The present invention relates to a tuneable optical microcavity, characterised in that it comprises electrodes (12) on substrates (11), wherein the electrodes are comprised in the structure of dielectric or metal mirrors (13), or each of the electrodes has at least one dielectric or metal minor (13) on it, or the electrodes are semitransparent metal minors (13), wherein the mirrors are preferably located at a separation being a multiple of ½ lambda, where lambda is the central wavelength of the cavity mode, the cavity between the mirrors being filled with material (15) that changes the effective refractive index under the influence of external fields, preferably such as electric, magnetic field, thermal and mechanical stress.

A light emitting device includes: a mounting board; a light source positioned on the mounting board; a light diffusion plate; a diffuse reflector positioned between the mounting board and the light diffusion plate, and above at least part of an emission face of the light source; and a wavelength conversion layer positioned on or above the diffuse reflector.

The display device includes a mirror display element, a display, an optical element array, an external light reflection suppression layer, and a driving unit. The mirror display element reflects a part of external light and transmits a part of the external light. A display is disposed on an opposite side of an outer surface of the mirror display element, in which a plurality of pixels are two-dimensionally arranged. An optical element array is disposed between the mirror display element and the display in parallel with a light emission surface of the display, in which a plurality of optical elements corresponding to a predetermined unit of pixels among the plurality of pixels are arranged. An external light reflection suppression layer is disposed between the mirror display element and the display to suppress reflection of the external light. The driving unit drives the display to turn on a predetermined pixel among the plurality of pixels.

An optical element 1 includes a first layer (A1) and a second layer (A2) that faces the first layer (A1). The first layer (A1) includes a plurality of first structural bodies (B1) that each have optical anisotropy. In reflection of light entering from the first layer (A1), the second layer (A2) reflects the light while maintaining a polarization state of the light at incidence and at the reflection. The first layer (A1) changes, according to directions of orientation of the first structural bodies (B1), a phase of the light from a phase at incidence to the first layer (A1) from outside of the first layer (A1) to a phase at output from the first layer (A1) toward the second layer (A2). The first layer (A1) changes the phase of the light from a phase at incidence to the first layer (A1) from the second layer (A2) to a phase at output from the first layer (A1) toward the outside of the first layer (A1) according to the directions of orientation of the first structural bodies (B1).

Multi-mode displays are described. In particular, multi-mode displays having an emissive display element, a partial reflector disposed on the emissive display element, a spatial light modulator disposed on the partial reflector, and an absorbing polarizer disposed on the spatial light modulator are described. Multi-mode displays having at least reflective display modes and emissive display modes are described. The display is configured such that switching between these modes happens quickly or even automatically.

A light emitting device includes: a mounting board; a plurality of light sources positioned on the mounting board; a light diffusion plate; a half mirror positioned between the light diffusion plate and the plurality of light sources; and a plurality of diffuse reflectors positioned between the mounting board and the light diffusion plate, and above at least part of each emission face of the plurality of light sources. The diffuse reflectors comprise a resin, and particles dispersed in the resin. Each of the diffuse reflectors is positioned in an area that, in the top view, is larger than and includes the emission face of each light source. A density of the particles in said area, in the top view, is higher in a first portion located immediately above the emission face of each light source than in a second portion located around a periphery of the first portion.

Multi-mode displays are described. In particular, multi-mode displays having an emissive display element, a partial reflector disposed on the emissive display element, a spatial light modulator disposed on the partial reflector, and an absorbing polarizer disposed on the spatial light modulator are described. Multi-mode displays having at least reflective display modes and emissive display modes are described. The display is configured such that switching between these modes happens quickly or even automatically.

Provided are a color change module using a reflective display, and an independent type color change control apparatus providing an electrical signal for changing a color of the color change module. The color change module can include a module base, the reflective display, a first external electrode and a second external electrode. The module base has a shape corresponding to an object for attachment. The reflective display is provided on an upper surface of the module base, and displays information in a manner wherein light coming from outside is reflected. The first external electrode and the second external electrode are provided to be connected to the reflective display and to be exposed to outside for receiving the information to be displayed on the reflective display from the independent type color change control apparatus.

A mirror display apparatus that subjects a mirror optical element to pulse voltage driving so that a reflectivity in a mirror mode can be changed by means of a duty cycle of the pulse voltage is provided. A mirror display apparatus includes a monitor display device and a mirror optical element disposed on the front side of the monitor display device. The mirror optical element includes a liquid-crystal panel with a reflection-type polarizer disposed on the back side thereof. The mirror optical element has a reflectivity and a transmissivity that are changed in respective directions opposite to each other via electric driving using a voltage applied to the liquid-crystal panel. A control circuit drives the liquid-crystal panel using a pulse voltage and performs control to change the reflectivity and the transmissivity of the mirror optical element by changing a duty cycle of the pulse voltage.

The disclosure provides a display device, including a liquid crystal cell and at least one reflective dielectric layer. The at least one reflective dielectric layer is configured to increase reflection of projected light emitted into the display device, thereby reducing loss of the projected light, which is emitted from a projection pointer, in the display device.