Optical Compensation Film for Improving Optical Characteristics of Organic Light-Emitting Devices

Abstract

The present invention relates to an optical compensation film for improving the optical properties of an organic light-emitting element, and has a technical gist of including a positive C plate, a negative biaxial retardation film having reverse wavelength dispersion and laminated on the C plate, and a polarizer laminated on the negative biaxial retardation film.

Description

Technical Field

[0001] The present invention relates to an optical compensation film for improving the optical characteristics of an organic light emitting device.

Background Art

[0002] An organic light emitting diode (hereinafter referred to as "OLED") is different from an LCD in that it does not require a backlight, so it is light in weight, can be made into a thin film, has excellent color reproducibility, and has the advantage of a fast response speed. It is applied and used in various devices such as smartphones and televisions.

[0003] However, when external light such as sunlight flows in from the outside, the organic light emitting device has a problem that the visibility and contrast ratio of the organic light emitting device deteriorate due to the external light being reflected by a reflector including a metal electrode of the organic light emitting device and leaking outside the organic light emitting device.

[0004] To solve this problem, conventionally, a circular polarizing plate composed of a linear polarizing plate and a retardation plate has been used to prevent the reflected external light from leaking outside the organic light emitting device.

[0005] However, the circular polarizing plate according to the prior art can solve the above-described problem caused by external light when viewed from the front, but since the viewing angle dependence is strong, the performance of preventing the reflected external light from leaking outside at a side viewing angle, that is, the so-called antireflection performance, deteriorates, and there is a problem that the visibility of the organic light emitting device is poor.

Summary of the Invention

Problems to be Solved by the Invention

[0006] The present invention is for solving the above-described problems, and an object thereof is to provide an optical compensation film for improving the optical characteristics of an organic light-emitting element, which can prevent reflection of external light from the organic light-emitting element and also prevent problems due to reflection of external light even in a side viewing angle, by including a negative biaxial retardation film and a positive C-plate.

[0007] The object of the present invention is not limited to the above-described object, and another object not described above will be clearly understood from the following description.

Means for Solving the Problems

[0008] An optical compensation film for improving the optical characteristics of an organic light-emitting element according to an aspect of the present invention for achieving the above object includes a positive C-plate, a negative biaxial retardation film having reverse wavelength dispersion laminated on the C-plate, and a polarizer laminated on the negative biaxial retardation film.

Effects of the Invention

[0009] The optical compensation film for improving the optical characteristics of an organic light-emitting element according to an embodiment of the present invention with the above-described configuration solves the problem of external light being reflected by the reflector of the organic light-emitting element when viewed from the front, and also has an effect of preventing problems due to reflection of external light even in a side viewing angle.

Brief Description of the Drawings

[0010]

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[0011] An optical compensation film for improving the optical characteristics of an organic light-emitting device according to one aspect of the present invention for achieving the above-described object includes a positive C plate, a negative biaxial retardation film laminated on the C plate and having reverse wavelength dispersibility, and a polarizer laminated on the negative biaxial retardation film.

[0012] The optical compensation film for improving the optical characteristics of the organic light-emitting device is characterized in that the average of reflectance measured at an inclination angle of 70° and an azimuth angle of 0 to 360° with respect to light having a wavelength of 380 to 780 nm is 0.0377 to 0.0597.

[0013] The C plate is characterized in that the retardation value represented by the following Mathematical formula 1 is 30 to 191 nm. (Mathematical formula 1) Δnd=(n e -n o )×d In the formula, Δnd is the retardation value of the C plate, n e is the abnormal refractive index of the C plate, n o is the normal refractive index of the C plate, and d is the thickness of the C plate.

[0014] The retardation film is characterized in that the refractive index ratio represented by the following Mathematical formula 2 at a wavelength of 380 to 780 nm is 1 to 1.5. (Mathematical formula 2) N z =(n x -n z ) / (n x -n y )

[0015] In the formula, N z is the refractive index ratio of the retardation film, and n x , n y , n z are the refractive indexes in the x-axis, y-axis, and z-axis directions of the retardation film, respectively.

[0016] The angle formed by the absorption axis of the polarizer and the optical axis of the retardation film is characterized by being 43 to 47° or 133 to 137°.

Embodiments for Carrying Out the Invention

[0017] The advantages, features, and methods for achieving these of the present invention will become apparent by referring to the embodiments described in detail below together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below and can be realized in various different forms. However, this embodiment is provided to make the disclosure of the present invention complete and to fully inform those with ordinary knowledge in the technical field to which the present invention pertains of the scope of the invention. On the other hand, the terms used in this specification are for explaining the embodiments and do not limit the present invention. In this specification, the singular form includes the plural form as well, unless otherwise specified in the context.

[0018] Hereinafter, with reference to the drawings, an optical compensation film for improving the optical characteristics of an organic light-emitting device according to an embodiment of the present invention will be described.

[0019] On the other hand, referring to FIGS. 1 to 3, an optical compensation film 20 for improving the optical characteristics of an organic light-emitting device according to an embodiment of the present invention can be laminated on the organic light-emitting device 10.

[0020] At this time, the organic light-emitting device 10 may have a structure according to the prior art, for example, it may include an anode 11, an organic light-emitting layer 12, and a cathode 13.

[0021] The anode 11 may be an electrode into which holes are injected and can be manufactured from a conductive material with a high work function.

[0022] The cathode 13 may be an electrode into which electrons are injected and can be manufactured from a conductive material with a low work function.

[0023] The organic light-emitting layer 12 can contain an organic substance capable of emitting light when a voltage is applied between the anode 11 and the cathode 13.

[0024] At this time, if at least one of the anode 11 and the cathode 13 is a metal electrode, the part corresponding to the metal electrode can act as a reflector to reflect external light that has entered the organic light-emitting element 10.

[0025] Also, the organic light-emitting layer 12 can contain an inorganic substance capable of reflecting light. When the organic light-emitting layer 12 contains an inorganic substance capable of reflecting light, the organic light-emitting layer 12 can also act as a reflector to reflect external light that has entered the organic light-emitting element 10.

[0026] That is, when at least one of the anode 11, the organic light-emitting layer 12, and the cathode 13 acts as a reflector, the external light that has entered can be reflected, which may reduce the brightness and visibility of the organic light-emitting element 10.

[0027] The optical compensation film 20 for improving the optical characteristics of the organic light-emitting element according to an embodiment of the present invention may be laminated relatively above the cathode 13 of the organic light-emitting element 10, and preferably, may be laminated on the cathode 13.

[0028] The optical compensation film 20 for improving the optical characteristics of the organic light-emitting element according to an embodiment of the present invention can include a C-plate 100, a retardation film 200, and a polarizer 300.

[0029] The C-plate 100 can be a positive uniaxial retardation optical element with n x1 =n y1 <n z1 .

[0030] n x1 is the refractive index in the x-axis direction of the C-plate 100, n ny1 is the refractive index in the y-axis direction of the C-plate 100, n nz1can be the refractive index of the C-plate 100 in the z-axis direction.

[0031] The C-plate 100 has an n x1 =n y1 <n z1 positive uniaxial retardation film.

[0032] That is, the C-plate 100 can be a positive C-plate.

[0033] The C-plate 100 may be attached to and laminated on the lower surface of the organic light-emitting element 10. Preferably, the C-plate 100 may be laminated on the cathode 13.

[0034] The C-plate 100 may mean a film in which liquid crystal is aligned inside, and a commercially available one can be used, or one manufactured by a normal manufacturing method obvious to those skilled in the art can be used.

[0035] The C-plate 100 may be manufactured using a liquid crystal composition, may be manufactured by solidifying the liquid crystal composition, or may be manufactured by curing the liquid crystal composition.

[0036] On the other hand, when a film composed of a retardation film 200 and a polarizer 300 is attached to the organic light-emitting element 10, external light reflection in the front direction of the organic light-emitting element 10 can be prevented. However, there is a problem that the external light reflection prevention performance is somewhat inferior at the side viewing angle, resulting in a decrease in the visibility of the organic light-emitting element 10 and poor viewing angle characteristics.

[0037] The C-plate 100 is for improving the side viewing angle characteristics of the organic light-emitting element 10. When an optical compensation film 20 including the retardation film 200 and the polarizer 300 is laminated on the organic light-emitting element 10, the reduction in the external light reflection prevention performance may not occur relatively even at the side viewing angle of the organic light-emitting element 10.

[0038] The thickness of the C plate 100 is not limited as long as it is the thickness of a commonly used C plate 100 and can be adjusted according to the object of the present invention, but it can preferably be 2 to 5 μm.

[0039] If the thickness of the C plate 100 is 2 to 5 μm, the external light reflection prevention performance can be more effectively improved at the side viewing angle of the optical compensation film 20.

[0040] The retardation film 200 can be a negative biaxial retardation film.

[0041] More specifically, the retardation film 200 can be a negative biaxial retardation film with n x2 >n y2 >n z2 .

[0042] n x2 is the refractive index in the x-axis direction of the retardation film 200, n y2 is the refractive index in the y-axis direction of the retardation film 200, and n z2 can be the refractive index in the z-axis direction of the retardation film 200.

[0043] The retardation film 200 can be a negative biaxial retardation film having a reverse wavelength dispersion characteristic in which the retardation increases as the wavelength of the incident light becomes longer.

[0044] At this time, the wavelength may correspond to the visible light region and can be, for example, 380 to 780 nm.

[0045] If the retardation film 200 is a negative biaxial retardation film having a reverse wavelength dispersion characteristic, the optical compensation film 20 according to the embodiment of the present invention can have excellent external light reflection prevention performance not only in the front but also at the side viewing angle.

[0046] The in-plane retardation value and the thickness-direction retardation value of the retardation film 200 are represented by the following Formula 1 and Formula 2, respectively. [Formula 1] R in =(n x2 -n y2 )×d1

[0047] In the formula, R in is the in-plane retardation value of the retardation film 200, n x2 is the refractive index of the retardation film 200 in the x-axis direction, n y2 is the refractive index of the retardation film 200 in the y-axis direction, and d1 can be the thickness of the retardation film 200. [Formula 2] R th ={((n x2 +n y2 ) / 2)-n z2}×d1

[0048] In the formula, R th is the retardation value in the thickness direction of the retardation film 200, n x2 is the refractive index of the retardation film 200 in the x-axis direction, n y2 is the refractive index of the retardation film 200 in the y-axis direction, n z2 is the refractive index of the retardation film 200 in the z-axis direction, and d1 can be the thickness of the retardation film 200.

[0049] The in-plane retardation value of the retardation film 200 is 5 to 15 μm, and the retardation value in the thickness direction can be more than 0 and 20 μm or less.

[0050] When the in-plane retardation value and the retardation value in the thickness direction of the retardation film 200 satisfy the above ranges respectively, the optical compensation film 20 can more effectively improve the problem of external light reflection of the organic light-emitting element 10, and can more effectively prevent the deterioration of the reflectance prevention performance on the side surface.

[0051] The refractive index ratio N z of the retardation film 200 is represented by the following Formula 3, and the refractive index ratio of the retardation film 200 can be 1 to 1.5. [Formula 3] N z =(n x2 -n z2 ) / (n x2 -n y2 )

[0052] In the formula, N z is the ratio of the retardation value in the thickness direction of the retardation film 200 to the retardation value on the surface of the retardation film 200, n x2 is the refractive index of the retardation film 200 in the x-axis direction, n y2 is the refractive index of the retardation film 200 in the y-axis direction, n z2 can be the refractive index of the retardation film 200 in the z-axis direction.

[0053] If the ratio of the retardation value in the thickness direction of the retardation film 200 to the retardation value on the surface of the retardation film 200 is less than 1, since the retardation is small, the light transmitted through the retardation film 200 does not reach circularly polarized light, so the optical compensation film 20 cannot smoothly prevent external light reflection of the organic light-emitting element 10. If it exceeds 1.5, since irregular reflection occurs when light passes through the retardation film 200, the optical compensation film 20 cannot effectively prevent external light reflection of the organic light-emitting element 10.

[0054] The thickness of the retardation film 200 is not limited as long as it is the thickness of the commonly used retardation film 200 and can be adjusted according to the purpose of the present invention, but it can preferably be 30 to 500 μm.

[0055] If the thickness of the retardation film 200 is 30 to 500 μm, the optical compensation film 20 can effectively prevent external light reflection of the organic light-emitting element 10.

[0056] On the other hand, the C-plate 100 may have a retardation value Δnd represented by the following mathematical formula 4. At this time, the retardation value Δnd may be 30 to 191 nm, may be 30 to 100 nm, may be 45 to 115 nm, may be 65 to 137 nm, may be 84 to 155 nm, may be 104 to 175 nm, or may be 122 to 191 nm. [Equation 4] Δnd=(n e -n o )×d2 In the formula, Δnd is the phase difference value of the C-plate 100, n e is the extraordinary refractive index of the C-plate 100, n o is the ordinary refractive index of the C-plate 100, and d2 can be the thickness of the C-plate 100.

[0057] When the phase difference value Δnd of the C-plate 100 deviates from the value corresponding to the above range, the light passing through the C-plate 100 has an elliptical polarization state instead of a circular polarization state. Therefore, not only can the optical compensation film 20 not improve the problem of external light reflection of the organic light-emitting element 10, but the external light reflection prevention performance may decrease at the side viewing angle. When having a value corresponding to the above range, the optical compensation film 20 can not only prevent external light reflection in the front direction of the organic light-emitting element 10, but also effectively prevent external light reflection at the side viewing angle.

[0058] The phase difference value Δnd of the C-plate 100 and the refractive index ratio N of the retardation film 200 z may be proportional. At this time, so that the optical compensation film 20 can more effectively prevent external light reflection of the organic light-emitting element 10, for a unit increase amount 1 of the refractive index ratio N of the retardation film 200, the phase difference value Δnd of the C-plate 100 can increase by 150 - 220 nm. z

[0059] However, at this time, the phase difference value Δnd of the C-plate 100 when the refractive index ratio N of the retardation film 200 z is 1 can be 30 - 100 nm.

[0060] That is, the phase difference value Δnd of the C-plate 100 and the refractive index ratio N of the retardation film 200 z may be in a relationship satisfying the following Equation 5. [Equation 5] Δnd = (Δnd)0 + αβ

[0061] In the formula, (Δnd)0 is the retardation value Δnd of the C-plate 100 when the refractive index ratio N z of the retardation film 200 is 1, which is 30 to 100 nm, and α is the retardation value Δnd of the C-plate 100 with respect to the unit increase amount of the refractive index ratio N z of the retardation film 200, which is 150 to 220 nm, and β is the increase amount of the refractive index ratio N z of the retardation film 200 and can be an increase amount.

[0062] That is, the retardation value Δnd of the C-plate 100 calculated by Equation 5 can be the retardation value Δnd when the refractive index ratio N z of the retardation film 200 is 1 + β.

[0063] For example, referring to Equation 5, if (Δnd)0 is 100 nm, α is 150 nm, and β is 0.1, the retardation value Δnd of the C-plate 100 when the refractive index ratio N z of the retardation film 200 is 1.1 can be calculated as 115 nm.

[0064] If the retardation value Δnd of the C-plate 100 and the refractive index ratio N z of the retardation film 200 satisfy Equation 5, the optical compensation film 20 can not only prevent external light reflection in the front direction of the organic light-emitting element 10, but also prevent the external light reflection performance from deteriorating in the side viewing angle.

[0065] The polarizer 300 can be laminated on the retardation film 200.

[0066] The polarizer 300 may be a commonly used linear polarizer, and may linearly polarize the transmitted light so as to vibrate in any direction.

[0067] The polarizer 300 is not limited as long as it is a normal linear polarizer. For example, an iodine-based polarizer composed of a film of a polyvinyl alcohol (PVA)-based resin, a dichroic dye-based polarizer, etc. can be used.

[0068] The absorption axis of the polarizer 300 and the optical axis of the retardation film 200 may be inclined and oriented. The angle formed by the absorption axis of the polarizer 300 and the optical axis of the retardation film 200 may be 43 to 47°, or may be 133 to 137°.

[0069] The C plate 100 of the optical compensation film 20, the retardation film 200, and the retardation film 200 and the polarizer 300 can be adhered via at least one of a commonly used adhesive and an adhesive to maintain a laminated state. At this time, an optically transparent adhesive and an optically transparent adhesive can be used as the adhesive and the adhesive, respectively.

[0070] Moreover, the C plate 100 of the optical compensation film 20, the retardation film 200, and the retardation film 200 and the polarizer 300 may be laminated to each other by direct coating.

[0071] <Example 1> An optical compensation film 20 including a C plate 100, a retardation film 200 laminated on the C plate 100, and a polarizer 300 laminated on the retardation film 200 was prepared.

[0072] At this time, as the C plate 100, a positive C plate having a retardation value Δnd represented by Equation 4 of 70 nm was used.

[0073] As the retardation film 200, a negative biaxial retardation film having a refractive index ratio N z represented by Equation 3 of 1 and having an inverse wavelength dispersion characteristic was used.

[0074] As the polarizer 300, a PVA-based linear polarizer having an absorption axis in one direction is used, and one having an absorption axis at an angle of 45° with the optical axis of the retardation film 200 is used.

[0075] <Example 2> An optical compensation film 20 was prepared in the same manner as in Example 1.

[0076] However, as the C-plate 100, instead of the positive C-plate having a retardation value Δnd of 70 nm, a positive C-plate having a retardation value Δnd of 30 nm was used to prepare the optical compensation film 20.

[0077] <Example 3> An optical compensation film 20 was prepared in the same manner as in Example 1.

[0078] However, as the C-plate 100, instead of the positive C-plate having a retardation value Δnd of 70 nm, a positive C-plate having a retardation value Δnd of 100 nm was used to prepare the optical compensation film 20.

[0079] <Example 4> An optical compensation film 20 was prepared in the same manner as in Example 1.

[0080] However, as the C-plate 100, instead of the positive C-plate having a retardation value Δnd of 70 nm, a positive C-plate having a retardation value Δnd of 90 nm was used, and as the retardation film 200, instead of the negative biaxial retardation film having a refractive index ratio N z of 1, a negative biaxial retardation film having a refractive index ratio N z of 1.1 was used to prepare the optical compensation film 20.

[0081] <Example 5> An optical compensation film 20 was prepared in the same manner as in Example 1.

[0082] However, as the C plate 100, instead of the positive C plate with a retardation value Δnd of 70 nm, a positive C plate with a retardation value Δnd of 109 nm is used, and as the retardation film 200, instead of the negative biaxial retardation film with a refractive index ratio N z of 1, a negative biaxial retardation film with a refractive index ratio N z of 1.2 is used to prepare the optical compensation film 20.

[0083] <Example 6> The optical compensation film 20 was prepared in the same manner as in Example 1.

[0084] However, as the C plate 100, instead of the positive C plate with a retardation value Δnd of 70 nm, a positive C plate with a retardation value Δnd of 126 nm is used, and as the retardation film 200, instead of the negative biaxial retardation film with a refractive index ratio N z of 1, a negative biaxial retardation film with a refractive index ratio N z of 1.3 is used to prepare the optical compensation film 20.

[0085] <Example 7> The optical compensation film 20 was prepared in the same manner as in Example 1.

[0086] However, as the C plate 100, instead of the positive C plate with a retardation value Δnd of 70 nm, a positive C plate with a retardation value Δnd of 142 nm is used, and as the retardation film 200, instead of the negative biaxial retardation film with a refractive index ratio N z of 1, a negative biaxial retardation film with a refractive index ratio N z of 1.4 is used to prepare the optical compensation film 20.

[0087] <Example 8> The optical compensation film 20 was prepared in the same manner as in Example 1.

[0088] However, as the C plate 100, instead of the positive C plate with a retardation value Δnd of 70 nm, a positive C plate with a retardation value Δnd of 160 nm is used, and as the retardation film 200, instead of the negative biaxial retardation film with a refractive index ratio N z of 1, a negative biaxial retardation film with a refractive index ratio N z of 1.5 is used to prepare the optical compensation film 20.

[0089] <Comparative Example 1> An optical compensation film was prepared in the same manner as in Example 1.

[0090] However, as the C plate 100, instead of the positive C plate with a retardation value Δnd of 70 nm, a negative C plate with a retardation value Δnd of -70 nm is used to prepare the optical compensation film.

[0091] <Comparative Example 2> An optical compensation film was prepared in the same manner as in Example 1.

[0092] However, an optical compensation film composed of a retardation film 200 and a polarizer 300 laminated on the retardation film 200 without a C plate is prepared.

[0093] <Comparative Example 3> An optical compensation film was prepared in the same manner as in Example 1.

[0094] However, as the C plate 100, instead of the positive C plate with a retardation value Δnd of 70 nm, a positive C plate with a retardation value Δnd of 10 nm is used to prepare the optical compensation film 20.

[0095] <Comparative Example 4> An optical compensation film was prepared in the same manner as in Example 1.

[0096] However, as the C plate 100, instead of the positive C plate with a retardation value Δnd of 70 nm, a positive C plate with a retardation value Δnd of 120 nm was used to prepare the optical compensation film 20.

[0097] <Comparative Example 5> An optical compensation film was prepared in the same manner as in Example 1.

[0098] However, as the retardation film 200, instead of the negative biaxial retardation film with a refractive index ratio N z of 1, a negative biaxial retardation film with a refractive index ratio N z of 0.5 was used to prepare the optical compensation film 20.

[0099] <Comparative Example 6> An optical compensation film was prepared in the same manner as in Example 1.

[0100] However, as the retardation film 200, instead of the negative biaxial retardation film with a refractive index ratio N z of 1, a negative biaxial retardation film with a refractive index ratio N z of 2 was used to prepare the optical compensation film 20.

[0101] Table 1 below summarizes the conditions of the C plate 100 and the retardation film 200 used in the optical compensation films according to Examples 1 to 8 and Comparative Examples 1 to 6.

[0102]

Table 1

[0103] <Test Example 1> In Test Example 1, the average reflectance of the optical compensation films according to Examples 1 to 8 and Comparative Examples 1 to 6 at an omnidirectional angle (0 to 360°) and a maximum tilt angle of 90° with respect to light having a wavelength of 380 to 780 nm was simulated using a simulator (Techwiz 1D plus, manufactured by Sanaichi Systems Co., Ltd.).

[0104] For the test according to Test Example 1, the simulator was set to a structure in which the optical compensation films 20 according to Examples 1 to 8 and the optical compensation films according to Comparative Examples 1 to 6 were respectively laminated on a plurality of organic light emitting elements 10.

[0105] At this time, the lower surface of the positive C plate 100 was attached to the organic light emitting element 10, and when the positive C plate 100 was not provided, the lower surface of the retardation film 200 was brought into contact with the organic light emitting element 10 and laminated.

[0106] The test results are shown in FIGS. 4 to 17.

[0107] FIGS. 4 to 17 are diagrams showing the omnidirectional reflectance simulation results according to Test Example 1 of the optical compensation films 20 according to Examples 1 to 8 and the optical compensation films according to Comparative Examples 1 to 6.

[0108] More specifically, referring to FIGS. 4 to 17, the center of the circle means the front (tilt angle 0°, azimuth angle 0°), and it shows that the tilt angle increases from a minimum of 0° to a maximum of 90° as going from the center of the circle in the circumferential direction.

[0109] Also, referring to FIGS. 4 to 17, it means that the azimuth angle increases as going counterclockwise from the right side (0°) along the diameter direction of the circle, and the angles described along the circumference mean the azimuth angle.

[0110] Also, referring to FIGS. 4 to 17, it can be meant that the closer to black, the lower the average reflectance with respect to light having a wavelength of 380 to 780 nm, and the closer to white, the higher the average reflectance with respect to light having a wavelength of 380 to 780 nm.

[0111] Referring to FIGS. 4 to 17, the averages of the reflectances measured at a tilt angle of 70° and an azimuth angle of 0 to 360° with respect to light having a wavelength of 380 to 780 nm of the optical compensation films according to Examples 1 to 8 and Comparative Examples 1 to 6 are shown in Table 2 below.

[0112]

Table 2

[0113] Referring to FIGS. 4 to 17 and Table 2, it can be confirmed that the average reflectance of the optical compensation films according to Comparative Examples 1 to 6 is higher than that of the optical compensation film 20 according to Examples 1 to 8. This is a result that can confirm that the optical compensation film 20 according to Examples 1 to 8 exhibits superior external light reflection prevention performance compared to the optical compensation films according to Comparative Examples 1 to 6.

[0114] In particular, it can be confirmed that the average reflectance of the optical compensation film according to Comparative Example 4 is higher than the average reflectance of the optical compensation film 20 according to Examples 1 to 8. This is because when the increase amount of the retardation value Δnd of the C-plate 100 is much larger than the increase amount of the refractive index ratio N z of the retardation film 200, it is a result that can confirm that the external light reflection prevention performance is inferior at the side viewing angle of the optical compensation film 20.

[0115] <Test Example 2> In Test Example 2, when light having a short wavelength of 550 nm was incident in the diagonal direction (tilt angle 45°, azimuth angle 45°) on the optical compensation film 20 according to Examples 1 to 8 and the optical compensation films according to Comparative Examples 1 to 6, the polarization state was simulated and shown on a Poincare sphere. At this time, a simulator for the simulation was Techwiz 1D plus (manufactured by Sanaichi Systems Co., Ltd.).

[0116] For the test according to Test Example 2, the simulator was set to a structure in which the optical compensation film 20 according to Examples 1 to 8 and the optical compensation films according to Comparative Examples 1 to 6 were respectively laminated on a plurality of organic light emitting elements 10.

[0117] The test results are shown in FIGS. 18 to 31.

[0118] On the one hand, the arrival point A shown in FIGS. 18 to 31 indicates the arrival point of the polarization state of the light transmitted through the optical compensation film, and the arrival point A can have coordinate values corresponding to the S1 axis D, the S2 axis E, and the S3 axis F. At this time, if the arrival point A is located on the circumference of the circle B passing through the S1 axis D and the S3 axis F and the coordinate value corresponding to the S2 axis E is 0, it can be determined that the light transmitted through the optical compensation film 20 has reached the circular polarization state.

[0119] In order to determine the degree to which the polarization states of the lights transmitted through the optical compensation film 20 according to Examples 1 to 8 and the optical compensation films according to Comparative Examples 1 to 6 deviate from the circular polarization state, the departure angle θ is shown in Table 3 below with reference to FIGS. 18 to 31.

[0120] At this time, referring to FIG. 32, the departure angle θ can mean the angle between the line C passing through the origin of the coordinate system and the arrival point A and the S3 axis F.

[0121]

Table 3

[0122] Referring to FIGS. 18 to 31 and Table 3, it can be confirmed that the departure angles of the optical compensation films 20 according to Examples 1 to 8 are smaller than those of the optical compensation films according to Comparative Examples 1 and 3 to 6. This is a result that can confirm that the optical compensation films 20 according to Examples 1 to 8 are inferior in anti-reflection performance at the side viewing angle compared to the optical compensation films according to Comparative Examples 1 and 3 to 6.

[0123] In particular, it can be confirmed that the departure angle θ of the optical compensation film according to Comparative Example 4 is larger than the departure angle θ of the optical compensation films 20 according to Examples 1 to 8. This is because when the retardation value Δnd of the C plate 100 is too large compared to the refractive index ratio N z of the retardation film 200, it can be confirmed that not only is the external light reflection prevention performance of the optical compensation film 20 inferior in the front direction, but also the external light reflection prevention performance at the side viewing angle deteriorates.

[0124] Those having ordinary knowledge in the technical field to which the present invention pertains will be able to understand that the present invention can be implemented in other specific forms without changing its technical idea and essential features. Therefore, it should be understood that the above-described embodiments are exemplary in all aspects and not restrictive. The scope of the present invention is indicated by the claims described below rather than the above detailed description. All changes or modifications derived from the claims and the equivalent concept thereof should be construed as being included in the scope of the present invention.

Industrial Applicability

[0125] When viewed from the front, the present invention can solve the problem caused by the reflection of external light on the reflector of the organic light-emitting element, and can also prevent the problem caused by the reflection of external light at the side viewing angle. Therefore, the present invention is applicable to industrial fields that require organic light-emitting elements with improved optical characteristics.

Claims

1. A positive C-plate having a retardation value represented by the following formula (1) of 109 nm, A negative biaxial retardation film laminated on the C-plate, having inverse wavelength dispersion, and having a refractive index ratio represented by the following formula (2) of 1.2 at a wavelength of 380 to 780 nm, A polarizer laminated on the negative biaxial retardation film, and The average of the reflectance measured at an inclination angle of 70° and an azimuth angle of 0 to 360° with respect to light having a wavelength of 380 to 780 nm is 0.0378, An optical compensation film for improving the optical characteristics of an organic light emitting element, wherein the retardation value of the C-plate and the refractive index ratio of the biaxial retardation film satisfy the following formula (5). (Formula (1)) Δnd = (n ｅ - n ｏ ) × d (In the formula, Δnd is the retardation value of the C-plate, n ｅ is the extraordinary refractive index of the C-plate, n ｏ is the ordinary refractive index of the C-plate, and d is the thickness of the C-plate.) (Formula (2)) N ｚ = (n ｘ - n ｚ ) / (n ｘ - n ｙ ) (In the formula, N ｚ is the refractive index ratio of the retardation film, and n ｘ , n ｙ , n ｚ are the refractive indices in the x-axis, y-axis, and z-axis directions of the retardation film, respectively.) (Formula (5)) Δnd = (Δnd) ０ + αβ (In the formula, Δnd is the retardation value of the C-plate, and (Δnd) ０is the retardation value of the C-plate when the refractive index ratio of the retardation film is 1, which is 30 to 100 nm, α is the increase amount of the retardation value of the C-plate with respect to the unit increase amount of the refractive index ratio of the retardation film, which is 150 to 220 nm, and β is the increase amount of the refractive index ratio of the retardation film.)

2. The angle formed by the absorption axis of the polarizer and the optical axis of the retardation film is 43 to 47° or 133 to 137°. The optical compensation film for improving the optical characteristics of the organic light-emitting element according to claim 1.

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