JP2018116205A - Optical element and image display device and organic electroluminescence display device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical element having a high transmittance in a blue wavelength region.SOLUTION: The optical element simultaneously satisfies conditions of Ts_B≥Ts_G, Ts_B≥Ts_R, |ar|≤10 and |br|≤10. In these expressions, Ts_B represents the transmittance of the optical element at one wavelength in the wavelength region from 440 nm to 470 nm; Ts_G represents the transmittance of the optical element at one wavelength in the wavelength region from 520 nm to 570 nm; Ts_R represents the transmittance of the optical element at one wavelength in the wavelength region from 580 nm to 650 nm; and ar and br represent hues determined in accordance with JIS Z8781-4 by the measurement of reflection colors when a reflector having substantially no wavelength dispersion in the reflectance is disposed on a retardation layer side of the optical element.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an optical element, an image display device using the same, and an organic electroluminescence display device.

  An organic electroluminescence display device (Organic Light Emitting Diode: hereinafter referred to as OLED) is used as a display device. OLEDs are suitable for display devices such as mobile phones, smartphones, and tablet computers because they can be easily thinned and have a wide viewing angle.

  In the OLED, a technique is known in which a circularly polarizing element is provided in order to avoid a decrease in contrast of display light due to reflected light from internal electrodes. Specifically, the antireflection performance is enhanced by arranging an optical element for circular polarization, which is composed of a linearly polarizing element and a retardation plate such as a quarter-wave plate, on the output surface side of the OLED.

  Patent Document 1 discloses a technique for improving the balance between single transmittance and parallel transmitted light in a polarizing element used in a reflective liquid crystal display device (LCD). Patent Documents 2 and 3 disclose techniques for improving the reflected hue based on the hue of the polarization element alone and the characteristics of the retardation plate.

JP 2003-344656 A JP-A-2015-163940 Japanese Patent Laying-Open No. 2015-505988

  By the way, in the red (R), green (G), and blue (B) emission wavelength regions in the OLED, the efficiency in the blue (B) wavelength region is the lowest. In addition, in the conventional polarizing element, the transmittance in the blue (B) wavelength region is lower than the red (R) and green (G) wavelength regions, and it is necessary to increase the emission of blue (B) in the OLED. there were. Therefore, there is a problem that the power consumption of the OLED increases. In addition, there is a problem that the lifetime of the element is shortened by increasing the light emission in the blue (B) wavelength region in the OLED.

  Therefore, an object of the present invention is to provide an optical element having an increased transmittance in the blue (B) wavelength region, an image display device and an organic electroluminescence display device using the optical element.

One aspect of the present invention is an optical element in which a polarizing element comprising a base material having a polarizing function and a retardation layer are laminated,
Ts_B ≧ Ts_G (1)
Ts_B ≧ Ts_R (2)
| A ^* r | ≦ 10 (3)
| B ^* r | ≦ 10 (4)
here,
Ts_B is the transmittance of the optical element at any wavelength within the wavelength region of 440 nm or more and 470 nm or less,
Ts_G is the transmittance of the optical element at any wavelength within the wavelength region of 520 nm or more and 570 nm or less,
Ts_R is the transmittance of the optical element at any wavelength in the wavelength region of 580 nm or more and 650 nm or less,
a ^* r and b ^* r are hues obtained in accordance with JIS Z 8781-4 at the time of reflection color measurement when a reflection plate having substantially no wavelength dispersion of reflectance is disposed on the retardation layer side of the optical element. ,
The optical element is characterized by satisfying the above mathematical expressions (1) to (4) at the same time.

Another aspect of the present invention is an optical element in which a polarizing element made of a base material having a polarizing function and a retardation layer are laminated,
| A ^* r | ≦ 10 (3)
| B ^* r | ≦ 10 (4)
Ts_B / Ts_G ≧ 1.0 (5)
R_B / R_G ≦ 1.3 (6)
here,
Ts_B is the transmittance of the optical element at any wavelength within the wavelength region of 440 nm or more and 470 nm or less,
Ts_G is the transmittance of the optical element at any wavelength within the wavelength region of 520 nm or more and 570 nm or less,
R_B is the reflectance of the optical element at any wavelength within a wavelength region of 440 nm or more and 470 nm or less when a reflector having substantially no wavelength dispersion of reflectance is disposed on the retardation layer side of the optical element. ,
R_G is the reflectance of the optical element at any wavelength within a wavelength region of 520 nm or more and 570 nm or less when a reflection plate having substantially no wavelength dispersion of reflectance is disposed on the retardation layer side of the optical element. ,
a ^* r and b ^* r are hues obtained in accordance with JIS Z 8781-4 at the time of reflection color measurement when a reflection plate having substantially no wavelength dispersion of reflectance is disposed on the retardation layer side of the optical element. ,
The optical element is characterized by satisfying the above mathematical expressions (3) to (6) at the same time.

In addition,
Ts_B ≧ 46% (7)
The polarizing element is preferably characterized by satisfying the above.

  Moreover, it is suitable to contain an azo compound.

  The retardation layer is preferably a quarter wavelength plate. The retardation layer functions as a quarter-wave plate by combining two layers of a first retardation plate and a second retardation plate, and the first retardation plate is a quarter-wave plate, The second retardation plate is preferably a half-wave plate. The retardation layer is preferably a quarter wavelength plate made of a reverse wavelength dispersion material. The retardation layer is preferably a quarter wave plate on which a positive C plate is laminated.

In addition, the retardation layer is
_{0 <(n x -n z)} / (n x -n y) <1 ··· (8)
here,
_nx is the main refractive index in the direction parallel to the film plane in the refractive index ellipse formed by the retardation layer,
n _y is parallel to the film plane in the refractive index ellipsoid the retardation layer is formed, and, the refractive index in the direction orthogonal to the direction of the n _x,
nz is the refractive index in the direction perpendicular to the film plane in the refractive index ellipsoid formed by the retardation layer,
It is preferable that the above mathematical formula (8) is satisfied.

Another aspect of the present invention is an optical laminate in which a polarizing element made of a substrate having a polarizing function, a retardation layer, and a reflective electrode disposed on the retardation layer side are provided. An optical element comprising:
Ts_B ≧ Ts_G (1)
Ts_B ≧ Ts_R (2)
| A ^* c | ≦ 10 (3)
| B ^* c | ≦ 10 (4)
here,
Ts_B is the transmittance of the optical layered body at any wavelength within a wavelength region of 440 nm or more and 470 nm or less,
Ts_G is the transmittance of the optical laminate at any wavelength within the wavelength region of 520 nm or more and 570 nm or less,
Ts_R is the transmittance of the optical laminate at any wavelength in the wavelength range of 580 nm or more and 650 nm or less,
a ^* c and b ^* c are hues determined according to JIS Z 8781-4 when measuring the reflected color of the optical element,
The optical element is characterized by satisfying the above mathematical expressions (1) to (4) at the same time.

  Another embodiment of the present invention is an image display device including the optical element. Another aspect of the present invention is an organic electroluminescence display device including the optical element.

  Here, the pixel corresponding to each of red (R), green (G), and blue (B) is included, and Ts_B at the emission peak wavelength of the blue (B) pixel is the emission of the green (G) pixel. It is preferable that Ts_G at the peak wavelength and Ts_R at the emission peak wavelength of the red (R) pixel be larger.

  According to the present invention, an optical element having high transmittance in the blue (B) wavelength region can be realized. In addition, by applying the optical element, it is possible to provide an image display device and an organic electroluminescence display device in which power consumption is reduced and the lifetime of the light-emitting element is extended.

It is a cross-sectional schematic diagram which shows the structure of the organic electroluminescent display apparatus in embodiment of this invention. It is a cross-sectional schematic diagram which shows the structure of the test body in the Example in embodiment of this invention. It is a figure which shows the characteristic measurement result in the Example and comparative example in embodiment of this invention.

  An organic electroluminescence display device (organic EL display device, hereinafter referred to as OLED) 100 according to an embodiment of the present invention includes an organic EL layer 10, a retardation layer 12, and a polarizing layer 14 as shown in the schematic cross-sectional view of FIG. It is comprised including.

  The organic EL layer 10 is a light emitting layer including a light emitting diode element made of an organic processed product. The organic EL layer 10 includes, for example, a structure in which a negative electrode, an electron injection layer, an electron transport layer, a light emitting layer, a hole transport layer, a hole injection layer, a transparent electrode, and a transparent substrate are stacked. Thereby, light is emitted by recombining electrons and holes. The organic EL layer 10 is colored by each of the red (R), green (G), and blue (B) color coding methods.

  The phase difference layer 12 is a member that transmits the light with a phase shifted by a quarter wavelength (λ / 4). The retardation layer 12 is arranged so that the slow axis thereof and the absorption axis of the polarizing layer 14 described later are 45 °. Thereby, the retardation layer 12 and the polarizing layer 14 function as a circularly polarizing plate. The retardation layer 12 preferably has reverse wavelength dispersion.

  The retardation layer 12 is not particularly limited to the material, and can be selected from, for example, a cycloolefin polymer (COP) film, a polycarbonate (PC) film, an acrylic film, a liquid crystal film, and the like. The retardation layer 12 can be obtained by uniaxially stretching these materials.

  The retardation layer 12 may be configured by combining a plurality of retardation plates. For example, the retardation layer 12 may be configured by superposing two layers, a first retardation plate that is a quarter-wave plate and a second retardation plate that is a half-wave plate. The retardation layer 12 may be a quarter wavelength plate with a wide viewing angle on which positive C plates are stacked. In any case, it is preferable that the retardation layer 12 be a broadband wave plate having a wide applicable wavelength band. For example, the retardation layer 12 is preferably applicable in a wide band of 350 nm or more and 750 nm or less.

The phase difference layer 12 preferably satisfies the following mathematical formula (8). Here, _nx is the main refractive index in the direction parallel to the film plane in the refractive index ellipse formed by the retardation plate. Further, n _y is parallel in the refractive index ellipsoid retardation plate is formed to the film plane, and the refractive index in the direction perpendicular to the direction of n _{x. Nz} is the refractive index in the direction perpendicular to the film plane in the refractive index ellipsoid formed by the retardation plate.

_{0 <(n x -n z)} / (n x -n y) <1 ··· (8)

  The polarizing layer 14 is a layer that linearly polarizes and transmits the visible light region (wavelength 350 nm or more and 750 nm or less). That is, the polarizing layer 14 is a layer including a polarizing element 14a that transmits only light polarized in a specific direction. The polarizing element 14a can be formed by staining with a dichroic dye. The polarizing element 14a can be formed by, for example, dyeing a polyvinyl alcohol (PVA) film with a dichroic material and performing a stretching process.

  Specifically, the polarizing layer 14 can be manufactured by the method shown below. A film as a substrate is immersed in an aqueous solution containing a dye for a predetermined time. Thereafter, the film is stretched in one direction while immersed in an aqueous boric acid solution. The polarizing plate 14a is obtained by drying the resultant product thus obtained. The polarizing layer 14 is obtained by bonding the base materials 14b and 14c on both surfaces of the obtained polarizing element 14a with a PVA adhesive and drying them.

  As an example of the PVA film, Kuraray VF-PE having an average degree of polymerization of 2400 can be applied. The PVA film is preferably swelled with warm water of about 35 ° C. for several minutes before use. At this time, the PVA film may be stretched at a predetermined ratio for uniform swelling. For example, it is good to make it extend so that it may become a ratio of about 1.5 times along the flow direction of a PVA film.

The dichroic material can be, for example, a material containing an azo compound and / or a salt thereof. Specifically, for example, Kayfect. Orange. G, C.I. I. Direct blue 71 etc. are mentioned. Further, it is preferable to use a dye represented by the chemical formula (1).

  A PVA film serving as a substrate is immersed in an aqueous solution containing these dyes for a predetermined time. At this time, the aqueous solution preferably contains sodium tripolyphosphate and anhydrous sodium sulfate.

  For example, 0.01 part by weight or more and 1 part by weight or less of sodium tripolyphosphate, 0.01 part by weight or more and 1 part by weight or less of anhydrous sodium sulfate, and Kayfect. Orange. G is 0.001 part by weight or more and 0.1 part by weight or less; I. It is preferable to use an aqueous solution containing 0.001 part by weight or more and 0.1 part by weight or less of Direct Blue 71 and a dye represented by the above chemical formula (1) in a proportion of 0.001 part by weight or more and 0.1 part by weight or less. It is.

  The aqueous solution is preferably at a temperature of 30 ° C. or higher and 60 ° C. or lower so that the PVA film is immersed. The immersion time is preferably 30 seconds or longer and 30 minutes or shorter. At this time, for uniform dyeing, it is preferable that the film is stretched so as to have a ratio of 0.5 to 5 times in the flow direction of the PVA film.

  Furthermore, polarization can be imparted by stretching the PVA film. For example, the PVA film is stretched so that the stretching ratio is about 1 to 10 times. At this time, it is preferable to perform the stretching treatment in a state where the PVA film is immersed in a boric acid aqueous solution.

  For example, it is preferable to stretch the PVA film in a state where it is immersed in an aqueous boric acid solution of 45% to 70 ° C. for 1.5 seconds to 5.0% by weight for 30 seconds to 30 minutes. . Moreover, before the said extending | stretching process, the process immersed in 1.5 to 5.0 mass% boric-acid aqueous solution 30 degreeC or more and 65 degrees C or less over 10 second or more and 20 minutes or less is given. May be.

  The polarizing element 14a can be obtained by washing the stretched PVA film with water and drying it with a drying furnace or the like.

  The polarizing layer 14 may have a structure in which the base materials 14b and 14c are bonded to the polarizing element 14a. The base materials 14b and 14c are members that serve as a protective layer for the polarizing element 14a. Although the base materials 14b and 14c can be selected arbitrarily, for example, a triacetyl cellulose (TAC) film, a cycloolefin polymer (COP) film, an acrylic film, a cyclic olefin film, or the like is preferably used. As an example, TG-40 made by Fuji Film can be applied. Although the thickness of the base materials 14b and 14c is not limited to this, it is suitable to set it as 20 micrometers or more and 200 micrometers or less. As shown in FIG. 1, it is preferable to provide the base materials 14b and 14c on both surfaces of the polarizing element 14a, respectively.

  The base materials 14b and 14c are preferably bonded to the polarizing element 14a using, for example, an adhesive. The adhesive is not particularly limited, but an adhesive obtained by dissolving polyvinyl alcohol in water may be used. For example, a solution obtained by dissolving Z-200 manufactured by Nippon Gosei Co., Ltd. in water at 6% can be used as an adhesive.

The optical element in which the retardation layer 12 and the polarizing layer 14 are overlapped preferably satisfies the following mathematical formulas (1) to (4). Here, Ts_B is the transmittance of the optical element at any wavelength within the wavelength range of 440 nm to 470 nm, which is the blue (B) wavelength range. Ts_G is the transmittance of the optical element at any wavelength within the wavelength region of 520 nm or more and 570 nm or less, which is the green (G) wavelength region. Ts_R is the transmittance of the optical element at any wavelength in the wavelength range of 580 nm to 650 nm, which is the red (R) wavelength range. Further, a ^* r and b ^* r are obtained in accordance with JIS Z 8781-4 at the time of measurement of reflected color when a reflection plate having substantially no wavelength dispersion of reflectance is arranged on the phase difference layer 12 side of the optical element. Hue.

Ts_B ≧ Ts_G (1)
Ts_B ≧ Ts_R (2)
| A ^* r | ≦ 10 (3)
| B ^* r | ≦ 10 (4)
Here, the conditions of the mathematical formulas (1) to (4) may be satisfied between any wavelengths included in the wavelength regions for the above Ts_B, Ts_G, and Ts_R, and do not need to be satisfied in all the wavelength regions.

  Further, it is preferable that the optical element simultaneously satisfies the above mathematical expressions (3) and (4) and the following mathematical expressions (5) and (6). Here, Ts_B is the transmittance of the optical element at any wavelength within the wavelength range of 440 nm to 470 nm, which is the blue (B) wavelength range. Ts_G is the transmittance of the optical element at any wavelength within the wavelength region of 520 nm or more and 570 nm or less, which is the green (G) wavelength region. R_B is any wavelength within a wavelength range of 440 nm or more and 470 nm or less, which is a wavelength range of blue (B) when a reflection plate having substantially no wavelength dispersion of reflectance is disposed on the phase difference layer 12 side of the optical element. Is the reflectance of the optical element at that wavelength. R_G is any wavelength within a wavelength range of 520 nm or more and 570 nm or less, which is a wavelength range of green (G) when a reflection plate having substantially no wavelength dispersion of reflectance is disposed on the phase difference layer 12 side of the optical element. Is the reflectance of the optical element at that wavelength.

Ts_B / Ts_G ≧ 1.0 (5)
R_B / R_G ≦ 1.3 (6)
Here, the conditions of the mathematical formulas (3) to (6) may be satisfied between any wavelengths included in the wavelength regions for Ts_B, Ts_G, R_B, and R_G, and need to be satisfied in all wavelength regions. Absent.

In the optical element, Ts_B, which is the transmittance of the optical element in any wavelength within the wavelength range of 440 nm to 470 nm that is the wavelength range of blue (B), is 46% or more. It is preferable to satisfy
Ts_B ≧ 46% (7)
Such an optical element can be obtained by applying the manufacturing method under the above conditions. That is, the dichroic dye for expressing the polarization characteristics is not a general iodine compound, but a dye is used to adjust the hue of monochromatic transmitted light and orthogonal transmitted light. The hue can be adjusted.

  Each of the above layers can be adhered to each other by the adhesive layer 16. Although the adhesive used for the adhesion layer 16 is not specifically limited, For example, it is suitable to use an acrylic adhesive, a urethane adhesive, a rubber adhesive, etc.

[Example]
Using a PVA film having an average polymerization degree of 2400 (VF-PE manufactured by Kuraray Co., Ltd.) as a base material, it was swollen with hot water at 35 ° C. for 5 minutes. In order to achieve uniform swelling, the PVA film was stretched at a ratio of about 1.5 times.

  Thereafter, the PVA film was immersed in a 47.5 ° C. aqueous solution containing a dye (azo compound) for 8 minutes and 30 seconds. The aqueous solution was 100 parts by mass of water, 0.1 part by mass of sodium tripolyphosphate, 0.1 part by mass of anhydrous sodium sulfate, Kayfect. Orange. 0.0057 parts by mass of G, C.I. I. The direct blue 71 contained 0.0079 parts by mass, and the dye having the structure of the chemical formula (1) contained 0.0065 parts by mass. In order to achieve uniform dyeing, the PVA film was stretched at a ratio of about 1.3 times.

  The base material thus treated was stretched in a 2.9 wt% boric acid aqueous solution at 58 ° C. so that the stretch ratio was about 3 times. Thereafter, the substrate was washed with water at 20 ° C. and dried in a drying furnace at 50 ° C. to obtain a polarizing element 14a.

  Furthermore, using an adhesive obtained by dissolving polyvinyl alcohol (Z-200 manufactured by Nihon Gosei Co., Ltd.) in water at 6%, a TAC film (TG-40 manufactured by Fuji Film) was bonded to both surfaces of the polarizing element 14a obtained. The polarizing layer 14 was obtained by drying at 70 ° C. for 3 minutes.

  Further, as shown in FIG. 2, a quarter wave plate (Pure Ace RM-147 manufactured by Teijin Limited) was laminated as the retardation layer 12 on the obtained polarizing layer 14. When laminating, an acrylic adhesive (PTR-3000 manufactured by Nippon Kayaku Co., Ltd.) was used. The retardation layer 12 was laminated so that its slow axis was at an angle of 45 ° with respect to the absorption axis of the polarizing layer 14.

  In addition, in order to obtain back surface reflection at the time of characteristic measurement, a mirror 20 serving as a reflection plate having substantially no wavelength dispersion of reflectivity was provided on the phase difference layer 12 side.

[Comparative Example 1]
Instead of the polarizing layer 14 in the examples, SKN-18243T manufactured by Polatechno, which includes a polarizing element manufactured from an iodine compound, was applied.

[Comparative Example 2]
Instead of the polarizing layer 14 in the examples, SKW-18245T manufactured by Polatechno, which includes a polarizing element manufactured from an iodine compound, was applied.

[Characteristic measurement results]
FIG. 3 shows the results of measuring the characteristics of the above-mentioned Examples, Comparative Example 1 and Comparative Example 2. Specifically, the transmittance of the specimen at a wavelength of 440 nm in the blue (B) wavelength region was measured as Ts_B. Moreover, the transmittance | permeability of the test body in the wavelength of 550 nm which is a wavelength range of green (G) was measured as Ts_G. Moreover, the transmittance | permeability of the test body in the wavelength of 620 nm which is a wavelength range of red (R) was measured as Ts_R. Further, a ^* r and b ^* r are obtained in accordance with JIS Z 8781-4 at the time of measuring the reflected color when the mirror 20 having substantially no wavelength dispersion of reflectance is arranged on the phase difference layer 12 side of the optical element. Hue was measured.

  From these results, it was found that the conditions (1) to (4) were satisfied in the example, and not satisfied in Comparative Examples 1 and 2. Moreover, in the Example, it turned out that the conditions of said (3)-(6) are satisfy | filled and the comparative examples 1 and 2 are not satisfy | filled.

  As described above, according to the present embodiment, an optical element including the polarizing layer 14 having high transmittance in the blue (B) wavelength region can be provided. In particular, it is possible to provide an optical element in which the transmittance in the blue (B) wavelength region is higher than the transmittance in the green (G) wavelength region and the transmittance in the red (R) wavelength region.

  In addition, by applying the optical element in this embodiment mode to an image display device, particularly to an OLED, power consumption of the device can be reduced and the lifetime of the light-emitting element can be extended.

  At this time, a configuration in which a reflective electrode is provided on the phase difference layer 12 side of the OLED is preferable. Specifically, the electrode layer of the organic EL layer 10 provided on the phase difference layer 12 side of the OLED may be used as a reflective electrode.

  In addition, by using a dye-based polarizing element, the polarizing characteristics deteriorate even at high temperatures (for example, 105 ° C. or higher) and high temperature and humidity (for example, 80 ° C. or higher and 90% RH or higher) at which the characteristics of iodine-based polarizing elements deteriorate. There is no. Therefore, display characteristics can be improved also in the image display apparatus. Also, a hue close to natural can be realized by a combination with a general retardation layer.

  Note that by applying the polarizing element and the optical element in this embodiment to an OLED including pixels corresponding to red (R), green (G), and blue (B), light emission of the blue (B) pixel is performed. The transmittance Ts_B at the peak wavelength can be made larger than the transmittance Ts_G at the emission peak wavelength of the green (G) pixel and the transmittance Ts_R at the emission peak wavelength of the red (R) pixel. Specifically, the transmittance Ts_B in the wavelength region of 450 nm to 460 nm that is the wavelength region of blue (B) is the transmittance Ts_G in the wavelength region of 545 nm to 550 nm that is the wavelength region of green (G) and the wavelength region of red (R). The transmittance Ts_R in a certain range from 625 nm to 630 nm can be made larger.

  Thereby, in particular, in an OLED having a difficulty in coloring in the blue (B) wavelength region, it is possible to reduce power consumption and extend the life of the light emitting element.

  DESCRIPTION OF SYMBOLS 10 Organic EL layer, 12 Phase difference plate, 14 Polarizing layer, 14a Polarizing element, 14b, 14c Base material, 16 Adhesive layer, 20 Mirror, 100 Organic EL apparatus.

Claims (14)

An optical element in which a polarizing element made of a substrate having a polarizing function and a retardation layer are laminated,
Ts_B ≧ Ts_G (1)
Ts_B ≧ Ts_R (2)
| A ^* r | ≦ 10 (3)
| B ^* r | ≦ 10 (4)
here,
Ts_B is the transmittance of the optical element at any wavelength within the wavelength region of 440 nm or more and 470 nm or less,
Ts_G is the transmittance of the optical element at any wavelength within the wavelength region of 520 nm or more and 570 nm or less,
Ts_R is the transmittance of the optical element at any wavelength in the wavelength region of 580 nm or more and 650 nm or less,
a ^* r and b ^* r are hues obtained in accordance with JIS Z 8781-4 at the time of reflection color measurement when a reflection plate having substantially no wavelength dispersion of reflectance is disposed on the retardation layer side of the optical element. ,
The optical element characterized by satisfying the above mathematical expressions (1) to (4) at the same time. An optical element in which a polarizing element made of a substrate having a polarizing function and a retardation layer are laminated,
| A ^* r | ≦ 10 (3)
| B ^* r | ≦ 10 (4)
Ts_B / Ts_G ≧ 1.0 (5)
R_B / R_G ≦ 1.3 (6)
here,
Ts_B is the transmittance of the optical element at any wavelength within the wavelength region of 440 nm or more and 470 nm or less,
Ts_G is the transmittance of the optical element at any wavelength within the wavelength region of 520 nm or more and 570 nm or less,
R_B is the reflectance of the optical element at any wavelength within a wavelength region of 440 nm or more and 470 nm or less when a reflector having substantially no wavelength dispersion of reflectance is disposed on the retardation layer side of the optical element. ,
R_G is the reflectance of the optical element at any wavelength within a wavelength region of 520 nm or more and 570 nm or less when a reflection plate having substantially no wavelength dispersion of reflectance is disposed on the retardation layer side of the optical element. ,
a ^* r and b ^* r are hues obtained in accordance with JIS Z 8781-4 at the time of reflection color measurement when a reflection plate having substantially no wavelength dispersion of reflectance is disposed on the retardation layer side of the optical element. ,
In the above, an optical element satisfying the above mathematical expressions (3) to (6) at the same time. The optical element according to claim 1, further comprising:
Ts_B ≧ 46% (7)
An optical element characterized by satisfying: The optical element according to any one of claims 1 to 3,
An optical element comprising an azo compound. The optical element according to any one of claims 1 to 4,
The optical element, wherein the retardation layer is a quarter wavelength plate. The optical element according to claim 5,
The retardation layer functions as a quarter-wave plate by combining two layers of a first retardation plate and a second retardation plate, and the first retardation plate is a quarter-wave plate, The optical element, wherein the two phase difference plate is a half-wave plate. The optical element according to claim 5 or 6,
The optical element, wherein the retardation layer is a quarter-wave plate made of a reverse wavelength dispersion material. The optical element according to any one of claims 5 to 7,
The optical element, wherein the retardation layer is a quarter wave plate on which a positive C plate is laminated. The optical element according to any one of claims 5 to 8,
The retardation layer is
_{0 <(n x -n z)} / (n x -n y) <1 ··· (8)
here,
_nx is the main refractive index in the direction parallel to the film plane in the refractive index ellipse formed by the retardation layer,
n _y is parallel to the film plane in the refractive index ellipsoid the retardation layer is formed, and, the refractive index in the direction orthogonal to the direction of the n _x,
nz is the refractive index in the direction perpendicular to the film plane in the refractive index ellipsoid formed by the retardation layer,
And an optical element satisfying the above formula (8).   An image display device comprising the optical element according to claim 1.   An organic electroluminescent display device comprising the optical element according to claim 1. The organic electroluminescence display device according to claim 11,
Including pixels corresponding to each of red (R), green (G) and blue (B),
Ts_B at the emission peak wavelength of the blue (B) pixel is larger than Ts_G at the emission peak wavelength of the green (G) pixel and Ts_R at the emission peak wavelength of the red (R) pixel. Luminescence display device. An optical element comprising a polarizing element made of a base material having a polarizing function, an optical laminate in which a retardation layer is laminated, and a reflective electrode disposed on the retardation layer side,
Ts_B ≧ Ts_G (1)
Ts_B ≧ Ts_R (2)
| A ^* c | ≦ 10 (3)
| B ^* c | ≦ 10 (4)
here,
Ts_B is the transmittance of the optical layered body at any wavelength within a wavelength region of 440 nm or more and 470 nm or less,
Ts_G is the transmittance of the optical laminate at any wavelength within the wavelength region of 520 nm or more and 570 nm or less,
Ts_R is the transmittance of the optical laminate at any wavelength in the wavelength range of 580 nm or more and 650 nm or less,
a ^* c and b ^* c are hues determined according to JIS Z 8781-4 when measuring the reflected color of the optical element,
The optical element characterized by satisfying the above mathematical expressions (1) to (4) at the same time.   An organic electroluminescence display device comprising the optical element according to claim 13.

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