JP2021120949A - Display device and selection method of optical film in display device - Google Patents

Abstract

To provide a display device having excellent color reproducibility even when being observed through polarizing sunglasses.SOLUTION: In a display device, an L1 is a light that has a polarizer a and an optical film X on a surface of a light emission surface side of a display element, enters to a vertical direction to the optical film X from a light entering from a display element side to the optical film X, and satisfies a specific condition. In the display device, an L2 is a light emitted to the vertical direction of the optical film X from a light emission side surface of the optical film X, and is the light passed through a polarizer b having an adsorption axis in parallel with the adsorption axis of the polarizer a, and the L1 and L2 satisfy the specific condition.SELECTED DRAWING: Figure 10

Description

The present invention relates to a display device and a method for selecting an optical film for the display device.

Display devices typified by liquid crystal displays are rapidly improving in performance such as brightness, resolution, and color gamut. In proportion to these advances in performance, the number of display devices such as portable information terminals and car navigation systems that are intended for outdoor use is increasing.
In an environment such as outdoors where the sunlight is strong, the display device may be observed while wearing sunglasses having a polarization function (hereinafter, referred to as "polarized sunglasses") in order to reduce glare.

When the display device includes a polarizing plate, there is a problem that the screen becomes dark and invisible when the polarization absorption axis of the display device and the polarization absorption axis of the polarized sunglasses are orthogonal to each other (hereinafter, referred to as “blackout”). ..
In order to solve the above problem, the means of Patent Document 1 has been proposed.

Japanese Unexamined Patent Publication No. 2011-107198

Patent Document 1 describes in a liquid crystal display device using a white light emitting diode (white LED) as a backlight source, a polymer film having a retardation of 3,000 to 30,000 nm is arranged at a specific angle on the visible side of a polarizing plate. It is characterized by doing. The problem of blackout can be solved by the means of Patent Document 1.
Further, in Patent Document 1, in a liquid crystal display device using a white light emitting diode (white LED) as a backlight light source, interference unevenness peculiar to a retardation value is prevented.

On the other hand, in recent years, light sources and display elements of display devices have been diversified in order to improve brightness, resolution, color gamut, and the like. For example, the white LED used in Patent Document 1 is often used as the light source for the backlight of the liquid crystal display device, but in recent years, a liquid crystal display device using quantum dots as the light source for the backlight has begun to be proposed. .. The current mainstream of display elements is liquid crystal display elements, but in recent years, practical use of organic EL elements has been expanding.
When these recent display devices are observed through polarized sunglasses, there are cases where problems occur in color reproducibility even if the above problems (blackout and interference unevenness) do not occur.

An object of the present invention is to provide a display device having good color reproducibility and a method for selecting an optical sheet for the display device.

In order to solve the above problems, the present inventors have focused on the difference between a liquid crystal display device using a white LED, which has been the mainstream in the past, and a display device which has been developed in recent years.
As a result, recent display devices have a sharper RGB spectral spectrum and a sharper spectral spectrum than liquid crystal displays using white LEDs in order to improve color rendering properties (to widen the color gamut). Therefore, it has been found that passing through the polarization absorption axis of the optical film having retardation and the polarized sunglasses tends to cause a problem in color reproducibility.
As a result of further studies by the present inventors, the problem of color reproducibility in a display device having a wide color gamut cannot be solved only by considering the spectral spectrum of the light source, and the spectrum of light immediately before it is incident on the optical film. We found that it was necessary to consider the spectrum, and came to solve the above problem.

The present invention provides the following display device and a method for selecting an optical film for the display device.
[1] A display device having a polarizer a and an optical film X on a surface of the display element on the light emitting surface side, and satisfying the following conditions 1-1 and 2-1.
<Condition 1-1>
Wherein among the light incident from the display device side to the optical film X, the light incident perpendicularly to the optical film X and L _1. The intensity of L ₁ is measured every 1 nm. The blue wavelength range is 400 nm or more and less than 500 nm, the green wavelength range is 500 nm or more and less than 600 nm, and the red wavelength range is 600 nm or more and 780 nm or less. Maximum intensity _{B max} of the blue wavelength region of the _{L 1,} the maximum intensity _{G max} of the green wavelength region of the _{L 1,} the maximum intensity in the wavelength range of red of said _{L 1} and _{R max.}
Let _{L 1 λ B be the} wavelength indicating the B _{max , L 1} λ _{G be the} wavelength indicating the G _{max , and L 1} λ _{R be the} wavelength indicating the R _max .
The _{B max} of less than 1/2 of the intensity a wavelength showing an _{L 1} lambda minimum wavelength + alpha located in the positive direction side of the _{B B,} a wavelength showing an intensity of 1/2 or less of the _{G max} L _The maximum wavelength located on the negative side of 1 λ _{G is −α G} , and the minimum wavelength located on the positive side of _{L 1} λ _{G is + α G} , which is a wavelength showing an intensity of 1/2 or less of the _{G max.} Let _{−α R be} the maximum wavelength that is 1/2 or less of the intensity of R _max and is located on the negative side of _{L 1 λ R.}
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} be the light emitted from the light emitting surface side of the optical film X in the vertical direction of the optical film X and passing through the polarizing element b having an absorption axis parallel to the absorption axis of the polarizer a. .. The intensity of L ₂ is measured every 1 nm.
The minimum wavelength located on the positive side of _{L 1} λ _R , which is a wavelength showing an intensity of 1/2 or less of the _{R max , is + α R} , and the wavelength showing an intensity of 1/2 or less of the _{B max, L. 1} Let _{−α B be} the maximum wavelength located on the negative side of _{λ B.}
The wavelength range of −α _R or more and + α _R or less and 600 nm or more and 780 nm or less is R _α , _{and the wavelength range of −α G} or more and + α _G or less and 500 nm or more and less than 600 nm. The wavelength range is G _α , _{and the wavelength range of −α B} or more and + α _B or less and 400 nm or more and less than 500 nm is B _α .
"Intensity ratio R _alpha" the said sum of the intensity of the L ₁ in the wavelength range of the sum / the R _alpha in the intensity of the L ₂ in a wavelength region of R _alpha], wherein in the wavelength range of [the G _alpha L the sum of the intensities of L _1] in the wavelength range of the sum / the G _{alpha 2} intensity "intensity ratio of G _alpha", [wherein B _alpha of the L ₂ of the intensity of the sum / the B _alpha in the wavelength range of _{The total intensity of L 1} in the wavelength range] is defined as the “intensity ratio of _{B α”.}
The maximum value among the intensity ratio of R _α, the intensity ratio of G _α , and _{the intensity ratio of B α is “the maximum RGB intensity ratio of α} ”, the intensity ratio of R α, the intensity ratio of G _α , And _{the minimum value in the intensity ratio of B α} is defined as “the RGB minimum intensity ratio of α”.
The intensity ratio of R _α, the intensity ratio of G _α , and the intensity ratio of B _α are all 0.35 or more, and [RGB minimum intensity ratio of α / RGB maximum intensity ratio of α] is 0. .70 or more.

[2] A method for selecting an optical film of a display device having a polarizer a and an optical film on the surface of the display element on the light emitting surface side, in which the light incident on the optical film satisfies the above condition 1-1. In addition, a method for selecting an optical film for a display device, which selects an optical film that satisfies the above condition 2-1.

The display device of the present invention can suppress a decrease in color reproducibility when observed through polarized sunglasses. In addition, the method for selecting an optical film for the display device of the present invention can efficiently select an optical film capable of suppressing a decrease in color reproducibility when observed through polarized sunglasses.

It is sectional drawing which shows one Embodiment of the display device of this invention. An example of the spectral spectrum of _{light (L 1} ) incident on an optical film from the display element side in a display device having a polarizer a and an optical film on a three-color independent organic EL display element having a microcavity structure. be. In a display device in which the display element is a liquid crystal display element, the light source of the backlight is a cold cathode fluorescent fluorescent lamp (CCFL), and the display element has a polarizing element a and an optical film, the light incident on the optical film from the display element side. This is an example of the spectral spectrum of (L _1). In a display device in which the display element is a liquid crystal display element, the light source of the backlight is a white LED, and the polarizing element a and the optical film are on the display element, the light (L ₁ ) incident on the optical film from the display element side. This is an example of a spectral spectrum. In a display device in which the display element is a liquid crystal display element, the primary light source of the backlight is a blue LED, the secondary light source is a quantum dot, and the polarizing element a and the optical film are provided on the display element, the display element is formed on the optical film. This is an example of the spectral spectrum of the light (L _{1) incident from the side.} Light emitted from the optical film of a display device having a polarizer a and an optical film on a three-color independent organic EL display element having a microcavity structure, and an absorption axis parallel to the absorption axis of the polarizer a. This is an example of the spectral spectrum of _{the light (L 2} ) that has passed through the polarizer b having the light (L 2). The display element is a liquid crystal display element, the light source of the backlight is a cold cathode fluorescent fluorescent lamp (CCFL), and the light emitted from the optical film of the display device having the polarizing element a and the optical film on the liquid crystal display element. This is an example of the spectral spectrum of _{light (L 2} ) that has passed through the polarizing element b having an absorption axis parallel to the absorption axis of the polarizer a. The display element is a liquid crystal display element, the light source of the backlight is a white LED, and the light emitted from the optical film of the display device having the polarizing element a and the optical film on the liquid crystal display element, and the absorption of the polarizing element a. This is an example of the spectral spectrum of _{light (L 2} ) that has passed through a polarizer b having an absorption axis parallel to the axis. The display element is a liquid crystal display element, the primary light source of the backlight is a blue LED, the secondary light source is a quantum dot, and the light emitted from the optical film of a display device having a polarizing element a and an optical film on the display element. This is an example of the spectral spectrum of _{light (L 2} ) that has passed through the polarizer b having an absorption axis parallel to the absorption axis of the polarizer a. It is the figure which superposed the spectroscopic spectrum of FIG. 2 and the spectroscopic spectrum of FIG. It is the figure which superposed the spectroscopic spectrum of FIG. 3 and the spectroscopic spectrum of FIG. It is the figure which superposed the spectroscopic spectrum of FIG. 4 and the spectroscopic spectrum of FIG. It is the figure which superposed the spectroscopic spectrum of FIG. 5 and the spectroscopic spectrum of FIG. In a display device in which the display element is a liquid crystal display element, the primary light source of the backlight is a blue LED, the secondary light source is a quantum dot, and the polarizing element a and the optical film are provided on the display element, the display element is formed on the optical film. This is another example of the spectral spectrum of _{light (L 1} ) incident from the side. In a display device having a polarizer a and an optical film on a color filter type organic EL display element provided with a white light emitting layer and a color filter, light (L ₁ ) incident on the optical film in the vertical direction from the display element side. This is an example of a spectral spectrum.

Hereinafter, embodiments of the present invention will be described.
[Display device]
The display device of the present invention has a polarizer a and an optical film X on a surface of the display element on the light emitting surface side, and satisfies the following conditions 1-1 and 2-1.

<Condition 1-1>
Wherein among the light incident from the display device side to the optical film X, the light incident perpendicularly to the optical film X and L _1. The intensity of L ₁ is measured every 1 nm. The blue wavelength range is 400 nm or more and less than 500 nm, the green wavelength range is 500 nm or more and less than 600 nm, and the red wavelength range is 600 nm or more and 780 nm or less. Maximum intensity _{B max} of the blue wavelength region of the _{L 1,} the maximum intensity _{G max} of the green wavelength region of the _{L 1,} the maximum intensity in the wavelength range of red of said _{L 1} and _{R max.}
Let _{L 1 λ B be the} wavelength indicating the B _{max , L 1} λ _{G be the} wavelength indicating the G _{max , and L 1} λ _{R be the} wavelength indicating the R _max .
The _{B max} of less than 1/2 of the intensity a wavelength showing an _{L 1} lambda minimum wavelength + alpha located in the positive direction side of the _{B B,} a wavelength showing an intensity of 1/2 or less of the _{G max} L _The maximum wavelength located on the negative side of 1 λ _{G is −α G} , and the minimum wavelength located on the positive side of _{L 1} λ _{G is + α G} , which is a wavelength showing an intensity of 1/2 or less of the _{G max.} Let _{−α R be} the maximum wavelength that is 1/2 or less of the intensity of R _max and is located on the negative side of _{L 1 λ R.}
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} be the light emitted from the light emitting surface side of the optical film X in the vertical direction of the optical film X and passing through the polarizing element b having an absorption axis parallel to the absorption axis of the polarizer a. .. The intensity of L ₂ is measured every 1 nm.
The minimum wavelength located on the positive side of _{L 1} λ _R , which is a wavelength showing an intensity of 1/2 or less of the _{R max , is + α R} , and the wavelength showing an intensity of 1/2 or less of the _{B max, L. 1} Let _{−α B be} the maximum wavelength located on the negative side of _{λ B.}
The wavelength range of −α _R or more and + α _R or less and 600 nm or more and 780 nm or less is R _α , _{and the wavelength range of −α G} or more and + α _G or less and 500 nm or more and less than 600 nm. The wavelength range is G _α , _{and the wavelength range of −α B} or more and + α _B or less and 400 nm or more and less than 500 nm is B _α .
"Intensity ratio R _alpha" the said sum of the intensity of the L ₁ in the wavelength range of the sum / the R _alpha in the intensity of the L ₂ in a wavelength region of R _alpha], wherein in the wavelength range of [the G _alpha L the sum of the intensities of L _1] in the wavelength range of the sum / the G _{alpha 2} intensity "intensity ratio of G _alpha", [wherein B _alpha of the L ₂ of the intensity of the sum / the B _alpha in the wavelength range of _{The total intensity of L 1} in the wavelength range] is defined as the “intensity ratio of _{B α”.}
The maximum value among the intensity ratio of R _α, the intensity ratio of G _α , and _{the intensity ratio of B α is “the maximum RGB intensity ratio of α} ”, the intensity ratio of R α, the intensity ratio of G _α , And _{the minimum value in the intensity ratio of B α} is defined as “the RGB minimum intensity ratio of α”.
The intensity ratio of R _α, the intensity ratio of G _α , and the intensity ratio of B _α are all 0.35 or more, and [RGB minimum intensity ratio of α / RGB maximum intensity ratio of α] is 0. .70 or more.

FIG. 1 is a cross-sectional view showing an embodiment of the display device of the present invention. The display device (100) of FIG. 1 has a polarizer a (40) and an optical film X (20) on the light emitting surface of the display element (10). In the display device (100) of FIG. 1, an organic EL display element (10a) is used as the display element. Further, in the display device (100) of FIG. 1, another optical film (30) is arranged between the polarizing element a (40) and the optical film X (20).
In FIG. 1, another optical film (30) is arranged between the polarizer a (40) and the optical film X (20), but the other optical film (30) is arranged at a location. It may be between the display element and the polarizer a, or on the observer side of the optical film X. Further, when the display element of the display device is a liquid crystal display element, a backlight (not shown) is required on the back surface of the liquid crystal display element.

(Condition 1-1)
Condition 1-1 is a condition indicating that the RGB (red, green, blue) spectral spectrum of the display device is sharp. Condition 1-1 will be described more specifically with reference to the figure.

FIG. 2 shows a display device having a polarizer a and an optical film on a three-color independent organic EL display element having a microcavity structure, and when the display element is displayed in white, the display element side is displayed on the optical film. This is an example of a spectral spectrum when the intensity of _{light (L 1} ) incident in the vertical direction is measured every 1 nm. The spectral spectrum of FIG. 2 is a standardized intensity of each wavelength with a maximum intensity of 100.
In FIG. 2, B _max is the maximum intensity in the blue wavelength range (400 nm or more and less than 500 nm), G _max is the maximum intensity in the green wavelength range (500 nm or more and less than 600 nm), and R _max is the red wavelength range (600 nm or more and less than 780 nm). ) Indicates the maximum strength.
Further, in FIG. 2, L ₁ λ _B indicates a wavelength indicating B _{max , L 1} λ _G indicates a wavelength indicating G _{max , and L 1} λ _R indicates a wavelength indicating R _max.
Further, in FIG. 2, + α _B is a wavelength showing an intensity of 1/2 or less of _{B max} , and indicates the minimum wavelength located on the plus direction side of _{L 1} λ _B. −α _G is a wavelength showing an intensity of 1/2 or less of _{G max} , and indicates the maximum wavelength located on the negative side of _{L 1} λ _G. + Α _G is a wavelength indicating an intensity of 1/2 or less of _{G max} , and indicates the minimum wavelength located on the positive side of _{L 1} λ _G. −α _R is a wavelength showing an intensity of 1/2 or less of _{R max} , and indicates the maximum wavelength located on the negative side of _{L 1} λ _R.
The spectroscopic spectra of FIG. 2 are all sharp in RGB spectra, and L ₁ λ _B , L ₁ λ _G , L ₁ λ _R , + α _B , −α _G , + α _G and −α _R are as follows (1). The relationship of ~ (4) is satisfied.
+ 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)

FIG. 3 shows a display element in a display device in which the display element is a liquid crystal display element with a color filter, the light source of the backlight is a cold cathode fluorescent lamp (CCFL), and the display element has a polarizer a and an optical film. This is an example of a spectral spectrum when the intensity of _{light (L 1} ) incident on the optical film in the vertical direction from the display element side is measured every 1 nm when the white display is displayed. In FIG. 3, the spectroscopic spectra of RGB are all sharp and satisfy the above relationships (1) to (4). The spectral spectrum of FIG. 3 is a standardized intensity of each wavelength with a maximum intensity of 100.

In FIG. 4, the display element is a liquid crystal display element with a color filter, the light source of the backlight is a white LED, and the display element is displayed in white in a display device having a polarizer a and an optical film on the display element. This is an example of the spectral spectrum of _{the light (L 1} ) incident on the optical film in the vertical direction from the display element side. In FIG. 4, since the spectral spectrum of B (blue) is sharp and the spectral spectrum of G (green) is relatively sharp, the relationship (1) to (3) above is satisfied, but R (red). Since the spectral spectrum of is broad, the relationship (4) above is not satisfied. The spectral spectrum of FIG. 4 is a standardized intensity of each wavelength with the maximum intensity set to 100.

As a spectroscopic spectrum similar to the spectroscopic spectrum of FIG. 4, the type of FIG. 15 can be mentioned. The spectral spectrum of FIG. 15 shows the display element on the optical film when the display element is displayed in white in a display device having the polarizer a and the optical film on the organic EL display element provided with the white light emitting layer and the color filter. This is an example of a spectral spectrum when the intensity of _{light (L 1} ) incident vertically from the side is measured every 1 nm. In the spectroscopic spectrum of FIG. 15, the spectral spectrum of B (blue) is sharp, while the spectral spectrum of G (green) on the high wavelength side and the spectral spectrum of R (red) are broad. Therefore, although the spectral spectrum of FIG. 15 satisfies the relationship of (1) and (2), it does not satisfy the relationship of (3) and (4). The spectral spectrum of FIG. 15 is a standardized intensity of each wavelength with a maximum intensity of 100.

FIG. 5 shows a display in which the display element is a liquid crystal display element with a color filter, the primary light source of the backlight is a blue LED, the secondary light source is a quantum dot, and the polarizing element a and an optical film are provided on the display element. This is an example of a spectral spectrum when the intensity of _{light (L 1} ) incident on the optical film in the vertical direction from the display element side is measured every 1 nm when the display element is displayed in white in the apparatus. In FIG. 5, the spectroscopic spectra of RGB are all sharp and satisfy the above relationships (1) to (4). The spectral spectrum of FIG. 5 is a standardized intensity of each wavelength with the maximum intensity set to 100.

Next, the relationship between the RGB spectral spectrum and the wide color gamut will be described.
The color gamut that can be reproduced by mixing the three colors of RGB is indicated by a triangle on the CIE-xy chromaticity diagram. The triangle is formed by defining the coordinates of the vertices of each color of RGB and connecting the vertices.
When each of the RGB spectral spectra is sharp, in the CIE-xy chromaticity diagram, the vertex coordinates of R have a large x value and a small y value, and the G vertex coordinates have a small x value and a y value. As the coordinates of the vertices of B become larger, the value of x becomes smaller and the value of y becomes smaller. That is, when each of the RGB spectral spectra is sharp, the area of the triangle connecting the vertex coordinates of each of the RGB colors in the CIE-xy chromaticity diagram becomes large, and the width of the reproducible color gamut becomes wide. It should be noted that widening the color gamut leads to an improvement in the power and presence of the moving image.
Examples of the standard representing the color gamut include "ITU-R Recommendation BT.2020 (hereinafter referred to as" BT.2020 ")" and the like. ITU-R is an abbreviation for "International Telecommunication Union-Radiocommunication Sector", and ITU-R Recommendation BT. 2020 is an international standard for the color gamut of Super Hi-Vision. BT. Based on the CIE-xy chromaticity diagram represented by the following formula. When the coverage rate of 2020 is within the range described later, it is possible to easily improve the power and presence of the moving image.
<BT. Formula for 2020 coverage>
[Out of the area of the CIE-xy chromaticity diagram of the _{L 1,} BT. Area overlapping with the area of the 2020 CIE-xy chromaticity diagram / BT. Area of CIE-xy chromaticity diagram of 2020] x 100 (%)

Next, the problem of color reproducibility will be described.
In a display device having a wide color gamut that satisfies the condition 1-1, a problem of color reproducibility is likely to occur when an image is observed through polarized sunglasses. This cause is the retardation value of the optical film, due to the influence of the wavelength dependency of the birefringence, the period of change in the intensity of the spectrum of the L ₂ is considered to become larger as the wavelength increases.
6-9, the retardation value L ₁ having a spectrum of Figure 2~5: 11,000nm is incident on the optical film, there in the light exiting in the vertical direction of the optical film from the light emitting surface side of the optical film It is a spectroscopic spectrum of _{light (L 2} ) that has passed through a polarizer b having an absorption axis parallel to the absorption axis of the polarizer a. The spectral spectrum of L ₂ can be regarded as the spectral spectrum visually recognized through polarized sunglasses. Looking at the spectral spectra _{of L 2} in FIGS. 6 to 9, the period of change in the intensity of the spectral spectra of _{L 2 increases as the wavelength increases.} The spectral spectra _{of L 2} in FIGS. 6 to 9 are obtained by normalizing the intensities of each wavelength with the maximum intensity of the spectral spectra of _{L 1 as 100. Further, L 2} in FIGS. 6 to 9 is P-polarized light (polarized light in the vertical direction with respect to the optical film X).

10 is a stack of 2 and 6, FIG. 11 is a stack of 3 and 7, FIG. 12 is a stack of 4 and 8, and FIG. 13 is a stack of FIG. 5. And FIG. 9 are superimposed.
_{L 1 in} FIG. 12 does not satisfy the condition 1-1. In FIG. 12, most of the spectral spectrum of L _{2 is included in the spectral spectrum of L 1.} That is, as shown in FIG. 12, when _{the spectral spectrum of L 1} is not sharp, the color gamut is narrow, _{but a large difference between the spectral spectrum of L 1 and} the spectral spectrum of L ₂ is unlikely to occur, so that there is a problem of color reproducibility. Is unlikely to occur.
On the other hand, as shown in FIGS. 10, 11 and 13, when the spectral spectrum of _{L 1} is sharp, it becomes difficult for the spectral spectrum of _{L 2} to be included in the spectral spectrum of _{L 1, and the color reproducibility is improved.} Problems are likely to occur. In particular, in the red (R) wavelength region, it becomes difficult for the spectral spectrum of _{L 2} to enter the spectral spectrum of _{L 1.} This is because the period of change in the intensity of the spectral spectrum of _{L 2} increases as the wavelength increases due to the influence of the retardation value of the optical film and the wavelength dependence of the birefringence.

In the present invention, _{the spectral spectra of L 1} and L ₂ are preferably the spectral spectra when the display element is displayed in white. These spectral spectra can be measured using a spectrophotometer. At the time of measurement, the receiver of the spectrophotometer is installed so as to be perpendicular to the light emitting surface of the display device, and the viewing angle is 1 degree. Further, the light to be measured is preferably light that passes through the center of the effective display area of the display device. The spectral spectrum can be measured by, for example, a spectral radiance meter CS-2000 manufactured by Konica Minolta.
In addition, BT. "Area of CIE-xy chromaticity diagram of the _{L 1"} that is required when calculating the coverage 2020, red (R) display, green (G) display, and blue (B) display during CIE- The x and y values of the Yxy color system are measured, respectively, and the "red (R) vertex coordinates", "green (G) vertex coordinates", and "blue (B) vertex coordinates" obtained from the measurement results are measured, respectively. Can be calculated from. The x-value and y-value of the CIE-Yxy color system can be measured by, for example, a spectral radiance meter CS-2000 manufactured by Konica Minolta.

(Condition 2-1)
Condition 2-1 indicates a condition for not causing a problem of color reproducibility.
In Condition 2-1 the "polarizer b" is intended to be a "polarizer of polarized sunglasses". That is, in the condition 2-1 as "light emitted in the vertical direction of the optical film X and passing through the polarizing element b having an absorption axis parallel to the absorption axis of the polarizer a (L ₂ )". , "Light emitted in the vertical direction of the optical film X, which has passed through the polarizer of the polarized sunglasses (light that is visible to humans through the polarized sunglasses)" is intended.
Further, in the condition 2-1 that R _α is defined as “a wavelength range of −α _R or more and + α _R or less and a wavelength range of 600 nm or more and 780 nm or less” is a wavelength of less than 600 nm or more than 780 nm. Regarding the region, it means _{that even in the wavelength region of −α R} or more and + α _R or less, it is not subject to the total intensity. Similarly, in condition 2-1 G _α is defined as “a wavelength range of −α _G or more and + α _G or less and a wavelength range of 500 nm or more and less than 600 nm”, which is less than 500 nm or 600 nm or more. Regarding the wavelength range, it means that even the wavelength range of _{−α G} or more and + α _{G or less is not subject to the total intensity.} Similarly, in condition 2-1 that B _α is defined as “a wavelength range of −α _B or more and + α _B or less and a wavelength range of 400 nm or more and less than 500 nm” is less than 400 nm or 500 nm or more. Regarding the wavelength range, it means that even the wavelength range of _{−α B} or more and + α _{B or less is not subject to the total intensity.}

The solid line in FIG. 10 corresponds to FIG. 2, and the broken line in FIG. 10 corresponds to FIG.
In FIG. 10, −α _R , + α _R , −α _G , + α _G , −α _B , and + α _B indicate the following wavelengths.
−α _R : Wavelength showing intensity of 1/2 or less of _{R max} and maximum wavelength located on the minus side of _{L 1} λ _{R + α R} : Wavelength showing intensity of 1/2 or less of _{R max} Minimum wavelength located on the positive side of L ₁ λ _{R -α G} : Wavelength showing an intensity of 1/2 or less of _{G max} and maximum wavelength located on the negative side of _{L 1} λ _{R + α G} : G _max The minimum wavelength located on the plus side of _{L 1} λ _R , which is a wavelength showing an intensity of 1/2 or less of L 1 λ R: _{-α B} : A wavelength showing an intensity of 1/2 or less of _{B max , which is L 1} λ _R Maximum wavelength located on the negative side + α _B : Wavelength showing an intensity of 1/2 or less of _{B max and} the minimum wavelength located on the positive side of _{L 1} λ _R

Condition 2-1 first requires that the " _{intensity ratio of R α} ", "intensity ratio of G _α ", and " _{intensity ratio of B α} " are all 0.35 or more.
In condition 2-1 "intensity ratio R _alpha" indicates "sum of the intensity of the L ₁ in the wavelength range of the sum / R _alpha in the intensity of the L ₂ in a wavelength region of R _alpha". In other words, the "R _{α intensity ratio" is the sum of the light intensities of the wavelength range R α} that the human eye can see when observing the image from the front with polarized sunglasses / from the front without wearing polarized sunglasses. when observing the image, indicating the total intensity of light entering the human eye wavelength range R _alpha ". Similarly, in condition 2-1 the “G _α intensity ratio” is the sum / polarization of the light intensity in the _{wavelength range G α} that the human eye can see when observing the image from the front with polarized sunglasses. When observing the image from the front without wearing sunglasses, the total intensity of light in the _{wavelength range G α that can be seen by the human eye is shown, and the “B α} intensity ratio” is “from the front with polarized sunglasses. _{Sum of the light intensity of the wavelength range B α that} enters the human eye when observing the image _{/ Polarized light of the wavelength range B α that} enters the human eye when observing the image from the front without wearing sunglasses "Sum of strength" is shown.
Further, _{the wavelength region of R α,} the wavelength region of G _α , and the wavelength region of B _α are wavelength regions in which the intensity of the spectral spectrum is strong and plays an important role in visibility.
Therefore, the fact that the " _{intensity ratio of R α} ", "intensity ratio of G _α ", and " _{intensity ratio of B α} " are all 0.35 or more is a wavelength range (R) that plays an important role in visibility. _{In the wavelength range of α,} the wavelength range of G _α , and the wavelength range of B _α ), the intensity of light visually recognized with polarized sunglasses is extremely higher than the intensity of light visually recognized without wearing polarized sunglasses. It means suppressing the decrease.

Condition 2-1 further requires that [RGB minimum intensity ratio of α / RGB maximum intensity ratio of α] be 0.70 or more.
In condition 2-1 the “minimum RGB intensity ratio of _α ” indicates “minimum value among the intensity ratio of R α, the intensity ratio of G _α , and _{the intensity ratio of B α} ”, and “maximum RGB intensity of α”. "Ratio" indicates "the maximum value among the intensity ratio of _{R α,} the intensity ratio of G _α , and _{the intensity ratio of B α".}
That is, under condition 2-1 that [RGB minimum intensity ratio of α / RGB maximum intensity ratio of α] is 0.70 or more means that “R _α intensity ratio”, “G _α intensity ratio”, and It means that the difference in "intensity ratio of B _{α" is small.} In other words, under condition 2-1 that [RGB minimum intensity ratio of α / RGB maximum intensity ratio of α] is 0.70 or more means that when the image is observed with polarized sunglasses, R _α and G It means that the balance of light intensity in the wavelength range of _α and B _{α is not easily lost.}

As described above, _{the intensity ratio of R α} , the intensity ratio of G _α , and the intensity ratio of B _α are all 0.35 or more, and [RGB minimum intensity ratio of α / RGB maximum intensity ratio of α]. ] Is 0.70 or more (satisfying condition 2-1), the intensity of light in the wavelength range of _{R α} , G _α, and B _{α is extremely high when the image is observed with polarized sunglasses.} It means that it does not decrease and the balance of light intensity in the wavelength range of _{R α} , G _α and B _{α is not easily lost.}
Therefore, by satisfying the condition 2-1 it is possible to suppress a decrease in color reproducibility when observing through polarized sunglasses.

In order to satisfy the condition 2-1 it is important to include a large amount of the spectral spectrum of _{L 2 in the spectral spectrum of L 1} in the wavelength range of _{R α} , G _α and B _α. In the wavelength range of _{R α} , G _α and B _α , it is difficult to include a large amount of the spectral spectrum _{of L 2} into the spectral spectrum of _{L 1} in the wavelength range of _{R α.} This is because the wavelength dispersibility of retardation increases the period of the spectroscopic spectrum as the wavelength becomes longer. Therefore, when _{the spectral spectrum of L 1} is sharp, the condition 2-1 cannot be satisfied in the normal design, and the color reproducibility is deteriorated. The present invention has made it possible to suppress a decrease in color reproducibility in consideration of the wavelength dispersibility of retardation (particularly, the wavelength dispersibility of retardation affected by the wavelength dependence of the double refractive index).
Incidentally, the liquid crystal display device using a white LED as a light source of a conventional mainstream a backlight, since the spectrum of the red (R) of L _1, as shown in FIG. 4 is a broad, wavelength ranges R _alpha L The spectral spectrum of L ₂ can be easily included in _{the spectral spectrum of 1.} That is, a decrease in color reproducibility when observed through polarized sunglasses is a problem that cannot occur in a conventional mainstream liquid crystal display device using a white LED unless an optical film having an extremely low retardation value is used. Is.

In condition 2-1 _{the intensity ratio of R α,} the intensity ratio of G _α , and the intensity ratio of B _α are all preferably 0.35 or more and 0.65 or less, and 0.40 or more and 0.60 or less. It is more preferable that it is 0.45 or more and 0.55 or less.
Further, under condition 2-1 the [RGB minimum intensity ratio of α / RGB maximum intensity ratio of α] is preferably 0.75 or more, more preferably 0.80 or more, and 0.85 or more. Is even more preferable, and 0.90 or more is even more preferable.

In condition 2-1 the L ₂ is polarized and may be P-polarized or S-polarized. Most ordinary polarized sunglasses cut S-polarized light. Therefore, it is preferable to satisfy the condition 2-1 when _{L 2 is P-polarized.} The same applies to condition 2-2, which will be described later.

Under condition 2-1 and condition 2-2 described later, _{the sum of the intensities of L 1} and L ₂ is the sum of the absorption axes of the polarizer of the polarizer a (the vibration direction of linearly polarized light) and the slow axis of the optical film X. It is preferable to calculate the angle θ to be formed as 45 degrees.

Further, the display device of the present invention preferably satisfies the following conditions 2-2 in order to further suppress the problem of color reproducibility. By satisfying the condition 2-2, the decrease in color reproducibility can be further suppressed.

<Condition 2-2>
A wavelength showing an intensity of 1/3 or less of the R _max , the maximum wavelength located on the minus side of _{L 1} λ _{R is −β R} , and a wavelength showing an intensity of 1/3 or less of the _{R max.} The minimum wavelength located on the positive side of _{L 1} λ _{R is + β R} , and the maximum wavelength located on the negative side of _{L 1} λ _{G is −β G} , which is a wavelength showing an intensity of 1/3 or less of the _{G max.} The minimum wavelength located on the positive side of _{L 1} λ _{G is + β G} , which is a wavelength showing an intensity of 1/3 or less of the _{R max} , and is a wavelength showing an intensity of 1/3 or less of the _{B max.} The maximum wavelength located on the negative side of _{L 1} λ _{B is −β B} , and the minimum wavelength located on the positive side of _{L 1} λ _{B is + β B} , which is a wavelength showing an intensity of 1/3 or less of the _{R max.} And.
The wavelength range of −β _R or more and + β _R or less and 600 nm or more and 780 nm or less is R _β , _{and the wavelength range of −β G} or more and + β _G or less and 500 nm or more and less than 600 nm. The wavelength range is G _β , _{and the wavelength range of −β B} or more and + β _B or less and 400 nm or more and less than 500 nm is B _β .
"Intensity ratio R _beta" the said sum of the intensity of the L ₁ in the wavelength range of the sum / the R _beta of the intensity of the L ₂ in a wavelength region of R _beta], wherein in the wavelength range of [the G _beta L the sum of the intensity of the L ₁ in the wavelength range of the sum / the G _beta of _second intensity] "intensity ratio of G _beta", [wherein B _beta of the L ₂ of the intensity of the sum / the B _beta in the wavelength range of _{The total intensity of L 1} in the wavelength range] is defined as the “intensity ratio of _{B β”.}
The maximum value among the intensity ratio of R _β, the intensity ratio of G _β , and _{the intensity ratio of B β is “the maximum RGB intensity ratio of β} ”, the intensity ratio of R β, the intensity ratio of G _β , And _{the minimum value in the intensity ratio of B β} is defined as “the RGB minimum intensity ratio of β”.
The intensity ratio of R _β, the intensity ratio of G _β , and the intensity ratio of B _β are all 0.35 or more, and [RGB minimum intensity ratio of β / RGB maximum intensity ratio of β] is 0. .70 or more.

Under condition 2-2, _{the intensity ratio of R β,} the intensity ratio of G _β , and the intensity ratio of B _β are all preferably 0.35 or more and 0.65 or less, and 0.40 or more and 0.60 or less. It is more preferable that it is 0.45 or more and 0.55 or less.
Further, under the condition 2-2, [RGB minimum intensity ratio of β / RGB maximum intensity ratio of β] is preferably 0.75 or more, more preferably 0.80 or more, and 0.85 or more. Is even more preferable, and 0.90 or more is even more preferable.

(Preferable aspect of _{L 1)
As described above, in order to satisfy the condition 1-1 (the spectral spectrum of L 1} is sharp), the display device of the present invention tends to cause a problem in color reproducibility in a normal design, but the condition 2-1 is satisfied. By satisfying, the problem of color reproducibility is suppressed.
Further, the display device of the present invention can suppress the problem of color reproducibility if the condition 2-1 is satisfied even if the spectral spectrum of _{L 1 is extremely sharp.} In recent years, in order to widen the color gamut, development of a display device in which the spectral spectrum of _{L 1 becomes extremely sharp has been promoted.} The display device of the present invention is suitable in that the problem of color reproducibility can be suppressed even in a display device in which the spectral spectrum of _{L 1 is extremely sharp.}
For example, the display device of the present invention is a display device in which _{the spectral spectrum of L 1} satisfies one or more of the following conditions 1-2 to 1-5 ( _{the spectral spectrum of L 1} is extremely sharp and the color gamut is extremely wide. It is suitable for a display device) in that the problem of color reproducibility can be suppressed. Conditions 1-1 to 1-4 mainly contribute to the expansion of the color gamut by increasing the color purity, and conditions 1-5 mainly contribute to the expansion of the color gamut in consideration of brightness.
By satisfying the conditions 1-2, it becomes easy to suppress the interference unevenness.

<Condition 1-2>
_{Based on the spectral spectrum of L 1} obtained by the measurement of condition 1-1, _{the average value B Ave} of the intensity of the spectral spectrum in the blue wavelength region _{, the average value G Ave} of the intensity of the spectral spectrum in the green wavelength region, and the red wavelength. _{The average value R Ave} of the intensity of the spectral spectrum in the region is calculated. In the blue wavelength range, the wavelength range in which the intensity _{of L 1} continuously exceeds _{B Ave is B p} , and in the green wavelength range, the wavelength range in which the intensity _{of L 1} continuously exceeds _{G Ave is G p} , and the red wavelength range. _{Let R p} be the wavelength range in which the intensity of L _{1 continuously exceeds R Ave.} There is only one wavelength range indicating B _p , G _p, and R _p.

The spectroscopic spectra of FIGS. 2, 4 and 5 _{all have one wavelength range indicating B p} , G _p and R _p , and satisfy the condition 1-2. On the other hand, the spectroscopic spectrum of FIG. 3 _{has two wavelength ranges showing B p} , G _p, and does not satisfy the condition 1-2.

<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)

The spectroscopic spectra of FIGS. 2, 3 and 5 satisfy the relationships of (5) and (6), and satisfy conditions 1-3. On the other hand, the spectral spectrum of FIG. 4 does not satisfy the relationship (6) and does not satisfy the conditions 1-3.

<Conditions 1-4>
The _{B max} of 1/3 or less of the intensity a wavelength showing an _{L 1} lambda beta minimum wavelength + positioned on the positive direction side of the _{B B,} a wavelength showing an intensity of 1/3 or less of the _{G max} L _The maximum wavelength located on the negative side of 1 λ _{G is −β G} , and the minimum wavelength located on the positive side of _{L 1} λ _{G is + β G} , which is a wavelength showing an intensity of 1/3 or less of the _{G max.} Let _{−β R be} the maximum wavelength that is 1/3 or less of the intensity of R _max and is located on the negative side of _{L 1 λ R.}
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)

The spectroscopic spectra of FIGS. 2, 3 and 5 all satisfy the relationship of (7) and (8), and satisfy the conditions 1-4. On the other hand, the spectral spectrum of FIG. 4 does not satisfy the relationship (8) and does not satisfy the conditions 1-4.

<Condition 1-5>
The maximum intensity of the B _max , the G _max, and the R _{max is defined} as L 1 max. B _max / L _1max , G _max / L _1max and R _max / L _1max are 0.27 or more, respectively.

In the spectroscopic spectra of FIGS. 2, 3 and 5, B _max / L _1max , G _max / L _1max and R _max / L _1max are 0.27 or more, respectively, and conditions 1-5 are satisfied. On the other hand, spectrum of Figure _4, R _{max / L 1max} are each less than 0.27, does not satisfy the conditions 1-5.
Under conditions 1-5, _{it is more preferable that B max} / L _1max , G _max / L _1max, and R _max / L _1max are 0.30 or more, respectively.

From the viewpoint of widening the color gamut, _{it is preferable that the spectral spectrum of L 1} is sharp, but from the viewpoint of facilitating the satisfaction of condition 2-1 it is preferable that _{the spectral spectrum of L 1} is not extremely sharp. Therefore, the + beta _R and the -β difference between _{R [+ β R - (-} β R)] is preferably 15～90Nm, more preferably 30～85Nm, is 50~80nm More preferably, it is more preferably 55 to 75 nm, and particularly preferably 60 to 70 nm.
From the same viewpoint, the difference between the _{+ β G} and the −β _{G [+ β G} − ( _{−β G} )] is preferably 20 to 80 nm, more preferably 25 to 60 nm, and 30 to 55 nm. Is even more preferable, and 30 to 40 nm is even more preferable. From the same viewpoint, the difference [+ β _B − ( _{−β B )] between the + β B} and the −β _B is preferably 15 to 50 nm, more preferably 20 to 40 nm, and 20 to 30 nm. Is more preferable.

Further, from the viewpoint of widening the color gamut and easily satisfying the condition 2-2, the difference [+ α _R − (−α _{R )] between the + α R} and the −α _R is 10 to 70 nm. It is preferably 20 to 60 nm, more preferably 30 to 55 nm, even more preferably 40 to 50 nm, and particularly preferably 45 to 50 nm.
From the same viewpoint, the difference between the-.alpha. _G and the _{+ α G [+ α G -} (- α G)] is preferably 10 to 60 nm, more preferably from 15 to 50 nm, 20 to 40 nm It is more preferably 20 to 30 nm, and even more preferably 20 to 30 nm. From the same viewpoint, the difference [+ α _B − (−α _{B )] between the + α B} and the −α _B is preferably 10 to 30 nm, more preferably 15 to 25 nm, and 15 to 20 nm. Is more preferable.

Examples of the display device having an extremely sharp spectral spectrum of L ₁ include a three-color independent organic EL display device, a liquid crystal display device using quantum dots for the backlight, and the like.

(Display element)
Examples of the display element include a liquid crystal display element, an organic EL display element, an inorganic EL display element, a plasma display element, and the like. The liquid crystal display element may be an in-cell touch panel liquid crystal display element having a touch panel function inside the element.
Among these display elements, the three-color independent organic EL display element _{tends to have a sharp spectral spectrum of L 1} , and the effect of the present invention is likely to be effectively exhibited. Further, the light extraction efficiency of the organic EL display element is an issue, and in order to improve the light extraction efficiency, the organic EL element of the three-color independent system is provided with a microcavity structure. The organic EL device of the three-color independent method with a micro-cavity structure, since the spectrum of the higher L ₁ makes it caused to improve the light extraction efficiency tends to be sharp, the effect is effectively exhibited easily to the present invention.
Further, the display device is a liquid crystal display device, even when using a quantum dot as a backlight, the spectrum of the L ₁ tends to be sharp, the effect is effectively exhibited easily to the present invention.

The display element is a BT. The coverage rate of 2020 is preferably 60% or more, more preferably 65% or more, and further preferably 70% or more.

(Polarizer a)
The polarizer a is installed on the exit surface of the display element and closer to the display element than the optical film X.
As the polarizer a, for example, sheet-type polarizers such as a polyvinyl alcohol film, a polyvinyl formal film, a polyvinyl acetal film, and an ethylene-vinyl acetate copolymer saponified film dyed and stretched with iodine or the like were arranged in parallel. Examples thereof include a wire grid type polarizer composed of a large number of metal wires, a lyotropic liquid crystal, a coating type polarizer coated with a bicolor guest-host material, and a multilayer thin film type polarizer. Note that these polarizers a may be reflective polarizers having a function of reflecting a polarizing component that does not transmit.
It is preferable that both sides of the polarizer a are covered with a transparent protective plate such as a plastic film or glass. It is also possible to use the optical film X as the transparent protective plate.

The polarizer a is used, for example, to impart antireflection property in combination with a 1 / 4λ plate. When the display element is a liquid crystal display element, a rear polarizing element is installed on the light incident surface side of the liquid crystal display element, and the absorption axis of the polarizing element a located above the liquid crystal display element and below the liquid crystal display element. It is used to impart the function of a liquid crystal shutter by arranging the absorption axis of the rear polarizing element located at right angles to the absorption axis.

Since polarized sunglasses absorb S-polarized light in principle, the direction of the absorption axis of the polarizer of polarized sunglasses is also horizontal in principle. Therefore, it is preferable to install the polarizing element a so that the angle in the direction of the absorption axis with respect to the horizontal direction of the display device is within a range of less than ± 10 °. The angle is more preferably in the range of less than ± 5 °.
When two or more polarizers are provided between the display element and the optical film X, the polarizer located on the side farthest from the display element is defined as the polarizer a.

(Optical film X)
The optical film X is installed on the surface of the display element on the light emitting surface side, and is installed on the light emitting surface side of the polarizer a. When the display device has a plurality of polarizers, the optical film X is installed on the light emitting surface side of the polarizing element (polarizer a) located closest to the light emitting surface side.
When a plurality of optical films are installed on the display element, the optical film X is preferably installed on the side farthest from the display element (viewer side).

The optical film X converts the light before passing through the optical film X, _{and the relationship between L 1} and L ₂ has a role of satisfying the condition 2-1.
The intensity of _{L 1} incident vertically on the optical film X _{is "I 0} ", the retardation value of the optical film X at a wavelength of 550 nm is "Re ₅₅₀ ", and [the wavelengths of the materials constituting the optical film X are 400 to 780 nm. The double refractive index of the material constituting the optical film X / the double refractive index of the material constituting the optical film X at a wavelength of 550 nm] is set to “N (λ)”, the absorption axis of the polarizer of the polarizer a (the vibration direction of linearly polarized light), and the delay of the optical film X. When the angle formed by the phase axis is "θ", the light is emitted in the vertical direction of the optical film X from the light emitting surface side of the optical film X, and has an absorption axis parallel to the absorption axis of the polarizer a. _{I, which is the intensity of the light (L 2} ) that has passed through the polarizer b, can be expressed by the following formula (A). It is assumed that L ₁ is linearly polarized light that has passed through the polarizer a located on the display element side of the optical film X.
I = I _0- I ₀ · sin ² (2θ) · sin ² (π · N (λ) · Re ₅₅₀ / λ) (A)
The configuration of the optical film X can be determined based on the above formula (A). Specifically, first, to measure a spectrum of L ₁ prior to passing through the optical film X. Next, based on the measurement result of the spectral spectrum of _{L 1} and the above formula (A), the spectral spectrum of _{L 2 corresponding to the retardation value of the optical film X is simulated.} Next, _{the spectral spectrum of L 1 is compared with the spectral spectrum of L 2} obtained in the simulation, and an optical film having a retardation satisfying the condition 2-1 is determined as the optical film X. By determining the configuration of the optical film X in this way, the color reproducibility can be improved without increasing the retardation of the optical film X more than necessary.
When the angle θ formed by the absorption axis (vibration direction of linearly polarized light) of the polarizer of the polarizer a and the slow axis of the optical film X is 45 degrees, the value of I indicates the maximum value. Therefore, it is preferable to perform the above simulation by the following equation (B) with θ set to 45 degrees.
I = I _0- I ₀ · sin ² (π · N (λ) · Re ₅₅₀ / λ) (B)

When a plurality of optical films are installed on the display element, as described above, the optical film X is preferably installed on the side farthest from the display element (viewer side). In this case, the above simulation may be performed by the interaction between the optical film X and the optical film located closer to the display element than the optical film X. For example, when the slow axis direction of the optical film X and the slow axis direction of the optical film located closer to the display element than the optical film X are the same, the materials constituting both optical films are the same. _{In some cases, the Re 550} can be calculated from the total thickness of both optical films and the above simulation can be performed.

Increasing the retardation value of the optical film X makes it easier to satisfy condition 2-1. However, simply increasing the retardation value may not satisfy condition 2-1. Further, if the retardation value of the optical film X is made too large, the thickness of the optical film X becomes too large, and it becomes necessary to use a special material having poor handleability as the material of the optical film X. Further, if the retardation value is too small, blackout and uneven interference are likely to occur when observing through polarized sunglasses.
Therefore, as the optical film X, it is preferable to use a film that satisfies the condition 2-1 in the range of the retardation value of 3,000 nm or more and 100,000 nm or less. The retardation value of the optical film X is more preferably 4,000 nm or more and 30,000 nm or less, further preferably 5,000 nm or more and 20,000 nm or less, and further preferably 6,000 nm or more and 15,000 nm or less. , 7,000 nm or more and 12,000 nm or less are more preferable. The retardation value referred to here is a retardation value at a wavelength of 550 nm.

_{The retardation value of the optical film X is the refractive index n x} in the slow axis direction, which is the direction in which the refractive index is the largest in the plane of the optical film, and the direction orthogonal to the slow axis direction in the plane of the light transmissive film. the refractive index n _y in the fast-axis direction is, by the thickness d of the optical film, are those represented by the following formula (C), is a so-called "in-plane retardation value".
Reference value (Re) = (n _{x −} n _y ) × d (C)
The retardation value can be measured by, for example, the trade names "KOBRA-WR" and "PAM-UHR100" manufactured by Oji Measuring Instruments Co., Ltd.
Further, after determining the orientation axis direction (main axis direction) of the optical film X using two or more polarizers, the refractive indexes of the two axes (the refractive index of the alignment axis and the axis orthogonal to the alignment axis) ( n _x, the _{n y),} determined by an Abbe refractometer (manufactured by Atago NAR-4T). Here, an axis showing a higher refractive index is defined as a slow-phase axis. The thickness d of the optical film is measured by, for example, a micrometer (trade name: Digimatic Micrometer, manufactured by Mitutoyo Co., Ltd.), and the unit is converted to nm. The retardation can also be calculated from the product of the birefringence index (n _{x −} n _{y) and the film thickness d (nm).}

Examples of the optical film X include those mainly composed of a light-transmitting base material such as a plastic film.
Examples of the light-transmitting base material include those obtained by stretching a plastic film such as a polyester film, a polycarbonate film, a cycloolefin polymer film, and an acrylic film. Among these, a stretched polyester film or polycarbonate film is preferable from the viewpoint of easily increasing the birefringence. Further, among the light-transmitting substrates, those exhibiting positive dispersibility (the property that the birefringence increases toward the short wavelength side) are preferable. In particular, a stretched polyester film (stretched polyester film) has a strong positive dispersibility and has a property that the double refractive index increases toward the short wavelength side (the double refractive index decreases toward the long wavelength side). Therefore, even if the retardation value is the same as that of other plastic films, it is preferable in that the above condition 2-1 can be easily satisfied. In other words, when a stretched polyester film is used as the base material of the optical film X, it is preferable in that the above condition 2-1 can be easily satisfied without making the base material thicker than necessary.
As the polyester film, a polyethylene terephthalate film (PET film), a polyethylene naphthalate film (PEN film) and the like are suitable.
Examples of the stretching include longitudinal uniaxial stretching, tenter stretching, sequential biaxial stretching, simultaneous biaxial stretching and the like.
Further, among the light-transmitting substrates, those exhibiting positive birefringence are preferable from the viewpoint of mechanical strength. _{The light-transmitting base material exhibiting positive birefringence includes a refractive index n 1 in} the direction of the orientation axis (direction of the main axis) of the light-transmissive base material and _{a refractive index n 2 in the} direction orthogonal to the orientation axis direction. , N ₁ > n ₂ means that the relationship is satisfied. Examples of the light-transmitting substrate exhibiting positive birefringence include PET film, polyester film such as PEN film, and aramid film. Polyester films and aramid films are preferable because they are extremely excellent in mechanical strength.

The thickness of the light-transmitting substrate is preferably 5 to 300 μm, more preferably 10 to 200 μm, and even more preferably 15 to 100 μm from the viewpoint of handleability and thinning.

The optical film X may have a functional layer on a light-transmitting substrate. Examples of the functional layer include a hard coat layer, an antiglare layer, an antireflection layer, an antistatic layer, an antifouling layer and the like.

(Other optical films)
The display device of the present invention may have other optical films such as a retardation film, a hard coat film, and a gas barrier film. It is preferable that the other optical film is installed closer to the display element than the optical film X. Further, from the viewpoint of mechanical strength, other optical films preferably have a retardation value of less than 3,000 nm, more preferably less than 2,000 nm, and even more preferably less than 1,000 nm.
Further, from the viewpoint of mechanical strength, the display device of the present invention preferably has a retardation value of 3,000 nm or more and does not have a light-transmitting substrate exhibiting negative birefringence.

(Touch panel)
The display device of the present invention may be a display device with a touch panel provided with a touch panel between the display element and the optical film X. The positional relationship between the polarizing element a on the display element and the touch panel is not particularly limited, but it is preferable to arrange the polarizing element (polarizer a) located closest to the light emitting surface side between the touch panel and the optical film X. ..
Examples of the touch panel include a resistive touch panel, a capacitance type touch panel, an in-cell touch panel, an electromagnetic induction type touch panel, an optical touch panel, an ultrasonic touch panel and the like.

(Backlight)
When the display device is a liquid crystal display device, a backlight is arranged on the back surface of the display element.
As the backlight, either an edge light type backlight or a direct type backlight can be used.
The light source of the backlight, LED, although CCFL and the like, a backlight using quantum dots as the light source, the spectrum of the L ₁ tends to be sharp, the effect is effectively exhibited easily to the present invention.

A backlight using quantum dots as a light source is composed of at least a primary light source that emits primary light and a secondary light source that is composed of quantum dots that absorb primary light and emit secondary light.
When the primary light source emits primary light having a wavelength corresponding to blue, the quantum dots that are secondary light sources are the first quantum dots that absorb the primary light and emit secondary light having a wavelength corresponding to red, and the primary light. It preferably contains at least one type of second quantum dot that absorbs light and emits secondary light having a wavelength corresponding to green, and more preferably contains both the first quantum dot and the second quantum dot.

Quantum dots are semiconductor nanometer-sized fine particles that are uniquely optically and electrically due to the quantum confinement effect (quantum size effect) in which electrons and exciters are confined in small nanometer-sized crystals. It exhibits properties and is also called semiconductor nanoparticles or semiconductor nanocrystals.
Quantum dots are nanometer-sized fine particles of a semiconductor, and are not particularly limited as long as they are materials that produce a quantum confinement effect (quantum size effect).
Quantum dots may be contained in the optical film constituting the backlight.

The size of the display device is not particularly limited. For example, it can be applied from the size of a mobile information terminal such as a smartphone to the size of a large TV.

[How to select the optical film for the display device]
The method of selecting the optical film of the display device of the present invention is a method of selecting the optical film of the display device having the polarizer a and the optical film on the surface of the display element on the light emitting surface side, and is incident on the optical film. When the light satisfies the above condition 1-1, an optical film satisfying the above condition 2-1 is selected.

The spectral spectra of L ₁ and L ₂ can be measured using a spectrophotometer. At the time of measurement, the receiver of the spectrophotometer is installed so as to be perpendicular to the light emitting surface of the display device, and at the time of measurement, the viewing angle is 1 degree. Further, the light to be measured is preferably light that passes through the center of the effective display area of the display device. The spectral spectrum of L ₂ is preferably calculated based on a simulation as described later.

The optical film satisfying the condition 2-1 is preferably selected by the following procedures (a) and (b).
(A) Based on the measurement result of the spectral spectrum of _{L 1} measured under the condition 1-1 and the above formula (A), the spectral spectrum of _{L 2 corresponding to the retardation value of the optical film X is calculated by simulation.} The above formula (B) may be used instead of the above formula (A).
(B) The spectral spectrum of _{L 1 is compared with the spectral spectrum of L 2} calculated by simulation, and an optical film having a retardation satisfying the condition 2-1 is selected as the optical film X.

According to the method for selecting an optical film for a display device of the present invention, an optical film capable of suppressing a decrease in color reproducibility when observed through polarized sunglasses can be efficiently selected, and workability can be improved.
The method for selecting an optical film for a display device of the present invention is particularly effective when the spectral spectrum of _{L 1 is extremely sharp.} Specifically, when _{the spectral spectrum of L 1} satisfies the above conditions 1-2 to 1-5, the problem of color reproducibility becomes more serious, so the method of selecting the optical film of the display device of the present invention is extremely high. It will be useful.

Further, in the method of selecting the optical film of the display device of the present invention, it is preferable to further set the above condition 2-2 as the selection condition from the viewpoint of improving the color reproducibility.

Next, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these examples. Unless otherwise specified, "parts" and "%" are based on mass.

1. 1. Preparation of Optical Film Polyethylene terephthalate was melted at 290 ° C., extruded into a sheet through a film forming die, and cooled by being brought into close contact with a water-cooled rotary quenching drum to prepare an unstretched film. This unstretched film is preheated at 120 ° C. for 1 minute in a biaxial stretching test apparatus (Toyo Seiki Co., Ltd.) and then stretched 4.0 times at 120 ° C. at a fixed end uniaxially to have in-plane birefringence. An optical film was produced. The refractive index _n x ₌ 1.701 at a wavelength of 550nm of the optical film, a n y = 1.6015, was [Delta] n = 0.0995.
The film thickness of this optical film was adjusted to obtain optical films i to iv having the following retardation values (Re).
Optical film i: Re = 5,000 nm
Optical film ii: Re = 6,000 nm
Optical film iii: Re = 7,000 nm
Optical film iv: Re = 8,000 nm
Optical film v: Re = 11,000 nm

2. Measurement of the spectral spectrum of L _{1 When} the following display devices A to E are displayed in white with a viewing angle of 1 degree using a spectrophotometer, the light (L _{1) vertically incident on the optical film from the display element side.} ) Was measured every 1 nm. In the display devices A to E, the angle formed by the absorption axis of the polarizer a (the vibration direction of linearly polarized light) and the slow axis of the optical film X is 45 degrees. The measurement location was set as the center of the effective display area of the display device. Figure 2 spectrum of L ₁ of the display device A, the display device FIG spectral spectrum of L ₁ of B 3, the display device C of L ₁ in spectrum Figure 4, Figure a spectrum of L ₁ of the display device D 5 shows the spectrum of _{L 1} of the display device E in FIG. Table 1 shows the numerical values related to the conditions 1-1 to 1-5 calculated based on the measurement results. Further, those satisfying the conditions 1-1 to 1-5 are designated as "○", and those not satisfying the conditions are designated as "x", which are also shown in Table 1.

<Display device A>
A commercially available display device having a polarizer a and an optical film on a three-color independent organic EL display element having a microcavity structure. BT. Based on the CIE-xy chromaticity diagram. Coverage rate for 2020: 77%.
<Display device B>
A commercially available display device in which the display element is a liquid crystal display element with a color filter, the light source of the backlight is a cold cathode fluorescent tube (CCFL), and a polarizer a and an optical film are provided on the display element.
<Display device C>
A commercially available display device in which the display element is a liquid crystal display element with a color filter, the light source of the backlight is a white LED, and the polarizing element a and an optical film are provided on the display element. BT. Based on the CIE-xy chromaticity diagram. Coverage rate for 2020: 49%.
<Display device D (Display device 1 using quantum dots)>
A commercially available display device in which the display element is a liquid crystal display element with a color filter, the primary light source of the backlight is a blue LED, the secondary light source is a quantum dot, and a polarizing element a and an optical film are provided on the display element. BT. Based on the CIE-xy chromaticity diagram. Coverage rate for 2020: 68%.
<Display device E (Display device 2 using quantum dots)>
A commercially available display device in which the display element is a liquid crystal display element with a color filter, the primary light source of the backlight is a blue LED, the secondary light source is a quantum dot, and a polarizing element a and an optical film are provided on the display element. BT. Based on the CIE-xy chromaticity diagram. Coverage rate for 2020: 52%.

3. 3. Display devices Ai to Av, display devices Bi to Bv, display devices Ci to Cv, display devices Di to Dv, and display devices Ei to Ev. Fabrication Optical films i to v are arranged as the optical films of the display devices A to E, and the display devices Ai to Av, the display devices Bi to Bv, and the display devices Ci to Cv are arranged. , Display devices D-i-Dv and display devices E-i-Ev were obtained.

4. Simulation of L _2, based on the spectrum of _{L 1} measured was measured by the "2" in the spectrum of _{L 2,} the formula and (B), the display device A-i~A-v, a display device B- From the light emitting surface side of the optical films of the i to Bv, the display devices Ci to Cv, the display devices Di to Dv, and the display devices Ei to Ev in the vertical direction of the optical film. I was calculated by simulation as the intensity I of _{the light (L 2} ) that was emitted and passed through the polarizer b having an absorption axis parallel to the absorption axis of the polarizer a. Tables 2 to 6 show the numerical values related to the conditions 2-1 and 2-2 calculated based on the simulation results. Further, those satisfying the conditions 2-1 and 2-2 are designated as "○", and those not satisfying the conditions are designated as "x", which are also shown in Tables 2 to 6.
When the numerical values related to the conditions 2-1 and 2-2 calculated by the simulation were calculated based on the measured values, the same results were obtained.

5. Evaluation As shown below, display devices Ai to Av, display devices Bi to Bv, display devices Ci to Cv, display devices Di to Dv, and display devices E- i to Ev were evaluated. The results are shown in Tables 2 to 6.

5-1. The screen of the blackout display device is displayed in white or almost white. The screen was observed from various angles through polarized sunglasses, and it was visually evaluated whether or not there was a part where the screen became dark.
A: There is no place where the screen becomes dark.
C: There is a part where the screen becomes dark.

5-2. Color reproducibility The screen of the display device is displayed in color. With polarized sunglasses on (state 1) and with polarized sunglasses removed and a glass plate dyed in the same color as polarized sunglasses installed on the screen (state 2), observe the screen from the front and wear polarized sunglasses. The color reproducibility in the applied state was visually evaluated.
Two points where the color difference between state 1 and state 2 is not noticeable, one point where the color difference between state 1 and state 2 is slightly noticeable, and the color difference between state 1 and state 2 is Twenty people evaluated and calculated the average score, with the ones that were terribly anxious as 0 points.
A: Average score is 1.6 points or more B: Average score is 1.2 points or more and less than 1.6 points C: Average score is less than 1.2 points

5-3. Realism of video The screen of the display device was set to a color video display, and the screen was observed with the polarized sunglasses removed, and the presence of the video was visually evaluated.
A: I feel a strong sense of presence.
B: I feel a sense of reality.
C: The sense of presence is unsatisfactory.

From the results of Tables 1 to 6, the display devices (display devices A-iii to Av, D-i to Dv, E-iii to Ev) satisfying the conditions 1-1 and 2-1 are Since the color gamut is wide, the presence of the moving image is excellent, and the problem of color reproducibility that tends to occur due to the wide color gamut can be suppressed.
Further, among the display devices satisfying the conditions 1-1 and 2-1 while further satisfying the conditions 1-2 to 1-5, the BT. The display devices (display devices A-iii to Av, D-i to Dv) having a coverage rate of 60% or more in 2020 had a more excellent sense of presence in the moving image.
Although not evaluated in the table, since the display devices B-i to B-v do not satisfy the conditions 1-2, it is difficult to suppress the interference unevenness peculiar to the retardation value.

10: Display element 10a: Organic EL display element 20: Optical film X
30: Other optical films 40: Polarizer a
100: Display device

Claims (9)

A polarizing element a and an optical film X are provided on the surface of the display element on the light emitting surface side, and the display element is an organic EL display element or an inorganic EL display element, and the following conditions 1-1 and 2-1 are satisfied. Display device to meet.
<Condition 1-1>
Wherein among the light incident from the display device side to the optical film X, the light incident perpendicularly to the optical film X and L _1. The intensity of L ₁ is measured every 1 nm. The blue wavelength range is 400 nm or more and less than 500 nm, the green wavelength range is 500 nm or more and less than 600 nm, and the red wavelength range is 600 nm or more and 780 nm or less. Maximum intensity _{B max} of the blue wavelength region of the _{L 1,} the maximum intensity _{G max} of the green wavelength region of the _{L 1,} the maximum intensity in the wavelength range of red of said _{L 1} and _{R max.}
Let _{L 1 λ B be the} wavelength indicating the B _{max , L 1} λ _{G be the} wavelength indicating the G _{max , and L 1} λ _{R be the} wavelength indicating the R _max .
The _{B max} of less than 1/2 of the intensity a wavelength showing an _{L 1} lambda minimum wavelength + alpha located in the positive direction side of the _{B B,} a wavelength showing an intensity of 1/2 or less of the _{G max} L _The maximum wavelength located on the negative side of 1 λ _{G is −α G} , and the minimum wavelength located on the positive side of _{L 1} λ _{G is + α G} , which is a wavelength showing an intensity of 1/2 or less of the _{G max.} Let _{−α R be} the maximum wavelength that is 1/2 or less of the intensity of R _max and is located on the negative side of _{L 1 λ R.}
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} be the light emitted from the light emitting surface side of the optical film X in the vertical direction of the optical film X and passing through the polarizing element b having an absorption axis parallel to the absorption axis of the polarizer a. .. The intensity of L ₂ is measured every 1 nm.
The minimum wavelength located on the positive side of _{L 1} λ _R , which is a wavelength showing an intensity of 1/2 or less of the _{R max , is + α R} , and the wavelength showing an intensity of 1/2 or less of the _{B max, L. 1} Let _{−α B be} the maximum wavelength located on the negative side of _{λ B.}
The wavelength range of −α _R or more and + α _R or less and 600 nm or more and 780 nm or less is R _α , _{and the wavelength range of −α G} or more and + α _G or less and 500 nm or more and less than 600 nm. The wavelength range is G _α , _{and the wavelength range of −α B} or more and + α _B or less and 400 nm or more and less than 500 nm is B _α .
"Intensity ratio R _alpha" the said sum of the intensity of the L ₁ in the wavelength range of the sum / the R _alpha in the intensity of the L ₂ in a wavelength region of R _alpha], wherein in the wavelength range of [the G _alpha L the sum of the intensities of L _1] in the wavelength range of the sum / the G _{alpha 2} intensity "intensity ratio of G _alpha", [wherein B _alpha of the L ₂ of the intensity of the sum / the B _alpha in the wavelength range of _{The total intensity of L 1} in the wavelength range] is defined as the “intensity ratio of _{B α”.}
The maximum value among the intensity ratio of R _α, the intensity ratio of G _α , and _{the intensity ratio of B α is “the maximum RGB intensity ratio of α} ”, the intensity ratio of R α, the intensity ratio of G _α , And _{the minimum value in the intensity ratio of B α} is defined as “the RGB minimum intensity ratio of α”.
The intensity ratio of R _α, the intensity ratio of G _α , and the intensity ratio of B _α are all 0.35 or more, and [RGB minimum intensity ratio of α / RGB maximum intensity ratio of α] is 0. .70 or more. The display device according to claim 1, which satisfies the following conditions 1-2.
<Condition 1-2>
_{Based on the spectral spectrum of L 1} obtained by the measurement of the above condition 1-1, _{the average value B Ave} of the intensity of the spectral spectrum in the blue wavelength region _{, the average value G Ave} of the intensity of the spectral spectrum in the green wavelength region, and the red _{The average value R Ave} of the intensity of the spectral spectrum in the wavelength region is calculated. In the blue wavelength range, the wavelength range in which the intensity _{of L 1} continuously exceeds _{B Ave is B p} , and in the green wavelength range, the wavelength range in which the intensity _{of L 1} continuously exceeds _{G Ave is G p} , and the red wavelength range. _{Let R p} be the wavelength range in which the intensity of L _{1 continuously exceeds R Ave.} The number of wavelength regions indicating B _p , G _p, and R _{p is one.} The display device according to claim 1 or 2, which satisfies the following conditions 1-3.
<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) The display device according to any one of claims 1 to 3, which satisfies the following conditions 1-4.
<Conditions 1-4>
The _{B max} of 1/3 or less of the intensity a wavelength showing an _{L 1} lambda beta minimum wavelength + positioned on the positive direction side of the _{B B,} a wavelength showing an intensity of 1/3 or less of the _{G max} L _The maximum wavelength located on the negative side of 1 λ _{G is −β G} , and the minimum wavelength located on the positive side of _{L 1} λ _{G is + β G} , which is a wavelength showing an intensity of 1/3 or less of the _{G max.} Let _{−β R be} the maximum wavelength that is 1/3 or less of the intensity of R _max and is located on the negative side of _{L 1 λ R.}
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) The display device according to any one of claims 1 to 4, which satisfies the following conditions 1-5.
<Condition 1-5>
The maximum intensity of the B _max , the G _max, and the R _{max is defined} as L 1 max. B _max / L _1max , G _max / L _1max and R _max / L _1max are 0.27 or more, respectively. The display device according to any one of claims 1 to 5, which satisfies the following condition 2-2.
<Condition 2-2>
A wavelength showing an intensity of 1/3 or less of the R _max , the maximum wavelength located on the minus side of _{L 1} λ _{R is −β R} , and a wavelength showing an intensity of 1/3 or less of the _{R max.} The minimum wavelength located on the positive side of _{L 1} λ _{R is + β R} , and the maximum wavelength located on the negative side of _{L 1} λ _{G is −β G} , which is a wavelength showing an intensity of 1/3 or less of the _{G max.} The minimum wavelength located on the positive side of _{L 1} λ _{G is + β G} , which is a wavelength showing an intensity of 1/3 or less of the _{R max} , and is a wavelength showing an intensity of 1/3 or less of the _{B max.} The maximum wavelength located on the negative side of _{L 1} λ _{B is −β B} , and the minimum wavelength located on the positive side of _{L 1} λ _{B is + β B} , which is a wavelength showing an intensity of 1/3 or less of the _{R max.} And.
The wavelength range of −β _R or more and + β _R or less and 600 nm or more and 780 nm or less is R _β , _{and the wavelength range of −β G} or more and + β _G or less and 500 nm or more and less than 600 nm. The wavelength range is G _β , _{and the wavelength range of −β B} or more and + β _B or less and 400 nm or more and less than 500 nm is B _β .
"Intensity ratio R _beta" the said sum of the intensity of the L ₁ in the wavelength range of the sum / the R _beta of the intensity of the L ₂ in a wavelength region of R _beta], wherein in the wavelength range of [the G _beta L the sum of the intensity of the L ₁ in the wavelength range of the sum / the G _beta of _second intensity] "intensity ratio of G _beta", [wherein B _beta of the L ₂ of the intensity of the sum / the B _beta in the wavelength range of _{The total intensity of L 1} in the wavelength range] is defined as the “intensity ratio of _{B β”.}
The maximum value among the intensity ratio of R _β, the intensity ratio of G _β , and _{the intensity ratio of B β is “the maximum RGB intensity ratio of β} ”, the intensity ratio of R β, the intensity ratio of G _β , And _{the minimum value in the intensity ratio of B β} is defined as “the RGB minimum intensity ratio of β”.
The intensity ratio of R _β, the intensity ratio of G _β , and the intensity ratio of B _β are all 0.35 or more, and [RGB minimum intensity ratio of β / RGB maximum intensity ratio of β] is 0. .70 or more. The display device according to any one of claims 1 to 6, wherein the optical film X has a light-transmitting substrate exhibiting positive birefringence. The display device according to claim 7, wherein the light-transmitting base material is a polyester film. A method for selecting an optical film of a display device having a polarizer a and an optical film on the surface of the display element on the light emitting surface side. The display element is an organic EL display element or an inorganic EL display element, and the optical film. A method for selecting an optical film for a display device, which selects an optical film that satisfies the following condition 2-1 when the light incident on the light meets the following condition 1-1.
<Condition 1-1>
Wherein among the light incident from the display device side to the optical film X, the light incident perpendicularly to the optical film X and L _1. The intensity of L ₁ is measured every 1 nm. The blue wavelength range is 400 nm or more and less than 500 nm, the green wavelength range is 500 nm or more and less than 600 nm, and the red wavelength range is 600 nm or more and 780 nm or less. Maximum intensity _{B max} of the blue wavelength region of the _{L 1,} the maximum intensity _{G max} of the green wavelength region of the _{L 1,} the maximum intensity in the wavelength range of red of said _{L 1} and _{R max.}
Let _{L 1 λ B be the} wavelength indicating the B _{max , L 1} λ _{G be the} wavelength indicating the G _{max , and L 1} λ _{R be the} wavelength indicating the R _max .
The _{B max} of less than 1/2 of the intensity a wavelength showing an _{L 1} lambda minimum wavelength + alpha located in the positive direction side of the _{B B,} a wavelength showing an intensity of 1/2 or less of the _{G max} L _The maximum wavelength located on the negative side of 1 λ _{G is −α G} , and the minimum wavelength located on the positive side of _{L 1} λ _{G is + α G} , which is a wavelength showing an intensity of 1/2 or less of the _{G max.} Let _{−α R be} the maximum wavelength that is 1/2 or less of the intensity of R _max and is located on the negative side of _{L 1 λ R.}
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} be the light emitted from the light emitting surface side of the optical film X in the vertical direction of the optical film X and passing through the polarizing element b having an absorption axis parallel to the absorption axis of the polarizer a. .. The intensity of L ₂ is measured every 1 nm.
The minimum wavelength located on the positive side of _{L 1} λ _R , which is a wavelength showing an intensity of 1/2 or less of the _{R max , is + α R} , and the wavelength showing an intensity of 1/2 or less of the _{B max, L. 1} Let _{−α B be} the maximum wavelength located on the negative side of _{λ B.}
The wavelength range of −α _R or more and + α _R or less and 600 nm or more and 780 nm or less is R _α , _{and the wavelength range of −α G} or more and + α _G or less and 500 nm or more and less than 600 nm. The wavelength range is G _α , _{and the wavelength range of −α B} or more and + α _B or less and 400 nm or more and less than 500 nm is B _α .
"Intensity ratio R _alpha" the said sum of the intensity of the L ₁ in the wavelength range of the sum / the R _alpha in the intensity of the L ₂ in a wavelength region of R _alpha], wherein in the wavelength range of [the G _alpha L the sum of the intensities of L _1] in the wavelength range of the sum / the G _{alpha 2} intensity "intensity ratio of G _alpha", [wherein B _alpha of the L ₂ of the intensity of the sum / the B _alpha in the wavelength range of _{The total intensity of L 1} in the wavelength range] is defined as the “intensity ratio of _{B α”.}
The maximum value among the intensity ratio of R _α, the intensity ratio of G _α , and _{the intensity ratio of B α is “the maximum RGB intensity ratio of α} ”, the intensity ratio of R α, the intensity ratio of G _α , And _{the minimum value in the intensity ratio of B α} is defined as “the RGB minimum intensity ratio of α”.
The intensity ratio of R _α, the intensity ratio of G _α , and the intensity ratio of B _α are all 0.35 or more, and [RGB minimum intensity ratio of α / RGB maximum intensity ratio of α] is 0. .70 or more.

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