Viewing angle control system and image display device
A viewing angle control system is used in combination with a high-definition image display device and sufficiently shields light emitted in a direction oblique to a normal direction of a film. The viewing angle control system includes at least a first polarizer, a retardation layer, and a second polarizer in this order, where an absorption axis of the first polarizer forms an angle of 45° or greater with respect to a surface, the retardation layer satisfies Expression (1): an in-plane retardation Re of the retardation layer satisfies an expression of 80 nm<Re<250 nm, and Expression (2): in a case of Nz=Rth/Re+0.5, an expression of 1.5<Nz<6 or −5<Nz<−0.5 is satisfied, where Rth represents a retardation of the retardation layer in a thickness direction, and the second polarizer has an absorption axis in an in-plane direction.
1 . A viewing angle control system comprising at least:
a first polarizer;
a retardation layer; and
a second polarizer in this order,
wherein an absorption axis of the first polarizer forms an angle of 45° or greater with respect to a top surface of the viewing angle control system,
the retardation layer satisfies Expression (1) and Expression (2), and
the second polarizer has an absorption axis in an in-plane direction,
Expression (1): an in-plane retardation Re of the retardation layer satisfies an expression of 80 nm<Re<250 nm, and Expression (2): in a case of Nz=Rth/Re+0.5, an expression of 1.5<Nz<6 or −5<Nz <−0.5 is satisfied, where Rth represents a retardation of the retardation layer in a thickness direction.
2 . The viewing angle control system according to claim 1 ,
wherein the absorption axis of the first polarizer is perpendicular to the top surface of the viewing angle control system.
3 . The viewing angle control system according to claim 1 ,
wherein the retardation layer is a B-plate having an Nz coefficient of greater than 1.5, and
an angle between a slow axis of the B-plate and the absorption axis of the second polarizer is 10° or less.
4 . The viewing angle control system according to claim 1 ,
wherein the retardation layer is a B-plate having an Nz coefficient of less than −0.5, and
an angle between a slow axis of the B-plate and the absorption axis of the second polarizer is 80° or greater and 100° or less.
5 . The viewing angle control system according to claim 1 ,
wherein the retardation layer includes at least a positive A-plate and a positive C-plate,
the positive A-plate is provided on a side of the first polarizer, and
an angle between a slow axis of the positive A-plate and the absorption axis of the second polarizer is 80° or greater and 100° or less.
6 . The viewing angle control system according to claim 1 ,
wherein the retardation layer includes at least a negative A-plate and a negative C-plate,
the negative A-plate is provided on a side of the first polarizer, and
an angle between a slow axis of the negative A-plate and the absorption axis of the second polarizer is 10° or less.
7 . The viewing angle control system according to claim 1 ,
wherein the retardation layer includes at least a B-plate and a positive C-plate,
the B-plate is provided on a side of the first polarizer, and
an angle between a slow axis of the B-plate and the absorption axis of the second polarizer is 80° or greater and 100° or less.
8 . The viewing angle control system according to claim 1 ,
wherein the retardation layer includes at least a B-plate and a negative C-plate,
the B-plate is provided on a side of the first polarizer, and
an angle between a slow axis of the B-plate and the absorption axis of the second polarizer is 10° or less.
9 . An image display device comprising:
the viewing angle control system according to claim 1 .
10 . The viewing angle control system according to claim 2 ,
wherein the retardation layer is a B-plate having an Nz coefficient of greater than 1.5, and
an angle between a slow axis of the B-plate and the absorption axis of the second polarizer is 10° or less.
11 . The viewing angle control system according to claim 2 ,
wherein the retardation layer is a B-plate having an Nz coefficient of less than −0.5, and
an angle between a slow axis of the B-plate and the absorption axis of the second polarizer is 80° or greater and 100° or less.
12 . The viewing angle control system according to claim 2 ,
wherein the retardation layer includes at least a positive A-plate and a positive C-plate,
the positive A-plate is provided on a side of the first polarizer, and
an angle between a slow axis of the positive A-plate and the absorption axis of the second polarizer is 80° or greater and 100° or less.
13 . The viewing angle control system according to claim 2 ,
wherein the retardation layer includes at least a negative A-plate and a negative C-plate,
the negative A-plate is provided on a side of the first polarizer, and
an angle between a slow axis of the negative A-plate and the absorption axis of the second polarizer is 10° or less.
14 . The viewing angle control system according to claim 2 ,
wherein the retardation layer includes at least a B-plate and a positive C-plate,
the B-plate is provided on a side of the first polarizer, and
an angle between a slow axis of the B-plate and the absorption axis of the second polarizer is 80° or greater and 100° or less.
15 . An image display device comprising:
the viewing angle control system according to claim 2 .
16 . An image display device comprising:
the viewing angle control system according to claim 3 .
17 . An image display device comprising:
the viewing angle control system according to claim 4 .
18 . An image display device comprising:
the viewing angle control system according to claim 5 .
19 . An image display device comprising:
the viewing angle control system according to claim 6 .
20 . An image display device comprising:
the viewing angle control system according to claim 7 .