Abstract: Display apparatus includes reflective layer with reflective material with stacks of additional layers thereon. Each stack has an optically switchable layer. Switching elements are on a side of the reflective layer opposite to the stacks or form part of the reflective layer. Each switching element applies heating to a switchable portion of the optically switchable layer to change appearance of the switchable portion when viewed from the viewing side of the display apparatus. The optically switchable layer includes phase change material switchable between stable states each having a different refractive index. The phase change material switches by applying heat between the stable states. Switching the optically switchable layer causes the apparatus to provide one or both of the following effects for incident radiation within a predetermined frequency range: (i) a change in reflectivity of a factor of at least 50; or (ii) a change in phase within 5% of n?/2 radians, where n is an integer.

Abstract: A display apparatus includes a reflective layer with reflective material. One or more stacks of additional layers are provided on the reflective layer. Each stack has an optically switchable layer. A plurality of switching elements are located on a side of the reflective layer opposite to the one or more stacks or form part of the reflective layer. Each switching element is operable to apply heating to a switchable portion of the optically switchable layer and thereby change an appearance of the switchable portion when viewed from a viewing side of the display apparatus. The apparatus applies the heating by driving an electrical current through the switching element to generate Joule heating in the switching element. The electrical current flows in an electrical circuit including a portion of the reflective layer.

Abstract: The invention is notably directed to a transflective display device. The device comprises a set of pixels, wherein each of the pixels comprises a portion of bi-stable, phase change material, hereafter a PCM portion, having at least two reversibly switchable states, in which it has two different values of refractive index and/or optical absorption. The device further comprises one or more spacers, optically transmissive, and extending under PCM portions of the set of pixels. One or more reflectors extend under the one or more spacers. An energization structure is in thermal or electrical communication with the PCM portions, via the one or more spacers. Moreover, a display controller is configured to selectively energize, via the energization structure, PCM portions of the pixels, so as to reversibly switch a state of a PCM portion of any of the pixels from one of its reversibly switchable states to the other.

Abstract: The invention is notably directed to a transflective display device. The device comprises a set of pixels, wherein each of the pixels comprises a portion of bi-stable, phase change material, hereafter a PCM portion, having at least two reversibly switchable states, in which it has two different values of refractive index and/or optical absorption. The device further comprises one or more spacers, optically transmissive, and extending under PCM portions of the set of pixels. One or more reflectors extend under the one or more spacers. An energization structure is in thermal or electrical communication with the PCM portions, via the one or more spacers. Moreover, a display controller is configured to selectively energize, via the energization structure, PCM portions of the pixels, so as to reversibly switch a state of a PCM portion of any of the pixels from one of its reversibly switchable states to the other.

Abstract: An optical device comprising a stack of the following layers: a capping layer; a layer of light absorber material; and a reflective layer, wherein the refractive index of the capping layer is at least 1.6.

Abstract: The invention is notably directed to a transflective display device. The device comprises a set of pixels, wherein each of the pixels comprises a portion of bi-stable, phase change material, hereafter a PCM portion, having at least two reversibly switchable states, in which it has two different values of refractive index and/or optical absorption. The device further comprises one or more spacers, optically transmissive, and extending under PCM portions of the set of pixels. One or more reflectors extend under the one or more spacers. An energization structure is in thermal or electrical communication with the PCM portions, via the one or more spacers. Moreover, a display controller is configured to selectively energize, via the energization structure, PCM portions of the pixels, so as to reversibly switch a state of a PCM portion of any of the pixels from one of its reversibly switchable states to the other.

Abstract: A pattern is formed on an optical device, where the optical device includes a plurality of pixel elements. Each pixel element has a stack of layers that includes a colour control layer and a brightness control layer superposed over each other. For each of one or more of the pixel elements: energy is deposited into the colour control layer to change an effect of the colour control layer on the colour of light, and energy is deposited into the brightness control layer to change an effect of the brightness control layer on the intensity of light.

Abstract: The present invention is notably directed to an optical device (1) comprising a layer structure (2) with: a thermally conducting, optical reflector (15); a thermally conducting spacer (14), which is transmissive to light and arranged above the reflector (15); and a phase change material (10), or PCM, arranged above the spacer (14) and having at least two reversibly switchable states, in which the PCM exhibits two different values of refractive index. The reflector (15), the spacer (14) and the PCM (10) are successively stacked along a stacking direction (z) of the layer structure.

Abstract: An optical device comprising a stack of the following layers: a capping layer; a layer of light absorber material; and a reflective layer, wherein the refractive index of the capping layer is at least 1.6.

Abstract: An optical device comprising a stack of the following layers: a capping layer; a layer of light absorber material; and a reflective layer, wherein the refractive index of the capping layer is at least 1.6.

Abstract: Display apparatuses are disclosed. In one arrangement, a display apparatus comprises a plurality of pixel units. Each pixel unit comprises: an optically switchable element; a heater operable to apply heating to the optically switchable element and thereby change an optical property of the optically switchable element; and a drive unit for driving the heater in response to a drive signal. The drive unit is provided within a first layer. The optically switchable elements and heaters of the plurality of pixel units are separated from the first layer by at least a portion of a second layer. An average thermal conductivity of the second layer is lower than an average thermal conductivity of the first layer.

Abstract: The present invention is notably directed to display device (1, 1a d), comprising a set of pixels, each having a layer structure (2, 2c, 2d) that includes: a bi-stable, phase change material (10), or bi-stable PCM, having at least two reversibly switchable states, in which the PCM exhibits two different values of refractive index and/or optical absorption; and a heating element (17, 17c, 17d), electrically insulated from the PCM (10) and in thermal communication with the PCM (10) in the layer structure (2, 2c, 2d). The display device further comprises a set of nonlinear, monostable resistive switching elements (21), each in electrical communication with the heating element (17, 17c, 17d) of one of the pixels.

Abstract: An optical device comprising a stack of the following layers: a capping layer; a layer of light absorber material; and a reflective layer, wherein the refractive index of the capping layer is at least 1.6.

Abstract: A display apparatus includes an optically opaque layer and one or more stacks of additional layers provided on the optically opaque layer. Each stack has an optically switchable layer. A plurality of switching elements are located on a side of the optically opaque layer opposite to the one or more stacks. Each switching element is operable to apply a signal, for example an electrical signal or a thermal signal, through the optically opaque layer to a switchable portion of the optically switchable layer and thereby change an appearance of the switchable portion when viewed from a viewing side of the display apparatus. The surface area of the optically opaque layer on the viewing side is at least 10% larger than the total surface area of the switchable portions on the viewing side.

Abstract: An optical device comprising a stack of the following layers: a capping layer (16) having a high refractive index for guiding incident light; a layer of light absorber material (10), preferably a phase-changing material; and a reflective layer (12), wherein the refractive index of the capping layer is at least 1.6.

Abstract: The disclosure relates to displays. In one arrangement a plurality of pixels are provided. Each pixel comprises a first optical element reversibly switchable between at least two optical states, and a second optical element reversibly switchable between at least two optical states. The first optical element overlaps spatially with the second optical element in an overlap region when viewed from a viewing side of the display, such that an overall optical effect for the overlap region is defined by a combination of the optical state of the first optical element and the optical state of the second optical element. Row signal lines and column signal lines allow individual addressing of each pixel by applying a combination of a row control signal and a column control signal to the pixel. A driving controller applies the row control signals and the column control signals to the pixels.

Abstract: The present invention is notably directed to display device (1, la d), comprising a set of pixels, each having a layer structure (2, 2c, 2d) that includes: a bi-stable, phase change material (10), or bi-stable PCM, having at least two reversibly switchable states, in which the PCM exhibits two different values of refractive index and/or optical absorption; and a heating element (17, 17c, 17d), electrically insulated from the PCM (10) and in thermal communication with the PCM (10) in the layer structure (2, 2c, 2d). The display device further comprises a set of nonlinear, monostable resistive switching elements (21), each in electrical communication with the heating element (17, 17c, 17d) of one of the pixels.

Abstract: The invention is notably directed to a transflective display device. The device comprises a set of pixels, wherein each of the pixels comprises a portion of bi-stable, phase change material, hereafter a PCM portion, having at least two reversibly switchable states, in which it has two different values of refractive index and/or optical absorption. The device further comprises one or more spacers, optically transmissive, and extending under PCM portions of the set of pixels. One or more reflectors extend under the one or more spacers. An energization structure is in thermal or electrical communication with the PCM portions, via the one or more spacers. Moreover, a display controller is configured to selectively energize, via the energization structure, PCM portions of the pixels, so as to reversibly switch a state of a PCM portion of any of the pixels from one of its reversibly switchable states to the other.

Abstract: A display apparatus includes an optically opaque layer and one or more stacks of additional layers provided on the optically opaque layer. Each stack has an optically switchable layer. A plurality of switching elements are located on a side of the optically opaque layer opposite to the one or more stacks. Each switching element is operable to apply a signal, for example an electrical signal or a thermal signal, through the optically opaque layer to a switchable portion of the optically switchable layer and thereby change an appearance of the switchable portion when viewed from a viewing side of the display apparatus. The surface area of the optically opaque layer on the viewing side is at least 10% larger than the total surface area of the switchable portions on the viewing side.

Abstract: A display apparatus includes a reflective layer with reflective material. One or more stacks of additional layers are provided on the reflective layer. Each stack has an optically switchable layer. A plurality of switching elements are located on a side of the reflective layer opposite to the one or more stacks or form part of the reflective layer. Each switching element is operable to apply heating to a switchable portion of the optically switchable layer and thereby change an appearance of the switchable portion when viewed from a viewing side of the display apparatus. The apparatus applies the heating by driving an electrical current through the switching element to generate Joule heating in the switching element. The electrical current flows in an electrical circuit including a portion of the reflective layer.