Backlight unit, display device including the same, and method of fabricating the backlight unit

A display device comprising:

• a display panel which displays an image by using light;
• and
• a backlight unit which generates the light and provides the light to the display panel,
• wherein the backlight unit comprises:
• a light source which generates the light;
• a light guide plate which guides the light from the light source in an upper direction toward the display panel;
• and
• an optical member which receives the light from the light guide plate and condenses the light provided from the light guide plate in the upper direction toward the display panel,
• wherein in a top plan view, a top surface of the light guide plate includes a plurality of circular areas spaced apart from each other and a peripheral area which is around the circular areas,
• wherein each of the circular areas includes a central circular area and a ring area which surrounds the central circular area,
• wherein the optical member comprises:
• a first insulating layer disposed on the light guide plate, the first insulating layer:
• in contact with the top surface of the light guide plate at the central circular areas thereof, and
• spaced apart in the upper direction from the top surface of the light guide plate by a predetermined distance at the ring areas and at the peripheral area thereof to define a plurality of cavities;
• and
• a second insulating layer disposed on the first insulating layer.

A method of fabricating a backlight unit, the method comprising:

• preparing a light guide plate including a plurality of central circular areas, a plurality of first ring areas respectively surrounding the central circular areas, a plurality of second ring areas respectively surrounding the first ring areas, and a peripheral area around the second ring areas;
• forming a first photoresist pattern on the light guide plate in the second ring areas and in the peripheral area;
• applying a temperature of about 130 degrees Celsius to about 149 degrees Celsius to the first photoresist pattern in the second ring areas to form an inclined surface of the first photoresist pattern extended from the peripheral area to be disposed in the first and second ring areas, the inclined surface exposing a top surface of the light guide plate;
• forming a first insulating layer on the exposed top surface of the light guide plate, on the first photoresist pattern in the peripheral area and on the inclined surface of the photoresist pattern in the first and second ring areas;
• removing portions of the first insulating layer in predetermined areas of the peripheral area to define a plurality of holes in the first insulating layer which expose the first photoresist pattern under the first insulating layer;
• providing an etching solution to the first photoresist pattern through the holes to remove the first photoresist pattern and form a plurality of cavities under the first insulating layer;
• and
• forming a second insulating layer on the first insulating layer to commonly cover the holes in the first insulating layer,
• wherein the first insulating layer is spaced apart from the light guide plate by a predetermined distance at the first and second ring areas and at the peripheral area to define the plurality of cavities, and
• wherein the first insulating layer spaced apart from the light guide plate at the first and second ring areas and at the peripheral area extends toward the light guide plate to be in contact with the exposed top surface of the light guide plate at the central circular areas thereof.