Abstract: A projection system is provided, including: a projection unit to output a projection image; a retardation plate arranged obliquely with respect to an optical axis of the projection image, the retardation plate to modulate a polarization state of the projection image incident thereon; a reflective polarizing plate stacked on a side of the retardation plate opposite to that on which the projection image is incident, the reflective polarizing plate to reflect a first polarization component of the projection image transmitted through the retardation plate; and a retro-reflective element provided along a direction in which the projection image is reflected by the reflective polarizing plate, the retro-reflective element to output reflected light against a direction in which the light is incident, wherein the reflective polarizing plate transmits a second polarization component of the projection image reflected by the retro-reflective element and modulated by the retardation plate.

Abstract: A projection system is provided, including: a projection unit to output a projection image; a retardation plate arranged obliquely with respect to an optical axis of the projection image, the retardation plate to modulate a polarization state of the projection image incident thereon; a reflective polarizing plate stacked on a side of the retardation plate opposite to that on which the projection image is incident, the reflective polarizing plate to reflect a first polarization component of the projection image transmitted through the retardation plate; and a retro-reflective element provided along a direction in which the projection image is reflected by the reflective polarizing plate, the retro-reflective element to output reflected light against a direction in which the light is incident, wherein the reflective polarizing plate transmits a second polarization component of the projection image reflected by the retro-reflective element and modulated by the retardation plate.

Abstract: An optical device comprises: a transmittance changing unit that is provided in front of an eye of a user, and changes transmittance for light from the outside according to a voltage being applied; and a voltage control unit that controls a voltage to be applied to the transmittance changing unit by switching cyclically between a high voltage and a low voltage, wherein the voltage control unit switches the voltage at a cycle that is shorter than the sum of time required for transmittance of the transmittance changing unit to stabilize when changing from a minimum value to a maximum value by switching a voltage and time required for transmittance of the transmittance changing unit to stabilize when changing from a maximum value to a minimum value by switching a voltage.

Abstract: Conventional optical devices cannot cope with light entering from different directions in different light amounts. An optical device comprises: a transmittance changing unit that is provided in front of an eye of a user, and changes transmittance for light from the outside according to a voltage being applied; and a voltage control unit that controls a voltage to be applied to the transmittance changing unit, wherein by controlling the voltage, the voltage control unit switches between: a first relationship between frontal transmittance that is transmittance for light entering the transmittance changing unit from a frontal direction, and peripheral transmittance that is transmittance for light entering the transmittance changing unit from a direction inclined to the vertical direction relative to an entrance direction of light to which the frontal transmittance applies; and a second relationship between the frontal transmittance and the peripheral transmittance that is different from the first relationship.

Abstract: An optical device comprises: a transmittance changing unit that is provided in front of an eye of a user, and changes transmittance for light from the outside according to a voltage being applied; and a voltage control unit that controls a voltage to be applied to the transmittance changing unit by switching cyclically between a high voltage and a low voltage, wherein the voltage control unit switches the voltage at a cycle that is shorter than the sum of time required for transmittance of the transmittance changing unit to stabilize when changing from a minimum value to a maximum value by switching a voltage and time required for transmittance of the transmittance changing unit to stabilize when changing from a maximum value to a minimum value by switching a voltage.

Abstract: Conventional optical devices cannot cope with light entering from different directions in different light amounts. An optical device comprises: a transmittance changing unit that is provided in front of an eye of a user, and changes transmittance for light from the outside according to a voltage being applied; and a voltage control unit that controls a voltage to be applied to the transmittance changing unit, wherein by controlling the voltage, the voltage control unit switches between: a first relationship between frontal transmittance that is transmittance for light entering the transmittance changing unit from a frontal direction, and peripheral transmittance that is transmittance for light entering the transmittance changing unit from a direction inclined to the vertical direction relative to an entrance direction of light to which the frontal transmittance applies; and a second relationship between the frontal transmittance and the peripheral transmittance that is different from the first relationship.

Abstract: A display device including a diffraction grating from which a diffracted light of the zeroth order and a diffracted light of the first order having different color light components emerge to establish color separation. An array of micro-lenses is arranged on a liquid crystal panel. The liquid crystal panel has a plurality of picture elements and each picture element includes a plurality of color display dots. The color display dots in each picture element are arranged in the vertical relationship and in the order of wavelength of the light. A green light component of diffracted light of the first order is made incident normal to the liquid crystal panel, and the diffracted light of the zeroth order passes through the liquid crystal panel at a greater angle relative to the normal to the liquid crystal panel.

Abstract: A display device including liquid crystal display panels, arrays of convergently transmissive elements for forming an erect and real image, and fresnel lenses for magnifying the image. The configured surface of the fresnel lens is arranged on the light incident side. The configured surface includes periodic ridges with flat crests and inclined surfaces. Shading layers are provided on the flat crests to eliminate ghosts.

Abstract: A display device including liquid crystal display panels, arrays of convergently transmissive elements for forming an erect and real image, and fresnel lenses for magnifying the image. The configured surface of the fresnel lens is arranged on the light incident side. The configured surface includes periodic ridges with flat crests and inclined surfaces. Shading layers are provided on the flat crests to eliminate ghosts.

Abstract: A display device including a diffraction grating from which a diffracted light of the zeroth order and a diffracted light of the first order having different color light components emerge to establish color separation. An array of micro-lenses is arranged on a liquid crystal panel. The liquid crystal panel has a plurality of picture elements and each picture element includes a plurality of color display dots. The color display dots in each picture element are arranged in the vertical relationship and in the order of wavelength of the light. A green light component of diffracted light of the first order is made incident normal to the liquid crystal panel, and the diffracted light of the zeroth order passes through the liquid crystal panel at a greater angle relative to the normal to the liquid crystal panel.

Abstract: A display device including liquid crystal display panels, arrays of convergently transmissive elements for forming an erect and real image, and fresnel lenses for magnifying the image. The configured surface of the fresnel lens is arranged on the light incident side. The configured surface includes periodic ridges with flat crests and inclined surfaces. Shading layers are provided on the flat crests to eliminate ghosts.