Abstract: An electronic device may have a display with a cover layer. An ambient light sensor may be aligned with an ambient light sensor window formed from an opening in a masking layer on the cover layer in an inactive portion of the display. To help mask the ambient light sensor window from view, the ambient light sensor window may be provided with a black coating that matches the appearance of surrounding masking layer material while allowing light to reach the ambient light sensor. The black coating may be formed from a black physical vapor deposition thin-film inorganic layer with a high index of refraction. An antireflection layer formed from a stack of dielectric layers may be interposed between the black thin-film inorganic layer and the display cover layer.

Abstract: An electronic device may have a display with a cover layer. An ambient light sensor may be aligned with an ambient light sensor window formed from an opening in a masking layer on the cover layer in an inactive portion of the display. To help mask the ambient light sensor window from view, the ambient light sensor window may be provided with a black coating that matches the appearance of surrounding masking layer material while allowing light to reach the ambient light sensor. The black coating may be formed from a black physical vapor deposition thin-film inorganic layer with a high index of refraction. An antireflection layer formed from a stack of dielectric layers may be interposed between the black thin-film inorganic layer and the display cover layer.

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

Abstract: An electronic device may be provided with a display mounted in a housing. A color sensing ambient light sensor may measure the color of ambient light. The color sensing ambient light sensor may produce sensor output signals in a device-dependent color space. Control circuitry in the electronic device may convert the sensor output signals from the device-dependent color space to a device-independent color space using a color converting matrix. The color converting matrix may be determined using stored training data. The training data may include color data for different training light sources. The training data may be weighted to selectively control the influence of the training data on the color converting matrix. The training data may be weighted based on a distance between the training color data and a target color in the detected ambient light.

Abstract: An electronic device may be provided with one or more light-sensing components such as a camera and a color ambient light sensor. Optical structures such as camera lenses or a light pipe may be used to convey light from a window in an electronic device to a light-sensing component. One or more infrared-light-blocking-and-visible-light transmitting light filters may be interposed between a light-receiving window in an electronic device and a light-sensing component. The light filters may include infrared-light-blocking glass substrates, silver or other infrared-light-blocking thin films, and/or thin-film interference filters formed from stacks of dielectric layers that serve as infrared light-blocking layers.

Abstract: An electronic device may be provided with a display mounted in a housing. An ambient light sensor may measure the color of ambient light through an ambient light sensor window in the display. The ambient light sensor may have an array of light detectors on a semiconductor die. The light detectors may include color matching function light detectors that have spectral sensitivity profiles that match standard observer color matching functions and may include spectral sensing light detectors. The spectral sensing light detectors may have narrower full width at half maximum bandwidths than the color matching function light detectors and may be used with the color matching function light detectors to measure an ambient light spectrum. The color matching function light detectors may be used to measure the color of ambient light.

Abstract: An electronic device may be provided with a display mounted in a housing. A directional ambient light sensor may measure the intensity and direction of ambient light. The ambient light sensor may be mounted in alignment with a light sensor window formed in an inactive area of the display. The ambient light sensor may be formed from detectors on a semiconductor substrate. Incident light angle restriction structures may define openings for each detector. Each opening may be configured to allow light with a different range of angle of incidence values to be passed to a respective one of the detectors. The ranges of acceptance angle for adjacent detectors may overlap. A sensor may produce a diffuse light reading by processing ambient light data from a diffuse light detector and a directional light detector. The diffuse and directional light detectors may be formed on a common semiconductor substrate.

Abstract: An electronic device display may have an active area with an array of pixels and an inactive area. A light-transmitting window may be formed in the inactive area. A light-sensing component such as an ambient light sensor may be mounted within the housing in alignment with the window. Opaque masking material may be provided on one or more layers of the display in the inactive area and may have an opening for the window. Backlight structures in the display may generate backlight illumination for pixels in the active area. Stray portions of the backlight illumination may be blocked using a stray light absorption layer on one of the layers of the display such as a layer other than the layer on which the opaque masking material is formed. The stray light absorption layer may have an opening aligned with the window.

Abstract: An electronic device may have a housing in which a display is mounted. The display may have an active area in which images are displayed by an array of pixels and an inactive area that is free of pixels. A color ambient light sensor may make color and luminance measurements on ambient light received through an ambient light sensor window in the inactive area of the display or elsewhere in the electronic device. The color ambient light sensor may have color ambient light sensor elements of different colors. The ambient light sensor elements may extend in a row along an edge of the display or may have other configurations. Analog-to-digital converter circuitry and switching circuitry may gather color ambient light sensor measurements and measurements indicative of whether or not the color ambient light sensor has been obscured by an external object from the light sensor elements.

Abstract: A control computer for a magnetic resonance imaging system has an analog-to-digital conversion array, a multiplexer array connected to the analog-to-digital conversion array, and a control module that receives at least one input signal via the multiplexer array and the analog-to-digital conversion array. A signal processing board for a magnetic resonance imaging system has a substrate with the aforementioned components thereon that form the aforementioned control computer.

Abstract: An electronic device may have a display with a transparent layer such as a cover layer. An ambient light sensor may be aligned with an ambient light sensor window formed from an opening in a masking layer on the transparent layer in an inactive portion of the display. To help mask the ambient light sensor window from view, the ambient light sensor window may be provided with a black coating that matches the appearance of surrounding masking layer material while allowing light to reach the ambient light sensor. The black coating may include multiple pigments and may have a flat spectrum to enhance color ambient light measurements made with the ambient light sensor. The black coating may include a polymer binder or other binder that contains multiple pigments. The pigments may include a black pigment, a blue pigment, and an infrared-light-transparent pigment and/or other pigments.

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

Abstract: An electronic device may have a display with a cover layer. An ambient light sensor may be aligned with an ambient light sensor window formed from an opening in a masking layer on the cover layer in an inactive portion of the display. To help mask the ambient light sensor window from view, the ambient light sensor window may be provided with a black coating that matches the appearance of surrounding masking layer material while allowing light to reach the ambient light sensor. The black coating may be formed from a black physical vapor deposition thin-film inorganic layer with a high index of refraction. An antireflection layer formed from a stack of dielectric layers may be interposed between the black thin-film inorganic layer and the display cover layer.

Abstract: An electronic device display may have an active area with an array of pixels and an inactive area. A light-transmitting window may be formed in the inactive area. A light-sensing component such as an ambient light sensor may be mounted within the housing in alignment with the window. Opaque masking material may be provided on one or more layers of the display in the inactive area and may have an opening for the window. Backlight structures in the display may generate backlight illumination for pixels in the active area. Stray portions of the backlight illumination may be blocked using a stray light absorption layer on one of the layers of the display such as a layer other than the layer on which the opaque masking material is formed. The stray light absorption layer may have an opening aligned with the window.

Abstract: In an RF power calculation apparatus and method for an MRI system, a first power calculation processor calculates a first power of an RF signal received by a first receiving method, a second power calculation processor calculates a second power of the RF signal received by a second receiving method, a difference calculation processor calculates the difference between the first power and second power, an RF power calculation processor calculates an RF power of the RF signal on the basis of the first power and second power when the difference is smaller than a first threshold.

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

Abstract: An electronic device may be provided with a color sensing ambient light sensor. The color sensing ambient light sensor may measure the color of ambient light. Control circuitry in the electronic device may use information from the color sensing ambient light sensor in adjusting a display in the electronic device or taking other action. The color sensing ambient light sensor may have light detectors with different spectral responses. A test system may be used to calibrate the color sensing light sensor. The test system may have a tunable light source with light-emitting diodes that are turned on in sequence while gathering measured responses from the detectors. Numerical optimization techniques may be used to produce final versions of the spectral responses for the light detectors from the measured responses and corresponding calibration data that is stored in the electronic device.

Abstract: An electronic device may be provided with a display mounted in a housing. A color sensing ambient light sensor may measure the color of ambient light. The color sensing ambient light sensor may produce sensor output signals in a device-dependent color space. Control circuitry in the electronic device may convert the sensor output signals from the device-dependent color space to a device-independent color space using a color converting matrix. The color converting matrix may be determined using stored training data. The training data may include color data for different training light sources. The training data may be weighted to selectively control the influence of the training data on the color converting matrix. The training data may be weighted based on a distance between the training color data and a target color in the detected ambient light.

Abstract: An electronic device may be provided with a display mounted in a housing. A directional ambient light sensor may measure the intensity and direction of ambient light. The ambient light sensor may be mounted in alignment with a light sensor window formed in an inactive area of the display. The ambient light sensor may be formed from detectors on a semiconductor substrate. Incident light angle restriction structures may define openings for each detector. Each opening may be configured to allow light with a different range of angle of incidence values to be passed to a respective one of the detectors. The ranges of acceptance angle for adjacent detectors may overlap. A sensor may produce a diffuse light reading by processing ambient light data from a diffuse light detector and a directional light detector. The diffuse and directional light detectors may be formed on a common semiconductor substrate.

Abstract: An electronic device may be provided with a display mounted in a housing. A color sensing ambient light sensor may measure the color of ambient light. The color sensing ambient light sensor may be mounted in alignment with an ambient light sensor window formed in an inactive area of the display. The color sensing ambient light sensor may be formed from detectors on a semiconductor substrate. The detectors may include detectors that have spectral sensitivity profiles matching those of color matching functions. The color sensing ambient light sensor may include an infrared light detector. Light redirecting structures such as a diffuser, prism film, negative lens film, or privacy film may be used in directing light into the ambient light sensor. The color sensing ambient light sensor may be calibrated by exposing the sensor to light sources of different types.