A stereo display device includes plural projectors, a lens array, and a concave axicon lens array. The projectors project images to plural viewing regions at an image side. The lens array is disposed between the projectors and the image side. The concave axicon lens array is disposed between the lens array and the image side.

A spatial image projection apparatus including a receiver configured to receive an image signal; a display unit configured to display an image acquired by processing the image signal; a projection unit configured to project a spatial image to a prescribed space by reflecting light corresponding to the image displayed on the display unit. Further, the projection unit includes a plate having a first surface facing the display unit and a second surface opposite to the first surface; and a protrusion arranged on the first surface or the second surface of the plate. In addition, the protrusion includes first and second slopes tilted at about 45 degrees relative to the surface of the plate, and an angle between the first and second slopes is about 90 degrees.

A spatial image projection apparatus including a receiver configured to receive an image signal; a display unit configured to display an image acquired by processing the image signal; a projection unit configured to project a spatial image to a prescribed space by reflecting light corresponding to the image displayed on the display unit. Further, the projection unit includes a plate having a first surface facing the display unit and a second surface opposite to the first surface; and a protrusion arranged on the first surface or the second surface of the plate. In addition, the protrusion includes first and second slopes tilted at about 45 degrees relative to the surface of the plate, and an angle between the first and second slopes is about 90 degrees.

There is provided a lens array and an lens array capable of suitably preventing irregular brightness without reducing resolution. A micro lens array of a screen includes upper-level microlenses and lower-level microlenses which are formed on the incidence surface of the screen, which have the same effective diameter, and which have a structure that generates an optical path length difference Δ in transmission light. By disposing the upper-level microlenses and the lower-level microlenses at an interval based on the effective diameter, the basic periodic structure of a lens period is formed. Further, the upper-level microlenses and the lower-level microlenses form a basic block comprising a combination of the lenses having a structure that generates the optical path length difference. A concave-and-convex period PC based on the basic block is an integer multiple of the lens period.

There is provided a lens array and an lens array capable of suitably preventing irregular brightness without reducing resolution. A micro lens array of a screen includes upper-level microlenses and lower-level microlenses which are formed on the incidence surface of the screen, which have the same effective diameter, and which have a structure that generates an optical path length difference Δ in transmission light. By disposing the upper-level microlenses and the lower-level microlenses at an interval based on the effective diameter, the basic periodic structure of a lens period is formed. Further, the upper-level microlenses and the lower-level microlenses form a basic block comprising a combination of the lenses having a structure that generates the optical path length difference. A concave-and-convex period PC based on the basic block is an integer multiple of the lens period.

The present invention provides a diffuser plate in a simple structure capable of achieving optical properties with less luminance irregularity and color irregularity and good quality of appearance. A diffuser plate is a diffuser plate where a plurality of microlenses are placed on a principal surface, shapes of the plurality of microlenses along a cross-section perpendicular to the principal surface are different from one another and do not have an axis of symmetry. A method for designing the diffuser plate includes steps of determining a specific reference microlens; placing the reference microlens on the principal surface; forming a specific phase modulation shape; and determining a shape of the plurality of microlenses by combining the specific reference microlens and the specific phase modulation shape.

The present invention provides a diffuser plate in a simple structure capable of achieving optical properties with less luminance irregularity and color irregularity and good quality of appearance. A diffuser plate is a diffuser plate where a plurality of microlenses are placed on a principal surface, shapes of the plurality of microlenses along a cross-section perpendicular to the principal surface are different from one another and do not have an axis of symmetry. A method for designing the diffuser plate includes steps of determining a specific reference microlens; placing the reference microlens on the principal surface; forming a specific phase modulation shape; and determining a shape of the plurality of microlenses by combining the specific reference microlens and the specific phase modulation shape.

This disclosure relates to the field of projection display technology, and particularly to a projection screen and a projection display system so as to improve the uniformity of brightness throughout the projection screen. There is an anti-reflection coating arranged in a target area on a light incidence side surface of the projection screen to increase transmittivity in the target area, where the target area refers to an area where an incidence angle of projected light beams on the projection screen is above an angle threshold, and the projected light beams are light beams emitted by a projector.

An image display device a light source, an image display layer and a refractive structure layer. The light source emits a light beam. The image display layer is located over the light source. The image display layer includes plural pattern sections. The refractive structure layer has a reference plane. When the light beam is irradiated on the refractive structure layer and there is a first angle between the light beam and the reference plane, the light beam is guided to a first pattern section, so that a first image is displayed on the image display layer. When the light beam is irradiated on the refractive structure layer and there is a second angle between the light beam and the reference plane, the light beam is guided to a second pattern section, so that a second image is displayed on the image display layer.

An image display device a light source, an image display layer and a refractive structure layer. The light source emits a light beam. The image display layer is located over the light source. The image display layer includes plural pattern sections. The refractive structure layer has a reference plane. When the light beam is irradiated on the refractive structure layer and there is a first angle between the light beam and the reference plane, the light beam is guided to a first pattern section, so that a first image is displayed on the image display layer. When the light beam is irradiated on the refractive structure layer and there is a second angle between the light beam and the reference plane, the light beam is guided to a second pattern section, so that a second image is displayed on the image display layer.