Patent ID: 11874549
Assignee: SHARP DISPLAY TECHNOLOGY CORPORATION
Field: Optics (Instruments)
Classification: CPC G | IPC G

Claim 0:
1. An optical element comprising:
a first polarizer;
a first phase difference layer;
a second phase difference layer; and
a second polarizer,
the first polarizer, the first phase difference layer, the second phase difference layer, and the second polarizer being arranged in the stated order,
one of the first phase difference layer and the second phase difference layer satisfying the following formula (i) while the other of the first phase difference layer and the second phase difference layer satisfying the following formula (ii), or one of the first phase difference layer and the second phase difference layer satisfying the following formula (iii) while the other of the first phase difference layer and the second phase difference layer satisfying the following formula (iv),
the first polarizer and the second polarizer being linear polarizers,
a transmission axis of the first polarizer and a transmission axis of the second polarizer being parallel to each other,
a slow axis of the first phase difference layer and the second phase difference layer, whichever satisfies the following formula (i) or (iii), being orthogonal to a polarization axis of the first polarizer,

nx>ny≈nz   (i)

nz>nx≈ny   (ii)

ny<nx≈nz   (iii)

nz<nx≈ny   (iv), wherein nx represents a principal refractive index in a slow axis direction in a plane of each of the phase difference layers; ny represents a principal refractive index in a fast axis direction in a plane of each phase difference layer; and nz represents a principal refractive index in a direction vertical to a surface of each phase difference layer.