Display device including a diffraction grating
A display device has layers that are laminated. The layers includes: a display layer that has a display surface for displaying an image composed of unit pixels; a pixel electrode layer arranged to correspond to each of unit pixels; a light emitting element layer laminated on the pixel electrode layer and arranged to emit light with its luminance controlled by a current; a common electrode layer provided so as to be laminated on the light emitting element layer; and a sealing layer that seals a light emitting element. The layers include at least two layers for holding the light emitting element layer therebetween and having a microcavity structure. Diffraction gratings are formed on an interface between a first grating layer and a first organic layer and on an interface between a second grating layer and a second organic layer respectively, and consequently a viewing angle is widened.
1. A display device that includes a plurality of layers that are laminated, the plurality of layers comprising:
a display layer that includes a display surface;
a pixel electrode layer provided with a pixel electrode that corresponds to each of a plurality of unit pixels;
a light emitting element layer laminated on the pixel electrode layer;
a common electrode layer laminated on the light emitting element layer; and
a sealing layer laminated on the common electrode layer, wherein
the plurality of layers include at least two layers that hold the light emitting element layer therebetween and have a microcavity structure, and include at least one pair of layers laminated to each other and are located between the light emitting element layer and the display layer,
an interface of the at least one pair of layers constitutes at least one diffraction grating,
the at least one pair of layers for constituting the at least one diffraction grating comprises a first layer with a surface form that includes a first plurality of protrusion strip parts arranged with a plurality of intervals having different widths in a first direction that is parallel with the display surface, the first plurality of protrusion strip parts extending in a second direction that intersects the first direction, and a second layer that is laminated in contact with the surface form,
the at least one diffraction grating is formed on a surface of the first layer,
the at least one pair of layers for constituting the at least one diffraction grating comprises a third layer with a second surface form that includes a second plurality of protrusion strip parts each of which is arranged with an interval in the second direction and extends in the first direction, and a fourth layer that is laminated in contact with the second surface form, and
the at least one diffraction grating is formed also on a surface of the third layer.
2. The display device according to claim 1 , wherein
one of the pixel electrode layer and the common electrode layer comprises a reflection layer, and is one of the at least two layers for constituting the microcavity.
3. The display device according to claim 1 , wherein
the first layer includes a plurality of slits each of which extends in the second direction and between neighboring ones of the slits each of the first plurality of protrusion strip parts is formed.
4. The display device according to claim 1 , wherein
the first layer includes a plurality of recession strip parts each of which extends in the second direction and between neighboring ones of the recession strip parts each of the first plurality of protrusion strip parts is formed.
5. The display device according to claim 1 , wherein
the at least one diffraction grating formed on the surface of the first layer is a transmitting type diffraction grating and is arranged on a side where the display layer exists when seen from the light emitting element layer.
6. The display device according to claim 1 , wherein
the third layer includes a plurality of second slits each of which extends in the first direction and between neighboring ones of the second slits each of the second plurality of protrusion strip parts is formed.
7. The display device according to claim 1 , wherein
the third layer includes a plurality of second recession strip parts each of which extends in the first direction and between neighboring ones of the second recession strip parts each of the second plurality of protrusion strip parts is formed.
8. The display device according to claim 1 , wherein
the at least one diffraction grating formed on the surface of the third layer is a transmitting type diffraction grating and is arranged on a side where the display layer exists when seen from the light emitting element layer.
9. The display device according to claim 8 , wherein
one of the pixel electrode layer and the common electrode layer is separated from the display layer by a first distance,
the other one of the pixel electrode layer and the common electrode layer is separated from the display layer by a second distance, wherein the first distance from the display layer is less than the second distance from the display layer, and
one of the third layer and the fourth layer is the one of the pixel electrode layer and the common electrode layer.
10. The display device according to claim 1 , wherein
the at least one diffraction grating formed on the surface of the third layer is a reflecting type diffraction grating and is arranged on a side opposite to a side where the display layer exists when seen from the light emitting element layer.
11. The display device according to claim 10 , wherein
one of the pixel electrode layer and the common electrode layer is separated from the display layer by a first distance,
the other one of the pixel electrode layer and the common electrode layer is separated from the display layer by a second distance, wherein the first distance from the display layer is less than the second distance from the display layer, and
one of the third layer and the fourth layer is the other one of the pixel electrode layer and the common electrode layer.
12. The display device according to claim 1 , wherein
the plurality of unit pixels are composed of a plurality of colors for constituting a full color pixel;
the plurality of colors are properties of a plurality of kinds of light whose wavelength varies in accordance with the plurality of colors;
the at least one diffraction grating comprises a plurality of diffraction gratings that respectively correspond to the plurality of kinds of light; and
the plurality of diffraction gratings change mutual intervals of the first plurality of protrusion strip parts depending on the wavelength of a corresponding one of the plurality of kinds of light.
13. A display device comprising:
a pixel electrode;
a light emitting element layer disposed on the pixel electrode;
a common electrode disposed on the light emitting element layer; and
a sealing layer disposed on the common electrode, wherein
the sealing layer comprises a first diffraction grating and a second diffraction grating that is located between the first diffraction grating and the common electrode,
the sealing layer comprises a first inorganic layer that is made of an inorganic material, a second inorganic layer that is made of an inorganic material and is located between the first inorganic layer and the common electrode, and an organic layer that is made of an organic material and is located between the first inorganic layer and the second inorganic layer,
the first diffraction grating is located on the organic layer,
the second diffraction grating is located on the second inorganic layer,
the organic layer comprises a first organic layer that is in contact with the first inorganic layer and a second organic layer that is in contact with the first organic layer and the second inorganic layer, and
the first diffraction grating is located on an interface between the first organic layer and the second organic layer.