PATENT DOCUMENT

Publication Number: US-10094708-B2
Application Number: US-201715481313-A
Country: US
Kind Code: B2

Title: Light sensor windows for electronic devices

Abstract:
An electronic device may be provided with light sensors. The electronic device may have an electronic device housing in which a display is mounted. The display may have a transparent layer such as a transparent display cover layer, a thin-film transistor layer, or a color filter layer. An opaque masking layer such as a layer of black ink may be used to cover an inner surface of the transparent layer in an inactive area of the display. Sensor window openings may be formed in the black ink layer. A layer of ink may be formed in each sensor window opening. Each layer of ink may have a diffuse reflectivity that is matched to that of the black ink. A diffuser layer such as a polymer coating layer with light-scattering particles may be coated on the inner surface of the layer of ink in a sensor window opening.

Claims:
What is claimed is: 
     
       1. An electronic device, comprising:
 a housing; 
 a display mounted in the housing, wherein the display has an active area and an inactive area and wherein the display has a transparent layer that is coated with a layer of opaque masking material in the inactive area; 
 a sensor in the housing; and 
 a sensor window formed from an opening in the layer of opaque masking material, wherein the sensor window includes a layer of diffuser material, and wherein the sensor is aligned with the sensor window. 
 
     
     
       2. The electronic device defined in  claim 1  wherein the layer of diffuser material is formed from a pigment. 
     
     
       3. The electronic device defined in  claim 2  wherein the pigment comprises at least one light scattering particle. 
     
     
       4. The electronic device defined in  claim 1  wherein the layer of opaque masking material is a black masking layer. 
     
     
       5. The electronic device defined in  claim 1  further comprising a layer of sensor ink interposed between the transparent layer and the layer of diffuser material. 
     
     
       6. The electronic device defined in  claim 5  wherein the sensor is an ambient light sensor and the sensor ink is an ambient light sensor ink. 
     
     
       7. The electronic device defined in  claim 5  wherein the sensor is an infrared sensor and the sensor ink is an infrared ink. 
     
     
       8. The electronic device defined in  claim 1  wherein the layer of diffuser material comprises a polymer coating. 
     
     
       9. The electronic device defined in  claim 1  wherein the layer of diffuser material has a haze value of less than 95%. 
     
     
       10. A display, comprising:
 a transparent layer having opposing outer and inner surfaces; 
 an opaque masking layer on a portion of the inner surface; 
 a sensor window opening in the opaque masking layer; and 
 a coating in the sensor window opening, wherein at least a portion of the opaque masking layer is interposed between the coating and the transparent layer, wherein the opaque masking layer has a first transmittance at visible wavelengths, and wherein the coating has a second transmittance at visible wavelengths that is greater than the first transmittance. 
 
     
     
       11. The display defined in  claim 10  wherein the opaque masking layer is a black masking layer. 
     
     
       12. The display defined in  claim 11  wherein the black masking layer is a layer of black ink. 
     
     
       13. The display defined in  claim 10  wherein the coating comprises blue ink. 
     
     
       14. The display defined in  claim 10  wherein the coating is an ambient light sensor coating. 
     
     
       15. The display defined in  claim 14  wherein the ambient light sensor coating comprises at least one ink. 
     
     
       16. Apparatus, comprising:
 a transparent display cover layer; 
 a first opaque layer on the transparent display cover layer; 
 a sensor window opening in the first opaque layer; and 
 a second opaque layer in the opening, wherein the first opaque layer and the second opaque layer have diffuse reflectivities that differ by less than 50%. 
 
     
     
       17. The apparatus defined in  claim 16  further comprising a sensor aligned with the sensor window opening. 
     
     
       18. The apparatus defined in  claim 16  wherein the second opaque layer has a thickness of 2-8 microns. 
     
     
       19. The apparatus defined in  claim 16  wherein the second opaque layer has a transmission spectrum that is more transparent than the first opaque layer. 
     
     
       20. The apparatus defined in  claim 19  wherein the second opaque layer has a transmittance of 1-10%.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation of patent application Ser. No. 14/468,177 filed Aug. 25, 2014, which is hereby incorporated by reference herein in its entirety. This application claims the benefit of and claims priority to patent application Ser. No. 14/468,177, filed Aug. 25, 2014. 
    
    
     BACKGROUND 
     This relates generally to electronic devices, and, more particularly, to light sensor windows in electronic devices. 
     Electronic devices such as cellular telephones often contain light sensors. For example, a cellular telephone may use an ambient light sensor to measure the amount of ambient light in the environment in which a cellular telephone is operating. When a large amount of ambient light is detected, screen brightness may be increased to help offset the brightness of the environment. 
     Some cellular telephones contain proximity sensors that can detect when the cellular telephone has been brought close to a user&#39;s face. When the cellular telephone comes into close proximity to the user&#39;s face, the touch screen in the cellular telephone can be deactivated to avoid unintentional touch input. This type of proximity sensor may contain a light-emitting diode that emits infrared light and a corresponding infrared light sensor that measures the amount of the emitted infrared light that is reflected back to the infrared light sensor from the user&#39;s face. 
     It can be challenging to mount electronic components such as ambient light sensors and proximity sensors in electronic equipment. If care is not taken, sensors such as these will be exposed to view and may be unsightly. Covering the light sensors with cosmetic structures may help enhance device aesthetics, but can potentially interfere with the transmission and reception of light signals associated with the light sensors. 
     It would therefore be desirable to be able to provide improved light sensor structures for electronic devices. 
     SUMMARY 
     An electronic device may be provided with light sensors such as a proximity sensor and ambient light sensor. The electronic device may have an electronic device housing. A display may be mounted in the electronic device housing. The display may have a transparent layer such as a transparent display cover layer, a thin-film transistor layer, or a color filter layer. 
     The light sensors may be aligned with light sensor windows in the housing or display. As an example, a light sensor window may be formed in an inactive area of the display. 
     An opaque masking layer such as a layer of black ink may be used to cover an inner surface of the transparent layer in the inactive area. A sensor window opening may be formed in the black ink layer. A layer of ink may be formed in the sensor window opening. The layer of ink may have a diffuse reflectivity that is matched to that of the black ink. The layer of ink may be more transmissive than the opaque masking layer at infrared wavelengths and, if desired, may be more transmissive than the opaque masking layer at visible wavelengths. 
     A diffuser layer such as a polymer layer with light-scattering particles may be deposited on the inner surface of the layer of ink in the sensor window opening. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an illustrative electronic device with sensors and sensor windows in accordance with an embodiment. 
         FIG. 2  is a cross-sectional side view of an illustrative electronic device showing how windows may be formed to accommodate a light-based proximity sensor and a light sensor such as an ambient light sensor in accordance with an embodiment. 
         FIG. 3  is a graph of a transmission spectrum for an illustrative layer of black masking material and an illustrative layer of diffuser material in accordance with an embodiment. 
         FIG. 4  is a graph of a transmission spectrum for an illustrative ambient light sensor ink layer in accordance with an embodiment. 
         FIG. 5  is a graph of a transmission spectrum for an illustrative proximity sensor ink layer in accordance with an embodiment. 
         FIG. 6  is a diagram of an illustrative sensor window and associated sensor in a configuration in which the sensor window has a layer of diffuser material deposited over a layer of ambient light sensor ink in accordance with an embodiment. 
         FIG. 7  is a diagram of an illustrative sensor window in which two black masking layers have been deposited prior to deposition of the diffuser material in accordance with an embodiment. 
         FIG. 8  is a diagram of an illustrative sensor window in which two black masking layers have been deposited prior to deposition of an ambient light sensor ink layer and a diffuser layer in accordance with an embodiment. 
         FIG. 9  is a cross-sectional side view of diffuser material that has light-scattering particles in a polymer matrix in accordance with an embodiment. 
         FIG. 10  is a cross-sectional side view of diffuser material that has light-scattering features such as bubbles or hollow microspheres in accordance with an embodiment. 
         FIG. 11  is a cross-sectional side view of an illustrative diffuser layer having a textured inner surface to diffuse light in accordance with an embodiment. 
         FIG. 12  is a top view of an illustrative black masking layer opening for a sensor window in accordance with an embodiment. 
         FIG. 13  is a top view of an illustrative black masking layer opening formed from a group of perforations in accordance with an embodiment. 
         FIG. 14  is a cross-sectional side view of an illustrative sensor window formed from a perforated black masking layer covered with a diffuser layer in accordance with an embodiment. 
         FIG. 15  is a cross-sectional side view of a sensor window and adjacent portions of an opaque masking layer that are characterized by respective diffuse reflectivity values that differ by less than a given amount in accordance with an embodiment. 
         FIG. 16  is a cross-sectional side view of a sensor window formed from a lens in a display cover layer or other device structure in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     An electronic device such as electronic device  10  of  FIG. 1  may contain optical components such as light-based sensors. Electronic device  10  may have a housing such as housing  12 . Display  14  may be mounted in housing  12  on the front face of device  10  or in another suitable location. The light-based sensors in device  10  may be mounted in alignment with light sensor windows. The windows may be formed in housing  12 , a portion of display  14 , or other portion of device  10 . 
     Electronic device  10  may be a computing device such as 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 television, a computer display that does not contain an embedded computer, a gaming device, a navigation device, 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. In the illustrative configuration of  FIG. 1 , device  10  is a portable device such as a cellular telephone, media player, tablet computer, or other portable computing device. Other configurations may be used for device  10  if desired. The example of  FIG. 1  is merely illustrative. 
     In the example of  FIG. 1 , device  10  includes a display such as display  14  mounted in 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.). 
     Display  14  may be a touch screen display that incorporates a layer of conductive capacitive touch sensor electrodes or other touch sensor components (e.g., resistive touch sensor components, acoustic touch sensor components, force-based touch sensor components, light-based touch sensor components, etc.) or may be a display that is not touch-sensitive. Capacitive touch screen electrodes may be formed from an array of indium tin oxide pads or other transparent conductive structures. 
     Display  14  may include an array of display pixels formed from liquid crystal display (LCD) components, an array of electrophoretic display pixels, an array of plasma display pixels, an array of organic light-emitting diode display pixels or other light-emitting diodes, an array of electrowetting display pixels, or display pixels based on other display technologies. 
     Display  14  may be protected using a display cover layer such as a layer of transparent glass or clear plastic. Openings may be formed in the display cover layer. For example, an opening may be formed in the display cover layer to accommodate a button such as button  16 . An opening may also be formed in the display cover layer to accommodate ports such as speaker port  18 . Openings may be formed in housing  12  to form communications ports (e.g., an audio jack port, a digital data port, etc.), to form openings for buttons, etc. 
     Display  14  may have an active area such as active area AA and an inactive area such as inactive area IA. Active area AA may have a rectangular shape or other suitable shape. Active area AA contains pixels that display images for a user of device  10 . Inactive area IA is free of pixels and does not display images. Inactive area IA may form an inactive border region around one or more of the edges of display  14 . For example, inactive area IA may run around all four peripheral edges of rectangular active area AA or may extend along two of the edges of active area AA (e.g., in a configuration in which display  14  is borderless along two of its edges). 
     In active area AA, the outermost layer of display  14  such as the display cover layer for display  14  is free of border masking materials. This allows light from the pixels in active area AA to pass through the display cover layer. In inactive area IA, the underside of the outermost display layer (e.g., the display cover layer) may be coated with a layer of opaque masking material. The opaque masking material hides internal components from view by a user and prevents leakage of stray backlight from within device  10 . 
     The opaque masking material may be formed from polymers or other dielectrics, metals, or other materials. For example, the opaque masking material may be formed from one or more layers of white polymer, one or more layers of black polymer (e.g., black ink), or other suitable opaque materials. Configurations in which display  14  is coated with a black masking material such as black ink in inactive area IA may sometimes be described herein as an example. This is, however, merely illustrative. In general, any suitable opaque masking material may be used to coat the underside of display  14  in inactive area IA. 
     The opaque masking material in inactive region IA is opaque at visible wavelengths and may, if desired, be opaque at other wavelengths such as infrared wavelengths. For example, in configurations in which the opaque masking material is formed from black ink, the opaque masking material may include black particles such as carbon black particles in a polymer matrix. This type of opaque masking material may be opaque at visible and infrared wavelengths. 
     To accommodate light-based components such as light-based sensors, sensor windows may be formed within the opaque masking material. As an example, sensor windows may be formed at locations such as illustrative sensor window locations  22  and  24  in inactive area IA of display  14  of  FIG. 1 . A sensor window such as an ambient light sensor may be formed at a location such as sensor window location  22  and a sensor window such as a proximity sensor window may be formed at a location such as sensor window location  24  (as an example). Sensor windows may also be formed for other types of optical components (e.g., status indicator lights, light sensors for blood oximeters, light sensors for light-based input devices such as motion detectors, light-based components for a three-dimensional imaging system, etc.). 
     If desired, device  10  may have an opening such as opening  20  in the opaque masking layer of inactive area IA that is devoid of all non-transparent materials, thereby allowing unobstructed light to reach a camera in housing  12  (i.e., opening  20  may be a camera window opening). Sensor windows  22  and  24  need not be completely devoid of non-transparent materials. For example, layers of material may be formed in windows  22  and  24  to allow the sensors that are in alignment with these windows to operate normally while simultaneously hiding windows  22  and  24  from view by a user of device  10  to enhance device aesthetics. Because sensor windows of this type are fully or at least partly hidden from view by the naked eye in normal operating environments, these windows may sometimes be referred to as hidden windows, reduced-visibility windows, or invisible windows. 
     Consider, as an example, the cross-sectional side view of device  10  of  FIG. 2 .  FIG. 2  is a cross-sectional side view of a portion of display  14  taken through illustrative windows  24  and  22 . As shown in  FIG. 2 , a transparent layer in display  14  (e.g., the outermost layer of display  14 ) such as display cover layer  30  may have an outer surface such as surface  60  and an opposing inner surface such as surface  62 . A layer of opaque masking material  32  may be formed from a coating on inner surface  62  of display cover layer  30 . Display cover layer  30  may be formed from a transparent material such as clear glass, clear ceramic, clear plastic, clear crystalline material, sapphire, other transparent materials, combinations of two or more of these materials (e.g., two or more laminated layers) or other display cover layer structures. If desired, the transparent display layer on which opaque masking material  32  is deposited may be an extended portion of a thin-film transistor layer, color filter layer, or other display layer. In other illustrative configurations, opaque masking material  32  may be deposited on a separate transparent layer of material that serves as a protective cover layer for display  14  (i.e., a display cover layer that does not serve as a substrate for thin-film transistors, color filter elements, or other display structures). Configurations in which the supporting layer for opaque masking layer  32  is a display cover layer are sometimes described herein as an example. 
     Windows such as windows  24  and  22  may be used to allow light from the exterior of device  10  to pass into the interior of device  10  and/or to allow light from the interior of device  10  to pass to the exterior of device  10 . The light that passes through windows  24  and  22  may be visible light and/or infrared light. During operation of device  10 , a user such as viewer  64  may view inactive area IA of display  14  from the exterior of device  10  (e.g., in viewing direction  66  or other directions). Windows  24  and  22  may be formed from window structures such as window structure  34  and window structure  36  in respective openings in opaque masking layer  32 . Structures  34  and  36  are preferably configured to minimize or eliminate the ability of viewer  64  to detect the presence of windows  24  and  22 . With one suitable arrangement, windows  24  and  22  are invisible to the naked eye. 
     In the  FIG. 2  example, window  24  is a proximity sensor window that is aligned with light-based proximity sensor  38  and window  22  is an ambient light sensor window that is aligned with ambient light sensor  54 . This is merely illustrative. In general, any suitable light-based components (e.g., image sensors or other light detectors, light-emitting diodes, lasers, lamps, or other light emitters, or other light-based devices) may be mounted in alignment with windows in display  14  (e.g., windows in the opaque masking layer in inactive area IA or other device structures). 
     Proximity sensor  38  may include a light source such as light source  42 . Light source  42  may be a laser diode, a light-emitting diode, or other suitable light producing component. Light source  42  may emit light  44 . Light  44  may be visible light, infrared light, and/or light at other wavelengths. With one suitable arrangement, light source  42  may be in infrared light-emitting diode that emits infrared light  44 . In the absence of external objects, light  44  travels outwardly through window  24  (i.e., through window structure  34  and transparent layer  30 ) and is not reflected back to proximity sensor  38 . When an external object such as object  48  is presence in the vicinity of proximity sensor  38 , some of light  44  (i.e., reflected light portion  46 ) is reflected back from object  48  through window  24  to proximity sensor  38 . The amount of reflected light  46  that is measured by proximity detector  38  is indicative of the distance separating external object  48  from device  10  and can therefore be used by proximity sensor  38  to detect the presence or absence of an external object such as external object  48  in the vicinity of device  10 . 
     Light  46  may be detected by proximity sensor  38  using a light detecting component such as light detector  40 . Light detector  40  may be an infrared photodetector, a visible photodetector, a light sensor that captures light at multiple different wavelengths (e.g., both visible and infrared wavelengths), or other suitable light sensing component. Light detector  40  may be, for example, a light sensor that detects visible and/or infrared light and that produces a corresponding output signal proportional to the amount of reflected light  46  at the infrared wavelength associated with light  44 . 
     Ambient light sensor  54  may measure how much ambient light is present in the operating environment of device  10 . As shown in  FIG. 2 , external light sources such as light source  58  (e.g., the sun, one or more artificial light sources, etc.) may generate light (e.g., visible and/or infrared light) such as illustrative light ray  56 . Light rays such as light ray  56  may pass through window  22  (e.g., through display layer  30  and window structure  36  of window  22 ). To ensure that ambient light sensor  54  is able to detect the presence of light from directional light sources (e.g., source  58  in the example of  FIG. 2 ), window structure  36  may contain a diffuser structure that helps scatter light such as light  56  from directional sources towards light sensor  54  (see, e.g., scattered light ray  56 ′, which is being detected by light sensor  54  after being scattered by a diffuser in structure  36 ). Light sensor  54  may be a visible light photodetector, a photodetector that is sensitive to infrared light, and/or other light detecting component. The diffuser structure in window structure  36  may be formed from one or more layers of material with light scattering features (e.g., light-scattering particles, light-scattering voids or hollow particles, light-scattering surface features, etc.). The diffuser structure may be deposited as a coating on top of one or more other layers of material in structure  36 . 
     Control circuitry  50  may be coupled to proximity sensor  38 , ambient light sensor  54 , and other input-output devices  52 . Control circuitry  50  may include storage and processing circuitry for controlling the operation of sensors such as sensors  38  and  54  and other input-output devices  52  and for receiving data from sensors such as sensors  38  and  54  and other input-output devices  52 . Control circuitry  50  may, for example, 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  50  may be used to control the operation of device  10 . This processing circuitry may be based on one or more microprocessors, microcontrollers, digital signal processors, baseband processor integrated circuits, application specific integrated circuits, etc. 
     Control circuitry  50  may be used to run software on device  10 , such as internet browsing applications, instant messaging applications, mapping applications, telephone call applications, email applications, media playback applications, operating system functions, etc. During use of display  14 , control circuitry  50  may gather information from a user and/or information from ambient light sensor  54  and may use this information and/or other information about the operation of device  10  to adjust display brightness or take other actions. Control circuitry  50  may use information from proximity sensor  38  in controlling display  14  (e.g., to turn off display  14  and/or a touch sensor in display  14  whenever proximity sensor  38  indicates that device  10  has been placed against a user&#39;s ear as when device  10  is being used to support a cellular telephone call, etc.) or to take other actions. 
     Device  10  may, in general, use input-output devices such as sensors  38  and/or  54  and, if desired, additional input-output devices such as input-output devices  52  to gather input form a user and the environment in which device  10  is operating and to provide output (e.g., visible and/or audible output, wireless output, output on analog and/or digital data paths, etc.). The input-output devices of device  10  may include user interface devices, data port devices, and other input-output components. For example, input-output devices may include touch screens, displays without touch sensor capabilities, buttons, joysticks, scrolling wheels, touch pads, key pads, keyboards, microphones, cameras, buttons, speakers, status indicators, light sources, audio jacks and other audio port components, digital data port devices, light sensors such as ambient light sensor  54 , motion sensors (accelerometers), capacitance sensors, proximity sensors (e.g., a capacitive proximity sensor and/or an infrared proximity sensor such as sensor  38 ), magnetic sensors, connector port sensors that determine whether a connector such as an audio jack and/or digital data connector have been inserted in a connector port in device  10 , a connector port sensor or other sensor that determines whether device  10  is mounted in a dock, other sensors for determining whether device  10  is coupled to an accessory, and other sensors and input-output components. Input-output devices  52  may also include wireless communications circuitry (e.g., a cellular telephone transceiver, a wireless local area network transceiver, antennas, etc.). 
     In the graphs of  FIGS. 3, 4, and 5 , light transmission T has been plotted as a function of wavelength λ for different materials of the type that may be used in forming layers of material in structures  34  and  36  of sensor windows  24  and  22 . 
     Opaque masking material  32  is preferably sufficiently opaque to block internal device components from view by user  64 . Opaque masking material  32  may be formed from one or more layers of material (e.g., one or more layers of white ink, one or more layers of black ink, one or more layers of ink of other colors, metal layers, polymer layers, etc.). With one suitable arrangement, which may sometimes be described herein as an example, opaque masking layer  32  is formed from a dark polymer such as a black ink. Black ink for layer  32  may be deposited in one or more sublayers. The black ink may contain a black filler material such as carbon black supported by a polymer matrix formed from a polymer that is cured by application of heat, ultraviolet light, or chemical curing. An illustrative transmission spectrum for black ink  32  is shown by solid line  70  of  FIG. 3  (i.e., black ink  32  may transmit relatively light and may block both visible wavelengths VIS and infrared wavelengths IR). 
     Structure  36  in ambient light sensor window  22  may have a transmission spectrum that is more transparent than black masking material  32  and that can therefore allow ambient light  56  to be measured by sensor  54 . At the same time, structure  36  is preferably not too transparent, which would allow sensor  54  to be visible through window  22 . With one suitable arrangement, structure  36  includes a layer of ink (sometimes referred to as ambient light sensor ink) that has a transmission spectrum of the type shown by line  72  in  FIG. 4  (e.g., structure  36  may transmit more visible light VIS than black ink  32  and may transmit more infrared light IR than visible light VIS). 
     In proximity sensor  38 , light  44  and the reflected portion of light  44  (i.e., light  46 ) may be light at infrared wavelengths. To allow light  44  and reflected light  46  to pass through structure  34  without excessive attenuation, structure  34  may be formed from one or more layers of ink that is transparent at infrared wavelengths. To ensure that structure  34  blocks internal components from view by viewer  64 , the ink material in structure  34  may be opaque at visible wavelengths. For example, structure  34  may contain ink (sometimes referred to as infrared ink) that is transparent at infrared wavelengths IR and that blocks light at visible wavelengths VIS, as shown by illustrative infrared ink transmission spectrum  74  of  FIG. 5 . Infrared ink may, for example, transmit less light than ambient light sensor ink at visible wavelengths VIS while transmitting more light than the ambient light sensor ink at infrared wavelengths. The transmission of the infrared ink at infrared wavelengths IR may be greater than the transmission of the black ink of layer  32  at infrared wavelengths. 
     A diffuser for diffusing light (e.g., a diffuser to scatter light  56  to form scattered light  56 ′ that is detected by ambient light sensor  54 ) may have a transmission spectrum of the type shown by curve  76  of  FIG. 3  (e.g., the diffuser may transmit more light than the black masking layer of curve  70  and may be characterized by a relatively flat transmission spectrum in which the diffuser transmits both visible light VIS and infrared light IR). Other transmission spectrums may be used for the diffuser, if desired. 
       FIG. 6  is a cross-sectional side view of a portion of display  14  in which layers of material have been formed on inner surface  62  of display layer  30  (e.g., a display cover layer or other transparent display layer) to form structure  36  for ambient light sensor window  22 . As shown in  FIG. 6 , incoming light such as light ray  56  may be scattered by a diffuser formed from diffuser layer  78 . Ambient light sensor ink  80  may be interposed between inner surface  62  of display cover layer  30  and diffuser layer  78  to help hide diffuser layer  78  from view by viewer  64 . Diffuser  78  may be formed from a coating of polymer or other material formed on ambient light sensor ink  80 . During operation, scattered light  56 ′ from diffuser  78  may be detected by detector  54  (e.g., an ambient light sensor). Diffuser  78  is preferably characterized by a haze value of 30% or greater, 60% or greater, 70% or greater, 80% or greater, 85% or greater, 87% or greater, less than 95%, or other suitable values, as measured using the ASTM D1003 haze standard. 
     Black masking layer  32  may be formed from one or more sublayers. For example, black masking layer  32  may be formed from two sublayers such as outer sublayer  32 - 1  and inner sublayer  32 - 2 . The combined thickness of the sublayers (i.e., the total thickness of layers  32 - 1  and  32 - 2 ) is preferably sufficient to ensure that light is blocked by layer  32 . With one suitable arrangement, black masking layers  32 - 1  and  32 - 2  each have a thickness of about ten microns (e.g. 5-15 microns, more than 4 microns, less than 20 microns, etc.), ambient light sensor ink  80  has a thickness of about 4-6 microns, 2-8 microns, more than 3 microns, or less than 13 microns, and diffuser  78  has a thickness of 3-5 microns, more than 2 microns, less than 10 microns, or less than 7 microns. Other layers thicknesses may be used, if desired. The layers of  FIG. 6  (and the openings in these layers) may be formed using deposition and patterning techniques such as screen printing, pad printing, spraying, dripping, ink-jet printing, evaporation or other physical vapor deposition techniques, chemical vapor deposition, electrochemical deposition, laser etching, dry or wet chemical etching, machining, photolithography, or other suitable deposition and patterning techniques. 
     Ambient light sensor ink  80  transmits some ambient light to sensor  54  so that ambient light sensor  54  can make ambient light measurements. As an example, ambient light sensor ink  80  may have a transmittance of 1-10%, greater than 2%, less than 5%, or other suitable value. The transmittance of ambient light sensor ink  80  at visible wavelengths VIS is generally more than the transmittance of black ink layer  32 , so that ambient light sensor  54  can receive sufficient light to operate satisfactorily. The presence of diffuser layer  78  on the inner surface of ambient light sensor ink  80  helps scatter off-axis light into detector  54 , thereby ensuring that light from directional sources (e.g., spotlights) will be satisfactorily detected by ambient light sensor  54  and taken into account by control circuitry  50  when adjusting display brightness or taking other actions. 
     In the illustrative configuration of  FIG. 6 , black ink layer  32 - 1  was deposited first, ambient light sensor ink  80  was deposited second, diffuser layer  78  was deposited third, and black ink layer  32 - 2  was deposited fourth. If desired, the layers of material that form structure  36  in sensor window  22  may be deposited in different orders. In the example of  FIG. 7 , black ink layer  32 - 1  was deposited first, ambient light sensor ink  80  was deposited second, black ink layer  32 - 2  was deposited third, and diffuser layer  78  was deposited fourth.  FIG. 8  is a cross-sectional side view of structure  36  for window  22  in an illustrative configuration in which black ink layer  32 - 1  was deposited first, black ink layer  32 - 2  was deposited second, ambient light sensor ink layer  80  was deposited third, and diffuser layer  78  was deposited fourth. The visibility of features such as the edges of the opening for window  22  by viewer  64  can be minimized by depositing layer  32 - 1  before the other layers of structure  36 . If desired, however, other deposition orders may be used when depositing layers  32 - 1 ,  32 - 2 ,  80 , and  78 . The configurations of  FIGS. 6, 7, and 8  are merely illustrative. 
     Diffuser  78  may be formed from a layer of material such as a polymer that includes light-scattering features. As shown in  FIG. 9 , for example, diffuser  78  may be formed by polymer  102  that includes light-scattering particles  82 . Light scattering particles  82  may be pigments such as metal oxide particles or other particles (e.g., titanium dioxide particles, zinc oxide particles, particles of oxides and other materials containing elements and compounds such as antimony, barium, sulfur, sulfur oxide, plastic or glass beads, or other suitable light-scattering particles).  FIG. 10  shows how diffuser  78  may be formed by incorporating voids  84  into polymer matrix  102 . Voids  84  may be bubbles, voids associated with hollow structures such as microspheres, or voids in other gas-filled or vacuum-filled structures. In the example of  FIG. 11 , diffuser  78  has been formed by creating a textured surface such as surface  86  on the inside surface of polymer layer  102 . If desired, combinations of the approaches shown in  FIGS. 9, 10 , and  11  may be used and/or other approaches for forming diffuser layer  78  may be used. The configurations of  FIGS. 9, 10, and 11  are merely illustrative. 
       FIG. 12  is a top view of an illustrative sensor window opening for sensor windows such as windows  22  and  24 . Window openings such as opening  88  of  FIG. 12  may be formed in black masking layer  32  to allow light to pass through black masking layer  32 . Structures such as structures  34  and  36  of  FIG. 2  may be formed on the surface of transparent layer  30  within opening  88 . 
     In the example of  FIG. 12 , opening  88  in black masking layer  32  is circular in shape. The diameter of opening  88  may be 500 microns to 3 mm, may be 100-1000 microns, may be 300-800 microns, may be more than 20 microns, may be more than 400 microns, or may be less than 3 mm (as examples). Openings such as opening  88  may have other shapes, if desired (e.g., square, rectangular, oval, shapes with straight edges, shapes with curved edges, shapes with both curved and straight edges, etc.). 
     In the illustrative configuration of  FIG. 13 , opening  90  for a sensor window has been formed from a group of multiple smaller openings  92 . The overall outline of opening  90  may be circular, oval, square, rectangular, or may have a different shape. Opening  90  may have lateral dimensions of 500 microns to 3 mm or other suitable size (e.g., more than 300 microns, less than 3 mm, etc.). Openings  92  may be smaller perforations and may be formed by laser drilling or other suitable hole formation techniques. Openings  92  may, as an example, be circular openings having diameters of 10-60 microns, more than 5 microns, less than 75 microns, less than 60 microns, etc. Non-circular shapes may be used for perforations  92  if desired. 
     When openings  92  are sufficiently small (e.g., 10-60 microns in diameter or less), openings  92  will be invisible to the naked eye. In this situation and other suitable situations, some of the layers of structures  34  and/or  36  can be omitted. As an example, ambient light sensor ink layer  80  may be omitted from structure  36  in ambient light sensor window  22 , as shown in  FIG. 14 . With the illustrative configuration of  FIG. 14 , ambient light sensor window  22  has been formed by a group of multiple small openings such as perforations  92  (e.g., 2-50 perforations, 5-25 perforations, etc.). The area of each perforation  92  is preferably small enough to make perforations  92  invisible to the user, while the total area associated with perforations  92  is sufficient to allow ambient light to pass to detector  54 . Diffuser  78  may overlap perforations  92 . Portions of diffuser layer  78  such as portions  78 ′ may optionally penetrate partly or fully into perforations  92 . The presence of diffuser  78  may help scatter off-axis light (e.g., when window  22  is used as an ambient light sensor window for ambient light sensor  54 ). 
     If desired, optical characteristics of the outermost layer of material in a sensor window may be configured to match or nearly match the optical characteristics of black masking layer  32 . This may help hide the sensor window from view by user  64 . Consider, as an example, window  120  of  FIG. 15 . Window  120  has been formed from an opening in black masking layer  32  on inner surface  62  of a transparent display layer such as display cover layer  30 . The opening is filled with window structure  94 . Window structure  94  may include an outer layer (i.e., a layer of material that coats inner surface  62  of display cover layer  30 ) such as an outer layer of infrared ink, an outer layer of ambient light sensor ink, or other material. Window structure  94  may also include one or more inner layers (e.g., a diffuser layer such as diffuser layer  78 , etc.). In some scenarios (e.g., when forming a light-based proximity sensor) it may be desirable to omit inner layers such as diffuser layer  78 . 
     Window structure  94  (e.g., the outermost layer of material in structure  94  such as the infrared ink layer in proximity sensor window  24  or the ambient light sensor ink layer in ambient light sensor window  22 ) may be characterized by a diffuse reflectivity. As shown in  FIG. 15 , outer surface  60  of display cover layer  30  may have a surface normal such as surface normal  96 . Incoming light  98  may reflect from the material of structure  94  at the interface between structure  94  and inner surface  62  to produce reflected light ray  100 . In a scenario in which incoming light  100  is oriented at an angle B with respect to surface normal  96 , reflected light  100  that is oriented at angle B with respect to surface normal  96  is associated with a specular reflection. Viewer  64  may view structure  94  in direction  66 . Direction  66  may be oriented at an angle A with respect to surface normal  96  that is not the same as angle B. The amount that light  98  reflects from a structure such as structure  94  at angles such as angle A that differ from angle B of reflected light ray  100  is sometimes referred to as the diffuse reflectivity of the structure. As demonstrated on the right hand side of  FIG. 15 , both structure  94  and structure  32  may be characterized by respective diffuse reflectivity values. 
     To minimize the visibility of window  120 , the diffuse reflectivity of window structure  94  is preferably within a given amount of the diffuse reflectivity of black masking layer  32  (e.g., these values differ by less than 50%, less than 20%, less than 15%, less than 10%, or less than 5%). In situations in which the diffuse reflectivity of structure  94  in light sensor window  120  is the same (or nearly the same) as the diffuse reflectivity of opaque masking layer  32 , it will be difficult or impossible for viewer  64  to identify the location of window  120  (i.e., window  120  will be invisible to viewer  64 ). It may therefore be desirable to ensure that the diffuse reflectivity of structures such a structure  34  (e.g., an infrared ink layer) and structure  36  (e.g., an ambient light sensor ink layer covered with a diffuser layer) are equal (or nearly equal) to the diffuse reflectivity of black masking layer  32  in device  10  of  FIG. 2 . 
     If desired, a sensor window may be implemented using a lens that is installed within a display cover layer or other portion of device  10 . As shown in  FIG. 16 , for example, sensor window  120  may be formed from lens  202  in layer  200 . Layer  200  may be part of a display (e.g., a glass or plastic display cover layer or other display layer), may be part of an electronic device housing, or other structure on the exterior of device  10 . Layer  200  may be opaque to hide internal components from view and/or may be provided with an opaque coating such as coating  200 ′. Layer  200  may, for example, be a tinted glass or plastic layer and/or may have a coating such as coating  200 ′ that is formed from an inorganic or metallic coating. Polymer coatings and other opaque masking layer coatings may also be used in forming coatings such as coating  200 ′. 
     Lens  202  may be formed from glass, polymer, or other transparent material. Lens  202  may be tinted (e.g., by incorporating a pigment, dye, or other tint into the material that forms lens  202 ) and/or may be coated with a coating such as coating  202 ′. Coating  202 ′ may include an organic coating (e.g., an infrared-transparent ink or other ink), may include an inorganic coating (e.g., a tinted or clear oxide or nitride, etc.), may be formed from a metallic layer, or may be other suitable inorganic and/or organic coating for modifying light transmittance through lens  202 . Diffuser layer  78  may be included in coating  202 ′ (e.g., under or above an inorganic or metallic coating, etc.). To minimize the visibility of window  120 , the diffuse reflectivity of window structure  120  (e.g., lens  202  and coating  202 ′) is preferably within a given amount of the diffuse reflectivity of surrounding structures such as layer  200  (e.g., layer  200  with coating  200 ′) (e.g., these values differ by less than 50%, less than 20%, less than 15%, less than 10%, or less than 5%). The structures of  FIG. 16  may form part of the inactive area of display  14  or other portion of device  10 . 
     The foregoing is merely illustrative and various modifications can be made by those skilled in the art without departing from the scope and spirit of the described embodiments. The foregoing embodiments may be implemented individually or in any combination.

Metadata:
Filing Date: 20170406
Publication Date: 20181009
Grant Date: 20181009
Priority Date: 20140825
Inventors: JIA, ZHANG
ERICKSON, CHRISTOPHER S.
DUDLEY, JAMES J.
NAKAJIMA, KENICHI
LI, CHUNJI
Assignee: APPLE INC
CPC Classifications: [{"code": "G09G5/10", "inventive": false, "first": false, "tree": "[]"}, {"code": "G01J1/0418", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G2360/144", "inventive": false, "first": false, "tree": "[]"}, {"code": "G01J1/4204", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01J1/0474", "inventive": true, "first": true, "tree": "[]"}, {"code": "G01J1/0233", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01J1/0407", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/041", "inventive": false, "first": false, "tree": "[]"}, {"code": "G01J1/0411", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G5/003", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2360/144", "inventive": false, "first": false, "tree": "[]"}, {"code": "G01J1/0407", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01J1/4204", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G5/10", "inventive": false, "first": false, "tree": "[]"}, {"code": "G01J1/0233", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01J1/0418", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01J1/0411", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/041", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G5/003", "inventive": false, "first": false, "tree": "[]"}, {"code": "G01J1/0474", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 55348072