PATENT DOCUMENT

Publication Number: US-10670786-B2
Application Number: US-201815953281-A
Country: US
Kind Code: B2

Title: Color ambient light sensor with tunable filter

Abstract:
An electronic device may be provided with a color ambient light sensor. The color ambient light sensor may be used to measure an ambient light spectrum over a wavelength range of interest. Control circuitry in the electronic device can take actions based on the measured ambient light spectrum such as adjusting the brightness and color cast of content on a display. A display may have a display cover layer. The color ambient light sensor can be mounted under the display cover layer and may receive ambient light through the display cover layer. The color ambient light sensor may have a tunable wavelength filter such as an electrically adjustable Fabry-Perot resonator. A light collimator may be interposed between the display cover layer and the Fabry-Perot resonator to collimate ambient light that is passed to the Fabry-Perot resonator. A light detector measures the light passing through the Fabry-Perot resonator.

Claims:
What is claimed is: 
     
       1. An electronic device, comprising:
 a housing; 
 a display in the housing; 
 a color ambient light sensor having a tunable filter and having a photodiode that is configured to receive ambient light passing through the tunable filter; and 
 control circuitry in the housing that is configured to:
 measure an ambient light spectrum for the ambient light by measuring signals from the photodiode while sweeping a passband of the tunable filter across a visible light spectrum; and 
 adjust content on the display based on the measured ambient light spectrum. 
 
 
     
     
       2. The electronic device defined in  claim 1  wherein the tunable filter is an electrically adjustable Fabry-Perot resonator and wherein the control circuitry is configured to measure the ambient light spectrum by adjusting the Fabry-Perot resonator to sweep the passband over a wavelength range between a first wavelength and a second wavelength. 
     
     
       3. The electronic device defined in  claim 2  wherein the control circuitry includes an analog-to-digital converter configured to digitize signals from the photodiode. 
     
     
       4. The electronic device defined in  claim 3  wherein the photodiode and the analog-to-digital converter are formed in a semiconductor substrate. 
     
     
       5. The electronic device defined in  claim 4  wherein the Fabry-Perot resonator has at least one metal electrode formed on the semiconductor substrate. 
     
     
       6. The electronic device defined in  claim 2  wherein the Fabry-Perot resonator is a microelectromechanical systems device with metal mirrors separated by an air gap. 
     
     
       7. The electronic device defined in  claim 6  further comprising an infrared-light-blocking thin-film interference filter on one of the metal mirrors. 
     
     
       8. The electronic device defined in  claim 1  further comprising a light collimator configured to collimate the ambient light and before the ambient light passes through the tunable filter. 
     
     
       9. The electronic device defined in  claim 8  wherein the light collimator has first and second layers with prism structures. 
     
     
       10. The electronic device defined in  claim 9  wherein the prism structures of the first layer comprise parallel prism-shaped ridges that run along a first direction and wherein the prism structures of the second layer comprise parallel prism-shaped ridges that run along a second direction that is perpendicular to the first direction. 
     
     
       11. The electronic device defined in  claim 9  wherein the display is covered by a display cover layer, the electronic device further comprising:
 a light diffuser layer interposed between the display cover layer and the first layer. 
 
     
     
       12. The electronic device defined in  claim 1  further comprising a display cover layer overlapping the display, wherein the ambient light passes through the display cover layer before passing through the tunable filter. 
     
     
       13. The electronic device defined in  claim 1  wherein the control circuitry is configured to adjust a color cast of the content based on the measured ambient light spectrum. 
     
     
       14. A color ambient light sensor, comprising:
 a semiconductor substrate; 
 a photodiode on the semiconductor substrate; 
 analog-to-digital converter circuitry in the semiconductor substrate that is configured to digitize signals from the photodiode; and 
 a tunable light filter overlapping the photodiode and having a passband that is adjustable across a visible light spectrum. 
 
     
     
       15. The color ambient light sensor defined in  claim 14  wherein the tunable light filter comprises an electrically adjustable Fabry-Perot resonator formed from a microelectromechanical systems device. 
     
     
       16. The color ambient light sensor defined in  claim 15  further comprising a light collimator that is configured to collimate ambient light and provide the collimated ambient light to the photodiode through the Fabry-Perot resonator. 
     
     
       17. The color ambient light sensor defined in  claim 16  further comprising an infrared-light-blocking-and-visible-light-transmitting thin-film interference filter that overlaps the photodiode. 
     
     
       18. An electronic device, comprising:
 a display configured to display an image; 
 a light collimator configured to receive ambient light; 
 an adjustable filter that receives the ambient light from the light collimator; 
 a light detector configured to measure a color of the ambient light; 
 an infrared-light-blocking-and-visible-light-transmitting filter interposed between the adjustable filter and the light detector; and 
 control circuitry configured to adjust a color cast of the image on the display based on signals from the light detector so that the color cast of the image more closely matches the color of ambient light. 
 
     
     
       19. The electronic device defined in  claim 18  wherein the adjustable filter comprises an electrically adjustable Fabry-Perot resonator and wherein the control circuitry is configured to sweep a passband associated with the Fabry-Perot resonator over a wavelength range that includes visible light wavelengths while measuring the signals from the light detector to measure an ambient light spectrum for the ambient light.

Description:
BACKGROUND 
     This relates generally to electronic devices, and, more particularly, to light sensors for electronic devices. 
     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. Color ambient light sensors can detect changes in the color of ambient light so that compensating color cast adjustments can be made to displayed content. 
     It can be challenging to form a color ambient light sensor for an electronic device. If care is not taken, a color ambient light sensor may consume more space in an electronic device than desired or may lose accuracy when partially occluded. 
     SUMMARY 
     An electronic device may be provided with a color ambient light sensor. The color ambient light sensor may be used to measure an ambient light spectrum over visible light wavelengths or other wavelength range of interest. Control circuitry in the electronic device can take actions based on the measured ambient light spectrum such as adjusting the brightness and color cast of content on a display. 
     The color ambient light sensor may receive ambient light through a display cover layer. The color ambient light sensor may have a tunable wavelength filter such as an electrically adjustable Fabry-Perot resonator. A light collimator may be interposed between the display cover layer and the Fabry-Perot resonator to collimate ambient light that is passed to the Fabry-Perot resonator. 
     The control circuitry may use a light detector such as a photodiode to measure the ambient light that has passed through the Fabry-Perot resonator while the Fabry-Perot resonator is adjusted to sweep a passband of the Fabry-Perot resonator across the wavelength range of interest. A fixed filter such as an infrared-light-blocking-and-visible-light-transmitting filter may be interposed between the Fabry-Perot resonator and the photodiode. The color ambient light sensor may be compact and may be insensitive to occlusion-induced color inaccuracies. 
    
    
     
       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 an electronic device with an ambient light sensor in accordance with an embodiment. 
         FIG. 3  is a cross-sectional side view of an illustrative ambient light sensor in an electronic device in accordance with an embodiment. 
         FIG. 4  is a cross-sectional side view of an illustrative light collimator in accordance with an embodiment. 
         FIG. 5  is a circuit diagram of illustrative light sensor circuitry in accordance with an embodiment. 
         FIG. 6  is a graph showing the illustrative intensity versus wavelength response of a tunable wavelength light filter in accordance with an embodiment. 
         FIG. 7  is a graph of an illustrative triangular wave signal that may be used in controlling a tunable wavelength filter such as an electrically adjustable Fabry-Perot resonator in accordance with an embodiment. 
         FIG. 8  is a graph of an illustrative photodiode response during Fabry-Perot resonator tuning operations in accordance with an embodiment. 
         FIG. 9  is a cross-sectional side view of illustrative light sensor structures 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 a capacitive 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, and other sensors. Sensors  18  may also include one or more color ambient light sensors. A color ambient light sensor may be used to measure the color (color spectrum, color temperature, color coordinates, etc.) of ambient light and may be used to measure ambient light intensity. 
     To make color measurements, a color ambient light sensor in device  10  may have a light detector such as a photodiode that is overlapped by a tunable wavelength filter. The tunable wavelength filter may have a passband that is electrically adjustable. In one illustrative configuration, the tunable wavelength filter is an electrically adjustable Fabry-Perot resonator (sometimes referred to as a Fabry-Perot filter, Fabry-Perot interferometer, Fabry-Perot cavity, or Fabry-Perot etalon). During operation, the passband of the tunable filter can be swept across a wavelength range of interest (e.g., visible wavelengths and/or other wavelengths such as infrared and/or ultraviolet wavelengths) while capturing light intensity measurements with the photodiode. The captured data can be processed to produce an ambient light spectrum across the wavelength range of interest. 
     Using ambient light spectrum information, control circuitry  16  can produce ambient light color temperature measurements and other color measurements (e.g., colors represented in color coordinates, etc.). The ambient light spectrum information may be used in controlling display  14  and/or in taking other actions in device  10 . As an example, display brightness may be automatically increased by control circuitry  16  in response to detection of bright ambient light conditions and may be automatically decreased by control circuitry  16  in response to detection of dim ambient light conditions. The color cast of images displayed on display  14  can be adjusted based on ambient light color measurement (e.g., to make the images on display  14  yellower in warm ambient lighting conditions and to make the images on display  14  bluer in cold ambient lighting conditions). 
     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, 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 be a liquid crystal display, an electrophoretic display, an organic light-emitting diode display or other display with an array of light-emitting diodes, may be a plasma display, may be an electrowetting display, may be a display based on microelectromechanical systems (MEMs) pixels, or may be any other suitable display. Display  14  may have an array of pixels that extend across some or all of the front face of device  10  and/or other external device surfaces. The pixel array may be rectangular or may have other suitable shapes. 
     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 in an inactive portion of the display (e.g., a portion of the display without pixels), may be mounted along an edge of housing  22 , may be mounted on a rear housing wall, may be mounted in a location that allows light to pass between pixels in display  14 , and/or may be mounted in any other suitable location in device  10 . In one illustrative configuration, one or more openings (sometimes referred to as windows) may be formed in an opaque masking layer that is formed on an interior portion of the display cover layer for display  14 . For example, a light component window such as an ambient light sensor window may be formed in a peripheral portion of the front face of device  10  such as region  20 . Ambient light from the exterior of device  10  may be measured by an ambient light sensor in device  10  after passing through region  20  and the display cover layer in region  20 . If desired, other portions of device  10  may be provided with window regions to receive ambient light (e.g., openings may be formed in housing  12 , etc.). 
       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 , ambient light sensor  31  may be mounted in alignment with region (window)  20  (e.g., window  20  may overlap sensor  31 ). During operation, ambient light sensor  31  measures ambient light  38 . Ambient light  38  may be produced by one or more light sources (i.e., the sun, artificial lighting, etc.). Ambient light  38  may reach device  10  directly and/or may be reflected towards device  10  from objects in the environment surrounding device  10 . Ambient light  38  may be measured by ambient light sensor  31  after passing through window  20 . 
     Display cover layer  28  may have a portion that covers the active area of display  14 . Pixel array  29  (e.g., an organic light-emitting diode display, a liquid crystal display, and/or other display layers that produce images for display  14 ) may be formed under display cover layer  28  in the active area of display  14 . Display cover layer  28  may also cover an inactive display area. Opaque masking layer  26  may cover the interior of display cover layer  28  in the inactive display area. Window  20  may be formed from a partially transparent region in opaque masking layer  26  on the inner surface of display cover layer  28 . 
     Layer  28  may be formed from glass, plastic, ceramic, sapphire, or other transparent materials and may be a part of display  14  or a separate protective layer that covers active display structures. The opening associated with window  20  may be filled with window material  26 ′. Window material  26 ′ may be material that is sufficiently transparent to allow at least some of light  38  to reach ambient light sensor  31 . With one illustrative configuration, opaque masking layer  26  is formed from a material that is sufficiently opaque to block 99% or more or 99.5% or more of ambient light  38  and window material  26 ′ is sufficiently transparent to allow ambient light sensor  31  to make measurements of color and intensity on light  38 . Window material  26 ′ may be, for example, an ink or other material(s) that allows 4% of light  38  to pass or may have other suitable transmissivity values (i.e., the transmissivity of window material  26 ′ may be 2-10%, may be 2-6%, may be more than 1%, may be less than 10%, etc.). If desired, material  26 ′ may be omitted, may be formed from a transparent material such as a clear polymer, etc. Configurations in which material  26 ′ allows only a fraction of light  38  to pass may help enhance the appearance of device  10  by blocking light sensor  31  from view from the exterior of device  10 . 
     Color ambient light sensor  31  may have one or more light detectors such as photodiode  36 . Photodiode (photodetector)  36  may measure incoming ambient light  38  after light  38  has passed through material  26 ′, light collimator  30 , tunable filter  32 , and a fixed wavelength filter such as filter  34  (e.g., an infrared-light-blocking-and-visible-light-transmitting filter). Color ambient light sensor control circuitry such as portions of control circuitry  16  may gather signals from photodiode  36  while sweeping a passband associated with tunable filter  32  across a wavelength range of interest. This allows control circuitry  16  to gather light spectrum measurements on ambient light  38 . 
     Tunable filter  32  may be a wavelength-selective filter such as a tunable Fabry-Perot resonator. The Fabry-Perot resonator may, as an example, be an electrically adjustable microelectromechanical systems (MEMs) device having micromechanical mirror structures (e.g., MEMs diving board structures, etc.) with an electrostatically controlled mirror spacing to adjust the cavity length of the resonator. For satisfactory operation of the resonator, the angular range of ambient light  38  may be reduced by light collimator  30  before the ambient light passes through the resonator. A cross-sectional side view of light collimator  30  is shown in  FIG. 4 . In the illustrative configuration of  FIG. 4 , light collimator  30  has multiple layers such as light diffuser layer  42  and light collimator layer  44 . Diffuser layer  42  may be formed form a clear polymer or other clear substrate material. Light-scattering particles (e.g., inorganic particles, bubbles, etc.) can be embedded in the substrate material and/or coated on one or more of the surfaces of the substrate material to form diffuser layer  42 . The presence of light diffuser layer  42  may help homogenize incoming ambient light  38  before light  38  passes through light collimating layer  44  (e.g., layer  42  may help reduce the impact of specular highlights in light  38 ). 
     Light collimating layer  44  may collimate light using light refracting structures such as prism-shaped ridges. In the example of  FIG. 4 , light collimating layer  44  has two layers of prism structures: prism layer  44 - 1  and prism layer  44 - 2 . Each prism layer (sometimes referred to as a brightness enhancement film or prism film) may have a substrate (e.g., a 200 micron polyethylene terephthalate substrate) with an ultraviolet-cured clear polymer coating impressed with prismatic structures or other prism-shaped light refracting structures. The coating of the prismatic structures may have a thickness of about 30 microns or other suitable thickness. Layers  44 - 1  and  44 - 2  may, as an example, each have a set of parallel prismatic ridges. The ridges of layer  44 - 1  may run perpendicular to the ridges of layer  44 - 2 . The ridges of layer  44 - 1  may face downwardly (away from window  20  and toward photodiode  36 ) and the ridges of layer  44 - 2  may face upwardly (e.g., layers  44 - 1  and  44 - 2  may be arranged in a face-to-face configuration in which the ridges of these layers face each other). Other light collimating structures may be used in forming light collimator  44 . The arrangement of  FIG. 4  is illustrative. 
     Using light collimator  30  or other suitable light diffusing and collimating structures, incoming ambient light  38  that is distributed over a wide angular range A 1  about surface normal n of the upper surface of collimator  30  may be collimated to form collimated ambient light  38 ′ that is distributed over a narrow angular range A 2  about surface normal n′ of the lower surface of collimator  30 . As an example, the full-width-half-maximum (FWHM) intensity of light  38  may cover an angular range A 1  of 120° and the FWHM of light  38 ′ may cover an angular range A 2  of 40° (e.g., the angular spread of ambient light passing through window  20  may be reduced by a factor of at least 2, at least 3, at least 4, less than 10, or other suitable amount before this ambient light reaches filter  32 . 
       FIG. 5  is a diagram of color ambient light sensor  31  and associated control circuitry  16 . As shown in  FIG. 5 , ambient light  38  may be collimated by light collimator  30  to produce collimated ambient light  38 ′. Light  38 ′ may then pass through tunable filter  32 . Tunable filter  32  may be a tunable Fabry-Perot resonator having partially transparent mirrors  32 - 1  and  32 - 2  separated by a distance d (the cavity length of the Fabry-Perot resonator). Control circuitry  16  may use a triangular wave signal source or other alternating-current signal generator  48  to apply an alternating-current control signal to tunable filter  32  to adjust the value of d. The control signal may, as an example, be a triangular wave that is modulated at a frequency of at least 1 kHz, at least 10 kHz, at least 100 kHz, at least 1 MHz, less than 100 MHz, less than 10 MHz, or other suitable modulation frequency. Infrared-light-blocking-and-visible-light-transmitting filter  34  (sometimes referred to as an infrared light blocking filter) may be formed from a thin-film interference filter (e.g., a stack of inorganic dielectric layers or other dielectric layers of alternating refractive index values). The layer index values and thicknesses are selected so that filter  34  transmits light with a wavelength range of interest for measurement by photodiode  36  (e.g., light from 400-800 nm) while blocking other light (e.g., infrared light with wavelengths longer than 800 nm). The presence of infrared blocking filter  34  helps reduce noise in photodetector  36  due to ambient light of wavelengths out of the wavelength range of interest. 
     While control circuitry  16  adjusts the spacing d of mirrors  32 - 1  and  32 - 2  to tune the passband of filter  32 , control circuitry  16  gathers photodiode measurements from photodiode  36 . In the illustrative configuration of  FIG. 5 , control circuitry  16  digitizes the output of photodiode  36  using analog-to-digital converter  50 . As control circuitry  16  sweeps the passband of filter  32  across the wavelength range of interest, photodiode measurement data corresponding to each sweep can be stored in buffer  52  (e.g., the data can be added to a running average maintained in buffer  52 ). Averaged photodiode data corresponding to the measured ambient light spectrum can be read out of buffer  52  periodically (e.g., every 700 ms). Control circuitry  16  can use the measured ambient light spectrum data to take suitable actions (e.g., adjusting display brightness and color cast). 
       FIG. 6  is a graph of an illustrative light transmission characteristic for tunable filter  32 . Curve  54  of the graph of  FIG. 6  is a plot of light transmission T for filter  32  as a function of ambient light wavelength. The value of the control signal applied to filter  32  can be used to adjust mirror spacing d and thereby tune the location of the passband of filter  32  (e.g., the peak in transmission T). The bandwidth of the passband is determined by the finesse of the cavity formed from mirrors  32 - 1  and  32 - 2 . With one illustrative configuration, the FWHM bandwidth BW of the pass band is 30-40 nm, at least 5 nm, at least 15 nm, less than 80 nm, or other suitable width. The location of the center of the passband (wavelength WL) is swept dynamically over a desired spectral measurement range R by control circuitry  16 . Range R may cover some or all of the visible light wavelengths and/or other desired wavelengths (e.g., near-infrared and/or ultraviolet). With one illustrative configuration, range R spans from a short wavelength of 400 nm, a wavelength of less than 450 nm, or other suitable short wavelength to 800 nm, at least 650 nm, or other long wavelength, thereby covering most or all visible light wavelengths. Control circuitry  16  can use measurements over this spectral range or other wavelength range R in determining which actions to take in device  10 . 
       FIG. 7  is a graph showing how mirror spacing d (the cavity length of the Fabry-Perot microelectromechanical systems device) can have a triangular wave characteristic (curve  58 ) when signal generator  48  produces a triangular wave control signal for filter  32 . An illustrative corresponding output of analog-to-digital converter  50  as a function of time is shown by curve  60  in  FIG. 8  (corresponding to a spectral measurement for one sweep of the wavelength range of interest). 
       FIG. 9  is a cross-sectional side view of illustrative structures that may be used in forming color ambient light sensor  31 . As shown in  FIG. 9 , photodiode  32  may be formed from an n+ well (well  78 ) in a p-type substrate (substrate  80 ). These structures form a p-n junction for photodiode  36 . Substrate  80  may be formed from silicon or other semiconductor(s). Control circuitry (e.g., analog-to-digital converter circuitry and/or other control circuitry  50 ) may be formed in substrate  80  and may be electrically connected to photodiode  36  by interconnect paths formed from metal traces on substrate  80 . Tunable filter  32  may be formed from mirrors  32 - 1  and  32 - 2  that are separated by air gap  76 . Spacer structures such as silicon oxide spacers  74  at one or more ends of mirrors  32 - 1  and  32 - 2  may be used to establish a desired nominal separation distance d between the mirrors 
     Each mirror may have a metal electrode  70  (e.g., an aluminum electrode or other reflective metal electrode) and an optional stack of optional dielectric layers  72 . During operation, control circuitry  16  may supply a control voltage across the electrodes  70  using signal generator  48  ( FIG. 5 ), thereby adjusting distance d by electrostatic force (attraction and repulsion). If desired, the dielectric layers  72  in mirror  32 - 1  may be configured to form a thin-film interference filter mirror structure that increase the reflectivity of mirror  32 - 1  to a desired amount. The dielectric layers  72  in mirror  32 - 2  (e.g., the layers  72  overlapping the metal electrode  70  in mirror  32 - 2 ) may also be used in forming a thin-film interference filter that blocks infrared light (e.g., some or all of layers  72  may be configured to form infrared-light-blocking-and-visible-light-transmitting filter  34 ). 
     In the illustrative arrangement of  FIG. 9 , filter  32  and filter  34  have been formed on the upper surface of substrate  80  (e.g., circuitry  50 , photodiode  36 , filter  32 , and filter  34  are formed on a single integrated circuit substrate to form a single integrated component). If desired, filter  32  (and, if desired, filter  34 ) can be formed separately from substrate  80  (e.g., photodiode  36  and circuitry  50  may form an integrated circuit such as integrated circuit  82  that is separate from filter  32  (and, if desired filter  34 ). In another illustrative configuration, filter  32  may be formed on its own microelectromechanical systems device substrate and filter  32  (and, if desired, filter  34 ) may be separate from photodiode  36 , which in turn is separate from circuitry  50 . Other arrangements may be used, if desired. 
     
       
         
           
               
             
               
                   
               
               
                 Table of Reference Numerals 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
            
               
                   
                 10 
                 Electronic Device 
                 12 
                 Input-Output Device 
               
               
                   
                 14 
                 Display 
                 16 
                 Control Circuitry 
               
               
                   
                 18 
                 Sensors 
                 20 
                 Window/Region 
               
               
                   
                 22 
                 Housing 
                 24 
                 Line 
               
               
                   
                 25 
                 Direction 
                 26 
                 Masking Layer 
               
               
                   
                 26 
                 Window Material 
                 28 
                 Cover Letter 
               
               
                   
                 29 
                 Pixel Array 
                 30 
                 Light Collimator 
               
               
                   
                 31 
                 Light Sensor 
                 32 
                 Turnable Filter 
               
               
                   
                 32-1 
                 Transparent Mirrors 
                 32-2 
                 Transparent Mirrors 
               
               
                   
                 34 
                 Blocking Filter 
                 36 
                 Photodetector/Photodiode 
               
               
                   
                 38 
                 Ambient Light 
                 38′ 
                 Light 
               
               
                   
                 42 
                 Diffuser Layer 
                 44 
                 Collimator Layer 
               
               
                   
                 44-1 
                 Prism Film Layer 
                 44-2 
                 Prism Film 
               
               
                   
                 48 
                 Signal Generator 
                 50 
                 Control Circuitry 
               
               
                   
                 52 
                 Buffer 
                 70 
                 Electrodes 
               
               
                   
                 72 
                 Layers 
                 74 
                 Oxide Spacers 
               
               
                   
                 76 
                 Air Gap 
                 78 
                 Well 
               
               
                   
                   
               
            
           
         
       
     
     The foregoing is merely illustrative and various modifications can be made to the described embodiments. The foregoing embodiments may be implemented individually or in any combination.

Metadata:
Filing Date: 20180413
Publication Date: 20200602
Grant Date: 20200602
Priority Date: 20180413
Inventors: ZHENG, DONG
LYNGNES, OVE
HOLENARSIPUR, PRASHANTH S.
ISIKMAN, SERHAN O.
SUN, Tianbo
XU, Tingjun
ZHAO, Xianwei
CAI, Xingxing
Assignee: APPLE INC
CPC Classifications: [{"code": "G09G2320/0626", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L31/02165", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G2360/144", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02B27/30", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L31/02019", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01J3/51", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G2320/0666", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G3/2003", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B26/007", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L31/103", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B5/288", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02B5/282", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G2320/08", "inventive": false, "first": false, "tree": "[]"}, {"code": "H10F77/953", "inventive": true, "first": false, "tree": "[]"}, {"code": "H10F77/337", "inventive": true, "first": false, "tree": "[]"}, {"code": "H10F30/221", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01J1/32", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01J1/0411", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01J3/0256", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B27/30", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B5/208", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01J3/51", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G2320/0626", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/0666", "inventive": false, "first": false, "tree": "[]"}, {"code": "G01J1/4204", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01J1/0448", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G2360/144", "inventive": false, "first": false, "tree": "[]"}, {"code": "G01J3/0272", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G2360/144", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02B5/282", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B26/007", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B5/0236", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01J1/4204", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01J1/0407", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G3/2003", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G2320/0626", "inventive": false, "first": false, "tree": "[]"}, {"code": "G01J1/0204", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01J1/0204", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01J1/0448", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G3/2003", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B26/001", "inventive": true, "first": true, "tree": "[]"}, {"code": "G01J2001/446", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/08", "inventive": false, "first": false, "tree": "[]"}, {"code": "G01J3/51", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01J3/26", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01J1/44", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01J1/0474", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B5/288", "inventive": true, "first": true, "tree": "[]"}, {"code": "G01J3/0208", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01J1/0474", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01J1/0488", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G2320/0666", "inventive": false, "first": false, "tree": "[]"}, {"code": "G01J1/0233", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 68160747