PATENT DOCUMENT

Publication Number: US-10847071-B2
Application Number: US-201815967367-A
Country: US
Kind Code: B2

Title: Electronic devices having ambient light sensors with lens diffusers

Abstract:
An electronic device may be provided with a display mounted in a housing. The display may have an array of pixels configured to display images. A display cover layer may overlap the array of pixels. A light sensor such as a color ambient light sensor may be mounted in the electronic device and may receive ambient light through an ambient light sensor window region in the display cover layer or other portion of the electronic device. A diffuser may be located between the display cover layer and the ambient light sensor. The diffuser may have a substrate such as a glass substrate. A lens layer may be supported by the substrate. The lens layer may be formed from a layer of ultraviolet-light-curable polymer in which an array of lenses has been formed. An infrared-light-blocking-and-visible-light-transmitting filter may be used to reduce infrared light reaching the ambient light sensor.

Claims:
What is claimed is: 
     
       1. An electronic device, comprising:
 a display having pixels that displays images; 
 a display cover layer that overlaps the pixels; 
 a light diffuser having a substrate layer and a lens layer on the substrate layer, wherein the light diffuser is coupled to the display cover layer; 
 a coating layer on a curved surface of the lens layer; 
 an ambient light sensor configured to measure ambient light passing through the light diffuser; and 
 control circuitry configured to adjust the display using the measured ambient light. 
 
     
     
       2. The electronic device defined in  claim 1 , wherein the ambient light sensor is configured to measure the ambient light through the display cover layer. 
     
     
       3. The electronic device defined in  claim 2  wherein the lens layer has concave lenses. 
     
     
       4. The electronic device defined in  claim 3  wherein the diffuser has a first side facing the display cover layer and a second side facing away from the display cover layer and wherein the concave lenses are formed on the first side. 
     
     
       5. The electronic device defined in  claim 3  wherein the diffuser has a first side facing the display cover layer and a second side facing away from the display cover layer and wherein the concave lenses are formed on the second side. 
     
     
       6. The electronic device defined in  claim 2  wherein the lens layer has convex lenses. 
     
     
       7. The electronic device defined in  claim 6  wherein the diffuser has a first side facing the display cover layer and a second side facing away from the display cover layer and wherein the convex lenses are formed on the first side. 
     
     
       8. The electronic device defined in  claim 6  wherein the diffuser has a first side facing the display cover layer and a second side facing away from the display cover layer and wherein the convex lenses are formed on the second side. 
     
     
       9. The electronic device defined in  claim 1  wherein the lens layer comprises ultraviolet-curable polymer. 
     
     
       10. The electronic device defined in  claim 1  wherein the diffuser comprises a polymer buffer layer between the lens layer and the substrate layer. 
     
     
       11. The electronic device defined in  claim 10  further comprising light-scattering particles embedded in the polymer buffer layer. 
     
     
       12. The electronic device defined in  claim 1  wherein the substrate layer comprises an infrared-light-blocking-and-visible-light transmitting layer. 
     
     
       13. The electronic device defined in  claim 1  wherein the substrate layer comprises blue glass. 
     
     
       14. An electronic device, comprising:
 an ambient light sensor diffuser, comprising:
 a substrate layer; 
 a buffer layer on the substrate layer; and 
 a polymer lens layer on the buffer layer, wherein the buffer layer prevents delamination of the polymer lens layer from the substrate layer and wherein the buffer layer is interposed between the substrate layer and the polymer lens layer; and 
 
 an ambient light sensor that receives light that has passed through the ambient light sensor diffuser. 
 
     
     
       15. The electronic device defined in  claim 14  wherein the polymer lens layer has an array of lenses and wherein each lens has a diameter of 2-25 microns, the electronic device further comprising:
 a display having pixels that displays images; and 
 control circuitry configured to adjust the display based on a measurement from the ambient light sensor. 
 
     
     
       16. The electronic device defined in  claim 15  wherein the lenses are concave lenses. 
     
     
       17. The electronic device defined in  claim 15  wherein the lenses are convex lenses. 
     
     
       18. The electronic device defined in  claim 15  wherein the lenses are arranged in an irregular pattern, wherein the buffer layer is formed from a first polymer, and wherein the polymer lens layer is formed from a second polymer that is different than the first polymer. 
     
     
       19. An electronic device, comprising:
 a display; 
 a diffuser having a substrate and a continuous cured polymer layer with lenses; and 
 an ambient light sensor configured to measure ambient light that has been passed through the diffuser; and 
 control circuitry configured to adjust the display using the measured ambient light. 
 
     
     
       20. The electronic device defined in  claim 19  further comprising a polymer buffer layer interposed between the cured polymer layer and the substrate, wherein the substrate comprises a glass layer, wherein the cured polymer layer comprises a first polymer, and wherein the polymer buffer layer comprises a second polymer that is different than the first polymer.

Description:
FIELD 
     This relates generally to electronic devices, and, more particularly, to light sensors for electronic devices. 
     BACKGROUND 
     Electronic devices such as laptop computers, cellular telephones, and other equipment are sometimes provided with light sensors. For example, ambient light sensors may be incorporated into a device to provide the device with information on current lighting conditions. Ambient light readings may be used in controlling the device. If, for example, bright daylight conditions are detected, an electronic device may increase display brightness to compensate. In some configurations, color ambient light sensors are used to gather information on the color of ambient light. Adjustments to the color cast of a display can be made based on the color of the ambient light. 
     To help reduce the impact of directional light sources on ambient light sensor readings, ambient light sensors may be provided with light diffuser layers that include light-scattering particles. Challenges can arise, however, in forming light diffuser layers. If care is not taken, a light diffuser layer for an ambient light sensor may have undesired light transmission characteristics. 
     SUMMARY 
     An electronic device may be provided with a display mounted in a housing. The display may have an array of pixels configured to display images. A display cover layer may overlap the array of pixels. A light sensor such as a color ambient light sensor may be mounted in the device and may receive ambient light through an ambient light sensor window region in the display cover layer or other portion of the electronic device. 
     A light diffuser may be used to diffuse ambient light before the ambient light is measured by the ambient light sensor. The diffuser may be located between the display cover layer and the ambient light sensor. The diffuser may have a substrate such as a glass substrate. A lens layer may be supported by the substrate. The lens layer may be formed from a layer of ultraviolet-light-curable polymer in which an array of lenses has been formed. A polymer buffer layer that is formed from a different polymer material than the lens layer may be interposed between the lens layer and the substrate layer to help prevent delamination of the lens layer. An optional diffuser layer for the diffuser may be formed from the polymer buffer layer by incorporating light-scattering particles into the polymer buffer layer. Light-scattering particles such as these may also be incorporated into the lens layer. Concave and convex lenses in regular and irregular patterns may be formed in the lens layer on first and/or second opposing sides of the diffuser. 
     Infrared light in the ambient light measured by the ambient light sensor may be reduced by incorporating an infrared-light-blocking-and-visible-light-transmitting filter structure between the display cover layer and the ambient light sensor. The filter structure may be formed as a coating on the ambient light sensor, as a stand-alone filter layer interposed between the diffuser and the ambient light sensor, or as part of the diffuser (as examples). In an illustrative arrangement, the diffuser may have a glass substrate formed from blue glass to absorb infrared light and transmits visible light. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram of an illustrative electronic device having an ambient light sensor in accordance with an embodiment. 
         FIG. 2  is a perspective view of a portion of an electronic device with an ambient light sensor in accordance with an embodiment. 
         FIG. 3  is a cross-sectional side view of an illustrative light sensor in accordance with an embodiment. 
         FIG. 4  is a graph comparing light diffusing performance between different light diffusers in accordance with an embodiment. 
         FIG. 5  is a top view of an illustrative diffuser formed from an array of equally sized and regularly spaced lenses in accordance with an embodiment. 
         FIG. 6  is a top view of an illustrative diffuser formed from lenses having different center locations and different sizes to form an irregular lens array in accordance with an embodiment. 
         FIG. 7  is a cross-sectional side view of an illustrative diffuser having outwardly facing concave lenses in accordance with an embodiment. 
         FIG. 8  is a cross-sectional side view of an illustrative diffuser having inwardly facing concave lenses in accordance with an embodiment. 
         FIG. 9  is a cross-sectional side view of an illustrative diffuser having inwardly facing convex lenses in accordance with an embodiment. 
         FIG. 10  is a cross-sectional side view of an illustrative diffuser having outwardly facing convex lenses in accordance with an embodiment. 
         FIG. 11  is a cross-sectional side view of an illustrative diffuser having inwardly facing convex lenses in accordance with an embodiment. 
         FIG. 12  is a cross-sectional side view of an illustrative positive lens for a light diffuser in accordance with an embodiment. 
         FIG. 13  is a cross-sectional side view of an illustrative diffuser with one or more coatings in accordance with an embodiment. 
         FIG. 14  is a graph of optical transmittance versus wavelength for an illustrative diffuser structure such as a substrate in accordance with an embodiment. 
         FIG. 15  is a cross-sectional side view of an illustrative diffuser having a lens array layer on a substrate and having an interposed buffer layer in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     An illustrative electronic device of the type that may be provided with one or more light sensors is shown in  FIG. 1 . 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. 
     As shown in  FIG. 1 , electronic device  10  may have control circuitry  16 . Control circuitry  16  may include storage and processing circuitry for supporting the operation of device  10 . The storage and processing circuitry may include storage such as hard disk drive storage, nonvolatile memory (e.g., flash memory or other electrically-programmable-read-only memory configured to form a solid state drive), volatile memory (e.g., static or dynamic random-access-memory), etc. Processing circuitry in control circuitry  16  may be used to control the operation of device  10 . The processing circuitry may be based on one or more microprocessors, microcontrollers, digital signal processors, baseband processors, power management units, audio chips, application specific integrated circuits, etc. 
     Input-output circuitry in device  10  such as input-output devices  12  may be used to allow data to be supplied to device  10  and to allow data to be provided from device  10  to external devices. Input-output devices  12  may include buttons, joysticks, scrolling wheels, touch pads, key pads, keyboards, microphones, speakers, tone generators, vibrators, cameras, light-emitting diodes and other status indicators, data ports, etc. A user can control the operation of device  10  by supplying commands through input-output devices  12  and may receive status information and other output from device  10  using the output resources of input-output devices  12 . 
     Input-output devices  12  may include one or more displays such as display  14 . Display  14  may be a touch screen display that includes a touch sensor for gathering touch input from a user or display  14  may be insensitive to touch. A touch sensor for display  14  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. 
     Input-output devices  12  may also include sensors  18 . Sensors  18  may include an ambient light sensor and other sensors (e.g., a capacitive proximity sensor, a light-based proximity sensor, a magnetic sensor, an accelerometer, a force sensor, a touch sensor, a temperature sensor, a pressure sensor, a compass, a microphone or other sound sensor, or other sensors). 
     An ambient light sensor for device  10  may have a single light detector (e.g., the ambient light sensor may be a monochromatic ambient light sensor that measures ambient light intensity) or may have an array of detectors each of which is provided with a different respective color filter. Information from the detectors may be used to measure the total amount of ambient light that is present in the vicinity of device  10  (ambient light intensity). For example, the ambient light sensor may be used to determine whether device  10  is in a dark or bright environment. Based on this information, control circuitry  16  can adjust display brightness for display  14  or can take other suitable action. The array of colored detectors may also be used to make color measurements (i.e., the ambient light sensor may be a color sensing ambient light sensor). Color measurements may be gathered as color coordinates, color temperature, or correlated color temperature (as examples). Processing circuitry may be used to convert these different types of color information to other formats, if desired (e.g., a set of color coordinates may be processed to produce an associated correlated color temperature, etc.). 
     Color and brightness information from a color sensing ambient light sensor can be used to adjust the operation of device  10 . For example, the color cast of display  14  may be adjusted in accordance with the color of ambient lighting conditions. If, for example, a user moves device  10  from a cool lighting environment to a warm lighting environment (e.g., an incandescent light environment), the warmth of display  14  may be increased accordingly, so that the user of device  10  does not perceive display  14  as being overly cold. In general, any suitable actions may be taken based on color measurements and/or total light intensity measurements (e.g., adjusting display brightness, adjusting display content, changing audio and/or video settings, adjusting sensor measurements from other sensors, adjusting which on-screen options are presented to a user of device  10 , adjusting wireless circuitry settings, etc.). 
     A perspective view of a portion of an illustrative electronic device is shown in  FIG. 2 . In the example of  FIG. 2 , device  10  includes a display such as display  14  mounted in housing  22 . Housing  22 , 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  22  may be formed using a unibody configuration in which some or all of housing  22  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 protected using a display cover layer such as a layer of transparent glass, clear plastic, a crystalline material such as sapphire, or other clear layer. 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, a speaker port, or other components. Openings may be formed in housing  22  to form communications ports (e.g., an audio jack port, a digital data port, etc.), to form openings for buttons, etc. 
     Display  14  may include an array of display pixels formed from liquid crystal display (LCD) components, an array of electrophoretic pixels, an array of plasma pixels, an array of organic light-emitting diode pixels or other light-emitting diodes, an array of electrowetting pixels, or pixels based on other display technologies. The array of pixels forms an active area for displaying images on display  14 . One or more border regions of the display may be free of pixels and may form an inactive display area. To hide inactive circuitry and other components in the inactive area from view by a user of device  10 , the underside of the outermost layer of display  14  (e.g., the display cover layer or other display layer) may be coated with an opaque masking material such as a layer of black ink. Optical components (e.g., a camera, a light-based proximity sensor, an ambient light sensor, status indicator light-emitting diodes, camera flash light-emitting diodes, etc.) may be mounted under the inactive border area. One or more openings (sometimes referred to as windows) may be formed in the opaque masking layer of the inactive area to accommodate the optical components. For example, a light component window such as an ambient light sensor window may be formed in a region such as region  20  that lies in a peripheral portion of display  14  (e.g., an inactive border area). Ambient light from the exterior of device  10  may be measured by an ambient light sensor in the interior of device  10  that is aligned with region  20  (e.g., after the ambient light has passed through the ambient light sensor window of region  20 ). 
       FIG. 3  is a cross-sectional side view of display  14  of  FIG. 2  taken along line  24  and viewed in direction  25  of  FIG. 2 . As shown in  FIG. 3 , light sensor  26  may be mounted in alignment with window region (window)  20 . Region  20  may have a circular shape, a square shape, a shape with curved and/or straight edges, a circular ring shape with a central opaque region, or any other suitable shape. Light sensor  26  may be a monochromatic ambient light sensor or a color sensing ambient light sensor that is used in measuring ambient light in the vicinity of device  10 . 
     As shown in  FIG. 3 , display  14  may have an outermost layer such as display cover layer  30 . Display cover layer  30  has an outer surface such as surface  34 . Surface normal n is perpendicular to surface  34 . Rays of ambient light  52  are characterized by various angles of incidence A measured with respect to surface normal n. 
     Window region  20  may be formed from an opening in opaque masking layer  28  on inner surface  32  of display cover layer  30 . Layer  30  may be formed from glass, plastic, ceramic, sapphire, or other transparent materials and may be a part of a display module for display  14  or may be a separate protective layer that covers active display structures. The opening associated with window  20  may be filled with optical structures such as ambient light sensor ink  54 . 
     Ambient light sensor ink  54  may have sufficient transparency at visible and infrared wavelengths to allow sensor  26  to operate, while at the same time enhancing the outward appearance of window  20  (e.g., by partly obscuring the presence of window  20  to a user of device  10  by making window  20  have a visual appearance that is not too dissimilar from the portion of layer  30  that includes layer  28 ). If desired, ambient light sensor ink  54  may be omitted. Windows for sensor  26  may also be formed in other portions of device  10  (e.g., in housing walls, etc.). The example of  FIG. 3  is illustrative. 
     Sensor  26  may have light detectors  60  (e.g., photodiodes, phototransistors, or other semiconductor photodetector structures). Light detectors  60  may be formed in an array on a common semiconductor substrate such as substrate  62  or may be formed using two or more substrates. Each of light detectors  60  may be provided with a corresponding color filter  58 . To provide sensor  26  with the ability to accurately measure colors, sensor  26  may include two or more detectors  60  (e.g., 2-10 detectors, 3-8 detectors, 4-7 detectors, 5-7 detectors, only 4 detectors or more than 4 detectors, only 5 detectors or more than 5 detectors, only 6 detectors or more than 6 detectors, only 7 detectors or more than 7 detectors, only 8 detectors or more than 8 detectors, fewer than 8 detectors, or any other suitable number of detectors). Filters  58  may be thin-film interference filters and/or may be colored layers of polymer or other color filter elements (e.g., colored filters formed from dyes and/or pigments in polymer binder). If desired, an infrared-light-blocking filter such as filter  59  (sometimes referred to as an IR cut filter) can be included in device  10 . Filter  59  can be incorporated into filters  58 , may overlap filters  58 , may be implemented as a separate filter formed using a separate substrate, may be formed from a filter coating covering or formed within the material(s) forming filters  58 , or may be formed as part of a diffuser. 
     Diffuser  56  may be used to gather light  52  from a variety of angles of incidence A and to effectively pass this light to sensor  26  as diffused (collimated) light  52 ′. Diffuser  56  may include structures such as an array of small lenses to help redirect off-axis ambient light rays into sensor  26  at an angle that is close to perpendicular to the surface of substrate  62 , thereby reducing the dependence of ambient light readings on the relative orientation between device  10  and the sources of ambient light, enhancing sensor efficiency, and helping to reduce measurement errors that might arise if different rays of ambient light  52  with different incident angles A pass through different amounts of ink  54  and other materials before being measured. 
       FIG. 4  compares the operations of two different illustrative diffusers. 
     In a first illustrative arrangement, diffuser  56  is formed from a layer or layers of diffusing material such as a transparent polymer layer with embedded light-scattering particles. The particles and the polymer layer may have different refractive indices so that light is scattered as the light passes through the polymer layer and strikes the light-scattering particles. The light-scattering particles may be, for example, particles of titanium oxide or other inorganic materials with relatively high refractive index values. Configurations in which a diffuser is formed form gas bubbles entrapped in a polymer layer may also be used. This first illustrative diffuser type may scatter incoming ambient light rays  52  of angular orientation A with respect to surface normal n into outgoing rays detected by light sensor  26  (rays  52 ′ of  FIG. 3 ) of intensity I in accordance with first light scattering curve  64 . Curves such as curve  64  are sometimes said to correspond to a Lambertian (cosine function) light scattering profile. 
     As illustrated by the reduced values of intensity I at larger angles A with curve  64 , this first type of diffuser may not capture off-axis ambient light  52  as efficiently as on-axis light (ambient light  52  with an angle of incidence value A near to 0°). 
     Enhanced diffusion efficiency for off-axis light (larger angles A) can be achieved by using a second illustrative arrangement for diffuser  56 . In this second illustrative arrangement, diffuser  56  includes an array of lenses (sometimes referred to as microlenses). The lenses can direct (e.g., collimate) more off-axis light to sensor  26  as rays  52 ′ and can therefore exhibit larger values of captured light intensity I at larger values of incident angle A, as shown by curve  66 . Curve  66  exhibits a non-Lambertian characteristic. By providing diffuser  56  with an array of lenses that produce an intensity-versus-angle characteristic of the type shown by curve  66 , off-axis light measurement by light sensor  26  can be enhanced, thereby enhancing the ability of sensor  26  to respond accurately to changes in ambient lighting in the operating environment for device  10 . 
       FIG. 5  is a top view of an illustrative diffuser having microlenses. Diffuser  56  of  FIG. 5  has a circular outline (footprint when viewed from above along axis Z). Other shapes may be used for diffuser  56  if desired (e.g., rectangular outlines, triangular outlines, etc.). Lenses  68  of  FIG. 5  have the same shape and size and extend in regular rows and columns to form an array of lenses across the surface of diffuser  56  (e.g., lenses  68  form a regular array). Other lens patterns may be used, if desired. As shown in  FIG. 6 , for example, diffuser  56  may include a collection of lenses  68  of various different diameters. The centers of these lenses need not be located in regular rows and columns, but rather may be distributed in an irregular pattern of locations across the surface of diffuser  56 . Using random patterns for the locations and/or using random shapes, random sizes, random focal lengths, and/or other random lens attributes when forming lenses  68  in diffuser  56  (e.g., forming an irregular lens array) may help avoid undesired hotspots in diffused light  52 ′. Lenses  68  may be circular, may have truncated circular shapes (e.g., circles fit into rectangular or hexagonal outlines), and/or may have other suitable shapes. 
     Lenses  68  may be concave lenses and/or convex lenses. The diameter of diffuser  56  or other lateral dimension of diffuser  56  such as the length and/or width of diffuser  56  in the XY plane may be at least 100 microns, at least 200 microns, at least 400 microns, at least 600 microns, at least 1.5 mm, at least 2 mm, less than 1 mm, less than 600 microns, less than 400 microns, or other suitable size. Lenses  68  may have focal lengths of at least 2 microns, at least 5 microns, at least 20 microns, at least 50 microns, less than 300 microns, or other suitable focal lengths. The diameters of lenses  68  may be at least 1 micron, at least 2 microns, at least 5 microns, at least 10 microns, at least 20 microns, less than 300 microns, less than 50 microns, less than 25 microns, less than 20 microns, or other suitable diameter. Lenses  68  with diameters larger than visible and infrared wavelengths of interest retain desired refractive qualities (e.g., such lenses refract light more than diffracting light). Lenses of this size are also sufficiently small to allow multiple lenses to fit within the area consumed by diffuser  56 , thereby helping to avoid hotspots in the diffused light being supplied at the output of diffuser  56 . The distance separating diffuser  56  from sensor  26  may be, for example, 5-20 times the diameter of lenses  68 . 
     A cross-sectional side view of an illustrative diffuser is shown in  FIG. 7 . In the example of  FIG. 7 , diffuser  56  has an array of concave lenses  56  (e.g., negative lenses). Each lens  56  may have a surface that is characterized by portions that reach a relatively large angle B with respect to surface normal n. For example, line TG, which is tangential to a steep portion of the surface of lens  68 , may be characterized by an angle B of at least 40°, at least 50°, less than 70°, less than 60°, or other suitable value. 
     As shown in  FIG. 8 , diffuser  56  may be mounted in device  10  on an inner surface of layer  54  in window region  20 . In the illustrative arrangement of  FIG. 8 , diffuser  56  has a first side (e.g., a first surface) with concave inwardly facing lenses  68  and an opposing second side (surface) such as a planar surface that is attached to layer  54  using adhesive layer  70 . Adhesive layer  70  may be, for example, a layer of optically clear adhesive that is transparent to light  50 . 
     In the illustrative arrangement of  FIG. 9 , diffuser  56  has been mounted in an orientation in which concave lenses  68  face outwardly towards display cover layer  30 . Adhesive ring  72  may be used to attach diffuser  56  to display  14  (e.g., to layer  28 ). 
     If desired, lenses  68  may include convex lenses (e.g., positive lenses). Convex lenses  68  may be mounted in an outwardly facing configuration (see, e.g.,  FIG. 10 ) or an inwardly facing configuration (see, e.g.,  FIG. 11 ). As shown in  FIG. 12 , convex lenses can help collimate off-axis light  52  to form light  52 ′ at the output of diffuser  56 . If desired, diffuser  56  may include both concave and convex lenses  68  and/or may include lenses  68  on both sides of diffuser  56 . The configurations of  FIGS. 8, 9, 10, and 11  are illustrative. 
       FIG. 13  shows how diffuser  56  may have one or more coating layers such as coatings  82 . Coatings  82  may be formed on the upper and/or lower surfaces of diffuser portion  80  and may cover the curved surfaces of lenses  68  and/or a planar substrate surface or other surface associated with portion  80 . Portion  80  may be formed from one or more layers. Coatings  82  may form antireflection coatings (e.g., a coating that reduces light reflection at a surface of diffuser  56  to less than 2%, less than 1%, less than 0.5% or other suitable amount, an infrared-blocking filter or other filter exhibiting a wavelength-dependent light transmission characteristic, and/or other coatings). Coatings  82  may each be formed from a single layer of material (e.g., a polymer, an inorganic material such as silicon oxide, etc.) and/or may be formed using multiple layers  84 . Layers  84  may be, for example, stacked thin-film dielectric layers (e.g., at least 2 layers, at least 3 layers, at least 10 layers, fewer than 100 layers, etc.) of alternating refractive index that form a thin-film interference filter (e.g., a thin-film interference filter antireflection coating, a wavelength-dependent thin-film interference filter for blocking infrared light while transmitting visible light or other wavelength-dependent filter, etc.). Layers  84  may be formed from inorganic and/or organic materials. 
     To help reduce noise in sensor  26 , it may be desirable to prevent infrared ambient light from reaching sensor  26 . As an example, an infrared-light-blocking-and-visible-light-transmitting filter may overlap sensor  26  to help block infrared light while allowing visible ambient light to be received and measured by sensor  26 . In an arrangement of the type shown in  FIG. 3 , for example, the filter may be interposed between cover layer  30  (layer  54 ) and sensor  26  (e.g., between diffuser  56  and sensor  26  as illustrated by infrared-light-blocking-and-visible-light-blocking filter  59 ). With one illustrative configuration, the transmission T of the infrared-light-blocking-and-visible-light-transmitting filter has a light transmission at visible wavelengths VIS such as 500 nm that is at least 10 times greater than its light transmission at infrared wavelengths IR such as 850 nm. 
     An infrared-light-blocking-and-visible-light transmitting filter may be formed using a stack of dielectric layers such as layers  84  in a coating  82  that form a thin-film interference filter that passes visible light and blocks infrared light (see, e.g.,  FIG. 14 ) and/or may be formed by a substrate (e.g., a glass or polymer substrate) or other layer between cover layer  30  and sensor  26  whose bulk optical properties exhibit high visible light transmission and low infrared light transmission. 
     If desired, an infrared-light-blocking-and-visible-light transmitting layer(s) such as a substrate layer may be formed from an infrared-light-blocking (absorbing) material such as blue glass or other infrared-light-blocking glass. The blue glass may be, for example, blue borosilicate glass such as borosilicate glass with copper oxide particles (as an example). This infrared-light-absorbing material may be used as a stand-alone filter and/or may be incorporated into other layer(s) overlapped by window  20 . For example, infrared-light-blocking material such as blue glass may be used in forming a substrate layer in diffuser  56 . 
       FIG. 15  is a cross-sectional side view of diffuser  56  in an illustrative configuration in which diffuser  56  includes a substrate layer. As shown in  FIG. 15 , diffuser  56  may include multiple layers such as substrate layer  56 - 3 , buffer layer  56 - 2 , and lens coating layer  56 - 1 . Lens coating layer  56 - 1  may be formed from a polymer such as ultraviolet-light-cured epoxy or other ultraviolet-light-cured polymer (ultraviolet-light-curable polymer). The thickness of layer  56 - 1  may be at least 5 microns, at least 20 microns, at least 50 microns, less than 200 microns, less than 40 microns, or other suitable thickness. Substrate layer  56 - 3  may be formed from blue glass or other material (e.g., other material that blocks infrared light and transmits visible light). The thickness of substrate  56 - 3  may be at least 50 microns, at least 150 microns, at least 400 microns, at least 600 microns, at least 1 mm, less than 900 microns, less than 450 microns, less than 200 microns, less than 100 microns, or other suitable thickness. 
     Optional buffer layer  56 - 2  may be interposed between layers  56 - 1  and  56 - 3 . Buffer layer  56 - 2  may be formed from a soft polymer that helps prevent delamination of lens coating layer (lens layer)  56 - 1  from substrate  56 - 3 . Buffer layer  56 - 2  and layer  56 - 1  may be formed from different materials (e.g., different polymers). The thickness of layer  56 - 2  may be at least 3 microns, at least 10 microns, at least 50 microns, less than 40 microns, less than 20 microns, or other suitable thickness. 
     With one illustrative manufacturing process, substrate  56 - 3  may be a wafer (e.g., an 8 inch wafer) with sufficient surface area for forming multiple diffusers  56  in parallel. After depositing buffer layer  56 - 2 , layer  56 - 1  may be deposited (e.g., as an uncured liquid polymer layer). After depositing layers  56 - 2  and  56 - 1 , layer  56 - 1  may be patterned by pressing against layer  56 - 1  with a mold containing a three-dimensional lens pattern with a shape that is opposite to the desired shape for lenses  68  (e.g., a negative image of lenses  68  such as a pattern with convex lens bumps when it is desired to from an array of concave lenses  68 ). The stamp may be formed from an ultraviolet-light-transparent material (e.g., sapphire or fused silica) so that ultraviolet light may be transmitted through the stamp while the stamp is pressing against layer  56 - 1 . Layer  56 - 1  may be formed from an ultraviolet-light-curable polymer layer such as a layer of ultraviolet-light-curable epoxy. After exposure to ultraviolet light through the stamp, layer  56 - 1  cures and solidifies. Once layer  56 - 1  is in a hardened state, the stamp can be removed, leaving a desired pattern of lenses  68  in layer  56 - 1 . Other techniques may be used in forming an array of lenses  68  in diffuser  56 , if desired (e.g., a step-and-repeat stamp process in which a small stamp is used to pattern layer  56 - 1  on a larger wafer of substrate  56 - 3 ), etching, machining, etc. If desired, lenses  68  may be formed directly in substrate layer  56 - 3  (e.g., by etching, molding, machining, etc.). In this type of configuration, buffer layer  56 - 2  may be omitted. 
     If desired, a hybrid diffuser arrangement may be used for forming diffuser  56 . In this type of arrangement, light-scattering particles (e.g., high-refractive-index beads) may be embedded in buffer layer  56 - 2  or other polymer layer in diffuser  56  (e.g., a coating layer) in addition to forming an array of lenses  68  (e.g., in layer  56 - 1 ). With this approach, the presence of the embedded light-scattering particles in diffuser  56  (e.g., in buffer layer  56 - 2 ) may help diffuse ambient light  52  over a wide range of wavelengths (e.g., avoiding any wavelength dependencies in the optical properties of lenses  56 ) and may help diffuse ambient light  52  that is oriented at extremely off-axis angles. 
     
       
         
           
               
             
               
                   
               
               
                 Table of Reference Numerals 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
            
               
                   
                 10 
                 Electronic Device 
                 12 
                 Input-Output Device 
               
               
                   
                 16 
                 Control Circuitry 
                 18 
                 Sensors 
               
               
                   
                 20 
                 Window 
                 22 
                 Housing 
               
               
                   
                 24 
                 Line 
                 25 
                 Direction 
               
               
                   
                 26 
                 Light Sensor 
                 28 
                 Layer 
               
               
                   
                 30 
                 Layer 
                 32 
                 Inner Surface 
               
               
                   
                 34 
                 Surface 
                 52 
                 Ambient Light 
               
               
                   
                 52′ 
                 Light 
                 54 
                 Layer 
               
               
                   
                 56 
                 Diffuser 
                 56-1 
                 Coating Layer 
               
               
                   
                 56-2 
                 Buffer Layer 
                 56-3 
                 Substrate 
               
               
                   
                 58 
                 Filters 
                 59 
                 Filter 
               
               
                   
                 60 
                 Detectors 
                 62 
                 Substrate 
               
               
                   
                 68 
                 Lenses 
                 70 
                 Adhesive Layer 
               
               
                   
                 72 
                 Adhesive ring 
                 80 
                 Portion 
               
               
                   
                 82 
                 Coatings 
                 84 
                 Layers 
               
               
                   
                   
               
            
           
         
       
     
     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: 20180430
Publication Date: 20201124
Grant Date: 20201124
Priority Date: 20180430
Inventors: DODSON, CHRISTOPHER M.
HOLENARSIPUR, PRASHANTH S.
ISIKMAN, SERHAN O.
Assignee: APPLE INC
CPC Classifications: [{"code": "H10F77/413", "inventive": true, "first": false, "tree": "[]"}, {"code": "H10F55/20", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B3/0043", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02B3/0043", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B5/0215", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B5/0221", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G2320/0666", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2360/14", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02B2003/0093", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2360/144", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02B5/0278", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G2360/144", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G3/20", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02B3/0056", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G2320/08", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02B1/041", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G5/003", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G2320/08", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/0666", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/0626", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02B1/041", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G3/20", "inventive": true, "first": true, "tree": "[]"}, {"code": "G09G2360/144", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/0626", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L31/02327", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L31/16", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B5/0278", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G2320/08", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02B1/041", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B2003/0093", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02B3/0043", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B3/0056", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G2320/0666", "inventive": false, "first": false, "tree": "[]"}]
Family ID: 68290722