Abstract: An organic light-emitting diode (OLED) display may have an array of organic light-emitting diode pixels that each have OLED layers interposed between a cathode and an anode. Voltage may be applied to the anode of each pixel to control the magnitude of emitted light. The conductivity of the OLED layers may allow leakage current to pass between neighboring anodes in the display. To reduce leakage current and the accompanying cross-talk in a display, the pixel definition layer may disrupt continuity of the OLED layers. The pixel definition layer may have a steep sidewall, a sidewall with an undercut, or a sidewall surface with a plurality of curves to disrupt continuity of the OLED layers. A control gate that is coupled to a bias voltage and covered by gate dielectric may be used to form an organic thin-film transistor that shuts the leakage current channel between adjacent anodes on the display.

Abstract: An electronic device may include a display module that produces foveated images having high and low resolution regions. The module may include a reflective display panel that produces first reflected light during first time periods and second reflected light during second time periods. The first reflected light may reflect off of a beam splitter to form the low resolution region of the foveated image. The second reflected light may be transmitted by the beam splitter, de-magnified by a lens, and redirected by an optical steering element to produce the high resolution region at a desired, adjustable, location in the foveated image. The reflective display panel may be replaced by sets of emissive display panels that concurrently display the high and low resolution regions in the foveated image. The sets of emissive display panels may be replaced by front-lit reflective display panels.

Abstract: A vehicle may have a light-field head-up display that produces a light-field output allowing a viewer in the vehicle to observe three-dimensional content. An array of light-field display units and corresponding lenses may be used to direct the light-field output towards the viewer. The head-up display may have a transmissive display such as a liquid crystal display or other display with an array of backlit pixels. The pixels may have subpixels of different colors and may have elongated shapes extending along a given dimension. Lenticular lenses in the transmissive display that overlap the pixels may extend along the given dimension. A directional backlight may be used to adjust the direction of the light-field output produced by a light-field display unit. The directional backlight may be adjusted to alternately provide light-field output to the left and right eyes of a viewer.

Abstract: A vehicle may have optical structures such as windows and mirrors that have the potential to allow glare from external objects to shine into the eyes of a driver or other vehicle occupant. A control circuit may gather information on where the eyes of the driver are located using a camera mounted in the vehicle and may gather information on where the sun or other source of glare are located outside of the vehicle. Based on this information, the control circuit may direct a light modulator on a window or mirror to selectively darken an area that prevents the glare from reaching the eyes of the driver. The light modulator may have a photochromic layer that is adjusted by shining light onto the photochromic layer, may be a liquid crystal modulator, an electrochromic modulator, or other light modulator layer.

Abstract: An electronic device may include a display for displaying image content to a user and dynamic image stabilization circuitry for dynamically compensating the image content if the device is moving unpredictably to help keep the image content aligned with the user's gaze. The electronic device may include sensors for detecting the displacement of the device. The dynamic image stabilization circuitry may include a usage scenario detection circuit and a content displacement compensation calculation circuit. The usage scenario detection circuit receives data from the sensors and infers a usage scenario based on the sensor data. The content displacement compensation calculation circuit uses the inferred usage scenario to compute a displacement amount by which to adjust image content. When motion stops, the image content may gradually drift back to the center of the display.

Abstract: An optical system may include equipment with a housing that is configured to receive external equipment such as a cellular telephone. The external equipment may have a display mounted on a front face of the external equipment and may have additional components such as a front-facing camera. Communications circuitry in the equipment may support wired and wireless communications with the external equipment. An optical combiner in the equipment may be used to combine display image light emitted from pixels in the display with real-world image light received from external objects. The optical combiner may have a reflector with a concave lens shape that focuses light from the display towards eye boxes in which a viewer's eyes are located. The reflector may be a partial mirror or a reflective polarizer. The reflective polarizer and additional components may be used in implementing a tunable tint layer.

Abstract: An electronic device such as a head-mounted device may have displays. The display may have regions of lower and higher resolution to reduce data bandwidth and power consumption for the display while preserving satisfactory image quality. Data lines may be shared by lower and higher resolution portions of a display or different portions of a display with different resolutions may be supplied with different numbers of data lines. Data line length may be varied in transition regions between lower resolution and higher resolution portions of a display to reduce visible discontinuities between the lower and higher resolution portions. The lower and higher resolution portions of the display may be dynamically adjusted using dynamically adjustable gate driver circuitry and dynamically adjustable data line driver circuitry.

Abstract: A head-mounted display may include a display system and an optical system in a housing. The display system may have a pixel array that produces light associated with images. The display system may also have a linear polarizer through which light from the pixel array passes and a quarter wave plate through which the light passes after passing through the quarter wave plate. The optical system may be a catadioptric optical system having one or more lens elements. The lens elements may include a plano-convex lens and a plano-concave lens. A partially reflective mirror may be formed on a convex surface of the plano-convex lens. A reflective polarizer may be formed on the planar surface of the plano-convex lens or the concave surface of the plano-concave lens. An additional quarter wave plate may be located between the reflective polarizer and the partially reflective mirror.

Abstract: A head-mounted device may include a display that generates content and an optical system through which the content is viewable. The head-mounted device may include a lighting system that illuminates a periphery of the optical system. When the user places the device on his or her head in a brightly lit environment, control circuitry may operate the lighting system to provide bright illumination to the user's peripheral vision. The lighting system may gradually decrease in brightness until the user transitions from a bright-adapted state to a dark-adapted state. When the user is partially or fully dark-adapted, the lighting system may be turned off and the display may be turned on. In some arrangements, an ambient light sensor may measure ambient light conditions outside of the electronic device and the control circuitry may control the lighting system based on the ambient lighting conditions.

Abstract: An electronic device such as a head-mounted device may have displays that are viewable by the eyes of a viewer through adjustable lenses. The adjustable lenses may be liquid crystal lenses. A camera and other sensors in the head-mounted device may monitor the eyes of the user and gather other information. Control circuitry in the head-mounted device may control the adjustable lenses based on measured characteristics of the eyes of the user such as interpupillary distance and direction-of-view. The control circuitry may match the distance between the centers of the adjustable lenses to the measured interpupillary distance and may align the lens centers with the measured direction-of-view. The adjustable lenses may have transparent electrodes that are supplied with time-varying control signals by the control circuitry.

Abstract: A head-mounted display may include a display system and an optical system in a housing. The display system may have a pixel array that produces light associated with images. The display system may also have a linear polarizer through which light from the pixel array passes and a quarter wave plate through which the light passes after passing through the quarter wave plate. The optical system may be a catadioptric optical system having one or more lens elements. The lens elements may include a plano-convex lens and a plano-concave lens. A partially reflective mirror may be formed on a convex surface of the plano-convex lens. A reflective polarizer may be formed on the planar surface of the plano-convex lens or the concave surface of the plano-concave lens. An additional quarter wave plate may be located between the reflective polarizer and the partially reflective mirror.

Abstract: An electronic device such as a head-mounted device may have displays. The display may have regions of lower (L) and higher (M, H) resolution to reduce data bandwidth and power consumption for the display while preserving satisfactory image quality. Data lines may be shared by lower and higher resolution portions of a display or different portions of a display with different resolutions may be supplied with different numbers of data lines. Data line length may be varied in transition regions between lower resolution and higher resolution portions of a display to reduce visible discontinuities between the lower and higher resolution portions. The lower and higher resolution portions of the display may be dynamically adjusted using dynamically adjustable gate driver circuitry and dynamically adjustable data line driver circuitry.

Abstract: A lens module in a head-mounted device may include a fluid-filled chamber, a semi-rigid lens element that at least partially defines the fluid-filled chamber, and at least one actuator configured to selectively bend the semi-rigid lens element. The semi-rigid lens element may become rigid along a first axis when the lens element is curved along a second axis perpendicular to the first axis. Six actuators that are evenly distributed around the periphery of the semi-rigid lens element may be used to control the curvature of the semi-rigid lens element. The semi-rigid lens element may initially be planar or non-planar. For example, the semi-rigid lens element may initially have a spherically convex surface and a spherically concave surface. A tunable spherical lens may be incorporated into the lens module to offset a parasitic spherical lens power from the semi-rigid lens element.

Abstract: An electronic device may have a display. The display has pixels configured to display an image. The display is mounted in a housing. The housing may include head-mounted support structures configured to support the display for viewing through lenses. The pixels of the display may be covered by a layer of thin-film encapsulation. The thin-film encapsulation may be covered with a cover layer such as a glass cover layer that is attached to the thin-film encapsulation layer by a layer of adhesive. To suppress internal light reflections, the display may include reflection suppression structures. The reflection suppression structures may include an antireflection layer and/or polarizer and waveplate layers. The reflection suppression structures may be formed on an outwardly facing surface of the cover layer and/or between the thin-film encapsulation layer and the cover layer.

Abstract: A vehicle may have a head-up display that produces a display output allowing a viewer in the vehicle to observe two-dimensional or three-dimensional content. The head-up display may include a display unit that produces the display output and an optical combiner on a vehicle window that directs the display output towards the viewer. The optical combiner may be a holographic or diffractive optical element or may be an array of angled reflectors such as micromirrors embedded in an index-matching material. Optical combiners formed from holographic elements may be configured to reflect light at an angle of reflection that is different than the angle of incidence, thereby allowing light to reach a viewer's eyes even when the head-up display reflects light off of a side window on a vehicle door. A holographic optical element may include volume holographic media such as photopolymers or holographic polymer dispersed liquid crystal.

Abstract: A lens module in a head-mounted device may include a fluid-filled chamber, a semi-rigid lens element that at least partially defines the fluid-filled chamber, and at least one actuator configured to selectively bend the semi-rigid lens element. The semi-rigid lens element may become rigid along a first axis when the lens element is curved along a second axis perpendicular to the first axis. Six actuators that are evenly distributed around the periphery of the semi-rigid lens element may be used to control the curvature of the semi-rigid lens element. The semi-rigid lens element may initially be planar or non-planar. For example, the semi-rigid lens element may initially have a spherically convex surface and a spherically concave surface. A tunable spherical lens may be incorporated into the lens module to offset a parasitic spherical lens power from the semi-rigid lens element.

Abstract: An electronic device such as a head-mounted device may have displays that are viewable by the eyes of a viewer through adjustable lenses. The adjustable lenses may be liquid crystal lenses. A camera and other sensors in the head-mounted device may monitor the eyes of the user and gather other information. Control circuitry in the head-mounted device may control the adjustable lenses based on measured characteristics of the eyes of the user such as interpupillary distance and direction-of-view. The control circuitry may match the distance between the centers of the adjustable lenses to the measured interpupillary distance and may align the lens centers with the measured direction-of-view. The adjustable lenses may have transparent electrodes that are supplied with time-varying control signals by the control circuitry.

Abstract: An electronic device such as a head-mounted device may have displays that are viewable by the eyes of a viewer through adjustable lenses. The adjustable lenses may be liquid crystal lenses. A camera and other sensors in the head-mounted device may monitor the eyes of the user and gather other information. Control circuitry in the head-mounted device may control the adjustable lenses based on measured characteristics of the eyes of the user such as interpupillary distance and direction-of-view. The control circuitry may match the distance between the centers of the adjustable lenses to the measured interpupillary distance and may align the lens centers with the measured direction-of-view. The adjustable lenses may have transparent electrodes that are supplied with time-varying control signals by the control circuitry.

Abstract: A head-mounted display may include a display system and an optical system in a housing. The display system may have displays that produce images. Positioners may be used to move the displays relative to the eye positions of a user's eyes. An adjustable optical system may include tunable lenses such as tunable cylindrical liquid crystal lenses. The displays may be viewed through the lenses when the user's eyes are at the eye positions. A sensor may be incorporated into the head-mounted display to measure refractive errors in the user's eyes. The sensor may include waveguides and volume holograms, and a camera for gathering light that has reflected from the retinas of the user's eyes. Viewing comfort may be enhanced by adjusting display positions relative to the eye positions and/or by adjusting lens settings based on the content being presented on the display and/or measured refractive errors.

Abstract: A head-mounted display may include a display system and an optical system in a housing. The display system may have a pixel array that produces light associated with images. The display system may also have a linear polarizer through which light from the pixel array passes and a quarter wave plate through which the light passes after passing through the quarter wave plate. The optical system may be a catadioptric optical system having one or more lens elements. The lens elements may include a plano-convex lens and a plano-concave lens. A partially reflective mirror may be formed on a convex surface of the plano-convex lens. A reflective polarizer may be formed on the planar surface of the plano-convex lens or the concave surface of the plano-concave lens. An additional quarter wave plate may be located between the reflective polarizer and the partially reflective mirror.