Polarizing film and display device using the same

Abstract

The present application discloses a polarizing film and a display device using the same, wherein the polarizing film comprises a polarizing layer, a reverse wavelength dispersion quarter wave plate (QWP) disposed on the polarizing layer, and a light absorbing layer disposed on the polarizing layer, wherein the light absorbing layer comprises a light absorber to absorb light having a wavelength in the range of about 380 nm to about 430 nm.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to and the benefit of Korean Patent Application No. 10-2019-0020493, filed on February 21, 2019, which is hereby incorporated by reference for all purposes as if fully set forth herein. Technical Field

[0003] Exemplary embodiments of the present invention relate to a polarizing film and a display device using the same, and more particularly, to a polarizing film including a light absorbing layer and a display device using the polarizing film. Background Art

[0004] Display devices for forming images may include liquid crystal displays (LCDs), organic light emitting diode (OLED) display devices, electrophoretic display (EPD) devices, etc. Generally, display devices may employ polarizing films to prevent external light from being reflected by a front surface of the display device.

[0005] The above information disclosed in this Background section is only for understanding the background of the present inventive concept and therefore it may contain information that does not constitute prior art. Summary of the invention

[0006] The polarizing film constructed according to the exemplary embodiment of the present invention and the display device including the same have excellent anti-reflection characteristics and reflective chromaticity characteristics.

[0007] Additional features of the inventive concept will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the inventive concept.

[0008] The polarizing film according to an exemplary embodiment includes a polarizing layer, a reverse wavelength dispersion quarter wave plate (QWP) disposed on the polarizing layer, and a light absorbing layer disposed on the polarizing layer, wherein the light absorbing layer includes a light absorber to absorb light having a wavelength in the range of about 380 nm to about 430 nm.

[0009] The wavelength dispersion value DSP of the reverse wavelength dispersion QWP at a wavelength of 450nm and the transmittance of the polarizing film at a wavelength of 430nm may satisfy:

[0010] T(430nm)≤8.7875e (-3.715×DSP(450nm)) , where T(430nm) represents the transmittance at a wavelength of 430nm, DSP(450nm) represents the wavelength dispersion value at a wavelength of 450nm and is R(450nm) / R(550nm), and R(λ) represents the phase difference value at a wavelength of λ.

[0011] The polarizing film may have a light transmittance of less than 40% for light having a wavelength in a range of about 380 nm to about 430 nm.

[0012] The light absorber may include at least one of the following: anthraquinone-based dyes, methine-based dyes, azomethine-based dyes, oxadine-based dyes, azo-based dyes, styryl-based dyes, coumarin-based dyes, porphyrin-based dyes, dibenzofuranone-based dyes, diketopyrrolopyrrole-based dyes, rhodamine-based dyes, xanthene-based dyes, and pyrromethene-based dyes.

[0013] The light absorbing layer may include at least one of triacetyl cellulose (TAC), cycloolefin polymer, and polymethyl methacrylate (PMMA).

[0014] The light absorbing layer may include a pressure sensitive adhesive.

[0015] The polarizing film may further include a first protective layer and a second protective layer respectively disposed on the bottom surface and the top surface of the polarizing layer, wherein each of the first protective layer and the second protective layer may include at least one of triacetyl cellulose (TAC), cycloolefin polymer and polymethyl methacrylate (PMMA).

[0016] The polarizing film may further include an adhesive layer disposed on a bottom surface of the reverse wavelength dispersion QWP.

[0017] The polarizing layer may include a dichroic dye in polyvinyl alcohol (PVA).

[0018] The reverse wavelength dispersion QWP can satisfy: DSP(450nm)=R(450nm) / R(550nm)<1, and DSP(650nm)=R(650nm) / R(550nm)>1, where DSP(λ) represents the wavelength dispersion value DSP of the reverse wavelength dispersion QWP at a wavelength of λ, and R(λ) represents the phase difference value at a wavelength of λ.

[0019] A display device according to another exemplary embodiment includes: a substrate, a plurality of display elements disposed on the substrate, a sealing member that seals the plurality of display elements, and a polarizing film disposed on the sealing member, wherein the polarizing film includes a polarizing layer, a reverse wavelength dispersion quarter wave plate (QWP) disposed on the polarizing layer, and a light absorbing layer disposed on the polarizing layer, wherein the light absorbing layer includes a light absorber to absorb light having a wavelength in a range of about 380 nm to about 430 nm.

[0020] The wavelength dispersion value DSP of the reverse wavelength dispersion QWP at a wavelength of 450nm and the transmittance of the polarizing film at a wavelength of 430nm can satisfy: T(430nm)≤8.7875e (-3.715×DSP(450nm)), where T(430nm) represents the transmittance at a wavelength of 430nm, DSP(450nm) represents the wavelength dispersion value at a wavelength of 450nm and is R(450nm) / R(550nm), and R(λ) represents the phase difference value at a wavelength of λ.

[0021] The polarizing film may have a light transmittance of less than 40% for light having a wavelength in a range of about 380 nm to about 430 nm.

[0022] The light absorber may include at least one of the following: anthraquinone dyes, methine dyes, azomethine dyes, oxazine dyes, azo dyes, styryl dyes, coumarin dyes, porphyrin dyes, dibenzofuranone dyes, diketopyrrolopyrrole dyes, rhodamine dyes, xanthene dyes and pyrromethene dyes.

[0023] The light absorbing layer may include a pressure sensitive adhesive, wherein the light absorbing layer may be disposed between the reverse wavelength dispersion QWP and the sealing member.

[0024] The sealing member may be a thin film encapsulation layer including a first inorganic encapsulation layer, an organic encapsulation layer, and a second inorganic encapsulation layer which are sequentially stacked.

[0025] The sealing member may include a sealing substrate.

[0026] The display device may further include a first protective layer and a second protective layer respectively disposed on the bottom surface and the top surface of the polarizing layer, wherein each of the first protective layer and the second protective layer may include at least one of triacetyl cellulose (TAC), cycloolefin polymer and polymethyl methacrylate (PMMA).

[0027] The light absorbing layer may include at least one of triacetyl cellulose (TAC), cycloolefin polymer, and polymethyl methacrylate (PMMA).

[0028] The reverse wavelength dispersion QWP can satisfy: DSP(450nm)=R(450nm) / R(550nm)<1, and DSP(650nm)=R(650nm) / R(550nm)>1, where DSP(λ) represents the wavelength dispersion value DSP of the reverse wavelength dispersion QWP at a wavelength of λ, and R(λ) represents the phase difference value at a wavelength of λ.

[0029] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention and together with the description serve to explain the inventive concept.

[0031] Figure 1 is a cross-sectional view of a polarizing film according to an exemplary embodiment.

[0032] Figure 2A is a cross-sectional view of a polarizing film according to another exemplary embodiment.

[0033] Figure 2B is a cross-sectional view of a polarizing film according to another exemplary embodiment.

[0034] Figure 2C is a cross-sectional view of a polarizing film according to another exemplary embodiment.

[0035] Figure 3 Graphs showing wavelength dispersion values ​​of reverse wavelength dispersion quarter-wave plates (QWP) of types (a) to (d).

[0036] Figure 4 The reflection chromaticity of the reverse wavelength dispersion QWP of type (a) to type (d) in CIE L*a*b* coordinates is shown.

[0037] Figure 5 It is a graph showing the relationship between the wavelength dispersion value and the transmittance of the polarizing film.

[0038] Figure 6 is a graph showing transmittance of the related art and an exemplary embodiment.

[0039] Figure 7 The chromaticity of reflected light of the embodiment in the CIE L*a*b* coordinate system is shown.

[0040] Figure 8 TABLE 2 is a table showing the change in chromaticity in the related art and in the exemplary embodiment.

[0041] Fig. 9 is a plan view showing a display device according to an exemplary embodiment.

[0042] Fig.10 is a cross-sectional view showing a portion of a display device according to an exemplary embodiment. DETAILED DESCRIPTION

[0043] In the following description, for the purpose of explanation, many specific details are set forth in order to provide a thorough understanding of various exemplary embodiments or implementations of the present invention. As used herein, "implementation" and "implementation" are interchangeable words, which are non-limiting examples of devices or methods using one or more inventive concepts disclosed herein. However, it is apparent that various exemplary embodiments may be practiced without these specific details or with one or more equivalent arrangements. In other cases, well-known structures and devices are shown in block diagram form to avoid unnecessary confusion of various exemplary embodiments. In addition, various exemplary embodiments may be different, but do not have to be exclusive. For example, without departing from the inventive concept, the specific shape, configuration and characteristics of the exemplary embodiment may be used or implemented in another exemplary embodiment.

[0044] Unless otherwise noted, the illustrated exemplary embodiments should be understood as providing exemplary features that change the details of some ways of implementing the inventive concept in practice. Therefore, unless otherwise noted, the features, components, modules, layers, films, panels, regions and / or aspects, etc. (hereinafter individually or collectively referred to as "elements") of various embodiments may be combined, separated, interchanged and / or rearranged in other ways without departing from the inventive concept.

[0045] The use of cross hatching and / or shading is usually provided in the drawings to make the boundaries between adjacent elements clear. Thus, unless otherwise indicated, the presence or absence of cross hatching or shading does not express or indicate any preference or requirement for a specific material, material property, dimension, ratio, commonality between the elements shown, and / or any other characteristic, attribute, property, etc. of the elements. In addition, in the drawings, the size and relative size of the elements may be magnified for clarity and / or description purposes. When the exemplary embodiments can be implemented differently, the specific process sequence may be performed differently from the described sequence. For example, two processes described in succession may be performed substantially simultaneously or in an order opposite to the described sequence. Moreover, the same reference numerals represent the same elements.

[0046] When an element, such as a layer, is referred to as being "on", "connected to" or "coupled to" another element or layer, it may be directly on, directly connected to or directly coupled to another element or layer, or there may be an intermediate element or layer. However, when an element or layer is referred to as being "directly" "on", "directly connected to" or "directly coupled to" another element or layer, there is no intermediate element or layer. For this purpose, the term "connection" may refer to a physical connection, an electrical connection and / or a fluid connection with or without an intermediate element. In addition, the D1 axis, the D2 axis and the D3 axis are not limited to the three axes of a rectangular coordinate system, such as the x-axis, the y-axis and the z-axis, and may be interpreted in a broader sense. For example, the D1 axis, the D2 axis and the D3 axis may be perpendicular to each other, or may represent different directions that are not perpendicular to each other. For the purpose of this disclosure, "at least one of X, Y, and Z" and "at least one selected from the group consisting of X, Y, and Z" may be interpreted as only X, only Y, only Z, or any combination of two or more of X, Y, and Z, such as, for example, XYZ, XYY, YZ, and ZZ. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0047] Although the terms "first", "second", etc. may be used herein to describe various types of elements, these elements should not be limited by these terms. These terms are used to distinguish one element from another element. Therefore, without departing from the teachings of the present disclosure, the first element discussed below may be referred to as the second element.

[0048] Spatially relative terms, such as "below," "beneath," "below," "above," "upper," "above," "higher," "side" (e.g., as in "sidewall"), and the like, may be used herein for descriptive purposes, and thereby to describe the relationship of one element to another element(s) as shown in the accompanying drawings. Spatially relative terms are intended to include different orientations of the device in use, operation, and / or manufacture in addition to the orientation depicted in the accompanying drawings. For example, if the device in the drawings is turned over, elements described as being "below" or "beneath" other elements or features would then be oriented "above" the other elements or features. Thus, the exemplary term "below" may include both orientations of above and below. Furthermore, the device may be oriented in other ways (e.g., rotated 90 degrees or in other orientations), and as such, the spatially relative descriptors used herein are interpreted accordingly.

[0049] The terms used herein are for the purpose of describing specific embodiments and are not intended to be limiting. As used herein, the singular forms, "a", "an", and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. Moreover, the terms "comprises", "comprising", "includes", and / or "including" when used in this specification indicate the presence of the described features, integers, steps, operations, elements, components, and / or groups thereof, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. It should also be noted that, as used herein, the terms "substantially", "about", and other similar terms are used as terms of approximation rather than as terms of degree, and as such, are used to illustrate the inherent deviations of measured values, calculated values, and / or provided values ​​that would be recognized by those of ordinary skill in the art.

[0050] Various exemplary embodiments are described herein with reference to cross-sections and / or exploded illustrations that are schematic illustrations of idealized exemplary embodiments and / or intermediate structures. As such, variations from the shapes illustrated due to, for example, manufacturing techniques and / or tolerances are to be expected. Thus, the exemplary embodiments disclosed herein should not necessarily be construed as limited to the shapes of the specifically illustrated regions, but rather include deviations in shape that result, for example, from manufacturing. As such, the regions illustrated in the drawings may be schematic in nature, and the shapes of these regions may not reflect the actual shapes of regions of the device, and as such, are not necessarily intended to be limiting.

[0051] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present disclosure belongs. Terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning consistent with their meaning in the context of the relevant art, and should not be interpreted in an idealized or overly formal sense, unless expressly defined as such herein.

[0052] Figure 1 is a cross-sectional view of a polarizing film 500 according to an exemplary embodiment.

[0053] refer to Figure 1 , a polarizing film 500 according to an exemplary embodiment includes a polarizing layer 520 , a reverse wavelength dispersion quarter wave plate (hereinafter, reverse wavelength dispersion QWP) 510 , and a light absorbing layer 530 .

[0054] The polarizing layer 520 polarizes light incident from the light source into light having the same direction as the direction of the polarization axis. In some exemplary embodiments, the polarizing layer 520 may be formed by including a polarizer and / or a dichroic dye in a polyvinyl alcohol (PVA) film. The dichroic dye may be an iodine molecule and / or a dye molecule.

[0055] In some exemplary embodiments, polarizing layer 520 can be formed by extending the PVA film in one direction and immersing the PVA film in an iodine and / or dichroic dye solution. In this case, the iodine molecules and / or dichroic dye molecules are arranged in a direction parallel to the elongation direction. Because the iodine molecules and the dye molecules exhibit dichroism, the light vibrating in the elongation direction can be absorbed, and the light vibrating in the direction perpendicular to the elongation direction can be transmitted.

[0056] The reverse wavelength dispersion QWP 510 may be placed on one side of the polarization layer 520, and may circularly polarize polarized light passing through the polarization layer 520 by delaying the phase by λ / 4. Thus, light reflectivity may be reduced. The reverse wavelength dispersion QWP 510 may be placed farther from the light source than the polarization layer 520. For example, when external light is incident from above the polarization layer 520, the reverse wavelength dispersion QWP 510 may be placed below the polarization layer 520.

[0057] The reverse wavelength dispersion QWP 510 may depend on the wavelength, and for shorter wavelengths, the phase delay value may be reduced. The wavelength dispersion value DSP of the reverse wavelength dispersion QWP 510 may be expressed as DSP(λ)=R(λ) / R(550nm), where R(λ) represents the phase difference value at a wavelength of λ, and may satisfy:

[0058] DSP(450nm)=R(450nm) / R(550nm)<1, and

[0059] DSP(650nm)=R(650nm) / R(550nm)>1.

[0060] The light absorbing layer 530 may be placed on one side of the polarizing layer 520. Figure 1 The light absorbing layer 530 is shown to be placed above the polarizing layer 520, but the inventive concept is not limited thereto. Figure 2A In the polarizing film 501 shown in FIG. 5 , the light absorbing layer 530 may be placed between the polarizing layer 520 and the reverse wavelength dispersion QWP 510. In another exemplary embodiment, Figure 2B The polarizing film 502 shown in FIG. 5 may include a light absorbing layer 530 disposed below the reverse wavelength dispersion QWP 510 .

[0061] The light absorbing layer 530 according to the exemplary embodiment may reduce the reflection chromaticity. As such, the light absorbing layer 530 may absorb light of a short wavelength range within the visible light range, that is, light having a wavelength in the range of about 380 nm to about 430 nm.

[0062] The light absorbing layer 530 may include a light absorber for absorbing light having a wavelength in the range of about 380 nm to about 430 nm. For example, the light absorbing layer 530 may include a light absorber such as anthraquinone dyes, methine dyes, azomethine dyes, oxazine dyes, azo dyes, styryl dyes, coumarin dyes, porphyrin dyes, dibenzofuranone dyes, diketopyrrolopyrrole dyes, rhodamine dyes, xanthene dyes, and pyrromethene dyes.

[0063] The light transmittance of the light absorbing layer 530 may be adjusted by adjusting the amount of the light absorber included in the light absorbing layer 530. Through the light absorbing layer 530, the light transmittance T of the polarizing film 500 may satisfy:

[0064] T(430nm)≤8.7875e (-3.715×DSP(450nm))

[0065] Wherein T(430nm) represents the transmittance at a wavelength of 430nm. DSP(450nm) represents the wavelength dispersion value at a wavelength of 450nm. The wavelength dispersion value DSP is R(450nm) / R(550nm), and R(λ) represents the phase difference value at a wavelength of λ.

[0066] When the transmittance T satisfies the above conditions, the transmission of light generated below the polarizing film 500 and traveling toward the top surface of the polarizing film 500 can be ensured, and the color shift of light generated above the polarizing film 500 and reflected by the top surface of the polarizing film 500 can be minimized. That is, the reflection chromaticity of the light reflected by the top surface of the polarizing film 500 can be reduced. Figures 3 to 5 Describe this mechanism in more detail.

[0067] The light absorbing layer 530 may serve as a protective layer that supports the polarizing layer 520 and compensates for the mechanical strength of the polarizing layer 520. In this case, the light absorbing layer 530 may include at least one of triacetyl cellulose (TAC), cycloolefin polymer, and polymethyl methacrylate (PMMA).

[0068] In some exemplary embodiments, the polarizing film 500 may further include various elements such as a protective layer, a supporting layer, an adhesive layer, and a hard coating layer in addition to the reverse wavelength dispersion QWP 510 , the polarizing layer 520 , and the light absorbing layer 530 .

[0069] FIG. 2A to FIG. 2C is a cross-sectional view of a polarizing film according to an exemplary embodiment. Figures 2A to 2C In, with Figure 1 The same elements are denoted by the same reference numerals, and thus, repeated descriptions thereof will be omitted to avoid redundancy.

[0070] refer to Figure 2A , the polarizing film 501 according to the exemplary embodiment may include a reverse wavelength dispersion QWP 510, a light absorbing layer 530, and a polarizing layer 520, which are sequentially stacked. The light absorbing layer 530 may be placed between the reverse wavelength dispersion QWP 510 and the polarizing layer 520.

[0071] The light absorbing layer 530 may absorb light in the range of about 380 nm to about 430 nm, and may serve as a protective layer supporting the polarizing layer 520 and compensating for the mechanical strength of the polarizing layer 520. In this case, the light absorbing layer 530 may include at least one of TAC, cycloolefin polymer, and PMMA.

[0072] The light absorbing layer 530 may attach the polarizing layer 520 to the reverse wavelength dispersion QWP 510. In this case, the light absorbing layer 530 may include an adhesive. The adhesive may be a pressure sensitive adhesive (PSA).

[0073] refer to Figure 2B , the polarizing film 502 according to the exemplary embodiment may include a light absorbing layer 530, a reverse wavelength dispersion QWP 510, and a polarizing layer 520, which are sequentially stacked. The light absorbing layer 530 may be disposed on a bottom surface of the reverse wavelength dispersion QWP 510.

[0074] In this case, the light absorbing layer 530 may include a material for absorbing light having a wavelength in the range of about 380 nm to about 430 nm, and may include an adhesive. The adhesive may be PSA.

[0075] Since the light absorbing layer 530 is placed on the bottom surface of the reverse wavelength dispersion QWP 510 , the light absorbing layer 530 may attach the polarizing film 502 to the display device.

[0076] refer to Figure 2C , the polarizing film 503 according to the exemplary embodiment may include an adhesive layer 515 , a reverse wavelength dispersion QWP 510 , a light absorbing layer 530 , a first protective layer 541 , a polarizing layer 520 , a second protective layer 543 , and a hard coating layer 550 , which are sequentially stacked.

[0077] Adhesive layer 515 may be placed on the bottom surface of reverse wavelength dispersion QWP 510 and may include PSA. Adhesive layer 515 may attach polarizing film 503 to a display device.

[0078] The reverse wavelength dispersion QWP 510 may circularly polarize light incident on the polarizing film 503 together with the polarizing layer 520. The reverse wavelength dispersion QWP 510 may be wavelength dependent and may reduce the phase retardation value for shorter wavelengths.

[0079] The first protective layer 541 and the second protective layer 543 may be respectively disposed on the bottom surface and the top surface of the polarizing layer 520. The first protective layer 541 and the second protective layer 543 may serve as protective layers that support the polarizing layer 520 and compensate for the mechanical strength of the polarizing layer 520. The first protective layer 541 and the second protective layer 543 may each include at least one of TAC, cycloolefin polymer, and PMMA.

[0080] The hard coating layer 550 may be placed on the uppermost portion of the polarizing film 503 to protect elements of the polarizing film 503 from external impact. The hard coating layer 550 may have a function of preventing scratches and may have a strength of about 9H.

[0081] although Figure 2C The light absorption layer 530 is shown to be disposed between the reverse wavelength dispersion QWP 510 and the first protective layer 541 , but the inventive concept is not limited thereto. For example, the position of the light absorption layer 530 may be changed, and an additional light absorption layer 530 may be further formed.

[0082] In another exemplary embodiment, at least one of the hard coating layer 550, the first protective layer 541, the second protective layer 543, and the adhesive layer 515 may be used as the light absorbing layer 530. For example, a light absorber that may be included in the light absorbing layer 530 may also be included in at least one of the hard coating layer 550, the first protective layer 541, the second protective layer 543, and the adhesive layer 515.

[0083] The light absorbing layer 530 may include a light absorber and may absorb light having a wavelength in the range of about 380 nm to about 430 nm. Through the light absorbing layer 530, the light transmittance 503 of the polarizing film may satisfy:

[0084] T(430nm)≤8.7875e (-3.715×DSP(450nm))

[0085] Wherein T(430nm) represents the transmittance at a wavelength of 430nm. DSP(450nm) represents the wavelength dispersion value at a wavelength of 450nm. The wavelength dispersion value DSP is R(450nm) / R(550nm), and R(λ) represents the phase difference value at a wavelength of λ.

[0086] Each of the polarizing films 500 , 501 , 502 , and 503 according to the exemplary embodiment may include a light absorbing layer 530 , which may reduce reflection chromaticity and ensure excellent visibility.

[0087] Below, we will refer to Figures 3 to 5 The operating mechanism of the light absorbing layer 530 is described.

[0088] The reverse wavelength dispersion QWP 510 according to the exemplary embodiment may not accurately adjust the phase delay of λ / 4 according to the wavelength due to the characteristics of the material of the reverse wavelength dispersion QWP 510. More specifically, the wavelength dispersion value DSP of the reverse wavelength dispersion QWP 510 may vary according to its material.

[0089] Figure 3 It is a graph showing the wavelength dispersion value DSP of the reverse wavelength dispersion QWP of type (a) to type (d). Figure 4 The reflection chromaticity of the reverse wavelength dispersion QWP of type (a) to type (d) in CIE L*a*b* coordinates is shown.

[0090] Figure 3 The wavelength dispersion value DSP shown in is the ratio of the phase difference value according to the wavelength of λ, that is, R(λ) / R(550nm). At a wavelength of 450nm, the wavelength dispersion value (a)_DSP(450nm) of the (a) type reverse wavelength dispersion QWP is 0.77. At a wavelength of 450nm, the wavelength dispersion value (b)_DSP(450nm) of the (b) type reverse wavelength dispersion QWP is 0.82. At a wavelength of 450nm, the wavelength dispersion value (c)_DSP(450nm) of the (c) type reverse wavelength dispersion QWP is 0.86. At a wavelength of 450nm, the wavelength dispersion value (d)_DSP(450nm) of the (d) type reverse wavelength dispersion QWP is 0.91.

[0091] like Figure 3 As shown in FIG. 1 , the wavelength dispersion values ​​of the reverse wavelength dispersion QWPs of types (a) to (d) are different from the wavelength dispersion value of the ideal reverse wavelength dispersion QWP.

[0092] refer to Figure 4 , the chromaticity of the reflected light of the ideal reverse wavelength dispersion QWP in the CIE L*a*b* color space is located at a*=0, b*=0, which means that the chromaticity of the reflected light of the ideal reverse wavelength dispersion QWP is neutral black.

[0093] Since the chromaticity is far from a*=0, b*=0 in the CIE L*a*b* coordinate system, the first quadrant may indicate red, the second quadrant may indicate green, the third quadrant may indicate blue, and the fourth quadrant may indicate purple. For example, a* with a negative value may indicate green, while a positive value may indicate red / purple. In addition, b* with a negative value may indicate blue, while a positive value may indicate yellow.

[0094] like Figure 4, the chromaticity of the reflected light of each of the (a)-type to (d)-type reverse wavelength dispersion QWPs is located in the third quadrant, and therefore, may represent blue. The maximum color shift may occur in the (d)-type reverse wavelength dispersion QWP having the highest wavelength dispersion value, which may be a cyan blue shift. When the chromaticity of the reflected light moves away from a*=0, b*=0, it may mean that the chromaticity of the reflected light has increased. Also, when the chromaticity of the reflected light increases, it may mean that the color is visually recognized and the black visibility is reduced.

[0095] The following summarizes Figure 3 and Figure 4 data.

[0096] DSP(450nm) b* Type (a) 0.77 -0.57 Type (b) 0.82 -1.22 Type (c) 0.86 -2.06 Type (d) 0.91 -3.13

[0097] Referring to the above table, it can be seen that the absolute value of b* increases as the wavelength dispersion value DSP increases.

[0098] Therefore, in order to make b* converge to 0, the transmittance in the Z range (e.g., blue range) in the CIE XYZ coordinate system must be reduced. This can also be derived from the following equation, which is a conversion equation between the CIE L*a*b* coordinate system and the CIE XYZ coordinate system.

[0099] [Equation 1]

[0100]

[0101]

[0102]

[0103] in

[0104]

[0105] And where δ=6 / 29.

[0106] Furthermore, considering the blue spectrum emitted from the blue pixel of the display device, the transmittance at a wavelength of 430 nm or less must be adjusted, and therefore, the transmittance must satisfy the following equation associated with the wavelength dispersion value DSP of each reverse wavelength dispersion QWP.

[0107] [Equation 2]

[0108] T(430nm)≤8.7875e (-3.715×DSP(450nm))

[0109] Wherein T(430nm) represents the transmittance at a wavelength of 430nm. DSP(450nm) represents the wavelength dispersion value at a wavelength of 450nm. The wavelength dispersion value DSP is R(450nm) / R(550nm), and R(λ) represents the phase difference value at a wavelength of λ.

[0110] The graph of Equation 2 is shown in Figure 5 middle. Figure 5 The relationship between the wavelength dispersion value DSP and the transmittance of the polarizing film is shown. Figure 5 , the transmittance at 430nm decreases with the increase of the wavelength dispersion value DSP at 450nm.

[0111] Figure 6 Graphs showing light transmittance according to the related art and an embodiment to which the above Equation 2 is applied. Figure 7 The chromaticity of reflected light of the embodiment in the CIE L*a*b* coordinate system is shown.

[0112] exist Figure 6 , the transmittance according to the related art is the transmittance of the polarizing film not including the light absorbing layer. Embodiments 1 to 3 include a light absorbing layer. In particular, Embodiment 1 ((b)') includes a (b) type reverse wavelength dispersion QWP, Embodiment 2 ((c)') includes a (c) type reverse wavelength dispersion QWP, and Embodiment 3 ((d)') includes a (d) type reverse wavelength dispersion QWP.

[0113] refer to Figure 6 , it can be seen that the blue spectrum emitted by the blue pixel of the display device is distributed in the range of about 430nm to about 500nm. Therefore, the chromaticity of the reflected light may need to be reduced to the extent that the blue pixel range is not affected, and each of Embodiments 1 to 3 adjusts the transmittance at 430nm.

[0114] Furthermore, it can also be seen that the light transmittance at 430 nm decreases as the wavelength dispersion value of the reverse wavelength dispersion QWP included in the embodiment increases.

[0115] That is, in Embodiment 1 including the reverse wavelength dispersion QWP having a wavelength dispersion value DSP (450 nm) of 0.91, the transmittance at 430 nm is less than about 33%.

[0116] In Embodiment 2 including a reverse wavelength dispersion QWP having a wavelength dispersion value DSP (450 nm) of 0.86, the light transmittance at 430 nm is less than about 37%.

[0117] In Embodiment 3 including a reverse wavelength dispersion QWP having a wavelength dispersion value DSP (450 nm) of 0.82, the light transmittance at 430 nm is less than about 40%.

[0118] refer to Figure 7 , (a)' to (d)' correspond to the embodiments in which the light absorbing layer is applied to the (a) type to (d) type reverse wavelength dispersion QWP, respectively. It can be seen that the chromaticity of the reflected light in each embodiment is adjusted to be greater than Figure 4 The chromaticity shown in is closer to a*=0, b*=0, so no light absorbing layer is applied.

[0119] Figure 8 A table showing the change in chromaticity depending on the presence of a light absorbing layer. More specifically, Figure 8 The table shown in shows the chromaticity of reflected light of the (a) to (d) type reverse wavelength dispersion QWPs, and the chromaticity of reflected light of the (a) to (d) type reverse wavelength dispersion QWPs to which a light absorption layer is applied.

[0120] refer to Figure 8 , it can be seen that when the light absorbing layer is applied, the chromaticity of the reflected light is reduced by 0.24 to 1. When the chromaticity is reduced, it may mean that neutral black can be achieved and excellent visibility can be ensured.

[0121] The polarizing film according to the exemplary embodiment may be applied to a display device.

[0122] Fig. 9 is a plan view of a display device according to an exemplary embodiment.

[0123] A plurality of pixels PX including display elements (such as organic light emitting diodes) may be placed in the display area DA of the substrate 100. Each of the pixels PX may further include a plurality of thin film transistors (TFTs) for controlling the display elements and a storage capacitor. The number of TFTs included in one pixel is not particularly limited. For example, in some exemplary embodiments, the number of TFTS in one pixel may be 1 to 7.

[0124] Various circuits for applying electrical signals to the display area DA may be placed in the peripheral area PA of the substrate 100. TFTs may also be provided in the peripheral area PA, and in this case, the TFTs placed in the peripheral area PA may be part of a circuit unit for controlling electrical signals applied to the display area DA.

[0125] Hereinafter, although the display device will be described with reference to an organic light-emitting display device, the inventive concept is not limited thereto. For example, in another exemplary embodiment, any of various display devices, such as an inorganic electroluminescent (EL) display device (inorganic light-emitting display) or a quantum dot light-emitting display, may be used.

[0126] Fig.10 is a cross-sectional view showing a portion of a display device according to an exemplary embodiment.

[0127] refer to Fig.10 , the display device includes: a substrate 100, a first TFT T1 and a second TFT T2 placed on the substrate 100, and an organic light emitting diode 300 electrically connected to the first TFT T1 and the second TFT T2. Moreover, the organic light emitting display device may further include various insulating layers (e.g., a buffer layer 111, a first gate insulating layer 112, a second gate insulating layer 113, an interlayer insulating layer 115, a planarization layer 118, and a pixel defining film 119) and a storage capacitor Cst.

[0128] The substrate 100 may be formed of any of various materials such as a glass material, a metal material, or a plastic material. According to an exemplary embodiment, the substrate 100 may be a flexible substrate and may include a polymer resin such as polyethersulfone (PES), polyacrylate (PAR), polyetherimide (PEI), polyethylene naphthalate (PEN), polyethylene terephthalate (PET), polyphenylene sulfide (PPS), polyarylate, polyimide (PI), polycarbonate (PC), or cellulose acetate propionate (CAP).

[0129] The buffer layer 111 may be placed on the substrate 100, may reduce or prevent the penetration of exogenous materials, moisture or external air from the bottom of the substrate 100, and may flatten the substrate 100. The buffer layer 111 may include an inorganic material, such as an oxide or a nitride; an organic material; or a combination of an organic material and an inorganic material, and may have a single-layer or multi-layer structure including an inorganic material and an organic material. In some exemplary embodiments, a barrier layer for blocking the penetration of external air may be further provided between the substrate 100 and the buffer layer 111. In some exemplary embodiments, the buffer layer 111 may include silicon oxide (SiO 2 ) or silicon nitride (SiN x ).

[0130] The first TFT T1 and / or the second TFT T2 may be disposed on the buffer layer 111. The first TFT T1 includes a semiconductor layer A1, a gate electrode G1, a source electrode S1, and a drain electrode D1, and the second TFT T2 includes a semiconductor layer A2, a gate electrode G2, a source electrode S2, and a drain electrode D2. The first TFT T1 may be connected to the organic light emitting diode 300 and may be used as a driving TFT for driving the organic light emitting diode 300. The second TFT T2 may be connected to the data line DL and may be used as a switching TFT. Although Fig.10 Two TFTs are shown in FIG. 1 , but the present inventive concept is not limited thereto. The number of TFTs may be modified in various ways. For example, the number of TFTs may be 1 to 7.

[0131] Each of the semiconductor layers A1 and A2 may include amorphous silicon or polycrystalline silicon. In another exemplary embodiment, each of the semiconductor layers A1 and A2 may include an oxide of at least one metal selected from the group consisting of indium (In), gallium (Ga), tin (Sn), zirconium (Zr), vanadium (V), hafnium (Hf), cadmium (Cd), germanium (Ge), chromium (Cr), titanium (Ti), and zinc (Zn). Each of the semiconductor layers A1 and A2 may include a channel region and a source region and a drain region doped with impurities.

[0132] The gate electrode G1 is placed on the semiconductor layer A1, the first gate insulating layer 112 is between the gate electrode G1 and the semiconductor layer A1, and the gate electrode G2 is placed on the semiconductor layer A2, the first gate insulating layer 112 is between the gate electrode G2 and the semiconductor layer A2. Each of the gate electrodes G1 and G2 may include molybdenum (Mo), aluminum (Al), copper (Cu), or titanium (Ti), and may have a single-layer or multi-layer structure. For example, each of the gate electrodes G1 and G2 may have a single-layer structure formed of Mo.

[0133] The first gate insulating layer 112 may include silicon oxide (SiO 2 ), silicon nitride (SiN x ), silicon oxynitride (SiON), aluminum oxide (Al 2 O 3 ), titanium oxide (TiO 2 ), Tantalum Oxide (Ta 2 O 5 ), hafnium oxide (HfO 2 ) or zinc oxide (ZnO 2 ).

[0134] A second gate insulating layer 113 may be provided to cover the gate electrodes G1 and G2. The second gate insulating layer 113 may include SiO 2 、SiN x 、SiON、Al 2 O 3 、TiO 2 、 2 O 5 , HfO 2 or ZnO 2 .

[0135] The first storage electrode CE1 of the storage capacitor Cst may overlap with the first TFT T1. For example, the gate electrode G1 of the first TFT T1 may be represented as the first storage electrode CE1 of the storage capacitor Cst. However, the inventive concept is not limited thereto. In another exemplary embodiment, the storage capacitor Cst may not overlap with the first TFT T1 and may be spaced apart from the first TFT T1 and the second TFT T2.

[0136] The second storage electrode CE2 of the storage capacitor Cst overlaps the first storage electrode CE1, and the second gate insulating layer 113 is between the second storage electrode CE2 of the storage capacitor Cst and the first storage electrode CE1. In this case, the second gate insulating layer 113 may be used as a dielectric layer of the storage capacitor Cst. The second storage electrode CE2 may include a conductive material (including molybdenum (Mo), aluminum (Al), copper (Cu), or titanium (Ti)), and may have a single-layer or multi-layer structure including the conductive material. For example, the second storage electrode CE2 may have a single-layer structure formed of Mo, or may have a multi-layer structure formed of Mo / Al / Mo.

[0137] The interlayer insulating layer 115 is formed on the entire surface of the substrate 100 to cover the second storage electrode CE2. The interlayer insulating layer 115 may include SiO 2 、SiN x 、SiON、Al 2 O 3 、TiO 2 、 2 O 5 , HfO 2 or ZnO 2 .

[0138] The source electrodes S1 and S2 and the drain electrodes D1 and D2 are placed on the interlayer insulating layer 115. Each of the source electrodes S1 and S2 and the drain electrodes D1 and D2 may include a conductive material (including Mo, Al, Cu, or Ti), and may have a single-layer or multi-layer structure including a conductive material. For example, each of the source electrodes S1 and S2 and the drain electrodes D1 and D2 may have a multi-layer structure formed of Ti / Al / Ti.

[0139] A planarization layer 118 may be disposed on the source electrodes S1 and S2 and the drain electrodes D1 and D2, and an organic light emitting diode 300 may be disposed on the planarization layer 118. The organic light emitting diode 300 includes a first electrode 310, an intermediate layer 320 including an organic emission layer, and a second electrode 330.

[0140] The planarization layer 118 may have a flat top surface, thereby flatly forming the first electrode 310. The planarization layer 118 may have a single-layer or multi-layer structure including an organic material or an inorganic material. The planarization layer 118 may include benzocyclobutene (BCB), PI, hexamethyldisiloxane (HMDSO), a general polymer such as polymethylmethacrylate (PMMA) or polystyrene (PS), a polymer derivative having a phenolic group, an acrylic polymer, an imide polymer, an aryl ether polymer, an amide polymer, a fluorinated polymer, a paraxylene polymer, a vinyl alcohol polymer, or a blend thereof. The planarization layer 118 may include SiO 2、SiN x 、SiON、Al 2 O 3 、TiO 2 、 2 O 5 , HfO 2 or ZnO 2 After the planarization layer 118 is formed, chemical mechanical polishing may be performed to provide a planar top surface.

[0141] An opening through which one of the source electrode S1 and the drain electrode D1 of the first TFT T1 is exposed is formed in the planarization layer 118 , and the first electrode 310 contacts the source electrode S1 or the drain electrode D1 through the opening to be electrically connected to the first TFT T1 .

[0142] The pixel defining film 119 may be placed on the first electrode 310. The pixel defining film 119 defines a pixel by having an opening 119OP corresponding to each sub-pixel (i.e., an opening through which at least a central portion of the first electrode 310 is exposed). Also, the pixel defining film 119 may prevent arcing, etc., from occurring on the edge of the first electrode 310 by increasing the distance between the edge of the first electrode 310 and the second electrode 330. The pixel defining film 119 may be formed of an organic material such as PI or HMDSO.

[0143] In an exemplary embodiment, a spacer may be placed on the pixel defining film 119. The spacer may prevent damage to the mask during a mask process for forming the intermediate layer 320 of the organic light emitting diode 300. The spacer may be formed of an organic material such as PI or HMDSO. The spacer and the pixel defining film 119 may be formed of the same material at the same time. In this case, a halftone mask may be used.

[0144] The intermediate layer 320 of the organic light emitting diode 300 may include an organic emission layer EML. The organic emission layer EML may include an organic material including a fluorescent or phosphorescent material that emits red, green, blue, or white light. The organic emission layer may be formed of a low molecular weight organic material or a high molecular weight organic material, and functional layers such as a hole transport layer (HTL), a hole injection layer (HIL), an electron transport layer (ETL), and an electron injection layer (EIL) may be selectively further placed below and above the organic emission layer. The intermediate layer 320 may be placed to correspond to each of the plurality of first electrodes 310. However, the inventive concept is not limited thereto, and the intermediate layer 320 may be modified in various ways. For example, the intermediate layer 320 may be an integral layer placed above all the first electrodes 310.

[0145] The second electrode 330 may be a light-transmitting electrode or a reflective electrode. In some exemplary embodiments, the second electrode 330 may be a transparent electrode or a semi-transparent electrode, and may include a metal thin film having a small work function, including lithium (Li), calcium (Ca), LiF / Ca, LiF / Al, aluminum (Al), silver (Ag), magnesium (Mg), or a compound thereof. In addition, a transparent conductive oxide (TCO) film, such as indium tin oxide (ITO), indium zinc oxide (IZO), ZnO, or In 2 O 3 The second electrode 330 may be placed on the display area DA and the peripheral area PA, and may be placed on the intermediate layer 320 and the pixel defining film 119. The second electrode 330 may be integrally formed with the plurality of organic light emitting diodes 300 and may correspond to the plurality of first electrodes 310. The detailed configuration of the organic light emitting diode 300 will be described below.

[0146] A thin film encapsulation layer 400 for sealing the display area DA may be further provided on the organic light emitting diode 300. The thin film encapsulation layer 400 may protect the organic light emitting diode 300 from external moisture or oxygen by covering the display area DA. The thin film encapsulation layer 400 may include a first inorganic encapsulation layer 410, an organic encapsulation layer 420, and a second inorganic encapsulation layer 430.

[0147] The first inorganic encapsulation layer 410 may cover the second electrode 330 and may include ceramic, metal oxide, metal nitride, metal carbide, metal oxynitride, indium oxide (In 2 O 3 ), tin oxide (SnO 2 ), indium tin oxide (ITO), silicon oxide, silicon nitride and / or silicon oxynitride. If necessary, other layers, such as a capping layer, may be placed between the first inorganic encapsulation layer 410 and the second electrode 330. The first inorganic encapsulation layer 410 is formed along the underlying structure, and therefore, the top surface of the first inorganic encapsulation layer 410 may not be flat, such as Fig.10 Displayed in.

[0148] The organic encapsulation layer 420 may cover the first inorganic encapsulation layer 410 to have a substantially flat top surface, unlike the first inorganic encapsulation layer 410. In particular, the organic encapsulation layer 420 may be formed so that a portion of the organic encapsulation layer 420 corresponding to the display area DA has a substantially flat top surface. The organic encapsulation layer 420 may include at least one material selected from the group consisting of acryl, methacrylic acid, polyester, polyethylene, polypropylene, PET, PEN, PC, PI, polyethylene sulfonate, polyoxymethylene, polyarylate, and HMDSO.

[0149] The second inorganic encapsulation layer 430 may cover the organic encapsulation layer 420 and may include ceramics, metal oxides, metal nitrides, metal carbides, metal oxynitrides, In 2 O 3 SnO 2 , ITO, silicon oxide, silicon nitride and / or silicon oxynitride. Since the second inorganic encapsulating layer 430 contacts the first inorganic encapsulating layer 410 at the edge outside the display area DA, the organic encapsulating layer 420 may be prevented from being exposed to the outside.

[0150] Since the thin film encapsulation layer 400 includes the first inorganic encapsulation layer 410, the organic encapsulation layer 420, and the second inorganic encapsulation layer 430, even when a crack occurs in the thin film encapsulation layer 400, due to the multi-layer structure, the crack may not be connected between the first inorganic encapsulation layer 410 and the organic encapsulation layer 420 or between the organic encapsulation layer 420 and the second inorganic encapsulation layer 430. Therefore, a path through which external moisture or oxygen penetrates into the display area DA may be prevented or minimized.

[0151] although Fig.10 The thin film encapsulation layer 400 is shown as an encapsulation member for encapsulating the organic light emitting diode 300 , but the inventive concept is not limited thereto. For example, a sealing substrate closely attached to the substrate 100 by a sealant or frit may be used as a member for encapsulating the organic light emitting diode 300 .

[0152] According to an exemplary embodiment, the polarizing film 500 for improving outdoor visibility is placed over the thin film encapsulation layer 400 or the sealing substrate. Figure 1 , the polarizing film 500 may include a reverse wavelength dispersion QWP 510, a polarizing layer 520, and a light absorbing layer 530. In this case, the polarizing film 500 may be formed such that the reverse wavelength dispersion QWP 510 is closer to the thin film encapsulation layer 400 than the polarizing layer 520.

[0153] Moreover, it can be applied FIG. 2A to FIG. 2C Any one of the polarizing films 501, 502 and 503 is replaced Figure 1 The polarizing film 500 is provided.

[0154] Various functional layers, such as a touch screen layer and a window, may be further provided on the thin film encapsulation layer 400 , and a capping layer for improving light efficiency may be further provided between the second electrode 330 and the thin film encapsulation layer 400 .

[0155] The polarizing film according to the exemplary embodiment has low reflective chromaticity, thereby improving visibility of a display device employing the polarizing film.

[0156] Although certain exemplary embodiments and implementations have been described herein, other embodiments and modifications will be apparent from this description. Therefore, the inventive concept is not limited to such embodiments, but rather to the broader scope of the appended claims and to various obvious modifications and equivalent arrangements that will be apparent to those of ordinary skill in the art.

Claims

1. A polarizing film, comprising: Polarization layer; A reverse wavelength dispersion quarter wave plate disposed on the polarization layer; and A light absorbing layer disposed on the polarizing layer, wherein the light absorbing layer includes a light absorber to absorb light having a wavelength in the range of 380 nm to 430 nm, Wherein the wavelength dispersion value DSP of the reverse wavelength dispersion quarter wave plate at a wavelength of 450 nm and the light transmittance of the polarizing film at a wavelength of 430 nm satisfy: T(430nm)≤8.7875e (-3.715×DSP(450nm)) Wherein T(430nm) represents the transmittance at a wavelength of 430nm, DSP(450nm) represents the wavelength dispersion value at a wavelength of 450nm and is R(450nm) / R(550nm), and R(λ) represents the phase difference value at a wavelength of λ. 2 . The polarizing film according to claim 1 , wherein a light transmittance of the polarizing film is less than 40% for light having a wavelength in a range of 380 nm to 430 nm.

3. The polarizing film according to claim 1, wherein the light absorber comprises at least one of the following: anthraquinone dyes, methyl dyes, azomethine dyes, oxazine dyes, azo dyes, styryl dyes, coumarin dyes, porphyrin dyes, dibenzofuranone dyes, diketopyrrolopyrrole dyes, rhodamine dyes, xanthene dyes and pyrromethene dyes. 4 . The polarizing film according to claim 1 , wherein the light absorbing layer comprises at least one of triacetyl cellulose, cycloolefin polymer, and polymethyl methacrylate. The polarizing film according to claim 1 , wherein the light absorbing layer comprises a pressure sensitive adhesive.

6. The polarizing film according to claim 1, further comprising a first protective layer and a second protective layer respectively disposed on a bottom surface and a top surface of the polarizing layer, Each of the first protective layer and the second protective layer includes at least one of triacetyl cellulose, cycloolefin polymer and polymethyl methacrylate. 7 . The polarizing film according to claim 1 , further comprising an adhesive layer disposed on a bottom surface of the reverse wavelength dispersion quarter wave plate.

8. The polarizing film of claim 1, wherein the polarizing layer comprises a dichroic dye in polyvinyl alcohol.

9. The polarizing film according to claim 1, wherein the reverse wavelength dispersion quarter wave plate satisfies: DSP(450nm)=R(450nm) / R(550nm)<1, and DSP(650nm)=R(650nm) / R(550nm)>1 Wherein DSP(λ) represents the wavelength dispersion value DSP of the reverse wavelength dispersion quarter-wave plate at a wavelength of λ, and R(λ) represents the phase difference value at a wavelength of λ.

10. A display device, comprising: substrate; a plurality of display elements disposed on the substrate; a sealing member for sealing the plurality of display elements; and A polarizing film is provided on the sealing member, The polarizing film is the polarizing film according to any one of claims 1 to 9.

11. The display device according to claim 10, wherein: The light absorbing layer comprises a pressure sensitive adhesive; and The light absorbing layer is provided between the reverse wavelength dispersion quarter wave plate and the sealing member. 12 . The display device of claim 10 , wherein the sealing member comprises a thin film encapsulation layer including a first inorganic encapsulation layer, an organic encapsulation layer, and a second inorganic encapsulation layer sequentially stacked in this order. 13 . The display device according to claim 10 , wherein the sealing member comprises a sealing substrate.

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