Optical functional film for head-up display, optical laminate, functional glass, and head-up display system
An optical functional film for a head-up display according to the present disclosure includes (A) two or more phase difference layers and (B) an adhesive layer. The adhesive layer is adjacent to at least one phase difference layer, and an absolute value of difference between a refractive index of the adhesive layer and a refractive index of the phase difference layer adjacent to the adhesive layer in a direction of a fast axis is less than 0.060.
1 . An optical functional film for a head-up display, comprising (A) two or more phase difference layers and (B) an adhesive layer, wherein
all of (A) the two or more phase difference layers are ½ wavelength plates;
(B) the adhesive layer is provided adjacent to the two or more phase difference layers; and
an absolute value of difference between a refractive index of the adhesive layer and a refractive index of the phase difference layers adjacent to the adhesive layer in a direction of a fast axis is less than.
2 . The optical functional film for a head-up display according to claim 1 , wherein
absolute values of differences between the refractive index of the adhesive layer and refractive indices of the two or more phase difference layers in the direction of the fast axis are both less than 0.060.
3 . The optical functional film for a head-up display according to claim 1 , wherein in (B) the adhesive layer, a difference between an elastic modulus at 25° C. and an elastic modulus at 140° C. is 500 MPa or less.
4 . The optical functional film for a head-up display according to claim 1 , wherein (B) the adhesive layer is a cured film obtained by curing a curable compound.
5 . The optical functional film for a head-up display according to claim 4 , wherein the curable compound is a photocurable compound.
6 . An optical laminate for a head-up display, wherein (C) an intermediate film is further laminated on the optical functional film for a head-up display according to claim 1 .
7 . Functional glass for a head-up display, comprising: the optical functional film for a head-up display according to claim 1 .
8 . Functional glass for a head-up display, comprising: t the optical laminate for a head-up display according to claim 6 ; and (D) a glass plate.
9 . A head-up display system, comprising, as a display medium, the optical functional film according to claim 1 , and an optical laminate wherein (C) an intermediate film is further laminated on the optical functional film, or a functional glass for the head-up display.
10 . A head-up display system, comprising, as a display medium, the optical laminate for a head-up display according to claim 6 .
11 . A head-up display system, comprising, as a display medium, the functional glass for a head-up display according to claim 7 .
12 . The head-up display system according to claim 9 , wherein light emitted from a display image projection unit comes from a side on which a phase difference layer having a highest refractive index among (A) the two or more phase difference layers is disposed.
13 . The head-up display system according to claim 9 , wherein light emitted from a display image projection unit is S polarized light.