E Ink Corporation

Oxford University Innovation Ltd

Bodle Technologies Limited

Ben Broughton

Harish Bhaskaran

Peiman L Hosseini

Richard Holliday

Lokeshwar Bandhu

Peiman Hosseini

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.

Method of forming a pattern on an optical device

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.

Display apparatus

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. A backlight unit is furthermore configured, in the device, to allow illumination of the PCM portions through the one or more spacers. The backlight unit is controlled by a backlight unit controller, which is configured for modulating one or more physical properties of light emitted from the backlight unit. The invention is further directed to related devices and methods of operation.

Transflective, PCM-based display device

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.

Optical device

The present invention is notably directed to an optical device () comprising a layer structure () with: a thermally conducting, optical reflector (); a thermally conducting spacer (), which is transmissive to light and arranged above the reflector (); and a phase change material (), or PCM, arranged above the spacer () and having at least two reversibly switchable states, in which the PCM exhibits two different values of refractive index. The reflector (), the spacer () and the PCM () are successively stacked along a stacking direction (z) of the layer structure. The optical device further comprises: a heating element (), opposite to the PCM () with respect to the reflector (), the layer structure () being configured so as to electrically insulate the PCM () from the heating element (), while the heating element () is in thermal communication with the PCM () via the reflector () and the spacer (); and a controller () configured to energize the heating element (), so as to heat the PCM () and thereby reversibly change a refractive index and/or an absorption of said PCM (). The invention is further directed to related optical devices (notably devices comprising one or more pixels formed, each, by a set of layer structures such as described above) and actuation methods.

Optical device with thermally switching phase change material

The present invention is notably directed to display device (), comprising a set of pixels, each having a layer structure () that includes: a bi-stable, phase change material (), 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 (), electrically insulated from the PCM () and in thermal communication with the PCM () in the layer structure (). The display device further comprises a set of nonlinear, monostable resistive switching elements (), each in electrical communication with the heating element () of one of the pixels. The resistive switching elements are designed so as to exhibit, each: a low resistance, unstable state, which allows the heating element () to be energized via the resistive switching element (), so as to heat the PCM () and reversibly change a refractive index and/or an optical absorption thereof, in operation; and a high-resistance, stable state, which allows leakage currents to be mitigated, so as to prevent inadvertent switching of the PCM () from one of its states to the other, in operation. The device further comprises a controller () configured to energize any of the pixels via a respective one of the resistive switching elements (), so as to switch the latter from its high-resistance state to its low resistance state, in order to energize a respective heating element () and, in turn, reversibly change a refractive index and/or an optical absorption of a respective PCM (). The present invention is further directed to related devices or apparatuses, such as passive matrix addressing displays, and methods of operations.

Phase change material-based display device with resistive switching elements

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.

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

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Oxford, United Kingdom

Ben Broughton