Display device, and method for selecting optical film for display device

1. A display device comprising a display element, and a polarizer a and an optical film X on a surface on a light emitting surface side of the display element, and satisfying the following condition 1-1 and condition 2-1:

<Condition 1-1>

let L 1 represent light incident vertically on the optical film X, among light incident on the optical film X from a display element side; an intensity of the L 1 is measured every 1 nm; it is assumed that a blue wavelength band range from 400 nm to less than 500 nm, a green wavelength band range from 500 nm to less than 600 nm, and a red wavelength band range from 600 nm to 780 nm; let B max represent a maximum intensity of the blue wavelength band of the L 1 , G max represent a maximum intensity of the green wavelength band of the L 1 , and R max represent a maximum intensity of the red wavelength band of the L 1 ;

let L 1 λ B represent a wavelength showing the B max , L 1 λ G represent a wavelength showing the G max , and L 1 λ R represent a wavelength showing the R max ;

let +α B represent a minimum wavelength showing a ½ or less of the intensity of the B max , and located in a plus direction side of L 1 λ B , −α G represent a maximum wavelength showing a ½ or less of the intensity of the G max , and located in a minus direction side of L 1 λ G , +α G represent a minimum wavelength showing a ½ or less of the intensity of the G max , and located in a plus direction side of L 1 λ G , and −α R represent a maximum wavelength showing a ½ or less of the intensity of the R max , and located in a minus direction side of L 1 λ R ; and

L 1 λ B , L 1 λ G , L 1 λ R , +α B , −α G , +α G and −α R satisfy the following relationships (1) to (4),

+α B <L 1 λ G   (1)

L 1 λ B <−α G   (2)

+α G <L 1 λ R   (3)

L 1 λ G <−α R   (4);

<Condition 2-1>

let L 2 represent light that emits vertically from the light emitting surface side of the optical film X, and passes through a polarizer b having an absorption axis parallel to an absorption axis of the polarizer a; an intensity of the L 2 is measured every 1 nm; a wavelength at which an inclination of an optical spectrum of the L 2 changes from negative to positive is assumed to be a bottom wavelength, and a wavelength at which the inclination of the optical spectrum of the L 2 switches from positive to negative is assumed to be a peak wavelength;

let −β R represent the maximum wavelength showing a ⅓ or less of the intensity of the R max , and located in the minus direction side of L 1 λ R , +β R represent the minimum wavelength showing a ⅓ or less of the intensity of the R max , and located in a plus direction side of L 1 λ R , −β G represent the maximum wavelength showing a ⅓ or less of the intensity of the G max , and located in the minus direction side of L 1 λ G , +β G represent the minimum wavelength showing a ⅓ or less of the intensity of the G max , and located in the plus direction side of L 1 λ G , −β B represent the maximum wavelength showing a ⅓ or less of the intensity of the B max , and located in a minus direction side of L 1 λ B , and +β B represent the minimum wavelength showing a ⅓ or less of the intensity of the B max , and located in the plus direction side of L 1 λ B ;

let R β represent a wavelength band ranging from −β R to +β R in the range of 600 nm to 780 nm, G β represent a wavelength band ranging from −β G to +β G in the range of 500 nm to less than 600 nm, and B β represent a wavelength band ranging from −β B to +β B in the range of 400 nm to less than 500 nm; and

each of the wavelength bands of the R β , the G β , and the B β includes one or more bottom wavelengths and one or more peak wavelengths.

2. The display device according to claim 1 , wherein the following condition 1-2 is satisfied:

<Condition 1-2>

based on an optical spectrum of L 1 obtained by the measurement of the condition 1-1, an average value B Ave of intensities of an optical spectrum in the blue wavelength band, an average value G Ave of intensities of an optical spectrum in the green wavelength band, and an average value R Ave of intensities of an optical spectrum in the red wavelength band are calculated; let B p represent a wavelength band in which the intensities of L 1 continuously exceed B Ave in the blue wavelength band, G p represent a wavelength band in which the intensities of L 1 continuously exceed G Ave in the green wavelength band, and R p represent the wavelength band in which the intensities of L 1 continuously exceed R Ave in the red wavelength band; and the numbers of wavelength bands indicating B β , G p and R p are all 1.

3. The display device according to claim 1 , wherein the following condition 1-3 is satisfied:

<Condition 1-3>

the +α B , the −α G , the +α G and the −α R satisfy the following relationships (5) to (6),

+α B <−α G   (5)

+α G <−α R   (6).

4. The display device according to claim 1 , wherein the following condition 1-4 is satisfied:

<Condition 1-4>

let +β B represent a minimum wavelength showing a ⅓ or less of the intensity of the B max , and located in the plus direction side of L 1 λ B , −β G represent a maximum wavelength showing a ⅓ or less of the intensity of the G max , and located in the minus direction side of L 1 λ G , +β G represent a minimum wavelength showing a ⅓ or less of the intensity of the G max , and located in the plus direction side of L 1 λ G , and −β R represent a maximum wavelength showing a ⅓ or less of the intensity of the R max , and located in the minus direction side of L 1 λ R ; and

the +β B , the −β G , the +β G and the −β R satisfy the following relationships (7) to (8),

+β B <−β G   (7)

+β G <−β R   (8).

5. The display device according to claim 1 , wherein the following condition 1-5 is satisfied:

<Condition 1-5>

let L 1max represent the maximum intensity among the B max , the G max and R max ; and B max /L 1max , G max /L 1max , and R max /L 1max are each 0.27 or more.

6. The display device according to claim 1 , wherein the following condition 2-2 is satisfied:

<Condition 2-2>

let −α R represent the maximum wavelength showing a ½ or less of the intensity of the R max , and located in the minus direction side of L 1 λ R , +α R represent the minimum wavelength showing a ½ or less of the intensity of the R max , and located in the plus direction side of L 1 λ R , −α G represent the maximum wavelength showing a ½ or less of the intensity of the G max , and located in the minus direction side of L 1 λ G , +α G represent the minimum wavelength showing a ½ or less of the intensity of the G max , and located in the plus direction side of L 1 λ G , −α B represent the maximum wavelength showing a ½ or less of the intensity of the B max , and located in the minus direction side of L 1 λ B , and +α B represent the minimum wavelength showing a ½ or less of the intensity of the B max , and located in the plus direction side of L 1 λ B ;

let R α represent a wavelength band ranging from −α R to +α R in the range of 600 nm to 780 nm, G α represent a wavelength band ranging from −α G to +α G in the range of 500 nm to less than 600 nm, and B α represent a wavelength band ranging from −α B to +α B in the range of 400 nm to less than 500 nm; and

each of the wavelength bands of the R α , the G α , and the B α includes one or more bottom wavelengths of the L 2 and one or more peak wavelengths of the L 2 .

7. The display device according to claim 1 , wherein the optical film X comprises an optically transparent base material exhibiting a positive birefringence property.

8. The display device according to claim 7 , wherein the optically transparent base material is a polyester film.

9. A method of selecting an optical film of a display device comprising a display element, and a polarizer a and the optical film on a surface on a light emitting surface side of the display element, wherein, when light incident on the optical film satisfies the following condition 1-1, the optical film satisfying the following condition 2-1 is selected:

<Condition 1-1>

let L 1 represent light incident vertically on the optical film X, among light incident on the optical film X from a display element side; an intensity of the L 1 is measured every 1 nm; it is assumed that a blue wavelength band range from 400 nm to less than 500 nm, a green wavelength band range from 500 nm to less than 600 nm, and a red wavelength band range from 600 nm to 780 nm; let B max , represent a maximum intensity of the blue wavelength band of the L 1 , G max represent a maximum intensity of the green wavelength band of the L 1 , and R max represent a maximum intensity of the red wavelength band of the L 1 ;

let L 1 λ B represent a wavelength showing the B max , L 1 λ G represent a wavelength showing the G max , and L 1 λ R represent a wavelength showing the R max ;

let +α B represent a minimum wavelength showing a ½ or less of the intensity of the B max , and located in a plus direction side of L 1 λ B , −α G represent a maximum wavelength showing a ½ or less of the intensity of the G max , and located in a minus direction side of L 1 λ G , +α G represent a minimum wavelength showing a ½ or less of the intensity of the G max , and located in a plus direction side of L 1 λ G , and −α R represent a maximum wavelength showing a ½ or less of the intensity of the R max , and located in a minus direction side of L 1 λ R ; and

L 1 λ B , L 1 λ G , L 1 λ R , +α B , −α G , +α G and −α R satisfy the following relationships (1) to (4),

+α B <L 1 λ G   (1)

L 1 λ B <−α G   (2)

+α G <L 1 λ R   (3)

L 1 λ G <−α R   (4);

<Condition 2-1>

let L 2 represent light that emits vertically from the light emitting surface side of the optical film X, and passes through a polarizer b having an absorption axis parallel to an absorption axis of the polarizer a; an intensity of the L 2 is measured every 1 nm; a wavelength at which an inclination of an optical spectrum of the L 2 changes from negative to positive is assumed to be a bottom wavelength, and a wavelength at which the inclination of the optical spectrum of the L 2 switches from positive to negative is assumed to be a peak wavelength;

let −β R represent the maximum wavelength showing a ⅓ or less of the intensity of the R max , and located in the minus direction side of L 1 λ R , +β R represent the minimum wavelength showing a ⅓ or less of the intensity of the R max , and located in a plus direction side of L 1 λ R , −β G represent the maximum wavelength showing a ⅓ or less of the intensity of the G max , and located in the minus direction side of L 1 λ G , +β G represent the minimum wavelength showing a ⅓ or less of the intensity of the G max , and located in the plus direction side of L 1 λ G , −β B represent the maximum wavelength showing a ⅓ or less of the intensity of the B max , and located in a minus direction side of L 1 λ B , and +β B represent the minimum wavelength showing a ⅓ or less of the intensity of the B max , and located in the plus direction side of L 1 λ B ;

let R β represent a wavelength band ranging from −β R to +β R in the range of 600 nm to 780 nm, G β represent a wavelength band ranging from −β G to +β G in the range of 500 nm to less than 600 nm, and B β represent a wavelength band ranging from −β B to +β B in the range of 400 nm to less than 500 nm; and

each of the wavelength bands of the R β , the G β , and the B β includes one or more bottom wavelengths and one or more peak wavelengths.