CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims priority to and benefits of Korean Patent Application No. 10-2019-0105113 under 35 U.S.C. § 119, filed on Aug. 27, 2019 in the Korean Intellectual Property Office, the entire contents of which are incorporated herein by reference.

BACKGROUND

The disclosure relates to a display device, and more particularly, to a display device including an optical pattern layer disposed on a light emitting element layer.

Various display devices used for multimedia devices such as televisions, mobile phones, tablet computers, navigation units, and game consoles have been developed. When the above-described display devices are used, a color difference phenomenon according to a viewing angle occurs to degrade a display quality of the display device.

Thus, various methods have been introduced in order to improve the color difference phenomenon according to a viewing angle.

SUMMARY

The disclosure provides a display device including an optical pattern layer for improving a display quality difference according to a side viewing angle.

The disclosure also provides a display device having an improved display quality at a side viewing angle by minimizing reduction in front efficiency and optimizing a shape of a pattern layer.

In an embodiment, a display device may include a light emitting element layer; and an optical pattern layer disposed on the light emitting element layer. The optical pattern layer may include a first pattern layer having a first refractive index and including a base part and protruding parts spaced apart from each other on the base part; and a second pattern layer disposed on the first pattern layer and having a second refractive index less than the first refractive index.

In an embodiment, the light emitting element layer may include a first electrode; a second electrode facing the first electrode; a light emitting layer disposed between the first electrode and the second electrode and including an organic electroluminescent material or a quantum dot; and an encapsulation layer disposed on the second electrode. The first electrode may be a reflective electrode, and the second electrode may be a transmissive electrode or a transflective electrode.

In an embodiment, the display device may further include an optical member disposed on the light emitting element layer, and the optical member may include at least one of a polarizing layer or a color filter layer.

In an embodiment, the optical member may be disposed between the light emitting element layer and the optical pattern layer or disposed on the optical pattern layer.

In an embodiment, each of the protruding parts may have a cylindrical or prismatic shape protruding from the base part.

In an embodiment, each of the protruding parts may include a bottom surface adjacent to the base part; a ceiling surface facing the bottom surface; and a side surface extending between the bottom surface and the ceiling surface. An inclination angle of the side surface with respect to the bottom surface on a cross section perpendicular to the base part may be in a range from about 70° to about 90°.

In an embodiment, the bottom surface may have a width in a range from about 4 μm to about 10 μm on the cross section perpendicular to the base part.

In an embodiment, each of the protruding parts may have a height in a range from about 7 μm to about 15 μm and the height may be a minimum spaced distance between the bottom surface and the ceiling surface.

In an embodiment, the protruding parts may include a first protruding part and a second protruding part, which are adjacent to each other, and a minimum spaced distance between the bottom surface of the first protruding part and the bottom surface of the second protruding part may be in a range from about 4 μm to about 10 μm.

In an embodiment, the bottom surface may have a width that is different from a width of the ceiling surface.

In an embodiment, the first refractive index may range from about 1.5 to about 1.7, and a difference between the first refractive index and the second refractive index may be equal to or greater than about 0.1.

In an embodiment, the second pattern layer may be disposed between the protruding parts.

In an embodiment, a display device may include a light emitting element layer including a first electrode, a second electrode facing the first electrode, and a light emitting layer disposed between the first electrode and the second electrode; an optical pattern layer disposed on the light emitting element layer and including a first pattern layer having a first refractive index and a second pattern layer having a second refractive index less than the first refractive index; and an optical member. The optical member may be disposed between the light emitting element layer and the optical pattern layer or may be disposed on the optical pattern layer.

In an embodiment, the light emitting element layer may further include an encapsulation layer disposed on the second electrode, and the optical pattern layer may be directly disposed on the encapsulation layer.

In an embodiment, the first pattern layer may include a base part and protruding parts disposed on the base part and spaced apart from each other. Each of the protruding parts may include a bottom surface adjacent to the base part; a ceiling surface facing the bottom surface; and a side surface extending between the bottom surface and the ceiling surface. Each of the bottom surface and the ceiling surface may have a circular or polygonal shape on a cross section parallel to the base part.

In an embodiment, in each of the protruding parts, a width of the bottom surface may be in a range from about 4 μm to about 10 μm, a height that is minimum spaced distance between the bottom surface and the ceiling surface may be in a range from about 7 μm to about 15 μm, and an inclination angle of the side surface with respect to the bottom surface on a cross section perpendicular to the base part may be in a range from about 70° to about 90°.

In an embodiment, the first electrode may be a reflective electrode, and the second electrode may be a transmissive electrode or a transflective electrode.

In an embodiment, the light emitting element layer may include an organic electroluminescent element or a quantum dot light emitting element.

In an embodiment, the optical member may be a polarizing layer, and the optical pattern layer may be directly disposed on or below the polarizing layer.

In an embodiment, the optical member may be a color filter layer, and the optical pattern layer may be directly disposed on the color filter layer.

