Electro-optic unit having electro-optic material layer with variable refractive index, driving method of the electro-optic unit, and display apparatus having the same

A display device, comprising:

• a display panel to emit an image;
• a first electro-optic unit disposed on an upper portion of the display panel, and comprising a first electro-optic material layer, a refractive index of the first electro-optic material layer being changed according to a position corresponding to an electric field generated from an applied voltage to form a first graded refractive index lens;
• and
• a second electro-optic unit disposed on an upper portion of the first electro-optic unit, and comprising a second electro-optic material layer, a refractive index of the second electro-optic layer being changed according to a position corresponding to an electrical field generated from an applied voltage to form a second graded refractive index lens,
• wherein a two-dimensional image or a three-dimensional image is selectively displayed according to a mode of the first electro-optic unit and the second electro-optic unit.

An electro-optic unit, comprising:

• a first substrate;
• a second substrate;
• an electro-optic material layer disposed between the first substrate and the second substrate, and a refractive index of the electro-optic material layer being changed according to a position corresponding to an electrical field generated from an applied voltage, and the electric field being applied by the first substrate and the second substrate, to form a graded refractive index lens as a Fresnel lens having a plurality of sub-lenses;
• and
• an electric field interference protection wall corresponding to a boundary between adjacent sub-lenses of the plurality of sub-lenses, and extended to the electro-optic material layer from the first substrate.

A method of driving an electro-optic unit, wherein the electro-optic unit comprises an electro-optic material layer to operate in a first mode as a liquid crystal layer having a uniform refractive index and to operate in a second mode as a graded refractive index lens having a various refractive index corresponding to a poison according to an applied voltage, the applied voltage ranging from a first voltage to a second voltage and the first voltage through the second voltage being respectively applied to an outline through a center of the graded refractive index lens at the second mode, the method comprising:

• changing a voltage, which has a range from the first voltage to a third voltage, to the second voltage at a first section of the graded refractive index lens, and the third voltage being between the first voltage and the second voltage;
• changing a voltage, which has a range from the third voltage to the second voltage, to the first voltage at a second section of the graded refractive index lens during a first time period;
• and
• changing the voltage at the second section of the graded refractive index lens to the second voltage after the first time period,
• wherein the electro-optic material layer operates in the first mode as the liquid crystal layer where the graded refractive index lens is cleared off.