathering audio input, etc.). The control circuitry of device  10  can then take action based on this gathered information (e.g., by transmitting the information over a wired or wireless path to external equipment, by supplying a user with output using a haptic output device, visual output device, an audio component, or other input-output device in housing  12 , etc.). For example, the control circuitry of device  10  may gather information on ambient light color and ambient light intensity using an ambient light sensor and may use this information in adjusting the brightness and color cast of display  14 . 
     If desired, electronic device  10  may include a battery or other energy storage device, connector ports for supporting wired communications with ancillary equipment and for receiving wired power, and other circuitry. In some configurations, device  10  may serve as an accessory and/or may include a wired and/or wireless accessory (e.g., a keyboard, computer mouse, remote control, trackpad, etc.). 
     Ambient light sensor windows and other optical component windows in device  10  transmit sufficient light to allow aligned optical components to receive or emit light. For example, ambient light sensors that are overlapped by ambient light sensor widows may gather ambient light measurements through the windows. The transmission of an ambient light sensor window may be, for example, at least 0.5%, at least 1%, at least 2%, at least 10%, at least 50%, less than 100%, less than 60%, less than 20%, or other suitable value. 
       FIG. 2  is a cross-sectional side view of a portion of electronic device  10  that includes ambient light sensor assembly  36 . In the example of  FIG. 2 , layer  34  in inactive area IA includes opaque material  34 D (e.g., a black ink coating or other opaque material) and includes ambient light sensor window material  34 W (e.g., a coating of black ambient light sensor ink or other structure that is sufficiently transparent to ambient light to allow ambient light sensor assembly  36  to gather ambient light sensor readings). Ambient light sensor window  40  may be any suitable shape. For example, window  40  and underlying structures in assembly  36  may have a circular footprint when viewed along the Z axis, a rectangular footprint, a square footprint, or other suitable shape. 
     Ambient light sensor assembly  36  includes one or more support structures  42  that serve as a package and mounting structure for ambient light sensor components. These support structures may be formed from black polymer or other material. Adhesive and other coupling structures may be used to couple support structures together. 
     Assembly  36  may include ambient light sensor  80 . Assembly  36  may also include light guide  50  in central portion  48  for guiding ambient light that is received through ambient light sensor window  40  to ambient light sensor  80 . Optional optical structures may be interposed between light guide  50  and window  40  and between light guide  50  and sensor  80 . For example, optical system  44  may be interposed between light guide  50  and window  40  and optical system  54  may be interposed between light guide  50  and ambient light sensor  80 . 
     Optical system  44  may include one or more optical elements  46  (e.g., diffuser layers, infrared-light-blocking-and-visible-light-transmitting filters, etc.). Optical system  54  may include one or more optical elements  54  (e.g., infrared-light-blocking-and-visible-light-transmitting filter(s), etc.). Optical filters in systems  44  and/or  54  may be used to block undesired wavelengths of light (e.g., infrared and/or ultraviolet light) while passing desired wavelengths of light (e.g., visible wavelengths) to ambient light sensor  80 . If desired, light diffusing and/or light filtering capabilities may be incorporated into light guide  50  in addition to or instead of using components in systems  44  and/or  54  to perform these functions. 
     Ambient light sensor  80  may be mounted on a substrate such as substrate  58  (e.g., a printed circuit with signal lines coupled to signal lines in other printed circuits in device  10 ). Ambient light sensor  80  may be formed from a semiconductor die  56  (e.g., a silicon die) with multiple photodetectors  60 . Each photodetector  60  may have a corresponding color filter  65  through which light passes before reaching that photodetector. Color filters  65  may be formed from colored polymer layers or other materials that pass particular bands of wavelengths (e.g., different colors of light) and/or may be formed from thin-film interference filters with different pass bands. As an example, color filters  65  may include a first color filter that passes red light, a second color filter that passes blue light, and additional color filters that pass light of different colors. With this type of arrangement, different photodetectors  60  detect light of different colors. A multichannel light sensor such as sensor  80  of  FIG. 2  may therefore measure the relative contribution of each color of light that is present and may therefore serve as a color ambient light sensor that measures both the total light intensity of ambient light and ambient light color. Ambient light color measurements may be gathered as color coordinates, a color temperature, a correlated color temperature, a light spectrum, or as color measurement data represented using other color measurement formats. There may be, for example, at least 3, at least 6, at least 10, fewer than 20, fewer than 9, or other suitable number of photodetectors  60  on die  56 . 
     Ambient light sensor  80  may be mounted within ambient light sensor assembly  36  in alignment with exit  50 X of light guide  50 . During operation, ambient light from exterior  32  passes through window  40  and the optical components of system  44 , enters entrance  50 N of light guide  50 , is guided along longitudinal axis  82  of light guide  50 , exits exit  50 X of light guide  50 , passes through system  54 , and is received and measured by ambient light sensor  80 . 
     Light guide  50  may have a shape and size that helps accommodate ambient light sensor  80  within the interior of device  10  (e.g., by moving sensor  80  into an interior portion of device  10  where there is sufficient room to accommodate sensor  80 ). 
     In general, light guide  50  may have any suitable dimensions. For example, longitudinal (height) dimension DV may have a value of 1.7 mm, at least 0.1 mm, at least 1 mm, at least 10 mm, less than 30 mm, less than 3 mm, less than 0.3 mm, or other suitable length and lateral dimensions DH (distances along the X and/or Y axes) may be 0.7 mm, at least 0.1, at least 0.5 mm, at least 1 mm, at least 10 mm, less than 20 mm, less than 5 mm, less than 0.5 mm, or other suitable lateral dimension. The size of light guide  50  along the X and Y dimensions may be equal or may be different. Light guide  50  may have a footprint when viewed along the Z axis that is circular, oval, square, rectangular, that has curved and/or straight edges, etc. The ratio of DV to the smallest lateral dimension DH of light guide  50  may be at least 0.5, at least 1, at least 1.5, at least 2, at least 5, less than 10, less than 4, less than 2.5, less than 1, or other suitable ratio. 
     To help confine ambient light that is passing through light guide  50 , light guide  50  may be provided with a reflective coating. The reflective coating may, for example, include a layer of metal or other reflective material.  FIG. 3  is a cross-sectional side view of an illustrative light guide of the type that may include a reflective coating layer. In the illustrative configuration of  FIG. 3 , light guide  50  includes light guide core  50 C. Light guide core  50 C may be formed from transparent material  60  (e.g., a block of clear polymer, glass, etc.). Material  60  may, if desired, be configured to serve as a spectral filter. For example, material  60  may be blue glass or other material that absorbs infrared light and that therefore serves as an infrared-light-blocking filter. 
     If desired, light-scattering structures  62  may optionally be embedded in material  60 . Structures  62  may include voids, gas-filled bubbles, particles with a refractive index that differs from the refractive index of material  60  (e.g., inorganic dielectric particles), and/or other light-scattering structures. Texture may, if desired, be added to the entrance and/or exit surfaces of core  50 C to help diffuse light. With textured surfaces and/or embedded light-scattering structures  62 , light guide core  50 C may exhibit a haze of at least 10%, at least 50%, less than 99%, or other suitable value. 
     Some or all of the sides of core  50 C (other than the entrance and exit surfaces of core  50 C) may be covered with reflective coating layer  68  to help confine light that is traveling along core  50 C (e.g., along longitudinal axis  82  of  FIG. 2 ). Layer  68  may be formed from a reflective material such as metal (e.g., aluminum, silver, gold, a metal alloy, or other metal coating). During operation, layer  68  may help confine light within core  50 C due to the reflective nature of the material forming layer  68  rather than the principal of total internal reflection. Layer  68  may be a thin-film layer with a thicknesses of 0.150 microns, at least 0.03 microns at least 0.08 microns, less than 0.35 microns, less than 2 microns, less than 1 micron, less than 0.3 microns, at least 0.01 microns, at least 0.1 microns, at least 0.6 microns, or other suitable thicknesses. 
     Optional dielectric layer  64  may be interposed between reflective coating layer  68  and core  50 C. Layer  64  may contain one or more dielectric layers  66  (e.g., thin-film inorganic dielectric layers). As an example, an innermost layer of layers  66  may be formed from a material with satisfactory adhesion to core  50 C (e.g., a silicon oxide layer that adheres to core  50 C in a configuration in which core  50 C is formed from glass). In arrangements in which layer  68  is formed from a metal such as aluminum, the outermost of layers  66  may be formed from a dielectric with satisfactory adhesion to aluminum (e.g., aluminum oxide). As an illustrative example, layer  66  may contain a silicon oxide layer (e.g., a 50-150 nm silicon oxide layer), a titanium oxide layer (e.g., a 30-120 nm titanium oxide layer), a silicon oxide layer (e.g., a 30-120 nm thick silicon oxide layer), and an aluminum oxide layer (e.g., a 10-50 nm aluminum oxide layer). In general, there may be any suitable number of layers  66  in layer  64  (e.g., 3-6, at least 2, at least 3, at least 5, fewer than 10, fewer than 7, 4, etc.). These layers may be thin-film layers deposited by physical vapor deposition or other suitable deposition processes. 
     The stack of the dielectric thin-films that make up layer  64  may be provided with thicknesses and refractive index values that enhance the reflection of light rays from the interface between core  50 C and the coating on core  50 C (e.g., this stack of thin films may form a thin-film interference filter mirror structure with a high reflectivity at a range of angles associated with the angles of light rays traveling down the length of core  50 C). In addition to forming a thin-film interference mirror for light rays in core  50 C, layer  64  forms an adhesion promotion layer that helps attach layer  68  to the outer surface of core  50 C. Layers  66  and/or layer  64  may have thicknesses of less than 2 microns, less than 1 micron, less than 0.3 microns, at least 0.01 microns, or other suitable thicknesses. 
     Optional outer thin-film coating layer  70  may be formed on the outer surface of layer  68 . Layer  70  may include one or more thin-film coating layers  72 . Layers  72  and/or layer  70  may have thicknesses of less than 2 microns, less than 1 micron, less than 0.3 microns, at least 0.01 microns, or other suitable thicknesses. An innermost layer of layers  72  may be formed from a material with satisfactory adhesion to layer  68  (e.g., an aluminum oxide layer in a scenario in which layer  68  is formed from aluminum). An outermost layer of layers  72  (or all of layer  70  in an arrangement in which layer  70  contains only a single layer  72 ) may be a silicon oxide layer to promote adhesion of a polymer coating layer such as optional polymer coating layer  74 . As an example, an innermost of layers  72  may be an aluminum oxide layer with a thickness of 0.01-0.08 microns, a second-to-innermost of layers  72  may be a 0.02-0.1 microns silicon oxide layer, a third-to-innermost of layers  72  may be a titanium oxide layer with a thickness of 0.02-0.08 microns, and an outermost (fourth-to-innermost) of layers  72  may be a silicon oxide layer with a thickness of 0.03-0.15 microns. 
     Coating layer  74  may be formed from black ink (e.g., polymer with embedded black colorant such as black dye and/or pigment) or other suitable coating material. Layer  74  may help absorb stray light and may help prevent scratching to core  50 C and the coatings on core  50 C during assembly. During manufacturing, black polymer or other material may be molded over coating layer  74  (e.g., to form part of structures  42  of  FIG. 2 ). If desired, coating layer  74  may be omitted. 
     The coatings on light guide core  50 C of  FIG. 3  may be relatively thin, which can reduce the volume occupied by light guide  50  and assembly  36 . These coatings may be resistant to moisture-induced delamination and may therefore exhibit satisfactory reliability. Resistance to damage during unintentional drop events may be enhanced by forming an optional diffuser from light-scattering structures  62  in material  60 . Light guide  50  may exhibit high light transmission (e.g., at least 40%, at least 50%, at least 70%, or less than 90% end to end) and therefore may exhibit small light losses and measurement noise. Although illustrated in the context of a straight light guide, light guide structures for light guide  50  may have any suitable shapes (e.g., shapes with bends along the length of light guide  50 , etc.). 
     Light guide  50  may be used to transmit light from window  40  to light sensor  80  and may be used in other light-based devices. For example, light guide  50  may be used in a proximity sensor that emits infrared light and detects infrared light. In this type of configuration, the sensor may use light guide  50  to guide light from a light-emitting diode, laser, or other light emitter to exterior  30  and may use a light guide such as light guide  50  to guide light from exterior  30  to an infrared light detector. Light guide  50  may also be used with other optical components such as light-emitting devices that serve as status indicators lights, camera flash components, time-of-flight sensors, etc. 
     Device  10  may be operated in a system that uses personally identifiable information. It is well understood that the use of personally identifiable information should follow privacy policies and practices that are generally recognized as meeting or exceeding industry or governmental requirements for maintaining the privacy of users. In particular, personally identifiable information data should be managed and handled so as to minimize risks of unintentional or unauthorized access or use, and the nature of authorized use should be clearly indicated to users. 
     The foregoing is merely illustrative and various modifications can be made to the described embodiments. The foregoing embodiments may be implemented individually or in any combination. 
     
       
         
           
               
             
               
                   
               
               
                 Table of Reference Numerals 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
            
               
                 10 
                 Electronic Device 
                 12 
                 Housing 
               
               
                 14 
                 Display 
                 P 
                 Pixels 
               
               
                 36 
                 Ambient Light Sensor Assembly 
                 34 
                 Coating Layer 
               
               
                 30 
                 Interior 
                 F 
                 Front Side 
               
               
                 R 
                 Rear side 
                 AA 
                 Active Area 
               
               
                 IA 
                 Inactive Area 
                 32 
                 Exterior Region 
               
               
                 30 
                 Interior Region 
                 12F 
                 Display Cover Layer 
               
               
                 W 
                 Edges 
                 22 
                 Components 
               
               
                 24 
                 Printed Circuit 
                 34W 
                 Window Material 
               
               
                 34D 
                 Opaque Material 
                 42 
                 Support Structures 
               
               
                 46 
                 Components 
                 44 
                 Optical System 
               
               
                 DV 
                 Dimension 
                 DH 
                 Dimension 
               
               
                 82 
                 Longitudinal Axis 
                 48 
                 Central Portion 
               
               
                 50 
                 Light Guide 
                 50N 
                 Entrance 
               
               
                 50X 
                 Exit 
                 54 
                 Optical System 
               
               
                 65 
                 Color Filters 
                 60 
                 Photodetectors 
               
               
                 56 
                 Die 
                 80 
                 Ambient Light Sensor 
               
               
                 58 
                 Printed Circuit  
                 62 
                 Light-scattering  
               
               
                   
                   
                   
                 Structures 
               
               
                 60 
                 Materia 
                 50C 
                 Core 
               
               
                 64 
                 Dielectric Layer 
                 66 
                 Dielectric Layers 
               
               
                 68 
                 Reflective Coating Layer 
                 70 
                 Dielectric Layer 
               
               
                 72 
                 Dielectric Layers 
                 74 
                 Polymer Layer

Metadata:
Filing Date: 20190624
Publication Date: 20200623
Grant Date: 20200623
Priority Date: 20190624
Inventors: XU, Tingjun
SHAO, Guocheng
YU, LEI
LYNGNES, OVE
KANG, SUNGGU
SUN, Tianbo
ZHAO, Xianwei
FU, XIAOYONG
CAI, Xingxing
Assignee: APPLE INC
CPC Classifications: [{"code": "H05B47/11", "inventive": true, "first": true, "tree": "[]"}, {"code": "H05B45/22", "inventive": true, "first": false, "tree": "[]"}, {"code": "Y02B20/40", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02B6/4298", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02B6/0041", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02B27/017", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02B5/28", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02B5/201", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02B6/0035", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05B47/11", "inventive": true, "first": true, "tree": "[]"}, {"code": "G09G2360/144", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02B6/0041", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B5/285", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05B47/11", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02B5/285", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B6/0041", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G2360/144", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02B6/0035", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 71104968