An electronic device is disclosed herein that includes an infrared light source to emit infrared light, a rolling shutter sensor, and at least one processor. The at least one processor is to: cause the rolling shutter sensor to output a first signal corresponding to a first frame of image data during exposure to the infrared light, reset the rows of the rolling shutter sensor at a same time, cause the rolling shutter sensor to output a second signal corresponding to a second frame of image data without exposure to the infrared light from the infrared light source, determine a difference between the first signal and the second signal to generate an ambient infrared free frame, and recognize a face based on the ambient infrared free frame.

A reflective display apparatus includes three liquid crystal modules stacked in sequence for an incident light to enter from top to bottom sequentially. Each liquid crystal module includes a liquid crystal layer disposed between two substrates. A switchable electric field and a vertical alignment force are provided by the two substrates to the liquid crystal layer. The three liquid crystal modules are respectively: a blue light liquid crystal module located at a top layer, a green light liquid crystal module located in a middle layer and having the liquid crystal layer doped with a dichroic dye for absorbing a light within a blue light wavelength range, and a red light liquid crystal module located at a bottom layer and having the liquid crystal layer doped with a dichroic dye for absorbing a light within a green light wavelength range. A method for controlling the reflective display apparatus is also disclosed.

An optical filter for a display includes a filter film with at least one optical filter layer. The filter layer blocks a band of optical wavelengths and is transparent for optical wavelengths outside the band. The filter film has a thickness within the range of 25 microns through 1 mm. The filter film may include one or more laminate layers that are optically transparent in the wavelengths of the band blocked by the filter layer. The filter film may include one or more layers of liquid crystal polymers in layered contact with one or more transparent electrode layers and one or more layers of polymers in layered contact with the one or more layers of liquid crystal polymers.

A monochrome display is converted into a color display by including an electrically controllable planar color filter plate switchable between primary colors and operating the display in a color field sequential mode. Hence the requirement for a color switchable illumination source is eliminated. For example the illumination source may be a white OLED, an illumination type which, in combination with a microlens array, has proven well suited for directional displays. Further the need for a color mask is eliminated, thereby eliminating problems of moiree interference with a microlens array and further eliminating problems of diffraction patterns in infrared images captured through the display for example for observer tracking purposes. The electrically controllable planar color filter plate may comprise two wavelength dependent wave retarders and two liquid crystal cells.

A non-mechanical liquid crystal tunable filter (LCTF) assembly capable of switching between a multi-conjugate filter mode and a conformal filter mode is described. The non-mechanical LCTF architecture can include a plurality of LCTF components that each comprises a first optical filter comprising a first optical axis, a second optical filter comprising a second optical axis, wherein the second optical axis is rotated 90° relative to the first optical axis, and a first twisted nematic cell positioned between the first optical filter and the second optical filter, the first twisted nematic cell configured to polarize received light by 90° when a voltage is not applied and not polarize the received light when the voltage is applied. The non-mechanical LCTF assembly is configured to switch between a conformal filter mode and a multi-conjugate filter mode based on whether the voltage is applied to each of the plurality of LCTF components.

A multi-conjugate filter (MCF) can be operated in both a single bandpass mode and a multiple bandpass mode. By applying different voltages to different channels of a MCF, the MCF can be used to filter light into (1) a single narrow spectral output or (2) a broad ranged “white light” spectral output.

Provided is a display apparatus including a first cholesteric liquid crystal panel, a second cholesteric liquid crystal panel, and a third cholesteric liquid crystal panel. The first cholesteric liquid crystal panel has a light receiving surface. The second cholesteric liquid crystal panel overlaps the first cholesteric liquid crystal panel and is disposed on a side of the first cholesteric liquid crystal panel away from the light receiving surface. The third cholesteric liquid crystal panel overlaps the second cholesteric liquid crystal panel and is disposed on a side of the second cholesteric liquid crystal panel away from the first cholesteric liquid crystal panel. One of the first cholesteric liquid crystal panel, the second cholesteric liquid crystal panel, and the third cholesteric liquid crystal panel is provided with multiple first light shielding patterns separated from each other.

A reflective display tile can be used in connection with a static or video display. The tile includes a transparent substrate having a front surface, a rear surface, and a peripheral edge surrounding the front and rear surfaces, an electrostatic shutter array disposed at the front surface of said substrate, a reflective medium disposed at the rear surface of the substrate, and drive electronics disposed rearward of the reflective medium. The shutter array and drive electronics are configured so that the tile is tileable and can be abutted at any of its peripheral edges against identical tiles to form a display with substantially no perceived optical interface between adjacent tiles. Another embodiment includes an opaque substrate such as a circuit board. A further embodiment has a polymeric film coated on one side with a metal film and on another side with ink or blackening material.

An electronic device is disclosed herein that includes an infrared light source to emit infrared light, a rolling shutter sensor, and at least one processor. The at least one processor is to: cause the rolling shutter sensor to output a first signal corresponding to a first frame of image data during exposure to the infrared light, reset the rows of the rolling shutter sensor at a same time, cause the rolling shutter sensor to output a second signal corresponding to a second frame of image data without exposure to the infrared light from the infrared light source, determine a difference between the first signal and the second signal to generate an ambient infrared free frame, and recognize a face based on the ambient infrared free frame.

An object is to provide an optical element in which a wavelength dependence of reflection is small, a light guide element including the optical element, and an image display device including the light guide element. The optical element includes a plurality of cholesteric liquid crystal layers having different selective reflection center wavelengths, in which the cholesteric liquid crystal layer has a liquid crystal alignment pattern in which a direction of an optical axis derived from a liquid crystal compound changes while continuously rotating in at least one in-plane direction, and in a case where a length over which the optical axis rotates by 180° in the in-plane direction is set as a single period, a permutation of lengths of selective reflection center wavelengths and a permutation of lengths of the single periods match each other in the cholesteric liquid crystal layers.