PATENT DOCUMENT

Publication Number: US-12058916-B1
Application Number: US-202117208973-A
Country: US
Kind Code: B1

Title: Devices with displays having transparent openings and a diffractive layer

Abstract:
An electronic device may include a display and an optical sensor formed underneath the display. The electronic device may include a plurality of transparent windows that overlap the sensor. The resolution of the display panel may be reduced in some areas due to the presence of the transparent windows. To increase the apparent resolution of the display in portions of the display panel with the transparent windows, the display may include a light spreading layer that includes a plurality of diffractive elements. The light spreading layer may spread visible light from the array of pixels such that the display resolution at the outer surface of the display is greater than at the display panel. The light spreading layer may selectively spread visible light but not infrared light. The display may also include a lens layer that focuses light onto the transparent windows.

Claims:
What is claimed is: 
     
       1. An electronic device, comprising:
 a sensor; and 
 a display that overlaps the sensor, wherein the sensor is configured to sense light that passes through the display and wherein the display comprises:
 a display panel that includes an array of pixels in a portion having a first transparency and a plurality of additional portions having a second transparency that is greater than the first transparency, wherein the plurality of additional portions allow light to pass through to the sensor, wherein a pixel in the array of pixels emits light at a first wavelength, and wherein the sensor is configured to sense light at a second wavelength that is different than the first wavelength; 
 a display cover layer that covers the display panel; and 
 a diffractive layer between the display panel and the display cover layer, wherein the diffractive layer comprises first and second layers that have a first refractive index difference at the first wavelength and a second refractive index difference at the second wavelength and wherein the first refractive index difference is greater than the second refractive index difference. 
 
 
     
     
       2. The electronic device defined in  claim 1 , wherein the display further comprises:
 a polarizer that is interposed between the diffractive layer and the display cover layer. 
 
     
     
       3. The electronic device defined in  claim 1 , wherein each pixel of the array of pixels has a corresponding light-emitting area on the display cover layer and wherein the diffractive layer is configured to generate duplicate light-emitting areas on the display cover layer based on the light-emitting areas. 
     
     
       4. The electronic device defined in  claim 1 , wherein the diffractive layer is configured to generate duplicate pixels on the display cover layer. 
     
     
       5. The electronic device defined in  claim 4 , wherein the array of pixels has a first resolution in a first region of the display panel, wherein the display has a second resolution that is higher than the first resolution on a first region of an outer surface of the display cover layer, and wherein the first region of the outer surface of the display cover layer overlaps the first region of the display panel. 
     
     
       6. The electronic device defined in  claim 1 , wherein the second layer conforms to the first layer and wherein the first layer has a varying thickness. 
     
     
       7. The electronic device defined in  claim 6 , wherein the varying thickness of the first layer comprises a first thickness in first portions of the first layer and a second thickness that is different than the first thickness in second portions of the first layer. 
     
     
       8. The electronic device defined in  claim 6 , wherein the varying thickness of the first layer has a sinusoidal profile. 
     
     
       9. The electronic device defined in  claim 1 , wherein the diffractive layer is configured to spread light from the pixel to create first and second duplicate pixels on first and second opposing sides of the pixel and wherein the diffractive layer is configured to spread light from an additional pixel in the array of pixels to create third and fourth duplicate pixels on first and second opposing sides of the additional pixel and wherein the third duplicate pixel overlaps the second duplicate pixel. 
     
     
       10. The electronic device defined in  claim 1 , wherein the display further comprises:
 a lens layer between the display panel and the display cover layer, wherein the lens layer comprises third and fourth layers that have a third refractive index difference at the first wavelength and a fourth refractive index difference that is greater than the third refractive index difference at the second wavelength. 
 
     
     
       11. An electronic device, comprising:
 a display panel that includes a first portion having a first transparency, a plurality of pixels in the first portion that are configured to emit visible light, and a plurality of pixel-free second portions that have a higher transparency than the first transparency; 
 a lens layer, wherein the lens layer has a first refractive index difference at a visible wavelength and a second refractive index difference that is greater than the first refractive index difference at an infrared wavelength; and 
 a sensor that is overlapped by the plurality of pixel-free second portions and that is configured to sense infrared light, wherein the lens layer is configured to focus light through the pixel-free second portions towards the sensor. 
 
     
     
       12. The electronic device defined in  claim 11 , wherein the lens layer comprises first and second layers. 
     
     
       13. The electronic device defined in  claim 11 , further comprising:
 a display cover layer, wherein the display cover layer overlaps the display panel; and 
 a light spreading layer that is formed separately from the lens layer and that is interposed between the display cover layer and the display panel. 
 
     
     
       14. The electronic device defined in  claim 11 , wherein the lens layer is configured to focus the light towards the sensor without affecting additional light emitted from the display panel. 
     
     
       15. The electronic device defined in  claim 11 , wherein the lens layer comprises a plurality of refractive lenses, wherein each refractive lens has a circular outline when viewed from above, and wherein each refractive lens has a spherical upper surface. 
     
     
       16. An electronic device comprising:
 a display panel having an array of pixels, wherein the array of pixels has a first resolution in a first portion of the array of pixels and a second resolution that is less than the first resolution in a second portion of the array of pixels; 
 a display cover layer, wherein a first portion of the display cover layer overlaps the first portion of the display panel and a second portion of the display cover layer overlaps the second portion of the display panel; and 
 a light spreading layer that is interposed between the display cover layer and the display panel, wherein the light spreading layer is configured to spread light from a pixel in the array of pixels to create first and second duplicate pixels on first and second opposing sides of the pixel, wherein the light spreading layer is configured to spread light from an additional pixel in the array of pixels to create third and fourth duplicate pixels on first and second opposing sides of the additional pixel, and wherein the third duplicate pixel overlaps the second duplicate pixel. 
 
     
     
       17. The electronic device defined in  claim 16 , wherein the display panel includes a plurality of transparent windows in the second portion of the array of pixels and wherein the light spreading layer comprises a plurality of diffractive elements. 
     
     
       18. The electronic device defined in  claim 16 , further comprising:
 a sensor, wherein the pixel in the array of pixels emits light at a first wavelength, wherein the sensor is configured to sense light at a second wavelength that is different than the first wavelength, wherein the light spreading layer comprises first and second layers that have a first refractive index difference at the first wavelength and a second refractive index difference at the second wavelength, and wherein the first refractive index difference is greater than the second refractive index difference. 
 
     
     
       19. The electronic device defined in  claim 16 , wherein the light spreading layer spreads light from the second portion of the array of pixels to have the first resolution at the second portion of the display cover layer.

Description:
This application claims the benefit of provisional patent application No. 63/031,422, filed May 28, 2020, which is hereby incorporated by reference herein in its entirety. 
    
    
     BACKGROUND 
     This relates generally to electronic devices, and, more particularly, to electronic devices with displays. 
     Electronic devices often include displays. For example, an electronic device may have an organic light-emitting diode (OLED) display based on organic light-emitting diode pixels. In this type of display, each pixel includes a light-emitting diode and thin-film transistors for controlling application of a signal to the light-emitting diode to produce light. The light-emitting diodes may include OLED layers positioned between an anode and a cathode. 
     There is a trend towards borderless electronic devices with a full-face display. These devices, however, may still need to include sensors such as cameras, ambient light sensors, and proximity sensors to provide other device capabilities. Since the display now covers the entire front face of the electronic device, the sensors will have to be placed under the display stack. In practice, however, the amount of light transmission through the display stack is very low (i.e., the transmission might be less than 20% in the visible spectrum), which severely limits the sensing performance under the display. 
     It is within this context that the embodiments herein arise. 
     SUMMARY 
     An electronic device may include a display and an optical sensor formed underneath the display. The electronic device may include a plurality of non-pixel regions that overlap the optical sensor. Each non-pixel region may be devoid of thin-film transistors and other display components. The plurality of non-pixel regions is configured to increase the transmittance of light through the display to the sensor. The non-pixel regions may therefore be referred to as transparent windows in the display. 
     The resolution of the display panel may be reduced in some areas due to the presence of the transparent windows. To increase the apparent resolution of the display at the outer surface of the display, the display may include a light spreading layer that includes a plurality of diffractive elements. The light spreading layer may spread visible light from the array of pixels such that the display resolution at the outer surface of the display is greater than at the display panel. In this way, the display may have a uniform resolution at the outer surface despite the absence of some pixels in the transparent window areas. 
     The light spreading layer may be formed from first and second layers that have a refractive index difference at visible wavelengths. The first and second layers may have little to no refractive index difference at infrared wavelengths to avoid disrupting infrared light that is sensed by a sensor underneath the display. 
     The display may also include a lens layer that focuses light onto the transparent windows. The lens layer may be formed from first and second layers that have a refractive index difference at infrared wavelengths. The first and second layers may have little to no refractive index difference at visible wavelengths to avoid disrupting visible light that is emitted by the display. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a schematic diagram of an illustrative electronic device having a display and one or more sensors in accordance with an embodiment. 
         FIG.  2    is a schematic diagram of an illustrative display with light-emitting elements in accordance with an embodiment. 
         FIG.  3    is a cross-sectional side view of an illustrative display stack that at least partially covers a sensor in accordance with an embodiment. 
         FIG.  4    is a cross-sectional side view of an illustrative display stack with a pixel removal region that includes an opening in a substrate layer in accordance with an embodiment. 
         FIG.  5    is a top view of an illustrative display with transparent openings that overlap a sensor in accordance with an embodiment. 
         FIG.  6    is a cross-sectional side view of an illustrative display stack with a diffractive layer for increasing the apparent resolution of the display in accordance with an embodiment. 
         FIG.  7 A  is a top view of illustrative display pixels in accordance with an embodiment. 
         FIG.  7 B  is a top view of illustrative display pixels and non-overlapping duplicate pixels in accordance with an embodiment. 
         FIG.  7 C  is a top view of illustrative display pixels and overlapping duplicate pixels in accordance with an embodiment. 
         FIG.  7 D  is a top view of illustrative display pixels and duplicate pixels that are spread in multiple directions in accordance with an embodiment. 
         FIG.  8 A  is a cross-sectional side view of an illustrative diffractive layer that includes layers having different refractive indices and varying thicknesses in accordance with an embodiment. 
         FIG.  8 B  is a top view showing illustrative patterns for the diffractive layer of  FIG.  8 A  in accordance with an embodiment. 
         FIG.  9 A  is a cross-sectional side view of an illustrative diffractive layer that includes layers having different refractive indices and gradually varying thicknesses in accordance with an embodiment. 
         FIG.  9 B  is a top view showing illustrative patterns for the diffractive layer of  FIG.  9 A  in accordance with an embodiment. 
         FIG.  10    is a top view of an illustrative display having display pixels and duplicate pixels in accordance with an embodiment. 
         FIG.  11    is a cross-sectional side view of an illustrative display stack with a lens layer for focusing light into transparent openings in the display in accordance with an embodiment. 
         FIG.  12    is a cross-sectional side view of an illustrative display with a lens layer that includes layers having different refractive indices in accordance with an embodiment. 
         FIG.  13    is a top view of the illustrative display of  FIG.  12    in accordance with an embodiment. 
         FIG.  14    is a cross-sectional side view of an illustrative display stack with both a diffractive layer for increasing the apparent resolution of the display and a lens layer for focusing light into transparent openings in the display in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     An illustrative electronic device of the type that may be provided with a display 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 display, a computer display that contains an embedded computer, 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, or other electronic equipment. Electronic device  10  may have the shape of a pair of eyeglasses (e.g., supporting frames), may form a housing having a helmet shape, or may have other configurations to help in mounting and securing the components of one or more displays on the head or near the eye of a user. 
     As shown in  FIG.  1   , electronic device  10  may include control circuitry  16  for supporting the operation of device  10 . Control circuitry  16  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, sensors, light-emitting diodes and other status indicators, data ports, etc. A user can control the operation of device  10  by supplying commands through input resources of 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. A touch sensor for display  14  may be formed from electrodes formed on a common display substrate with the display pixels of display  14  or may be formed from a separate touch sensor panel that overlaps the pixels of display  14 . If desired, display  14  may be insensitive to touch (i.e., the touch sensor may be omitted). Display  14  in electronic device  10  may be a head-up display that can be viewed without requiring users to look away from a typical viewpoint or may be a head-mounted display that is incorporated into a device that is worn on a user&#39;s head. If desired, display  14  may also be a holographic display used to display holograms. 
     Control circuitry  16  may be used to run software on device  10  such as operating system code and applications. During operation of device  10 , the software running on control circuitry  16  may display images on display  14 . 
     Input-output devices  12  may also include one or more sensors  13  such as force sensors (e.g., strain gauges, capacitive force sensors, resistive force sensors, etc.), audio sensors such as microphones, touch and/or proximity sensors such as capacitive sensors (e.g., a two-dimensional capacitive touch sensor associated with a display and/or a touch sensor that forms a button, trackpad, or other input device not associated with a display), and other sensors. In accordance with some embodiments, sensors  13  may include optical sensors such as optical sensors that emit and detect light (e.g., optical proximity sensors such as transreflective optical proximity structures), ultrasonic sensors, and/or other touch and/or proximity sensors, monochromatic and color ambient light sensors, image sensors, fingerprint sensors, temperature sensors, proximity sensors and other sensors for measuring three-dimensional non-contact gestures (“air gestures”), pressure sensors, sensors for detecting position, orientation, and/or motion (e.g., accelerometers, magnetic sensors such as compass sensors, gyroscopes, and/or inertial measurement units that contain some or all of these sensors), health sensors, radio-frequency sensors, depth sensors (e.g., structured light sensors and/or depth sensors based on stereo imaging devices), optical sensors such as self-mixing sensors and light detection and ranging (lidar) sensors that gather time-of-flight measurements, humidity sensors, moisture sensors, gaze tracking sensors, and/or other sensors. In some arrangements, device  10  may use sensors  13  and/or other input-output devices to gather user input (e.g., buttons may be used to gather button press input, touch sensors overlapping displays can be used for gathering user touch screen input, touch pads may be used in gathering touch input, microphones may be used for gathering audio input, accelerometers may be used in monitoring when a finger contacts an input surface and may therefore be used to gather finger press input, etc.). 
     Display  14  may be an organic light-emitting diode display or may be a display based on other types of display technology (e.g., liquid crystal displays). Device configurations in which display  14  is an organic light-emitting diode display are sometimes described herein as an example. This is, however, merely illustrative. Any suitable type of display may be used, if desired. In general, display  14  may have a rectangular shape (i.e., display  14  may have a rectangular footprint and a rectangular peripheral edge that runs around the rectangular footprint) or may have other suitable shapes. Display  14  may be planar or may have a curved profile. 
     A top view of a portion of display  14  is shown in  FIG.  2   . As shown in  FIG.  2   , display  14  may have an array of pixels  22  formed on a substrate. Pixels  22  may receive data signals over signal paths such as data lines D and may receive one or more control signals over control signal paths such as horizontal control lines G (sometimes referred to as gate lines, scan lines, emission control lines, etc.). There may be any suitable number of rows and columns of pixels  22  in display  14  (e.g., tens or more, hundreds or more, or thousands or more). Each pixel  22  may include a light-emitting diode  26  that emits light  24  under the control of a pixel control circuit formed from thin-film transistor circuitry such as thin-film transistors  28  and thin-film capacitors. Thin-film transistors  28  may be polysilicon thin-film transistors, semiconducting-oxide thin-film transistors such as indium zinc gallium oxide (IGZO) transistors, or thin-film transistors formed from other semiconductors. Pixels  22  may contain light-emitting diodes of different colors (e.g., red, green, and blue) to provide display  14  with the ability to display color images or may be monochromatic pixels. 
     Display driver circuitry may be used to control the operation of pixels  22 . The display driver circuitry may be formed from integrated circuits, thin-film transistor circuits, or other suitable circuitry. Display driver circuitry  30  of  FIG.  2    may contain communications circuitry for communicating with system control circuitry such as control circuitry  16  of  FIG.  1    over path  32 . Path  32  may be formed from traces on a flexible printed circuit or other cable. During operation, the control circuitry (e.g., control circuitry  16  of  FIG.  1   ) may supply display driver circuitry  30  with information on images to be displayed on display  14 . 
     To display the images on display pixels  22 , display driver circuitry  30  may supply image data to data lines D while issuing clock signals and other control signals to supporting display driver circuitry such as gate driver circuitry  34  over path  38 . If desired, display driver circuitry  30  may also supply clock signals and other control signals to gate driver circuitry  34  on an opposing edge of display  14 . 
     Gate driver circuitry  34  (sometimes referred to as row control circuitry) may be implemented as part of an integrated circuit and/or may be implemented using thin-film transistor circuitry. Horizontal control lines G in display  14  may carry gate line signals such as scan line signals, emission enable control signals, and other horizontal control signals for controlling the display pixels  22  of each row. There may be any suitable number of horizontal control signals per row of pixels  22  (e.g., one or more row control signals, two or more row control signals, three or more row control signals, four or more row control signals, etc.). 
     The region on display  14  where the display pixels  22  are formed may sometimes be referred to herein as the active area. Electronic device  10  has an external housing with a peripheral edge. The region surrounding the active area and within the peripheral edge of device  10  is the border region. Images can only be displayed to a user of the device in the active region. It is generally desirable to minimize the border region of device  10 . For example, device  10  may be provided with a full-face display  14  that extends across the entire front face of the device. If desired, display  14  may also wrap around over the edge of the front face so that at least part of the lateral edges or at least part of the back surface of device  10  is used for display purposes. 
     Device  10  may include a sensor  13  mounted behind display  14  (e.g., behind the active area of the display).  FIG.  3    is a cross-sectional side view of an illustrative display stack of display  14  that at least partially covers a sensor in accordance with an embodiment. As shown in  FIG.  3   , the display stack may include a substrate such as substrate  300 . Substrate  300  may be formed from glass, metal, plastic, ceramic, sapphire, or other suitable substrate materials. In some arrangements, substrate  300  may be an organic substrate formed from polyethylene terephthalate (PET) or polyethylene naphthalate (PEN) (as examples). One or more polyimide (PI) layers  302  may be formed over substrate  300 . The polyimide layers may sometimes be referred to as an organic substrate (e.g., substrate  300  is a first substrate layer and substrate  302  is a second substrate layer). The surface of substrate  302  may optionally be covered with one or more buffer layers  303  (e.g., inorganic buffer layers such as layers of silicon oxide, silicon nitride, amorphous silicon, etc.). 
     Thin-film transistor (TFT) layers  304  may be formed over inorganic buffer layers  303  and organic substrates  302  and  300 . The TFT layers  304  may include thin-film transistor circuitry such as thin-film transistors, thin-film capacitors, associated routing circuitry, and other thin-film structures formed within multiple metal routing layers and dielectric layers. Organic light-emitting diode (OLED) layers  306  may be formed over the TFT layers  304 . The OLED layers  306  may include a diode cathode layer, a diode anode layer, and emissive material interposed between the cathode and anode layers. The OLED layers may include a pixel definition layer that defines the light-emitting area of each pixel. The TFT circuitry in layer  304  may be used to control an array of display pixels formed by the OLED layers  306 . 
     Circuitry formed in the TFT layers  304  and the OLED layers  306  may be protected by encapsulation layers  308 . As an example, encapsulation layers  308  may include a first inorganic encapsulation layer, an organic encapsulation layer formed on the first inorganic encapsulation layer, and a second inorganic encapsulation layer formed on the organic encapsulation layer. Encapsulation layers  308  formed in this way can help prevent moisture and other potential contaminants from damaging the conductive circuitry that is covered by layers  308 . Substrate  300 , polyimide layers  302 , buffer layers  303 , TFT layers  304 , OLED layers  306 , and encapsulation layers  308  may be collectively referred to as a display panel. 
     One or more polarizer films  312  may be formed over the encapsulation layers  308  using adhesive  310 . Adhesive  310  may be implemented using optically clear adhesive (OCA) material that offer high light transmittance. One or more touch layers  316  that implement the touch sensor functions of touch-screen display  14  may be formed over polarizer films  312  using adhesive  314  (e.g., OCA material). For example, touch layers  316  may include horizontal touch sensor electrodes and vertical touch sensor electrodes collectively forming an array of capacitive touch sensor electrodes. Lastly, the display stack may be topped off with a cover glass layer  320  (sometimes referred to as a display cover layer  320 ) that is formed over the touch layers  316  using additional adhesive  318  (e.g., OCA material). display cover layer  320  may be a transparent layer (e.g., transparent plastic or glass) that serves as an outer protective layer for display  14 . The outer surface of display cover layer  320  may form an exterior surface of the display and the electronic device that includes the display. 
     Still referring to  FIG.  3   , sensor  13  may be formed under the display stack within the electronic device  10 . As described above in connection with  FIG.  1   , sensor  13  may be an optical sensor such as a camera, proximity sensor, ambient light sensor, fingerprint sensor, or other light-based sensor. In such scenarios, the performance of sensor  13  depends on the transmission of light traversing through the display stack, as indicated by arrow  350 . A typical display stack, however, has fairly limited transmission properties. For instance, more than 80% of light in the visible and infrared light spectrum might be lost when traveling through the display stack, which makes sensing under display  14  challenging. 
     Each of the multitude of layers in the display stack contributes to the degraded light transmission to sensor  13 . In particular, the dense thin-film transistors and associated routing structures in TFT layers  304  of the display stack contribute substantially to the low transmission. In accordance with an embodiment, at least some of the display pixels may be selectively removed in regions of the display stack located directly over sensor(s)  13 . Regions of display  14  that at least partially cover or overlap with sensor(s)  13  in which at least a portion of the display pixels have been removed are sometimes referred to as pixel removal regions. Removing display pixels (e.g., removing transistors and/or capacitors associated with one or more sub-pixels) in the pixel free regions can drastically help increase transmission and improve the performance of the under-display sensor  13 . In addition to removing display pixels, portions of additional layers such as polyimide layers  302  and/or substrate  300  may be removed for additional transmission improvement. Polarizer  312  may also be bleached for additional transmission improvement. 
       FIG.  4    is a cross-sectional side view of an illustrative display showing how pixels may be removed in a pixel removal region to increase transmission through the display. As shown in  FIG.  4   , display  14  may include a pixel region  322  and a pixel removal region  324 . In the pixel region  322 , the display may include a pixel formed from emissive material  306 - 2  that is interposed between an anode  306 - 1  and a cathode  306 - 3 . Signals may be selectively applied to anode  306 - 1  to cause emissive material  306 - 2  to emit light for the pixel. Circuitry in thin-film transistor layer  304  may be used to control the signals applied to anode  306 - 1 . 
     In pixel removal region  324 , anode  306 - 1  and emissive material  306 - 2  may be omitted. Without the pixel removal region, an additional pixel may be formed in area  324  adjacent to the pixel in area  322 . However, to increase the transmittance of light to sensor  13  under the display, the pixels in area  324  are removed. The absence of emissive material  306 - 2  and anode  306 - 1  may increase the transmittance through the display stack. Additional circuitry within thin-film transistor layer  304  may also be omitted in pixel removal area to increase transmittance. 
     Additional transmission improvements through the display stack may be obtained by selectively removing additional components from the display stack in pixel removal area  324 . As shown in  FIG.  4   , a portion of cathode  306 - 3  may be removed in pixel removal region  324 . This results in an opening  326  in the cathode  306 - 3 . Said another way, the cathode  306 - 3  may have conductive material that defines an opening  326  in the pixel removal region. Removing the cathode in this way allows for more light to pass through the display stack to sensor  13 . Cathode  306 - 3  may be formed from any desired conductive material. The cathode may be removed via etching (e.g., laser etching or plasma etching). Alternatively, the cathode may be patterned to have an opening in pixel removal region  324  during the original cathode deposition and formation steps. 
     Polyimide layers  302  may be removed in pixel removal region  324  in addition to cathode layer  306 - 3 . The removal of the polyimide layers  302  results in an opening  328  in the pixel removal region. Said another way, the polyimide layer may have polyimide material that defines an opening  328  in the pixel removal region. The polyimide layers may be removed via etching (e.g., laser etching or plasma etching). Alternatively, the polyimide layers may be patterned to have an opening in pixel removal region  324  during the original polyimide formation steps. Removing the polyimide layer  302  in pixel removal region  324  may result in additional transmittance of light to sensor  13  in pixel removal region  324 . 
     Substrate  300  may be removed in pixel removal region  324  in addition to cathode layer  306 - 3  and polyimide layer  302 . The removal of the substrate  300  results in an opening  330  in the pixel removal region. Said another way, the substrate  300  may have material (e.g., PET, PEN, etc.) that defines an opening  330  in the pixel removal region. The substrate may be removed via etching (e.g., with a laser). Alternatively, the substrate may be patterned to have an opening in pixel removal region  324  during the original substrate formation steps. Removing the substrate  300  in pixel removal region  324  may result in additional transmittance of light to sensor  13  in pixel removal region  324 . The polyimide opening  328  and substrate opening  330  may be considered to form a single unitary opening. When removing portions of polyimide layer  302  and/or substrate  300 , inorganic buffer layers  303  may serve as an etch stop for the etching step. Openings  328  and  330  may be filled with air or another desired transparent filler. 
     In addition to having openings in cathode  306 - 3 , polyimide layers  302 , and/or substrate  300 , the polarizer  312  in the display may be bleached for additional transmittance in the pixel removal region. 
       FIG.  5    is a top view of an illustrative display showing how pixel removal regions may be incorporated into the display. As shown, the display may include a plurality of pixels. In  FIG.  5   , there are a plurality of red pixels (R), a plurality of blue pixels (B), and a plurality of green pixels (G). The red, blue, and green pixels may be arranged in any desired pattern. In pixel removal areas  324 , no pixels are included in the display (even though pixels would normally be present if the normal pixel pattern was followed). 
     As shown in  FIG.  5   , display  14  may include an array of pixel removal regions  324 . Each pixel removal region  324  may have an increased transparency compared to pixel region  322 . Therefore, the pixel removal regions  324  may sometimes be referred to as transparent windows  324 , transparent display windows  324 , transparent openings  324 , transparent display openings  324 , etc. The transparent display windows may allow for light to be transmitted to an underlying sensor, as shown in  FIG.  4   . The transparency of transparent openings  324  (for visible and/or infrared light) may be greater than 25%, greater than 30%, greater than 40%, greater than 50%, greater than 60%, greater than 70%, greater than 80%, greater than 90%, etc. The transparency of transparent openings  324  may be greater than the transparency of pixel region  322 . The transparency of pixel region  322  may be less than 25%, less than 20%, less than 10%, less than 5%, etc. The pixel region  322  may sometimes be referred to as opaque display region  322 , opaque region  322 , opaque footprint  322 , etc. Opaque region  322  includes light emitting pixels R, G, and B, and blocks light from passing through the display to an underlying sensor  13 . 
     In general, the display subpixels may be partially removed from any region(s) of display  14 . Display  14  may have one or more localized regions in which the pixels are selectively removed. The display may have various local pixel removal regions physically separated from one another (e.g., a first display area with a plurality of transparent windows  324  and a second, separate display area with a plurality of transparent windows  324 ). The various local areas might for example correspond to different sensors formed underneath display  14  (e.g., a first sensor under the first display area and a second sensor under the second display area). Display  14  may include transparent windows with one or more underlying sensors along the top border of display  14 , at a corner of display  14  (e.g., a rounded corner of display  14 ), in the center portion along the top edge of the display (e.g., a notch area in the display), etc. The areas in display  14  with transparent windows  324  may have different shapes and sizes. 
     The pattern of pixels and pixel removal regions in  FIG.  5    is merely illustrative. In  FIG.  5   , the display edge may be parallel to the X axis or the Y axis. The front face of the display may be parallel to the XY plane such that a user of the device views the front face of the display in the Z direction. In  FIG.  5   , every other subpixel may be removed for each color. The resulting pixel configuration has 50% of the subpixels removed. In  FIG.  5   , the remaining pixels follow a zig-zag pattern across the display (with two green sub-pixels for every one red or blue sub-pixel). In  FIG.  5   , the sub-pixels are angled relative to the edges of the display (e.g., the edges of the sub-pixels are at non-zero, non-orthogonal angles relative to the X-axis and Y-axis). This example is merely illustrative. If desired, each individual subpixel may have edges parallel to the display edge, a different proportion of pixels may be removed for different colors, the remaining pixels may follow a different pattern, etc. 
     Removing pixels from pixel removal regions  324  may be useful for allowing light to pass through the display to sensor  13  (as discussed in connection with  FIG.  3   ). However, the absence of pixels in the pixel removal regions may be detectable to a viewer of the display. To mitigate the disruption caused by the pixel removal regions, the display may also include a diffractive layer. 
       FIG.  6    is a side view of an illustrative display with a diffractive layer. Display  14  in  FIG.  6    may have the same arrangement as the display in  FIG.  3    and  FIG.  4   . The display includes a substrate  300 , polyimide layers  302 , buffer layers  303 , TFT layers  304 , OLED layers  306 , encapsulation layers  308 , adhesive  310 , polarizer  312 , adhesive  314 , touch layers  316 , adhesive  318 , and cover glass  320 . One or more of these layers may be patterned to allow light  350  to pass through the display to an underlying sensor  13 . Pixels may be removed as shown in  FIG.  5    to allow for light to pass through to the sensor. 
     Display  14  also includes diffractive layer  332  interposed between polarizer  312  and OLED layers  306 . Diffractive layer  332  may spread the light from a pixel (e.g., formed by OLED layers  306 ) to cover one or more non-light-emitting areas adjacent to that pixel (e.g., pixel removal regions  324 ). Directing light from the pixels to the non-light-emitting areas increases a perceived resolution of the display for the viewer. Because the diffractive layer  332  effectively expands the light-emitting area of a given pixel, the diffractive layer may instead be referred to as light spreading layer  332 , pixel expansion layer  332 , pixel widening layer  332 , etc. 
     The light spreading layer  332  may use diffraction of light to create duplicate light-emitting areas (e.g., duplicate pixels) that are shifted relative to the actual light-emitting areas (e.g., actual pixels or original pixels). The duplicate pixel areas may be shifted to occupy the otherwise non-light-emitting areas to increase the apparent resolution of the display and reduce screen door effect. The diffractive layer may have diffractive structures that create the duplicate pixels using diffraction. This example is merely illustrative, and other types of pixel expansion layers may be used if desired. For example, the pixel expansion layer may be a diffusion layer that evenly spreads the light from the light-spreading area, a refractive layer with prisms or other structures to direct the light in a desired manner, etc. 
     As shown in  FIG.  6   , adhesive layers such as adhesive layers  310  and  334  may be used to secure the pixel expansion layer within the display. In the example of  FIG.  6   , a first adhesive layer  310  is interposed between encapsulation layers  308  and pixel expansion layer  332 . A second adhesive layer  334  is interposed between pixel expansion layer  332  and polarizer  312 . Adhesive layers  310  and  334  may be optically clear adhesive (OCA), liquid optically clear adhesive (LOCA), or any other desired type of adhesive. 
     Positioning diffractive layer  332  beneath polarizer  312  may mitigate reflections off of the diffractive layer from being observed by the viewer. Covering the diffractive layer  332  with polarizer  312  mitigates potential rainbow artifacts caused by the diffractive layer. 
     Herein, the term pixel may be used to refer to both a light-emitting component on a display substrate (e.g., a pixel formed from OLED layers  306  and TFT layers  304 ) or a light-emitting area on the outer surface  336  of display cover layer  320  (e.g., on the outer surface of protective layer  320 ). Light  338  may be generated by pixels formed by OLED layers  306  and TFT layers  304 . Diffractive layer  332  may then redirect some of the light to different positions at output surface  336 . The pixels at the output surface of the cover glass (sometimes referred to as the output surface of the display) therefore may have a different arrangement (e.g., different sizes, spacing, positions, etc.) than the pixels formed by OLED layers  306  due to the pixel expansion performed by pixel expansion layer  332 . 
       FIGS.  7 A- 7 D  are top views of illustrative pixels on an output surface of a display cover layer showing how a diffractive layer such as diffractive layer  332  may increase the apparent resolution of the display.  FIG.  7 A  shows pixels on the output surface of the display cover layer (e.g., the outer surface of protective layer  320 ) without diffractive layer  332  present.  FIG.  7 B  shows pixels on the output surface of the display cover layer when diffractive layer  332  is present.  FIG.  7 A  shows six pixels  70  (A, B, C, D, E, and F) arranged in a grid of two row and three columns. Without diffractive layer  332 , a dark band  72  may be formed between the pixels (due to the absence of pixels in the pixel removal regions). Dark band  72  may be present due to relatively large spacing between pixels  70 . The area of dark band  72  is not illuminated by any of the pixels and therefore appears black when viewed by a user. 
     Diffractive layer  332  may create duplicate pixels that occupy the space between the original pixels to eliminate the presence of the dark band between the pixels.  FIG.  7 B  again has six pixels  70  (A, B, C, D, E, and F) arranged in a grid on the output surface of the display cover layer. However, diffractive layer  332  creates duplicate pixels  74  that are present on the outer surface of the display cover layer in addition to pixels  70 . Diffractive layer  332  may create any desired number of duplicate pixels. In the example of  FIG.  7 B , diffractive layer  332  creates 2 duplicate pixels that are positioned on opposing sides of each original pixel. 
     Pixel A has 2 associated duplicate pixels A′, pixel B has 2 associated duplicate pixels B′, pixel C has 2 associated duplicate pixels C′, pixel D has 2 associated duplicate pixels D′, pixel E has 2 associated duplicate pixels E′, and pixel F has 2 associated duplicate pixels F′. Because pixels  70  are originally present on the display (e.g., on a display panel for the display that includes OLED layers  306  and TFT layers  304 ), pixels  70  may sometimes be referred to as original pixels (in contrast to the duplicate pixels  74  which are not present on the display panel). 
     The duplicate pixels  74  generated by diffractive layer  332  occupy the space between original pixels  70 . Thus, the gap in light-emitting area between the original pixels (band  72  from  FIG.  7 A ) is not present. The diffractive layer therefore increases the apparent resolution of the display by generating duplicate pixels to occupy the space between the original pixels on the output surface of the display cover layer. 
     In  FIG.  7 B , each duplicate pixel may be separated from its associated original pixel by a distance  76 . Distance  76  may be greater than 5 micron, greater than 10 micron, greater than 25 micron, greater than 50 micron, greater than 70 micron, greater than 100 micron, greater than 500 micron, less than 200 micron, less than 100 micron, less than 50 micron, between 20 and 100 micron, etc. Distance  76  may be tuned depending on the spacing between original pixels  70 . Distance  76  may be more than 10% of the distance between adjacent original pixels  70 , more than 30% of the distance between adjacent original pixels  70 , less than 50% of the distance between adjacent original pixels  70 , between 10% and 50% of the distance between adjacent original pixels  70 , between 20% and 40% of the distance between adjacent original pixels  70 , between 30% and 70% of the distance between adjacent original pixels  70 , etc. In  FIG.  7 B , distance  76  is selected such that the duplicate pixels occupy the non-light-emitting areas between original pixels without overlapping adjacent original pixels or adjacent duplicate pixels. However, this example merely illustrative. 
     In another embodiment, shown in  FIG.  7 C , distance  76  is selected such that the duplicate pixels occupy the non-light-emitting areas between original pixels and overlap adjacent duplicate pixels. As shown in  FIG.  7 C , each pixel again has two associated duplicate pixels. However, the duplicate pixels between each adjacent row of original pixels overlap to form one unitary duplicate pixel. For example, pixel A has 2 associated duplicate pixels A′ and pixel D has 2 associated duplicate pixels D′. However, the center-to-center spacing  76  between original pixel A and duplicate pixel A′ is approximately half of the center-to-center spacing between original pixels A and D. Similarly, the center-to-center spacing  76  between original pixel D and duplicate pixel D′ is approximately half of the center-to-center spacing between original pixels A and D. Therefore, duplicate pixels A′ and D′ overlap and may form an apparent unitary duplicate pixel A′/D′ (as shown in  FIG.  7 C ). The brightness of duplicate pixel  74  will therefore be an average of the brightness of original pixels A and D. 
     Having duplicate pixels overlap as shown in  FIG.  7 C  may be useful for equalizing the brightness of the duplicate pixels and the original pixels. The original pixel at the display panel level may have a maximum brightness. Spreading the light to cover duplicate pixels results in a lower intensity in the pixels at the outer surface of the cover glass. Specifically, the original pixel (e.g., pixel A) at the output surface of the display cover layer may have a brightness of 50% (relative to the brightness at the display panel level) and each duplicate pixel may have a brightness of 25%. The light from the pixel in the display panel is therefore spread to different areas at the outer surface of the cover glass. With an arrangement of the type shown in  FIG.  7 C , the duplicate pixels overlap and therefore have a combined brightness of 50%. This means that, across the output surface, both the original pixels and the unitary duplicate pixels may have a brightness of 50% relative to at the panel level. 
     The example in  FIGS.  7 B and  7 C  of each original pixel having 2 associated duplicate pixels is merely illustrative. Each original pixel may have more than 2 associated duplicate pixels, more than 4 associated duplicate pixels, more than 6 associated duplicate pixels, more than 8 associated duplicate pixels, more than 10 associated duplicate pixels, less than 10 associated duplicate pixels, between 4 and 10 associated duplicate pixels, 1 associated duplicate pixel, etc. The depiction of discrete duplicate pixels in  FIGS.  7 B and  7 C  is also merely illustrative. In some cases, a duplicate light-emitting area may be created by diffractive layer  332  that has a different shape than original pixel  70 . For example, a duplicate pixel may be formed by a continuous ring of light that surrounds an original pixel and duplicates the light from the original pixel. 
     In  FIG.  7 B , the light from the original pixel is spread along one-dimension (e.g., the Y-axis). This example is merely illustrative. Each original pixel may have light spread along two or more axes.  FIG.  7 D  shows an example where light from the original pixels is spread along multiple axes.  FIG.  7 D  shows four original pixels  70  (A, B, C, and D) arranged in a 2×2 grid. Diffractive layer  332  creates 8 duplicate pixels that are arranged in a grid-like pattern around each original pixel. Pixel A has 8 associated duplicate pixels A′, pixel B has 8 associated duplicate pixels B′, pixel C has 8 associated duplicate pixels C′, and pixel D has 8 associated duplicate pixels D′. Light is therefore spread along both the X-axis and Y-axis in the embodiment of  FIG.  7 D . 
     Diffractive layer  332  may be formed in a variety of different ways. In one example, shown in  FIG.  8 A , diffractive layer  332  has a first layer  82  with a varying thickness. A second layer  84  may conform to the first layer. Layer  84  has a planar upper surface in  FIG.  8 A  and therefore also has a varying thickness. Layers  82  and  84  may have different refractive indices. The difference in refractive indices may cause diffraction at the interface between layers  82  and  84  when light passes through the diffractive layer. 
     Layer  82  has first portions with a first thickness  86  and second portions with a second thickness  88 . Thickness  88  is smaller than thickness  86 , creating gaps above the second portions and between the first portions. Layer  84  fills these gaps, creating a difference in refractive index in a plane (parallel to the XY-plane) that includes both portions of layer  84  and portions of layer  82 . 
     Layers  82  and  84  may be formed from any desired material (e.g., glass, silicon, polymer, etc.). The layers may be formed from a transparent polymer material in one example (e.g., photopolymer). In some cases, layer  82  and/or  84  may be formed from a layer that has another function in the electronic device. For example, layer  82  and/or layer  84  may be an adhesive layer. Layer  84  may be formed by adhesive layer  334  in  FIG.  6   , as one example. Layer  82  may be formed by adhesive layer  310  in  FIG.  6   , in another example. One of layers  82  and  84  may be formed from air (e.g., an air gap) if desired. 
     Thicknesses  86  and  88  may each be less than 3 micron, less than 5 micron, less than 10 micron, less than 20 micron, less than 50 micron, less than 1 micron, greater than 0.1 micron, greater than 1 micron, greater than 50 micron, between 1 and 10 micron, etc. The difference between the two thicknesses may be less than 3 micron, less than 5 micron, less than 10 micron, less than 20 micron, less than 50 micron, less than 1 micron, greater than 0.1 micron, greater than 1 micron, greater than 50 micron, between 1 and 10 micron, etc. Each one of layers  82  and  84  may have a refractive index that is greater than 1.0, greater than 1.2, greater than 1.3, greater than 1.4, greater than 1.5, greater than 1.6, less than 1.7, less than 1.5, less than 1.3, between 1.1 and 1.5, etc. The difference between the refractive indices of layers  82  and  84  may be greater than 0.1, greater than 0.2, greater than 0.3, greater than 0.5, less than 0.5, less than 0.3, between 0.1 and 0.5, between 0.1, and 0.3, etc. 
     It should be noted that, in some displays, the light  338  emitted by the display panel is a different type of light than the light  350  sensed by sensor  13 . For example, the OLED layers  306  in  FIG.  6    may emit visible light (e.g., light at wavelengths between 380 nanometers and 700 nanometers). In contrast, sensor  13  may be used to sense a different type of light such as infrared light (e.g., light at wavelengths between 700 nanometers and 1 millimeter). Of course, the exact wavelengths of each different type of light may vary. In general, sensor  13  may sense light at a peak wavelength that is different (e.g., greater) than a peak wavelength of light emitted by OLED layer  306 . 
     In an embodiment where sensor  13  senses a different type of light than OLED layer  306  emits, the diffractive layer  332  may be optimized to spread light only from the OLED layers  306 . In other words, the diffractive layer  332  may be designed to spread light  338  without spreading light  350 . The materials of the diffractive layer may have an index of refraction difference at visible wavelengths (e.g., a difference greater than 0.1, greater than 0.2, greater than 0.3, greater than 0.5, less than 0.5, less than 0.3, between 0.1 and 0.5, between 0.1, and 0.3, etc.) while having little to no index of refraction difference (e.g., a difference less than 0.1, less than 0.05, less than 0.01, etc.) at infrared wavelengths. As a result, the diffractive layer spreads the visible light from the OLED display panel without significantly affecting the infrared light passing through the display to sensor  13 . The materials in the diffractive layer  332  may use dispersion to achieve the wavelength-dependent refractive index difference. 
     Each portion of layer  82  with thickness  86  may sometimes be referred to as a diffractive element or diffractive structure. The repeating diffractive elements may be separated by pitch  90 . Pitch  90  may be less than 5 micron, less than 10 micron, less than 15 micron, less than 20 micron, less than 50 micron, less than 100 micron, greater than 1 micron, greater than 5 micron, greater than 10 micron, greater than 15 micron, greater than 20 micron, between 1 and 20 micron, between 5 and 10 micron, between 1 and 10 micron, between 1 and 5 micron, etc. Adhesive layers may be formed on either side of the diffractive layer of  FIG.  8 A . 
     As shown in  FIG.  8 B , the thicker portions of layer  82  extend in strips across the diffractive layer. The strips of layer  82  are separated by strips of layer  84  (e.g., a strip of layer  84  is interposed between each pair of adjacent strips of layer  82 ). With this type of arrangement, light may be spread in the positive and negative Y-direction (e.g., to create two duplicate pixels on either side of an original pixel as shown in  FIG.  7 C ). 
     It should be understood that diffractive layer  332  as shown in  FIG.  8 A  is formed over regions of the display with transparent openings  324  (e.g., as in  FIG.  5   ). In areas of the display without any transparent openings  324 , the display may have a full resolution of original pixels. Creating duplicate pixels to occupy non-light emitting areas associated with the transparent openings is therefore not necessary. Accordingly, in areas of the display that do not include transparent windows, one or more layers of the diffractive layer may optionally be omitted, may have a uniform thickness to prevent formation of diffractive elements, etc. In general, the diffractive layer may be designed to include diffractive elements for spreading light over areas of the display with transparent openings and to not include diffractive elements for spreading light over areas of the display without transparent openings. 
     The example of  FIGS.  8 A and  8 B  are merely illustrative. In another possible arrangement, diffractive layer  332  may be formed from a single layer that has a varying index of refraction within the XY-plane. The diffractive layer may also have a gradual thickness change instead of a thickness step change as in  FIG.  8 A .  FIG.  9 A  is a cross-sectional side view of an illustrative diffractive layer with a gradual thickness change. As shown in  FIG.  9 A , the thickness of layer  82  may vary in a curved pattern (sometimes referred to as a serpentine pattern, sinusoidal pattern, or wavy pattern) in the Y-direction. 
     The materials, refractive indices, thicknesses, and pitch magnitudes in  FIG.  9 A  may be the same as in  FIG.  8 A , but with a gradual thickness change between the thicknesses  86  and  88  in  FIG.  9 A  instead of a step change as in  FIG.  8 A . Each protruding portion of layer  82  with maximum thickness  86  may sometimes be referred to as a diffractive element  100  or diffractive structure. The repeating diffractive elements may be separated by pitch  90 . As shown in  FIG.  9 B , the diffractive elements  100  extend in strips across the diffractive layer. With this type of arrangement, light may be spread in the positive and negative Y-direction (e.g., to create two duplicate pixels on either side of an original pixel as shown in  FIG.  7 C ). 
     The example of the diffractive layer having a thickness that varies in only one direction (as in  FIG.  8 A  and  FIG.  9 A ) is merely illustrative. Alternatively, the diffractive layer  332  may have a layer with a varying thickness in two directions (e.g., in both the X-direction and Y-direction) in order to spread light in two directions (as in  FIG.  7 D , for example). The diffractive layer  332  may also have diffractive elements that extend parallel to the Y-axis instead of the X-axis (and therefore spread light in the X-direction). In yet another embodiment, the diffractive elements  100  may extend at an angle relative to the edge of the display (e.g., a non-zero, non-orthogonal angle relative to the X-axis in  FIG.  9 B ). The diffractive elements  100  may extend at a 45° angle or some other desired angle relative to the edge of the display. 
     The pitch  90  of the diffractive elements may be optimized for a particular wavelength of light. For example, the pitch  90  may be optimized to spread green light. Green light may have a wavelength of approximately (e.g., +/−5%) 550 nanometers. The diffractive elements may be optimized for green light because the human eye is most sensitive to green light. 
       FIG.  10    is a top view of the illustrative display of  FIG.  5    covered by the diffractive layer of  FIGS.  9 A and  9 B . As shown, duplicate pixels  74  may be formed between the original pixels  70 . For example, a duplicate green pixel G′ is formed from two duplicate versions of the original green pixel on either side of G (similar to as in  FIG.  7 C ). In this way, the pixel pattern has the same arrangement on the outer surface of the display as it would without the pixel removal regions. 
     The pixel pattern on the outer surface of the display is therefore uniform between areas with the pixel removal regions and areas without the pixel removal regions. For example, a portion of the display cover layer overlapping an area of the display panel without pixel removal regions may have a first resolution (associated with the full resolution of the display panel). A different portion of the display cover layer overlapping an area of the display with pixel removal regions may also have the first resolution (even though the overlapped portion of the display panel has a second resolution that is lower than the first resolution) due to the presence of the diffractive layer. Portions of the cover layer overlapping and not overlapping pixel removal regions may ultimately have the same pixel pattern (e.g., as shown in  FIG.  10   ). However, in portions of the cover layer not overlapping pixel removal regions the pattern is of all original pixels from the display panel. In portions of the cover layer overlapping pixel removal regions the pattern is of some original pixels and some duplicate pixels. 
     Incorporating pixel removal regions having an increased transparency relative to the rest of the display is one way to increase the amount of light received by a sensor underneath the display. Another possibility to increase the amount of light received by the sensor is include a lens layer with one or more lenses that focus light onto the pixel removal regions. 
       FIG.  11    is a side view of an illustrative display with a lens layer. Display  14  in  FIG.  11    may have the same arrangement as the display in  FIG.  3    and  FIG.  4   . The display includes a substrate  300 , polyimide layers  302 , buffer layers  303 , TFT layers  304 , OLED layers  306 , encapsulation layers  308 , adhesive  310 , polarizer  312 , adhesive  314 , touch layers  316 , adhesive  318 , and cover glass  320 . One or more of these layers may be patterned to allow light  350  to pass through the display to an underlying sensor  13 . Pixels may be removed as shown in  FIG.  5    to allow for light to pass through to the sensor. 
     Display  14  also includes lens layer  340  interposed between polarizer  312  and OLED layers  306 . Lens layer  340  (sometimes referred to as lens array  340 , light focusing layer  340 , etc.) may include one or more lenses (sometimes referred to as microlenses or lens elements) that focus ambient light onto the transparent windows in the display (e.g., pixel removal regions  324 ). Focusing light onto the transparent windows increases the amount of light received by sensor  13 . The light focusing layer  340  may use refraction of light to focus light onto transparent windows in the display panel. 
     Positioning lens layer  340  beneath polarizer  312  may mitigate reflections off of the lens layer from being observed by the viewer. Covering the lens layer  340  with polarizer  312  mitigates potential rainbow artifacts caused by the lens layer. 
       FIG.  12    is a side view showing an illustrative lens layer. As shown, lens layer  340  is formed over display panel  400  (which includes one or more of substrate  300 , polyimide layers  302 , buffer layers  303 , TFT layers  304 , OLED layers  306 , and encapsulation layers  308 ). Similar to as discussed in connection with  FIG.  4   , display panel  400  has pixel regions  322  and one or more pixel removal regions  324  (transparent windows) having a higher transparency than pixel regions  322 . Lens array  340  may focus light onto the transparent windows  324 . 
     As shown, lens array  340  may include a first layer  382  with a varying thickness. A second layer  384  may conform to the first layer. Layer  384  has a planar upper surface in  FIG.  12    and therefore also has a varying thickness. Layers  382  and  384  may have different refractive indices. The difference in refractive indices may cause refraction at the interface between layers  382  and  384  when light passes through the lens layer. 
     Layer  382  has a plurality of lenses  392  formed by protruding portions of layer  382 . Layer  382  may have a maximum thickness  386  at the peak of each lens  392  and may have a minimum thickness  388  between each lens  392 . Layer  384  fills the area between each lens  392 , creating a difference in refractive index in a plane (parallel to the XY-plane) that includes both portions of layer  384  and portions of layer  382 . 
     Layers  382  and  384  may be formed from any desired material (e.g., glass, silicon, polymer, etc.). The layers may be formed from a transparent polymer material in one example (e.g., photopolymer). In some cases, layer  382  and/or  384  may be formed from a layer that has another function in the electronic device. For example, layer  382  and/or layer  384  may be an adhesive layer. Layer  384  may be formed by adhesive layer  334  in  FIG.  11   , as one example. Layer  382  may be formed by adhesive layer  310  in  FIG.  11   , in another example. One of layers  382  and  384  may be formed from air (e.g., an air gap) if desired. 
     Thicknesses  386  and  388  may each be less than 3 micron, less than 5 micron, less than 10 micron, less than 20 micron, less than 50 micron, less than 100 micron, less than 75 micron, less than 1 micron, greater than 0.1 micron, greater than 1 micron, greater than 25 micron, greater than 50 micron, greater than 75 micron, between 1 and 10 micron, etc. The difference between the two thicknesses may be less than 3 micron, less than 5 micron, less than 10 micron, less than 20 micron, less than 50 micron, less than 1 micron, greater than 0.1 micron, greater than 1 micron, greater than 50 micron, between 1 and 10 micron, etc. Each one of layers  382  and  384  may have a refractive index that is greater than 1.0, greater than 1.2, greater than 1.3, greater than 1.4, greater than 1.5, greater than 1.6, less than 1.7, less than 1.5, less than 1.3, between 1.1 and 1.5, etc. The difference between the refractive indices of layers  382  and  384  may be greater than 0.1, greater than 0.2, greater than 0.3, greater than 0.5, less than 0.5, less than 0.3, between 0.1 and 0.5, between 0.1, and 0.3, etc. 
     In displays where the light  338  emitted by the display panel is a different type of light than the light  350  sensed by sensor  13 , the lens layer  340  may be optimized to focus light  350  without affecting light emitted from the display panel. The materials of the lens layer may have an index of refraction difference at infrared wavelengths (e.g., a difference greater than 0.1, greater than 0.2, greater than 0.3, greater than 0.5, less than 0.5, less than 0.3, between 0.1 and 0.5, between 0.1, and 0.3, etc.) while having little to no index of refraction difference (e.g., a difference less than 0.1, less than 0.05, less than 0.01, etc.) at visible wavelengths. As a result, the lens layer focuses the infrared light through transparent windows  324  to sensor  13  without significantly affecting the visible light  338  emitted by display panel  400 . The materials in the lens layer  340  may use dispersion used to achieve the wavelength-dependent refractive index difference. 
     Lenses  392  may be separated by pitch  390 . Pitch  390  may be less than 5 micron, less than 10 micron, less than 15 micron, less than 20 micron, less than 50 micron, less than 100 micron, greater than 1 micron, greater than 5 micron, greater than 10 micron, greater than 15 micron, greater than 20 micron, greater than 50 micron, greater than 75 micron, greater than 100 micron, between 20 and 100 micron, between 30 and 70 micron, between 1 and 20 micron, between 5 and 10 micron, between 1 and 10 micron, between 1 and 5 micron, etc. Adhesive layers may be formed on either side of the lens layer of  FIG.  12   . 
     It should be understood that lens layer  340  as shown in  FIG.  12    is formed over regions of the display with transparent openings  324 . In areas of the display without any transparent openings  324 , a lens layer for focusing light into transparent openings is not necessary. Accordingly, in areas of the display that do not include transparent windows, one or more layers of the lens layer may optionally be omitted, may have a uniform thickness to prevent formation of lenses, etc. In general, the lens layer may be designed to include lenses for focusing light over areas of the display with transparent openings and to not include lenses for focusing light over areas of the display without transparent openings. 
       FIG.  13    is a top view of a display with a lens layer of the type shown in  FIG.  12   . As shown, each transparent window  324  may be covered by a respective lens  392  of lens layer  340 . The lenses may have circular outlines when viewed from above (as shown in  FIG.  13   ). This example is merely illustrative. The lenses may have outlines of other shapes when viewed from above if desired. The lenses may have a spherical upper surface of upper surface of another desired shape/curvature. The lenses may use refraction to focus light onto the underlying transparent windows  324 . 
       FIG.  14    is a side view of an illustrative display that includes both a diffractive layer  332  and a lens layer  340 . Adhesive layers  310 ,  334 , and  342  may be used to secure layers  332  and  340  within the display stack. The display may include both layers  332  and  340  to optimize the emission of display light  338  and the sensing of light  350 . Layer  332  may selectively spread display light  338  without affecting light  350  that passes through to sensor  13 . Layer  340  may focus light  350  onto sensor  13  without affecting display light  338 . Layer  332  may be formed from materials that are approximately index-matched at a first wavelength (e.g., an infrared wavelength) and that have an index of refraction difference at a second wavelength (e.g., a visible wavelength). Layer  340  may be formed from materials that are approximately index-matched at a first wavelength (e.g., a visible wavelength) and that have an index of refraction difference at a second wavelength (e.g., an infrared wavelength). 
     As described above, one aspect of the present technology is the gathering and use of information such as information from input-output devices. The present disclosure contemplates that in some instances, data may be gathered that includes personal information data that uniquely identifies or can be used to contact or locate a specific person. Such personal information data can include demographic data, location-based data, telephone numbers, email addresses, twitter ID&#39;s, home addresses, data or records relating to a user&#39;s health or level of fitness (e.g., vital signs measurements, medication information, exercise information), date of birth, username, password, biometric information, or any other identifying or personal information. 
     The present disclosure recognizes that the use of such personal information, in the present technology, can be used to the benefit of users. For example, the personal information data can be used to deliver targeted content that is of greater interest to the user. Accordingly, use of such personal information data enables users to calculated control of the delivered content. Further, other uses for personal information data that benefit the user are also contemplated by the present disclosure. For instance, health and fitness data may be used to provide insights into a user&#39;s general wellness, or may be used as positive feedback to individuals using technology to pursue wellness goals. 
     The present disclosure contemplates that the entities responsible for the collection, analysis, disclosure, transfer, storage, or other use of such personal information data will comply with well-established privacy policies and/or privacy practices. In particular, such entities should implement and consistently use privacy policies and practices that are generally recognized as meeting or exceeding industry or governmental requirements for maintaining personal information data private and secure. Such policies should be easily accessible by users, and should be updated as the collection and/or use of data changes. Personal information from users should be collected for legitimate and reasonable uses of the entity and not shared or sold outside of those legitimate uses. Further, such collection/sharing should occur after receiving the informed consent of the users. Additionally, such entities should consider taking any needed steps for safeguarding and securing access to such personal information data and ensuring that others with access to the personal information data adhere to their privacy policies and procedures. Further, such entities can subject themselves to evaluation by third parties to certify their adherence to widely accepted privacy policies and practices. In addition, policies and practices should be adapted for the particular types of personal information data being collected and/or accessed and adapted to applicable laws and standards, including jurisdiction-specific considerations. For instance, in the United States, collection of or access to certain health data may be governed by federal and/or state laws, such as the Health Insurance Portability and Accountability Act (HIPAA), whereas health data in other countries may be subject to other regulations and policies and should be handled accordingly. Hence different privacy practices should be maintained for different personal data types in each country. 
     Despite the foregoing, the present disclosure also contemplates embodiments in which users selectively block the use of, or access to, personal information data. That is, the present disclosure contemplates that hardware and/or software elements can be provided to prevent or block access to such personal information data. For example, the present technology can be configured to allow users to select to “opt in” or “opt out” of participation in the collection of personal information data during registration for services or anytime thereafter. In another example, users can select not to provide certain types of user data. In yet another example, users can select to limit the length of time user-specific data is maintained. In addition to providing “opt in” and “opt out” options, the present disclosure contemplates providing notifications relating to the access or use of personal information. For instance, a user may be notified upon downloading an application (“app”) that their personal information data will be accessed and then reminded again just before personal information data is accessed by the app. 
     Moreover, it is the intent of the present disclosure that personal information data should be managed and handled in a way to minimize risks of unintentional or unauthorized access or use. Risk can be minimized by limiting the collection of data and deleting data once it is no longer needed. In addition, and when applicable, including in certain health related applications, data de-identification can be used to protect a user&#39;s privacy. De-identification may be facilitated, when appropriate, by removing specific identifiers (e.g., date of birth, etc.), controlling the amount or specificity of data stored (e.g., collecting location data at a city level rather than at an address level), controlling how data is stored (e.g., aggregating data across users), and/or other methods. 
     Therefore, although the present disclosure broadly covers use of information that may include personal information data to implement one or more various disclosed embodiments, the present disclosure also contemplates that the various embodiments can also be implemented without the need for accessing personal information data. That is, the various embodiments of the present technology are not rendered inoperable due to the lack of all or a portion of such personal information data. 
     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: 20210322
Publication Date: 20240806
Grant Date: 20240806
Priority Date: 20200528
Inventors: CUI, Yue
QIAO, YI
GUILLOU, Jean-Pierre S.
XU, MING
GETTEMY, SHAWN R.
Assignee: APPLE INC
CPC Classifications: [{"code": "H10K59/40", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02B5/3025", "inventive": true, "first": false, "tree": "[]"}, {"code": "H10K59/65", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B27/4205", "inventive": true, "first": false, "tree": "[]"}, {"code": "H10K59/12", "inventive": true, "first": true, "tree": "[]"}, {"code": "H10K59/40", "inventive": false, "first": false, "tree": "[]"}, {"code": "H10K59/12", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B5/3025", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B27/4205", "inventive": true, "first": false, "tree": "[]"}, {"code": "H10K59/65", "inventive": true, "first": true, "tree": "[]"}, {"code": "H10K59/40", "inventive": false, "first": false, "tree": "[]"}, {"code": "H10K59/12", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B27/4205", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B5/3025", "inventive": true, "first": false, "tree": "[]"}, {"code": "H10K59/65", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 92121087