Privacy protection film and liquid crystal display device including the same
Provided is a privacy protection film. The privacy protection film includes a transparent base substrate, a light control layer disposed on the transparent base substrate and including a plurality of optical pattern structures each having an upwardly protruding prism shape, a first electrode disposed on the light control layer, a second electrode spaced apart from the first electrode, and a variable light diffusion layer disposed between the first electrode and the second electrode and formed of a polymer dispersed liquid crystal (PDLC).
1. A privacy protection film, comprising:
a first transparent substrate and a second transparent substrate facing the first transparent substrate;
a first electrode on the first transparent substrate;
a second electrode on a lower surface of the second transparent substrate; and
a variable light diffusion layer disposed between the first electrode and the second electrode, the variable light diffusion layer comprising:
a plurality of optical pattern structures disposed directly on the first electrode and formed of a transparent material;
a polymer filling a space between the first electrode and the second electrode and covering the plurality of optical pattern structures; and
droplets including liquid crystal molecules dispersed in the polymer,
wherein each of the plurality of optical pattern structures has:
a height of approximately 100 nm to 200 nm,
a width of approximately 100 nm to 200 nm,
an interval of approximately 100 nm to 200 nm, and
a taper angle of approximately 3° to 15°.
2. The privacy protection film of claim 1 , wherein when a voltage is applied to the first electrode and the second electrode, the variable light diffusion layer is transparent, and
when no voltage is applied to the first electrode and the second electrode, the variable light diffusion layer is non-transparent or opaque.
3. The privacy protection film of claim 1 , wherein each of the plurality of optical pattern structures has a pyramid shape or a truncated pyramid shape formed of four inclined surfaces having identical inclinations.
4. The privacy protection film of claim 1 , wherein each of the plurality of optical pattern structures is one of the following:
a rod-type prism having two inclined surfaces with identical inclinations, and having a triangular cross-sectional shape, or
a rod-type prism having two inclined surfaces with identical inclinations, and having a trapezoidal cross-sectional shape.
5. The privacy protection film of claim 1 , wherein a refractive index of the plurality of optical pattern structures is greater than or equal to a refractive index of the polymer.
6. The privacy protection film of claim 1 , wherein an interval between the first electrode and the second electrode is approximately 300 μm to 500 μm.
7. A liquid crystal display device, comprising:
the privacy protection film of claim 1 ;
a backlight unit disposed under the privacy protection film; and
a liquid crystal display panel disposed on the privacy protection film.
8. The liquid crystal display device of claim 7 , wherein the backlight unit includes an optical sheet including a diffusion sheet and a prism sheet.