Display device including a flat panel display panel
View Patent ↗A display device includes a flat display panel in which a plurality of pixels are arrayed in a matrix at an interval and covered with an optically transparent material, and an optical sheet to impart the front directivity of the flat display panel. Light which is emitted from a predetermined one of the plurality of pixels and emerges outside from the surface of the optical sheet located on a region except the pixel to the front direction overlaps neighboring pixels arranged around the pixel in a width equal to or smaller than 20% of the pixel width of the neighboring pixels.
1. A display device comprising:
a flat display panel which includes a plurality of pixels that are arrayed in a matrix at an interval, and which includes an optically transparent material covering the pixels; and
an optical sheet which imparts a front directivity to light emerging from the flat display panel, and which includes a plurality of prisms each having a bottom surface which receives light from the pixels and a top surface from which light emerges imparted with the front directivity, wherein the prisms are continuous with one another so that a light emerging position of the top surface has no flat portion and has a shape of a sharpness angle α;
wherein a vertical height d from a given pixel to a corresponding light emerging position is set to satisfy
d
p
≦
tan
{
α
2
+
sin
-
1
(
1
n
sin
π
-
α
2
)
}
(
1
)
where:
n is a refractive index of an optical path from the pixel to the light emerging position; and
p is a horizontal width from the pixel to the light emerging position.
2. A device according to claim 1 , wherein the width p is not more than a width from the pixel to a neighboring pixel.
3. A device according to claim 2 , wherein the flat display panel comprises an electroluminescence display panel in which the pixels comprise electroluminescence elements; and
wherein a width of the pixel is a width of light emission of the electroluminescence element, and the width from the pixel to the neighboring pixel is a width of a non-light-emission region between electroluminescence elements adjacent to each other where no light emission occurs.
4. A device according to claim 1 , wherein a pitch of the plurality of prisms is smaller than a pitch of the plurality of pixels.
5. A device according to claim 1 , wherein the flat display panel comprises a mesh-shaped partition which defines a plurality of cells arrayed in a matrix in correspondence with said plurality of pixels; and
wherein the optically transparent material fills the plurality of cells.
6. A device according to claim 4 , wherein each of the plurality of prisms has a triangular shape in cross-section and the plurality of prisms are arrayed in parallel to each other on a surface of the optically transparent material.
7. A device according to claim 1 , wherein each of the pixels comprises an optically transparent electrode which passes light, an EL layer which causes electroluminescence, and a reflection suppressing layer to suppress reflection of light on an interface with the EL layer; and
wherein the optically transparent electrode, the EL layer and the reflection suppressing layer are positioned sequentially from one side of the optically transparent material.
8. A device according to claim 7 , wherein the reflection suppressing layer comprises an electrode.
9. A device according to claim 7 , wherein the reflection suppressing layer has a thickness of 50 to 150 nm.
10. A device according to claim 7 , wherein the reflection suppressing layer has an optical thickness which makes light entering the reflection suppressing layer from the EL layer and propagating in the EL layer again have a phase opposite to a phase of light propagating in the EL layer.
11. A device according to claim 7 , wherein the reflection suppressing layer comprises a black body which absorbs light.
12. A device according to claim 1 , wherein each of the plurality of prisms has a semi-circular shape in cross-section.
13. A device according to claim 1 , wherein each of the plurality of prisms has a semi-elliptical shape in cross-section.