CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is based on and claims priority under 35 U.S.C. § 119 to Korean Patent Application No. 10-2018-0122272, filed on Oct. 15, 2018, in the Korean Intellectual Property Office, the disclosure of which is incorporated by reference herein in its entirety.

BACKGROUND

1. Field

The disclosure relates to a display apparatus, and more particularly to a display apparatus including an optical film.

2. Description of Related Art

A display apparatus is a type of output device that visually displays data information such as characters and graphics, and images.

The display apparatus may include a self-emissive type display panel such as an organic light emitting diode (OLED) panel, or a non-self-emissive type display panel such as a liquid crystal display (LCD) panel.

A display apparatus having a liquid crystal display may include an optical film to improve a viewing angle. The optical film may include a plurality of refractive layers having different refractive indices. The optical film may improve the viewing angle of the display apparatus by utilizing the refraction phenomenon of light based on the refractive index difference among the plurality of refractive layers.

However, there is a limit in improving the viewing angle of a display apparatus using only an optical film that utilizes a refraction phenomenon of light caused by a refractive index difference among the plurality of refractive layers. When a material capable of maximizing the refractive index is used, the manufacturing cost of the optical film is increased.

SUMMARY

Therefore, it is an aspect of the present disclosure to provide a display apparatus having an improved viewing angle.

It is another aspect of the present disclosure to provide a display apparatus capable of reducing reflection of external light.

It is another aspect of the present disclosure to provide a display apparatus having an improved contrast ratio.

It is another aspect of the present disclosure to provide a display apparatus capable of simplifying a manufacturing process of an optical film.

It is another aspect of the present disclosure to provide a display apparatus capable of easily processing an optical film.

Additional aspects of the present disclosure will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the present disclosure.

In accordance with an aspect of the disclosure, a display apparatus includes a backlight unit configured to emit light, a display panel positioned to the front of the backlight unit, and an optical film positioned to the front of the display panel, and the optical film includes a base layer, a first refractive layer positioned to the front of the base layer, a second refractive layer positioned to the front of the first refractive layer and having a lower refractive index than the first refractive layer, a third refractive layer positioned to the rear of the base layer, and a fourth refractive layer positioned to the rear of the third refractive layer and having a lower refractive index than the third refractive layer.

The first refractive layer may include first patterns that each include a first inclined portion configured to totally reflect some beams of the light emitted from the backlight unit.

The second refractive layer may include a first filling portion filling between the first patterns of the first refractive layer.

The third refractive layer may include second patterns that each include a second inclined portion configured to refract at least a part of the light emitted from the backlight unit that passes through the fourth refractive layer.

The first inclined portion may have a greater inclination angle than the second inclined portion.

The first pattern may have a higher height than the second pattern.

The fourth refractive layer may include a second filling portion filling between the second patterns of the third refractive layer.

The first patterns and the second patterns may be embossed patterns.

A distance between the first patterns may be different from a distance between the second patterns.

Each of the first patterns may include a parallel portion extending parallel to a direction in which the first refractive layer extends.

The first refractive layer may include a pattern including a curved portion configured to totally reflect a portion of the light emitted from the backlight unit.

The third refractive layer may include a pattern including a curved portion configured to refract at least a portion of the light emitted from the backlight unit that passes through the fourth refractive layer.

The pattern may be an engraved pattern.

In accordance with another aspect of the disclosure, a display apparatus includes a display panel, and an optical film positioned to the front of the display panel, and the optical film includes a base layer, a first refractive layer positioned to the front of the base layer and including first patterns each including a first inclined portion configured to totally reflect a portion of light passing through the base layer, a second refractive layer positioned to the front of the first refractive layer and having a lower refractive index than the first refractive layer, a third refractive layer positioned to the rear of the base layer and including second patterns each including a second inclined portion configured to refract a portion of light incident from the display panel, and a fourth refractive layer positioned to the rear of the third refractive layer and having a lower refractive index than the third refractive layer.

The first patterns may be embossed patterns and the second refractive layer may include a first filling portion filling between the first patterns.

The second patterns may be embossed patterns or engraved patterns, and the fourth refractive layer may include a second filling portion filling between the second patterns.

The first inclined portion may have a greater inclination angle than the second inclined portion.

The first pattern may have a higher height than the second pattern.

A distance between the first patterns may be different from a distance between the second patterns.

In accordance with another aspect of the disclosure, a display apparatus includes a display panel, and an optical film positioned to the front of the display panel and the optical film includes a base layer, a first refractive layer positioned to the front of the base layer, and including first patterns each including a first inclined portion configured to totally reflect a portion of light passing through the base layer, a second refractive layer positioned to the front of the first refractive layer and having a lower refractive index than the first refractive layer, the second refractive layer including a first filling portion filling between the first patterns, a third refractive layer positioned to the rear of the base layer and including second patterns each including a second inclined portion having a less inclination angle than the first inclined portion, and a fourth refractive layer positioned to the rear of the third refractive layer and having a lower refractive index than the third refractive layer, the fourth refractive layer including a second filling portion filling between the second patterns.

