Abstract: An electronic display may include an ambient light sensor (ALS) located beneath an active area to sense ambient light above the active area. The ALS may have multiple response channels to perform fast sensing integration, which is synchronized with blanking periods of a pixel on the active area. An emission mask and a heat map may be generated for the ALS and used to generate a calibrated heat map for the ALS. The calibrated heat map of the ALS is used with display content to calculate a crosstalk compensation for the ALS.

Abstract: An electronic device may include a housing and relative humidity sensor in the housing. The relative humidity sensor may include a relative humidity-sensitive layer, a light emitter that emits light into the relative humidity-sensitive layer, and a light detector that detects light that has passed through the relative humidity-sensitive layer. The relative humidity may be determined based on the detected light. For example, the light may be measured interferometrically to determine a path length of the light to determine the relative humidity. Alternatively, the light may be scattered by plasmonic nanoparticles in a relative humidity-sensitive material to determine the relative humidity. As other examples, polarized light may pass through the relative humidity-sensitive layer and measured to determine the relative humidity, or light may be used to form sound waves that may be measured to determine the relative humidity.

Abstract: An electronic device may include a housing and relative humidity sensor in the housing. The relative humidity sensor may include an optical layer, a relative humidity-sensitive layer coupled to a surface of the optical layer, a light emitter that emits light into the optical layer, and a light detector that detects light that has reflected within the optical layer and off of the relative humidity-sensitive layer. The relative humidity may be determined based on the light detected by the light detector. The optical layer may be a layer with angled edges, a prism, a Bragg reflector, or a waveguide. A reference light detector and/or a temperature sensor may be included in the relative humidity sensor, and measurements from these additional sensors may be used in determining the relative humidity. In this way, an optical relative humidity sensor may be formed in the electronic device.

Abstract: Ambient light sensor modules may be formed using a wafer-level process in which a filter and a diffuser are stacked on a silicon substrate or a combination substrate that includes multiple photosensors. The stack may be diced, filled with opaque material, and diced again to form multiple ambient light sensor modules. The resulting modules may include a silicon substrate with a photosensor and through-silicon vias, a filter on the silicon substrate, and a diffuser coupled to the filter. There may be an air gap between a portion of the diffuser and the photosensor. The air gap may be formed from a recess in the diffuser or from spacers between the filter and the diffuser. Alternatively, the diffuser may be applied as a coating on the filter. By forming the ambient light sensor modules at the wafer level, the modules may have smaller footprints and/or volumes.

Abstract: A head-mounted device may have a gaze tracking system and an optical sensor. The gaze tracking system may include a camera, ambient light sensor, or other optical sensor to determine an angle/direction of a user's gaze. The optical sensor may be a camera, directional color ambient light sensor, or other optical sensor. After determining the user's gaze, the optical sensor may be used to determine the color of an external object in the direction of the determined angle/direction. For example, the color of the external object may be determined in response to an input from the user, such as a button press, a voice command, or a blink. The determined color may be used as an input color in a virtual space or on another device.

Abstract: An electronic device may be attached to an external item. The electronic device may include an optical identification sensor configured to sense a color-encoded tag in the external item when the item is attached to the device. The optical identification sensor may include a board layer, a protective filter layer, wall structures for supporting the protective filter layer on the board layer, a linear array of photodetectors disposed between the board layer and the protective filter layer, a field-of-view restriction filter interposed between the photodetectors and the protective filter layer, and a light source having multiple emitters for illuminating the color-encoded tag. The emitters may be activated sequentially to produce multiple images that are combined to reconstruct an accurate reading of the color-encoded tag, which can then be used to identify the type of external item currently attached to the electronic device.

Abstract: An electronic device may include an ambient light sensor or other semiconductor sensor. The sensor may produce signals in response to light incident on the electronic device and therefore incident on the sensor. In some cases, components within the electronic device, such as infrared components, or external light sources may interfere with the operation of the sensor. Therefore, the sensor may include a filter that transmits at least a portion of visible light while blocking infrared light. Because light may be incident on the electronic device from a variety of angles, a diffuser in the sensor may scatter the light into a desired angular distribution. To ensure that infrared light is blocked regardless of the angle of the incident light, the filter may include both thin-film dielectric layers and metal layers. The metal layers may be interleaved with the thin-film dielectric layers.

Abstract: An electronic device may be attached to an external item. The electronic device may include an optical identification sensor configured to sense a color-encoded tag in the external item when the item is attached to the device. The optical identification sensor may include a board layer, a protective filter layer, wall structures for supporting the protective filter layer on the board layer, a linear array of photodetectors disposed between the board layer and the protective filter layer, a field-of-view restriction filter interposed between the photodetectors and the protective filter layer, and a light source having multiple emitters for illuminating the color-encoded tag. The emitters may be activated sequentially to produce multiple images that are combined to reconstruct an accurate reading of the color-encoded tag, which can then be used to identify the type of external item currently attached to the electronic device.

Abstract: An electronic device may have a display. The display may have light-emitting diode pixels or other pixels. Due to aging-induced degradation of the pixels, the output intensity and color of the pixels may vary over the lifetime of the display. Control circuitry in the device may use an ambient light sensor to measure ambient light and stray display light. The display light measurements may be used in monitoring aging effects so that the control circuitry can compensate for aging-induced pixel degradation. Display light measurements may be made over a sequence of image frames. The image frames in the sequence of frames may include white and black frames or frames of different colors interleaved with black frames. Different frame intensities may be used during measurements of stray display light to gather gamma curves for the display.

Abstract: An electronic device may be attached to an external item. The electronic device may include an optical identification sensor configured to sense a color-encoded tag in the external item when the item is attached to the device. The optical identification sensor may include a board layer, a protective filter layer, wall structures for supporting the protective filter layer on the board layer, a linear array of photodetectors disposed between the board layer and the protective filter layer, a field-of-view restriction filter interposed between the photodetectors and the protective filter layer, and a light source having multiple emitters for illuminating the color-encoded tag. The emitters may be activated sequentially to produce multiple images that are combined to reconstruct an accurate reading of the color-encoded tag, which can then be used to identify the type of external item currently attached to the electronic device.

Abstract: An electronic device may have a display with an array of pixels configured to display images for a user. The electronic device may have an ambient light sensor for gathering ambient light information. A set of the pixels may overlap the ambient light sensor so that ambient light measurements may be made on ambient light passing through the set of pixels. Control circuitry in the electronic device may control light transmission through the set of pixels so that different light transmission levels can be used in different ambient light conditions. Directional light measurements may be made by moving transparent pixels dynamically across the surface of the display overlapping the light sensor and/or by using pixelated light modulators to vary the angle of light rays measured by the ambient light sensor.

Abstract: An electronic device has pixels that form an active area of a display for displaying images for a user. A layer of black ink or other opaque material may be formed on an inner surface of a display cover layer in an inactive area of the display that does not overlap pixels. The housing may have sidewalls such as a rear housing wall that faces away from the display. Ambient light sensor windows may be formed from tapered holes or other holes. The tapered holes may be formed in the opaque material on the display cover layer, may be formed in a rear housing wall or other hosing structure, or may be formed in other portions of the electronic device. Non-tapered holes may also form windows. Tapered holes may have sidewalls with portions that run parallel to their longitudinal axes and portions that are angled relative to their longitudinal axes.

Abstract: An electronic device may be attached to an external item. The electronic device may include an optical identification sensor configured to sense a color-encoded tag in the external item when the item is attached to the device. The optical identification sensor may include a board layer, a protective filter layer, wall structures for supporting the protective filter layer on the board layer, a linear array of photodetectors disposed between the board layer and the protective filter layer, a field-of-view restriction filter interposed between the photodetectors and the protective filter layer, and a light source having multiple emitters for illuminating the color-encoded tag. The emitters may be activated sequentially to produce multiple images that are combined to reconstruct an accurate reading of the color-encoded tag, which can then be used to identify the type of external item currently attached to the electronic device.

Abstract: An electronic device may include sensors such as a visible-light image sensor for capturing images. The sensors may also include optical sensors that operate at other wavelengths. An infrared light sensor may be used to gather an infrared light spectrum of a target object. The infrared light sensor may have a beam steerer and other adjustable components such as adjustable lenses and adjustable polarizers. During operation, an infrared beam emitted by the infrared light sensor may be steered onto the target object using information from a captured visible-light image and/or other sensor data such as distance sensor data, orientation sensor data, three-dimensional image sensor data, and data from other sensors. Infrared spectra, visible-light camera images, and/or data from other sensors may be used in characterizing target objects so that notifications can be provided to a user and other actions taken.

Abstract: An electronic device has pixels that form an active area of a display for displaying images for a user. A layer of black ink or other opaque material may be formed on an inner surface of a display cover layer in an inactive area of the display that does not overlap pixels. The housing may have sidewalls such as a rear housing wall that faces away from the display. Ambient light sensor windows may be formed from tapered holes or other holes. The tapered holes may be formed in the opaque material on the display cover layer, may be formed in a rear housing wall or other hosing structure, or may be formed in other portions of the electronic device. Non-tapered holes may also form windows. Tapered holes may have sidewalls with portions that run parallel to their longitudinal axes and portions that are angled relative to their longitudinal axes.

Abstract: An electronic device has pixels that form an active area of a display for displaying images for a user. A layer of black ink or other opaque material may be formed on an inner surface of a display cover layer in an inactive area of the display that does not overlap pixels. The housing may have sidewalls such as a rear housing wall that faces away from the display. Ambient light sensor windows may be formed from tapered holes or other holes. The tapered holes may be formed in the opaque material on the display cover layer, may be formed in a rear housing wall or other hosing structure, or may be formed in other portions of the electronic device. Non-tapered holes may also form windows. Tapered holes may have sidewalls with portions that run parallel to their longitudinal axes and portions that are angled relative to their longitudinal axes.

Abstract: An electronic device may include sensors such as a visible-light image sensor for capturing images. The sensors may also include optical sensors that operate at other wavelengths. An infrared light sensor may be used to gather an infrared light spectrum of a target object. The infrared light sensor may have a beam steerer and other adjustable components such as adjustable lenses and adjustable polarizers. During operation, an infrared beam emitted by the infrared light sensor may be steered onto the target object using information from a captured visible-light image and/or other sensor data such as distance sensor data, orientation sensor data, three-dimensional image sensor data, and data from other sensors. Infrared spectra, visible-light camera images, and/or data from other sensors may be used in characterizing target objects so that notifications can be provided to a user and other actions taken.

Abstract: An electronic device may have a display. The display may have light-emitting diode pixels or other pixels. Due to aging-induced degradation of the pixels, the output intensity and color of the pixels may vary over the lifetime of the display. Control circuitry in the device may use an ambient light sensor to measure ambient light and stray display light. The display light measurements may be used in monitoring aging effects so that the control circuitry can compensate for aging-induced pixel degradation. Display light measurements may be made over a sequence of image frames. The image frames in the sequence of frames may include white and black frames or frames of different colors interleaved with black frames. Different frame intensities may be used during measurements of stray display light to gather gamma curves for the display.

Abstract: An electronic device may have a display with an array of pixels that display images for a user. The electronic device may have an ambient light sensor for gathering ambient light information. A subset of the pixels in the array of pixels may overlap the ambient light sensor so that ambient light passing through the subset of pixels may be measured. Each pixel may have an emission enable transistor coupled in series with a light-emitting diode. Control circuitry in the electronic device may disable the subset of pixels to reduce stray light during ambient light measurements while enabling remaining pixels in the array of pixels to display an image. Ambient light sensor circuitry may gather ambient light sensor measurements over one or more periods by using transfer transistors to transfer change from the photodetectors to charge storage capacitors formed from floating diffusions in a common substrate.

Abstract: An electronic device has pixels that form an active area of a display for displaying images for a user. A layer of black ink or other opaque material may be formed on an inner surface of a display cover layer in an inactive area of the display that does not overlap pixels. The housing may have sidewalls such as a rear housing wall that faces away from the display. Ambient light sensor windows may be formed from tapered holes or other holes. The tapered holes may be formed in the opaque material on the display cover layer, may be formed in a rear housing wall or other hosing structure, or may be formed in other portions of the electronic device. Non-tapered holes may also form windows. Tapered holes may have sidewalls with portions that run parallel to their longitudinal axes and portions that are angled relative to their longitudinal axes.