JP2018147761A - Display device and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a display device capable of obtaining bright display while suppressing reflection of external light and also to provide a method of manufacturing the display device.SOLUTION: According to one standpoint of the present invention, provided is a display device which includes: a substrate having a luminescent layer; and a circularly polarizing plate and a phase difference layer which are arranged on the side of a display surface of the substrate. The phase difference layer includes a dichroic dye in which the axial direction having a larger optical absorptance is oriented perpendicular to the display surface. Moreover, according to another standpoint of the present invention, provided is a method of manufacturing the display device, which includes the steps of: forming the luminescent layer on the substrate; forming a phase difference layer including the dichroic dye in which the axial direction having larger optical absorptance is perpendicularly oriented, on the side of the display surface of the substrate; and arranging the circularly polarizing plate on the side of the display surface of the substrate.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a technique for reducing external light reflection in a display device.

  As a new display method of a display device, a display method using an organic EL element has attracted attention. In the organic EL display device, since the organic EL pixels arranged two-dimensionally emit light independently, the contrast ratio can be increased. Further, since a material such as liquid crystal having angle dependency is not used, the viewing angle characteristics are excellent.

  In a general organic EL display device, a circularly polarizing plate for reducing external light reflected by a TFT (thin film transistor element) or circuit wiring inside the organic EL panel is provided on the display surface side. For example, Patent Document 1 describes a technique for reducing external light reflection using a circularly polarizing plate having a retardation film, and in particular, a retardation film for reducing external light reflection from a wide angle. The phase difference condition in the thickness direction is described.

JP 2012-226996 A JP-A-5-273602 JP-A-11-160538

  However, although the reflection of external light can be reduced by using the circularly polarizing plate described in Patent Document 1, almost 60% of the light emitted from the organic EL element is absorbed by the polarizing layer in the circularly polarizing plate. It will be done. As a result, there is a problem that the brightness of the display is lowered. SUMMARY OF THE INVENTION An object of the present invention is to provide a display device capable of obtaining a bright display while suppressing external light reflection, and a method for manufacturing the same.

  According to one aspect of the present invention, a substrate having a light emitting layer, a circularly polarizing plate and a retardation layer disposed on the display surface side of the substrate are provided, and the retardation layer has an axial direction with a large light absorption rate. Is provided that includes a dichroic dye that is oriented perpendicular to the display surface.

  Further, according to another aspect of the present invention, a step of forming a light emitting layer on a substrate and a retardation layer containing a dichroic dye in which an axial direction having a large light absorption rate is vertically aligned are provided on the display surface side of the substrate. There is provided a method for manufacturing a display device, comprising: a step of forming; and a step of disposing a circularly polarizing plate on a display surface side of a substrate.

  ADVANTAGE OF THE INVENTION According to this invention, the display apparatus which can obtain a bright display, suppressing the reflection of external light, and its manufacturing method can be provided.

It is a figure which shows typically the structure of the display apparatus which concerns on 1st Embodiment. It is a figure for demonstrating the dichroism of the dichroic dye used for the display apparatus which concerns on 1st Embodiment. It is a figure which shows typically the polarization ability of a linearly polarized light layer when the display surface of the display apparatus which concerns on 1st Embodiment is seen from diagonally. It is a figure which shows the light transmission characteristic of the dichroic dye used for the display apparatus which concerns on 1st Embodiment. It is a figure which shows the relationship between the phase difference of the film thickness direction of the phase difference layer in the display apparatus which concerns on 1st Embodiment, and a viewing angle characteristic. It is a figure which shows the viewing angle characteristic of the display apparatus which concerns on 1st Embodiment. It is a figure which shows typically the structure of the display apparatus which concerns on 2nd Embodiment. It is a figure which shows the dispersion characteristic of (lambda) / 4 layer in the display apparatus which concerns on 2nd Embodiment. It is a figure which shows the viewing angle characteristic of the display apparatus which concerns on 2nd Embodiment. It is a figure which shows typically the structure of the display apparatus which concerns on 3rd Embodiment. It is a figure which shows the viewing angle characteristic of the display apparatus which concerns on 3rd Embodiment.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In addition, this invention is not limited to the following embodiment, In the range which does not deviate from the summary, it can change suitably. In addition, components having the same or corresponding functions in each drawing are denoted by the same reference numerals, and the description thereof may be omitted or simplified.

(First embodiment)
The display device according to the first embodiment will be described with reference to FIGS. FIG. 1 is a diagram schematically illustrating a configuration of a display device according to the first embodiment. The display device according to this embodiment includes a circularly polarizing plate 1, substrates 2 a and 2 b, and an organic EL element 3. In the following description, a display device using an organic EL element is assumed. However, the display device of the present embodiment only needs to have a light emitting layer 33 that can emit light independently. Instead, a display device using a semiconductor LED may be used.

  The organic EL element 3 includes a transparent electrode 31 (Anode) such as ITO (Indium Tin Oxide), a hole transport layer 32 (HTL), a white light emitting layer 33 (EL), an electron transport layer 34 (ETL), and a metal electrode. 35 (Cathode). Here, the hole transport layer 32 (HTL) includes a hole injection layer (HIL) and the like, and the electron transport layer 34 (ETL) includes an electron injection layer (EIL) and the like. As the metal electrode 35, for example, a metal whose main material is MgAg or Al can be used.

  The substrates 2a and 2b are bonded to both surfaces of the organic EL element 3 to protect the light emitting layer 33 from moisture and oxygen. Of the substrates 2 a and 2 b, the substrate 2 b is bonded to the organic EL element 3 through the adhesive layer 4. Glass substrates are typically used as the substrates 2a and 2b, but may be flexible base materials such as polyimide. The substrate 2a on the display surface side includes a thin film transistor element (TFT) (not shown) for driving the light emitting element, a cathode of the light emitting element, and other circuit wiring. Between the substrate 2a on the display surface side and the organic EL element 3, a color filter 5 having three primary colors of R (red) / G (green) / B (blue) is provided.

  The circularly polarizing plate 1 is disposed on the display surface side of the organic EL element 3 to reduce external light reflection. The circularly polarizing plate 1 includes a linearly polarizing layer 11, a λ / 4 layer 12, and a retardation layer 13. The linearly polarizing layer 11 linearly polarizes light incident from the display surface. The λ / 4 layer 12 is combined with the linearly polarizing layer 11 so that it is incident from the front on the display surface side and is reflected by circuit wiring such as the transparent electrode 31 and the metal electrode 35 in the organic EL element 3. Reduce. Further, the retardation layer 13 is combined with the linearly polarizing layer 11 and the λ / 4 layer 12 so that external light incident from a wide angle on the display surface side and reflected by circuit wiring in the organic EL element 3 or the like. To reduce.

  As the retardation layer 13 of the circularly polarizing plate 1, for example, C-plate showing a retardation in the film thickness direction is used. Regarding C-plate indicating a phase difference in the film thickness direction, for example, Patent Document 1 describes a method for absorbing external light reflection incident from a wide angle on the display surface side using C-plate. Then, detailed explanation is omitted.

In a conventional display device, the degree of polarization of the linearly polarizing layer 11 of the circularly polarizing plate 1 is set to 99% or more in order to effectively absorb external light reflection. Here, the degree of polarization P of the linearly polarizing layer 11 is such that the transmittance at the time of superimposing the two polarizing layers so that the absorption axes thereof are parallel to each other is T _// , and the two polarizing layers have the absorption axes of each other. When the transmittance when superposed so as to be vertical is T _⊥ , it is expressed by the following formula (1).

  As a result, as described above, approximately 60% of the light emitted from the light emitting layer 33 of the display device has been absorbed by the linearly polarizing layer 11. Thus, in the configuration of the conventional display device, it is difficult to achieve both the ability to absorb external light reflection by the circularly polarizing plate 1 and the brightness of the display device. That is, when the degree of polarization of the linearly polarizing layer 11 of the circularly polarizing plate 1 is increased and the ability of the circularly polarizing plate 1 to absorb external light is increased, the display on the display device becomes dark. On the other hand, when the degree of polarization of the linearly polarizing layer 11 of the circularly polarizing plate 1 is lowered to brighten the display of the display device, the ability of the circularly polarizing plate 1 to absorb external light is reduced.

  Therefore, in the present embodiment, it is considered to obtain a bright display while preferentially suppressing external light reflection from a wide angle that is particularly conspicuous among external light reflections. For this purpose, the retardation layer 13 of the circularly polarizing plate 1 of the present embodiment includes a dichroic dye for absorbing outside light from a wide angle, as shown in FIG.

  Specifically, the display device according to the present embodiment uses C-plate containing polymer liquid crystal vertically aligned with respect to the display surface as the retardation layer 13 of the circularly polarizing plate 1. The polymer liquid crystal in the retardation layer 13 is added with about 2.0% by weight of a dichroic dye, and the axial direction in which the light absorption rate of the dichroic dye is large is vertically aligned along the polymer liquid crystal. ing. In the display device according to the present embodiment, it is possible to absorb external light reflection from a wide angle by including the retardation layer 13 containing the dichroic dye oriented perpendicularly to the display surface of such a display device.

  Further, since the retardation layer 13 of the circularly polarizing plate 1 absorbs external light reflection from a wide angle, instead, the degree of polarization of the linearly polarizing layer 11 of the circularly polarizing plate 1 is lowered to brighten the display of the display device. Can do. For example, when the degree of polarization of the linearly polarizing layer 11 of the circularly polarizing plate 1 is lowered to 97.9%, the front emission transmittance is improved to 43.2%.

  A mechanism in which the retardation layer 13 containing a dichroic dye oriented perpendicular to the display surface absorbs external light reflection from a wide angle will be described with reference to FIG. FIG. 2 is a diagram for explaining the dichroism of the dichroic dye used in the display device according to the first embodiment. FIG. 2A shows the apparent shape of the absorption ellipsoid of the dichroic dye when the dichroic dye is viewed from the long axis direction (hereinafter referred to as “front”). On the other hand, FIG. 2 (b) shows the apparent ellipsoid of the absorption ratio of the dichroic dye when the dichroic dye is viewed from a direction having an angle with respect to the major axis (hereinafter referred to as "wide angle"). The shape is shown.

  As shown in FIG. 2A, when the dichroic dye is viewed from the front, the absorptive ellipsoid is generally circular and isotropic, but as shown in FIG. When the chromatic dye is viewed from a wide angle, anisotropy occurs in the absorption ellipsoid. Since the dichroic dye has different molecular light absorption rates in the major axis direction and the minor axis direction, light incident from a wide angle of the dichroic dye is largely absorbed as shown in FIG. As shown in FIG. 2A, light incident from the front is hardly absorbed. That is, the dichroic dye exhibits anisotropy (dichroism). Therefore, by providing the circularly polarizing plate 1 with the retardation layer 13 containing the dichroic dye oriented perpendicular to the display surface, external light reflection from a wide angle can be absorbed.

  Further, the linearly polarizing layer 11 of the circularly polarizing plate 1 has a property that the polarization ability is reduced with respect to light incident from a wide angle. Therefore, by having the retardation layer 13 containing the dichroic dye oriented perpendicularly to the display surface, it is possible to supplement the decrease in the polarization ability of the linearly polarizing layer 11 with respect to external light incident from a wide angle.

  FIG. 3 is a diagram schematically illustrating the polarization capabilities 7a to 7d of the linearly polarizing layer 11 when the display surface of the display device according to the first embodiment is viewed obliquely. In the following description, it is assumed that when the display surface of the display device is viewed from the front, the polarization axis (absorption axis) 7 of the linearly polarizing layer 11 faces in the left-right direction as shown in the center of FIG. . The top, bottom, left, and right of FIG. 3 schematically show the polarization powers 7 a to 7 d of the linear polarizing layer 11 when the linear polarizing layer 11 is viewed from an oblique direction.

  When the linearly polarizing layer 11 is viewed obliquely from above or obliquely below, no change occurs in the polarizing ability of the linearly polarizing layer 11 as shown by the polarizing ability 7a and 7b. On the other hand, when the linearly polarizing layer 11 is viewed from diagonally left or diagonally right, the polarization ability of the linearly polarizing layer 11 decreases as shown by the polarization ability 7c and 7d. Therefore, by having the retardation layer 13 containing the dichroic dye oriented perpendicularly to the display surface of the display device, it is possible to compensate for the decrease in the polarization ability of the linearly polarizing layer 11 with respect to external light incident from a wide angle. .

  FIG. 4 is a diagram showing the light transmission characteristics T1 and T2 of the dichroic dye used in the display device according to the first embodiment. The light transmission characteristic T1 indicates an actual measured value of light transmittance when the dichroic dye of this embodiment is irradiated with light polarized in a direction parallel to the long axis of the dichroic dye. On the other hand, the light transmission characteristic T2 indicates an actual measurement value of light transmittance when the dichroic dye of this embodiment is irradiated with light polarized in a direction perpendicular to the long axis of the dichroic dye.

  The light transmission characteristics T1 and T2 shown in FIG. 4 were measured by the following method. First, a dichroic dye was added to a polymer liquid crystal (nematic liquid crystal E7) at a concentration of 2.0% by weight to prepare a parallel alignment cell (cell gap 2.0 μm). Then, a spectrum was measured when one linearly polarizing plate (G1220Du, manufactured by Nitto Denko) was superimposed on this parallel alignment cell.

  As shown in FIG. 4, the dichroic dye used in the display device of this embodiment has a light transmittance of about 10% for light polarized in a direction parallel to the long axis of the molecule, whereas The light transmittance for light polarized in a direction perpendicular to the long axis was approximately 30%. That is, the dichroic dye of this embodiment has anisotropy (dichroism) that absorbs light polarized in the major axis direction relatively large and absorbs light polarized in the minor axis direction relatively small. You can see that

  Further, the dichroic dye used in the display device of the present embodiment absorbs light in the visible light region substantially uniformly as shown in FIG. The retardation layer 13 having such a neutral color characteristic can be obtained by mixing at least two kinds of dichroic dyes having different absorption wavelengths in the visible light region. For example, at least two kinds of materials shown in [Chemical 9] of Patent Document 2 may be mixed. Alternatively, at least two kinds of materials shown in [FIG. 4] of Patent Document 3 may be mixed.

  In addition, in order to align the long axis direction of the molecules of the dichroic dye perpendicularly to the surface of the retardation layer 13, a polymer liquid crystal (liquid crystal polymer) to which the dichroic dye is added is, for example, vertically aligned. What is necessary is just to perform vertical alignment using a conductive polyimide or the like. As the polymer liquid crystal, for example, materials shown in [Chemical Formula 1] to [Chemical Formula 4] of Patent Document 2 can be used. Alternatively, the material shown in FIG. 3 of Patent Document 3 may be used.

In the present embodiment, the position in the film thickness direction (at a wavelength of 589 nm) of the polymer liquid crystal included in the retardation layer 13 of the circularly polarizing plate 1 is further reduced so that external light reflection from the wide angle of the display surface is further reduced. The phase difference Rth was Rth = −50 nm. Here, the phase difference Rth, the thickness d of the retardation layer 13, the refractive index _{n z} in the thickness direction z of the phase difference layer 13, a direction perpendicular to the thickness direction z x, the refractive index of y _n x, n It is represented by the following formula (2) using _y .
Rth = {(n _x + n _y ) / 2−n _z } × d (2)

  FIG. 5 is a diagram illustrating a relationship between the retardation Rth in the film thickness direction of the retardation layer 13 and the viewing angle characteristics in the display device according to the first embodiment. FIG. 5 shows measured values of the viewing angle characteristics of external light reflection when the phase difference Rth of the retardation layer 13 is changed in 20 ways in the range of −100 nm ≦ Rth ≦ −5 nm. In FIG. 5, when the retardation Rth of the retardation layer 13 is −65 nm ≦ Rth ≦ −30 nm, the external light reflection of the display device is reduced to less than 3% in all viewing angles. In addition, when the retardation Rth of the retardation layer 13 is set to Rth = −50 nm, the viewing angle characteristics of external light reflection of the display device are most improved. Therefore, in the present embodiment, the retardation Rth in the film thickness direction of the polymer liquid crystal contained in the retardation layer 13 of the circularly polarizing plate 1 is set to Rth = −50 nm.

  Next, an example of the manufacturing method of the retardation layer 13 of this embodiment is demonstrated. First, a solution for forming a polymer liquid crystal layer is prepared by adding and dissolving a dichroic dye at a concentration of 2.0% by weight in a predetermined polymer liquid crystal solvent. Next, an alignment film of vertically-aligned polyimide is formed on an isotropic and non-retarded film such as triacetyl cellulose or norbornene-based film to obtain a base film of the retardation layer 13.

  Subsequently, the prepared solution is coated on the base film on which the alignment film of the vertically aligning polyimide is formed, thereby forming a coating film containing a polymer liquid crystal and a dichroic dye. Thereafter, the coating film containing the polymer liquid crystal and the dichroic dye is irradiated with ultraviolet light having a predetermined wavelength to cure the coating film. As a result, the molecules of the polymer liquid crystal are aligned perpendicular to the base film, and the molecules of the dichroic dye are aligned perpendicular to the base film.

  Note that the above-described method is an example of a method for manufacturing the retardation layer 13 according to the present embodiment, and any method can be used as long as the dichroic dye can be vertically aligned with respect to the base film. You may use manufacturing methods other than the method. For example, instead of using vertical alignment polyimide or the like, a polymer liquid crystal that spontaneously exhibits vertical alignment may be used.

  FIG. 6 is a diagram illustrating a simulation result of the viewing angle characteristics of external light reflection in the display device according to the first embodiment. Example 1 in FIG. 6 shows the viewing angle characteristics of external light reflection measured using the display device of the present embodiment. In addition, Comparative Examples 1 to 4 in FIG. 6 show the viewing angle characteristics of external light reflection measured using a display device different from the present embodiment as a comparative example. In FIG. 6, the in-plane retardation value R0 of the λ / 4 layer 12 is 137 nm. Further, the wavelength dispersion Δn (450 nm) / Δn (589 nm) of the λ / 4 layer 12 was set to 1.01 (positive dispersion).

  Comparative Examples 1 and 2 are external light reflection viewing angle characteristics measured using a display device that does not include the retardation layer 13. Of Comparative Examples 1 and 2, in Comparative Example 1, the degree of polarization of the linearly polarizing layer 11 of the circularly polarizing plate 1 is increased to 99.9%, and in Comparative Example 2, the polarization of the linearly polarizing layer 11 of the circularly polarizing plate 1 is increased. The degree was lowered to 97.9%. Since the comparative examples 1 and 2 do not have the retardation layer 13 of the circularly polarizing plate 1, the reflection of external light from a wide angle is increased.

  Comparative Examples 3 and 4 are viewing angle characteristics of external light reflection measured using a display device having a retardation layer 13 that does not contain a dichroic dye. Among Comparative Examples 3 and 4, in Comparative Example 3, the degree of polarization of the linearly polarizing layer 11 of the circularly polarizing plate 1 is increased to 99.9%, and in Comparative Example 4, the polarization of the linearly polarizing layer 11 of the circularly polarizing plate 1 is increased. The degree was lowered to 97.9%. The retardation Rth of the retardation layer 13 was set to Rth = −50 nm.

  Since the comparative examples 3 and 4 have the retardation layer 13 of the circularly polarizing plate 1, external light reflection from a wide angle is reduced as compared with the comparative examples 1 and 2. However, although the comparative example 3 is excellent in the viewing angle characteristic of external light reflection, the front transmittance is greatly inferior. On the other hand, Comparative Example 4 is excellent in the front transmittance, but is largely inferior in the viewing angle characteristics of external light reflection. That is, it can be seen that the configuration using the retardation layer 13 that does not contain the dichroic dye does not achieve both the ability to absorb external light reflection by the circularly polarizing plate 1 and the brightness of the display device.

  Example 1 is a viewing angle characteristic of external light reflection measured using a display device having a retardation layer 13 containing 2.0% by weight of a dichroic dye. In Example 1, the degree of polarization of the linearly polarizing layer 11 of the circularly polarizing plate 1 was lowered to 97.9%. The retardation Rth of the retardation layer 13 was Rth = −50 nm.

  In Example 1, it turns out that the viewing angle characteristic of external light reflection is improving rather than any Comparative Examples 1-4. Moreover, although the front transmittance of Example 1 is a little inferior to the comparative example 4, it turns out that the same level as the comparative example 4 is maintained substantially. That is, in Example 1, by having the retardation layer 13 containing the dichroic dye oriented perpendicularly to the display surface of the display device, the ability to absorb external light reflection by the circularly polarizing plate 1 and the brightness of the display device. It can be seen that both are compatible.

  As described above, the display device of this embodiment includes the circularly polarizing plate disposed on the display surface side of the substrate having the light emitting layer, and the retardation layer of the circularly polarizing plate has an axial direction with a large light absorption rate. It contains a dichroic dye oriented perpendicular to the display surface. The circularly polarizing plate includes a linearly polarizing layer, a λ / 4 layer, and a retardation layer, and the retardation layer is disposed on the substrate side with respect to the linearly polarizing layer and the λ / 4 layer. According to such a configuration, the light emitted from the light emitting layer is hardly absorbed, and only external light reflection from a wide angle can be reduced. That is, it is possible to provide a display device capable of obtaining a bright display while suppressing external light reflection from a wide angle, and a manufacturing method thereof.

  In the present embodiment, a bright display can be obtained by setting the polarization degree of the linearly polarizing layer of the circularly polarizing plate to 98% or less. Moreover, the viewing angle characteristic of external light reflection can be further improved because the retardation layer has a retardation of −65 nm to −30 nm in the film thickness direction.

  The circularly polarizing plate 1 of the present embodiment desirably includes all of the linearly polarizing layer 11, the λ / 4 layer 12, and the retardation layer 13, but is not limited to such a configuration. The circularly polarizing plate 1 of the present embodiment only needs to have at least the retardation layer 13. For example, as will be described later in the third embodiment, even if the layer corresponding to the retardation layer 13 of the present embodiment is arranged outside the circularly polarizing plate 1 independently, it reflects outside light. Although the viewing angle characteristics are reduced, substantially the same effect can be obtained.

  Further, the display surface of the display device may be further subjected to anti-reflection (AR) processing. By the anti-reflection treatment, reflection of external light on the display outermost surface can be further suppressed. The anti-reflection treatment has a structure in which materials having different refractive indexes are laminated, and can be formed by coating or vacuum deposition.

  Further, the dichroic dye used in the display device of the present embodiment has a property of absorbing light polarized in the major axis direction relatively large and absorbing light polarized in the minor axis direction relatively small. However, it is not limited to this. The dichroic dye only needs to have at least two axes having different light absorption coefficients. For example, the dichroic dye absorbs light polarized in the major axis direction relatively small and relatively reflects light polarized in the minor axis direction. It may be one that absorbs significantly.

  In the above description, the dichroic dye is added to the polymer liquid crystal at a concentration of 2.0% by weight, but the concentration of the dichroic dye added to the polymer liquid crystal is at least 2.0% by weight. That is all you need. However, if the concentration of the dichroic dye in the polymer liquid crystal is increased too much, the brightness of the liquid crystal display decreases.

  Further, in FIG. 1, a bottom emission structure in which EL light emission is extracted to the driving TFT formation substrate side is used. However, a similar effect can be obtained even in a top emission structure in which EL emission is extracted to the opposite side of the TFT formation substrate. it can.

(Second Embodiment)
A display device according to the second embodiment will be described with reference to FIGS. FIG. 7 is a diagram schematically illustrating a configuration of a display device according to the second embodiment. This embodiment is different from the previous first embodiment in that the λ / 4 layer 12b of the circularly polarizing plate 1 has reverse dispersion wavelength dispersion. Since others are the same as those in the first embodiment, description thereof will be omitted.

  FIG. 8 is a diagram illustrating dispersion characteristics of the λ / 4 layer 12b in the display device according to the second embodiment. In the first embodiment, the chromatic dispersion Δn (450 nm) / Δn (589 nm) of the λ / 4 layer 12 is 1.01 (positive dispersion) as indicated by the dispersion characteristic D1. On the other hand, in this embodiment, the wavelength dispersion Δn (450 nm) / Δn (589 nm) of the λ / 4 layer 12b is set to 0.75 (reverse dispersion) as indicated by the dispersion characteristic D2. Due to the inverse dispersibility of the λ / 4 layer 12b, as the wavelength of light increases, the phase difference increases accordingly, so that substantially circular polarization can be realized in the entire wavelength region of visible light (380 to 780 nm).

  FIG. 9 is a diagram illustrating a simulation result of the viewing angle characteristics of external light reflection in the display device according to the second embodiment. Example 2 in FIG. 9 shows the viewing angle characteristics of external light reflection measured using the display device of the present embodiment. About the comparative example 4 and Example 1, it is the same as what was shown in FIG. 6 of previous 1st Embodiment. In FIG. 9, the in-plane retardation value R0 of the λ / 4 layer 12b is 137 nm.

  Comparative Example 4 and Example 1 are viewing angle characteristics of external light reflection measured by setting the wavelength dispersion Δn (450 nm) / Δn (589 nm) of the λ / 4 layer 12 to 1.01 (positive dispersion). Of Comparative Example 4 and Example 1, Comparative Example 4 is measured with a configuration in which the dichroic dye is not included in the retardation layer 13, and Example 1 includes the dichroic dye in the retardation layer 13. Measured in a configuration.

  On the other hand, Example 2 is a viewing angle characteristic of external light reflection measured by setting the wavelength dispersion Δn (450 nm) / Δn (589 nm) of the λ / 4 layer 12b to 0.75 (reverse dispersion). In Example 2, it can be seen that the viewing angle characteristics of external light reflection are improved as compared with Comparative Example 4 and Example 1. That is, by setting the wavelength dispersion of the λ / 4 layer 12b of the circularly polarizing plate 1 to inverse dispersion, the viewing angle characteristics of external light reflection can be further improved.

  As described above, in the circularly polarizing plate according to the present embodiment, the λ / 4 layer has wavelength dispersion of inverse dispersion. Thereby, in addition to the effect similar to 1st Embodiment, the viewing angle characteristic of external light reflection can be improved further.

(Third embodiment)
A display device according to the third embodiment will be described with reference to FIGS. 10 and 11. FIG. 10 is a diagram schematically illustrating a configuration of a display device according to the third embodiment. In the present embodiment, the phase difference layer 13 is not provided on the circularly polarizing plate 1, but instead the phase difference layer 6 is disposed on the display surface side of the circularly polarizing plate 1. And mainly different. In addition, the light emitting layer 33 (EL) of each of the three primary colors of the red light emitting layer (R), the green light emitting layer (G), and the blue light emitting layer (B) is provided in place of the white light emitting layer 33. Different from one embodiment. Accordingly, the color filter 5 is removed. Since others are the same as those in the first embodiment, description thereof will be omitted.

  FIG. 11 is a diagram illustrating simulation results of viewing angle characteristics of external light reflection in the display device according to the third embodiment. Example 3 in FIG. 11 shows the viewing angle characteristics of external light reflection measured using the display device of the present embodiment. Further, Comparative Examples 5 and 6 in FIG. 11 show the viewing angle characteristics of external light reflection measured using a display device different from the present embodiment as a comparative example. In FIG. 11, the in-plane retardation value R0 of the λ / 4 layer 12 is 137 nm. Further, the wavelength dispersion Δn (450 nm) / Δn (589 nm) of the λ / 4 layer 12 was set to 1.01 (positive dispersion).

  Comparative Examples 5 and 6 are viewing angle characteristics of external light reflection measured using a display device that does not include the retardation layer 6 on the display surface side. Among Comparative Examples 5 and 6, in Comparative Example 5, the degree of polarization of the linearly polarizing layer 11 of the circularly polarizing plate 1 is increased to 99.9%, and in Comparative Example 6, the polarization of the linearly polarizing layer 11 of the circularly polarizing plate 1 is increased. The degree was lowered to 97.9%. Since the comparative examples 5 and 6 do not have the retardation layer 6 on the display surface side, the reflection of external light from a wide angle is increased.

  On the other hand, Example 3 shows viewing angle characteristics of external light reflection measured using a display device having a retardation layer 6 containing 2.0% by weight of a dichroic dye. In Example 3, the degree of polarization of the linearly polarizing layer 11 of the circularly polarizing plate 1 was lowered to 97.9%.

  In Example 3, it can be seen that the viewing angle characteristics of external light reflection are improved as compared with Comparative Examples 5 and 6. Moreover, although the front transmittance of Example 3 is a little inferior to the comparative example 6, it turns out that the same level as the comparative example 6 is maintained substantially. That is, in Example 3, by having the retardation layer 6 containing the dichroic dye oriented perpendicularly to the display surface of the display device, both the external light reflection absorption capability and the brightness of the display device are compatible. I understand that. However, in Example 3, since the circularly polarizing plate 1 does not have the C-plate in which the phase difference Rth is optimized, compared with Example 1 of the first embodiment, the viewing angle characteristics of external light reflection are as follows. However, it can be seen that the same effect as in the first embodiment is obtained.

  As described above, the display device of this embodiment includes the circularly polarizing plate and the retardation layer disposed on the display surface side of the substrate having the light emitting layer, and the retardation layer has an axial direction with a large light absorption rate. It contains a dichroic dye oriented perpendicular to the display surface. Moreover, the phase difference layer is arrange | positioned rather than the circularly-polarizing plate at the display surface side. Even with such a configuration, the viewing angle characteristic of external light reflection is lower than that of the first embodiment, but the same effect as that of the first embodiment can be obtained.

  In the above description, the circularly polarizing plate 1 does not include the retardation layer 13. However, the circularly polarizing plate 1 is provided with the retardation layer 13 such as C-plate that shows a retardation in the film thickness direction. May be. Further, by combining the first embodiment and the present embodiment, the retardation layers 6 and 13 in which the dichroic dyes are vertically aligned are arranged on both the inside of the circularly polarizing plate 1 and the display surface side. It is good also as a structure. Even in this case, the same effect can be obtained.

(Other embodiments)
The above-described embodiments are merely examples of implementation in carrying out the present invention, and the technical scope of the present invention should not be construed as being limited thereto. That is, the present invention can be implemented in various forms without departing from the technical idea or the main features thereof. For example, the above-described embodiments can be applied in combination.

1: Circularly polarizing plates 2a, 2b: Substrate 3: Organic EL element 4: Adhesive layer 5: Color filter 6: Phase difference layer 11: Linearly polarizing layer 12: λ / 4 layer 13: Phase difference layer 31: Transparent electrode 32: Hole transport layer (HTL / HIL)
33: Light emitting layer (EL)
34: Electron transport layer (ETL / EIL)
35: Metal electrode

Claims (12)

A substrate having a light emitting layer;
A circularly polarizing plate and a retardation layer disposed on the display surface side of the substrate;
With
The retardation layer includes a dichroic dye in which an axial direction having a large light absorption rate is vertically aligned with respect to a display surface. The light emitting layer is an organic EL element,
The display device according to claim 1, wherein the substrate has a metal electrode for driving the organic EL element. The circularly polarizing plate has a linearly polarizing layer, a λ / 4 layer, and the retardation layer,
The display device according to claim 1, wherein the retardation layer is disposed closer to the substrate than the linearly polarizing layer and the λ / 4 layer. The display device according to claim 3, wherein the linear polarization layer has a polarization degree of 98% or less. The display device according to claim 3, wherein the λ / 4 layer has wavelength dispersion of reverse dispersion. The display device according to claim 3, wherein the retardation layer has a retardation of −65 nm to −30 nm in the film thickness direction. The display device according to claim 1, wherein the retardation layer is disposed closer to the display surface than the circularly polarizing plate. 8. The display device according to claim 1, wherein the retardation layer includes a polymer liquid crystal vertically aligned with respect to the display surface, and the dichroic dye is added to the polymer liquid crystal. . The display device according to claim 8, wherein a concentration of the dichroic dye added to the polymer liquid crystal is 2.0% by weight or more. The display device according to claim 1, wherein the retardation layer includes two or more types of the dichroic dyes having different absorption wavelengths in the visible light region. Forming a light emitting layer on a substrate;
Forming a retardation layer containing a dichroic dye in which the axial direction having a large light absorption rate is vertically aligned on the display surface side of the substrate;
Arranging a circularly polarizing plate on the display surface side of the substrate;
A method for manufacturing a display device. The step of forming the retardation layer includes
Forming a vertical alignment polyimide alignment film on a base film;
Coating the alignment film with a polymer liquid crystal solution to which the dichroic dye is added, and forming a coating film on the base film;
Irradiating the coating film with ultraviolet light to cure the coating film;
The manufacturing method of the display apparatus of Claim 11 which has these.