Display device

A display device comprising:

• a cover plate;
• an optical module located under the cover plate and comprising:
• a light guide plate having a first main surface and a second main surface opposite to each other, wherein the first main surface faces the cover plate and has a plurality of concave microstructures having non-gradient shapes;
• a first optical layer located on the first main surface, wherein a first ideal interfacial reflectance R0-1 is defined between the first optical layer and the first main surface;
• a second optical layer located on the second main surface, wherein a second ideal interfacial reflectance R0-2 is defined between the second optical layer and the second main surface;
• and
• a light source disposed on a lateral side of the light guide plate;
• and
• a color electrophoretic display module located under the optical module,
• wherein the light guide plate has a refractive index nLG of about 1.55 to about 1.65, the first optical layer has a refractive index n1 of about 1.38 to about 1.41, and the second optical layer has a refractive index n2 of about 1.48 to about 1.52,
• wherein a ratio of the first ideal interfacial reflectance R0-1 and the second ideal interfacial reflectance R0-2 is about 3 to about 13, and
• wherein the first ideal interfacial reflectance R0-1 and the second ideal interfacial reflectance R0-2 are calculated according to the following equations:
• R
• 0
• -
• 1
• =
• ❘
• "\[LeftBracketingBar]"
• n
• LG
• -
• n
• 1
• n
• LG
• +
• n
• 1
• ❘
• "\[RightBracketingBar]"
• 2
• ,
• R
• 0
• -
• 2
• =
• ❘
• "\[LeftBracketingBar]"
• n
• 2
• -
• n
• LG
• n
• 2
• +
• n
• LG
• ❘
• "\[RightBracketingBar]"
• 2
• ∘