JP2018112715A - Color filter and display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a color filter that can improve display characteristics without using a circularly polarizing plate, and a display.SOLUTION: A color filter for an organic EL display having light emitting layers in multiple colors is used to solve the above-mentioned problem, the color filter provided with colored layers in multiple colors on a transparent substrate according to the arrangement of the light emitting layers in multiple colors of the organic EL display and provided with an antireflection layer on the colored layers in multiple colors.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a color filter used in an organic electroluminescence (hereinafter referred to as EL) display device, and a display device using the color filter.

  2. Description of the Related Art Conventionally, an organic electroluminescence (hereinafter referred to as EL) display device using a multicolor coating method is known. Such an organic EL display device includes an organic EL element substrate having light emitting layers of a plurality of colors.

  One of the anode and the cathode of the organic EL element substrate is generally composed of a metal electrode. For this reason, in an organic EL display device provided with an organic EL element substrate, there is a problem that contrast is reduced and reflection occurs due to external light being reflected by the anode or the cathode. That is, the display characteristics of the organic EL display device are deteriorated.

  In order to solve such a problem, an organic EL display device has been proposed in which a circularly polarizing plate is disposed on the observer side of the organic EL element substrate to prevent external light from being reflected (for example, Patent Document 1). ).

JP 2001-155858 A

  However, since the circularly polarizing plate is expensive, the cost of the organic EL display device is increased. Further, the circularly polarizing plate prevents the light emitted from the organic EL element substrate from being transmitted. Therefore, it is necessary to increase the emission intensity of the organic EL element substrate in order to obtain a desired luminance. For this reason, power consumption increases and the element lifetime of the organic EL element substrate may be shortened.

  The present invention has been made in view of such points, and an object thereof is to provide a color filter and a display device that can improve display characteristics without using a circularly polarizing plate.

  That is, the invention according to claim 1 of the present invention is a color filter for an organic EL display device having light emitting layers of a plurality of colors, wherein the light emitting layers of the plurality of colors of the organic EL display device are formed on a transparent substrate. According to the arrangement, a color filter having a plurality of color layers is provided, and an antireflection layer is provided on the color layers of the plurality of colors.

  In the invention according to claim 2 of the present invention, the antireflection layer includes a first reflection light that is reflected from an upper surface of the antireflection layer, and a first reflection light that is reflected from an interface between the antireflection layer and the colored layer. The color filter according to claim 1, wherein the color filter is a transparent layer that reduces reflection by causing interference between two reflected lights.

  The invention according to claim 3 of the present invention is characterized in that the antireflection layer has a multilayer structure composed of a plurality of layers having different refractive indexes. It is a color filter.

  In the invention according to claim 4 of the present invention, the light having a wavelength incident on the antireflection layer from the upper surface side of the antireflection layer provided on the colored layers of the plurality of colors is in the range of 360 nm to 740 nm. The color filter according to any one of claims 1 to 3, wherein the reflectance is 5.5% or less.

  The invention according to claim 6 of the present invention is arranged such that an organic EL element substrate having a light emitting layer of a plurality of colors and an upper surface of the antireflection layer are directed to the organic EL element substrate. An organic EL display device comprising: the color filter according to claim 4.

  According to the present invention, display characteristics can be improved without using a circularly polarizing plate.

Schematic sectional view showing an example of a color filter according to the present invention The figure explaining reflection of the light which injects into the color filter shown in FIG. Schematic sectional view showing an example of a display device according to the present invention 3A and 3B illustrate reflection of external light in the display device illustrated in FIG. The figure shown about the evaluation method of the color filter which concerns on this invention The figure shown about the evaluation result of the comparative example 1 The figure shown about the evaluation result of Example 1 The figure shown about the evaluation result of Example 2

<Color filter>
First, the color filter according to the present invention will be described.
FIG. 1 is a schematic cross-sectional view showing an example of a color filter according to the present invention.
As shown in FIG. 1, the color filter 1 is provided with a colored layer 13 of three colors of red (13R), green (13G), and blue (13B) on a transparent substrate 11. In addition, the antireflection layer 14 is provided.

  The three colored layers 13 of red (13R), green (13G), and blue (13B) are arranged in accordance with the arrangement of the light emitting layers of the plurality of colors of the organic EL display device in which the color filter 1 is used. ing.

  In the color filter 1 shown in FIG. 1, the black matrix layer 12 is provided on the transparent substrate 11 and below the colored layer 13, but in the present invention, the black matrix is formed on the colored layer 13. The form in which the layer 12 is provided may be sufficient. Moreover, the form provided in both on the transparent substrate 11 and the colored layer 13 may be sufficient.

  1 shows the color filter 1 with the transparent substrate 11 on the lower side (ground side) and the antireflection layer 14 on the upper side (top side), the color filter 1 is an organic EL. When used in a display device, the transparent substrate 11 side of the color filter 1 is an observer side, and the antireflection layer 14 side is opposed to the light emitting layers of a plurality of colors of the organic EL display device.

  The antireflection layer 14 is a transparent layer provided to reduce reflection. The antireflection layer 14 may have a single layer structure or a multilayer structure composed of a plurality of layers having different refractive indexes. In order to prevent reflection with higher accuracy, a multilayer structure is preferable.

  The color filter according to the present invention has light reflection reduced as compared with a conventional color filter having an overcoat layer on a colored layer, and further reflects light with a wavelength in the range of 360 nm to 740 nm. The rate is preferably 5.5% or less.

As a method of preventing reflection of light using the antireflection layer 14,
(1) A method of reducing reflectance by causing a plurality of reflected lights to interfere with each other in a destructive manner,
(2) A method of reducing the refractive difference of the reflective interface,
There is. The above (1) and (2) may be used in combination.

FIG. 2 is a diagram illustrating reflection of light incident on the color filter 1 shown in FIG.
In the example shown in FIG. 2, light (incident light L <b> 11) incident from the upper surface (front surface) side of the antireflection layer 14 is incident on the upper surface (front surface) of the antireflection layer and between the antireflection layer 14 and the colored layer 13. Reflected at each of the interfaces.
In FIG. 2, the reflected light reflected on the upper surface (front surface) of the antireflection layer 14 is referred to as first reflected light L12, and the reflected light reflected at the interface between the antireflection layer 14 and the colored layer 13 is the second reflected light. Each of the reflected lights L13 is indicated by a dashed arrow.

Here, when the method (1) is adopted, the film thickness (D) of the antireflection layer 14 so that the first reflected light L12 and the second reflected light L13 interfere with each other in a destructive manner, The refractive index of the material constituting the antireflection layer 14 may be determined.
When there are a plurality of wavelengths of light of interest, for example, the antireflection layer 14 may have a multilayer structure, and the thickness and refractive index of each layer may be determined according to the wavelength of light of interest.

When the method (2) is adopted, a material having a low refractive index may be used as the material constituting the antireflection layer 14.
When the antireflection layer 14 has a multilayer structure, for example, it is preferable that the refractive index of each layer gradually decreases from the colored layer 13 side toward the upper surface side of the antireflection layer 14. This is because the difference in refraction at each layer interface can be reduced, and the overall reflectance can be greatly reduced.

  As a method of forming the antireflection layer 14, for example, a photosensitive material is used as a material constituting the antireflection layer 14, and the photosensitive material is applied onto the colored layer 13 in the same manner as a conventional overcoat layer. A method of performing steps such as exposure, development, drying, and baking can be used.

  As the photosensitive material, for example, a photosensitive resin having a reactive vinyl group such as acrylate, methacrylate, polyvinyl cinnamate, or cyclized rubber can be used. A photopolymerization initiator, a sensitizer, a coating property improver, a development improver, a crosslinking agent, a polymerization inhibitor, a plasticizer, a flame retardant, and the like may be added to the photosensitive resin as necessary.

  Alternatively, a method of attaching a resin film composed of a thin film having a predetermined refractive index and a predetermined film thickness on the colored layer 13 may be used.

  Hereinafter, other configurations of the color filter according to the present invention will be described.

(Transparent substrate)
The transparent substrate supports each component in the color filter, such as a black matrix layer, a plurality of colored layers, and an antireflection layer.

  As the material of the transparent substrate, any material generally used for color filters can be used. For example, a non-flexible inorganic substrate such as quartz glass, Pyrex (registered trademark) glass, synthetic quartz plate, etc. And a flexible resin substrate such as a transparent resin film and an optical resin plate.

  For example, in the case of an inorganic substrate, it is preferable to use a non-alkali type glass substrate. The alkali-free type glass substrate is excellent in dimensional stability and workability in high-temperature heat treatment, and since it does not contain an alkali component in the glass, it can be suitably used as a transparent substrate for a color filter for a display device. Because.

(Black matrix layer)
The black matrix layer is provided in a pattern on the transparent substrate, and prevents unnecessary light leakage.

  This material can be the same as that of a black matrix layer used in a conventional color filter. For example, a material in which a black color material is dispersed in a binder resin can be used.

  Examples of the black color material include carbon black and titanium black. The binder resin is appropriately selected according to the method for forming the black matrix layer.

  In the case of the photolithography method, as the binder resin, for example, a photosensitive resin having a reactive vinyl group such as acrylate, methacrylate, polyvinyl cinnamate, or cyclized rubber is used.

  In the case of a printing method or inkjet method, examples of the binder resin include polymethyl methacrylate resin, polyacrylate resin, polycarbonate resin, polyvinyl alcohol resin, polyvinyl pyrrolidone resin, hydroxyethyl cellulose resin, carboxymethyl cellulose resin, polyvinyl chloride resin, Examples include melamine resin, phenol resin, alkyd resin, epoxy resin, polyurethane resin, polyester resin, maleic acid resin, polyamide resin and the like.

  The black matrix layer may contain a photopolymerization initiator, a sensitizer, a coating property improver, a development improver, a crosslinking agent, a polymerization inhibitor, a plasticizer, a flame retardant, and the like as necessary.

  The film thickness of the black matrix layer can be the same as the film thickness of a general black matrix layer in a color filter, and can be set within a range of 0.5 μm to 2.5 μm, for example.

  The shape of the opening of the black matrix layer is not particularly limited, and examples thereof include those in which the arrangement of the colored layers is changed, such as a stripe shape, a dogleg shape, and a delta arrangement.

  The method for forming the black matrix layer is not particularly limited as long as it is a method capable of forming the black matrix layer in a pattern at a predetermined position on the transparent substrate. For example, a photolithography method is preferable.

(Colored layer)
The colored layer includes a red colored layer, a green colored layer, and a blue colored layer. However, the colored layer only needs to include at least the three colors of red, green, and blue. For example, red, green, and blue 3 The colors may be four colors of red, green, blue and yellow, or five colors of red, green, blue, yellow and cyan.

  The arrangement of the colored layers is not particularly limited, and may be a known arrangement such as a stripe type, a mosaic type, a triangle type, or a four-pixel arrangement type.

  The colored layer is, for example, a color material dispersed in a binder resin. Examples of the color material include pigments and dyes of each color.

  Examples of the coloring material used in the red coloring layer include perylene pigments, lake pigments, azo pigments, quinacridone pigments, anthraquinone pigments, anthracene pigments, and isoindoline pigments.

  Examples of the colorant used in the green coloring layer include phthalocyanine pigments such as halogen polysubstituted phthalocyanine pigments or halogen polysubstituted copper phthalocyanine pigments, triphenylmethane basic dyes, isoindoline pigments, and isoindolinones. And pigments.

  Examples of the color material used in the blue colored layer include copper phthalocyanine pigments, anthraquinone pigments, indanthrene pigments, indophenol pigments, cyanine pigments, dioxazine pigments, and the like.

These pigments and dyes may be used alone or in combination of two or more.
As the binder resin, for example, a photosensitive resin having a reactive vinyl group such as acrylate, methacrylate, polyvinyl cinnamate, or cyclized rubber is used.

  The colored layer may contain a photopolymerization initiator and, if necessary, a sensitizer, a coatability improver, a development improver, a crosslinking agent, a polymerization inhibitor, a plasticizer, a flame retardant, and the like.

  The thickness of the colored layer can be the same as the thickness of a general colored layer in a color filter, and can be set, for example, within a range of 1 μm to 5 μm.

  The colored layer may be formed by any method as long as a plurality of colored layers can be arranged on a plane, and examples thereof include a photolithography method, an inkjet method, and a printing method.

  Further, on the same plane on which the colored layer is formed, a white layer that does not contain the color material but contains the binder resin and transmits light may be formed. Similar to the red, green and blue colored layers, this white layer is also arranged in the corresponding sub-pixel region. The film thickness and formation method of the white layer can be the same as those of the colored layer.

<Display device>
Next, the display device according to the present invention will be described.
FIG. 3 is a schematic cross-sectional view showing an example of a display device according to the present invention. As shown in FIG. 3, the display device 2 includes an organic EL element substrate 20 having a light emitting layer 23 of a plurality of colors that emits light toward an observer side (upper side in FIG. 3), and an upper surface of the antireflection layer 14. The color filter 1 is disposed so as to face the organic EL element substrate 20.

  Note that the color filter 1 in FIG. 3 is in an inverted state (upside down) with respect to the color filter 1 shown in FIG.

The organic EL element substrate 20 is provided on the support substrate 21, the back electrode 22 provided on the support substrate 21, the plurality of light emitting layers 23 provided on the back electrode 22, and the light emitting layer 23. And a transparent electrode 24 that transmits light from the light emitting layer 23.
The plurality of light emitting layers 23 include a red light emitting layer 23R, a green light emitting layer 23G, and a blue light emitting layer 23B. The red colored layer 13R, the green colored layer 13G, and the blue colored layer 13B of the color filter 1, respectively. Are arranged to face each other.

  The back electrode 22 is either an anode or a cathode, but is generally provided on the support substrate 21 as an anode. Examples of the forming material include metals such as gold, silver, and chromium. Therefore, the back electrode 22 can reflect light.

The transparent electrode 24 functions as a counter electrode for the back electrode 22. The transparent electrode 24 is either a cathode or an anode, but is generally provided as a cathode. As a material for forming the transparent electrode 24, a transparent conductive material such as ITO (indium tin oxide), indium oxide, IZO (indium zinc oxide), SnO ₂ , or ZnO is used.

  A bonding layer 25 is provided between the organic EL element substrate 20 and the color filter 1. The bonding layer 25 has translucency. As a material of the bonding layer 25, a material used for a general organic EL display device may be used. For example, a photocurable resin such as a photosensitive polyimide resin, a thermosetting resin, or the like can be used.

FIG. 4 is a diagram illustrating reflection of external light in the display device shown in FIG.
In order to facilitate explanation of the reflection, in the example shown in FIG. 4, the back electrode 22 and the transparent electrode 24 of the organic EL element substrate 20 shown in FIG. 3 are omitted, and the gap between the adjacent light emitting layers 23 is omitted. Is omitted in the form.

  In the example shown in FIG. 4, the external light L <b> 21 enters from the transparent substrate 11 side of the color filter 1, passes through the colored layer 13, the antireflection layer 14, and the bonding layer 25, and then has multiple colors of the organic EL display device. The light is reflected by the light emitting layer 23 and enters the antireflection layer 14, and then passes through the colored layer 13 and the transparent substrate 11 to be emitted as reflected light L <b> 22 to the viewer side.

  In FIG. 4, the light reflected by the light-emitting layer 23 from the outside light L21 is indicated by a thick dashed arrow as reflected light L22.

  Then, the reflected light L22 is reflected by the upper and lower interfaces of the antireflection layer 14, and each reflected light is reflected again by the light emitting layer 23 and emitted from the transparent substrate 11 to the observer side as reflected light L23 and L24. To do.

Here, the organic EL display device provided with the conventional color filter has no solution for reducing the reflected light L23 and L24.
In addition, the organic EL display apparatus which prevents that external light is reflected by arrange | positioning a circularly-polarizing plate in the observer side of an organic EL element board | substrate reduces the reflected light L22 shown in FIG. Theoretically, it is possible to reduce the reflected light L22 to approximately 0% by using the circularly polarizing plate. However, the circularly polarizing plate has a disadvantage that light emission from the light emitting layer 23 is reduced by 50%. .

On the other hand, in the display device 2 including the color filter 1, the reflection light L <b> 23 and L <b> 24 can be reduced by having the antireflection layer 14.
More specifically, as shown in FIG. 4, the reflected light L22 reflected by the external light L21 by the light emitting layer 23 is then reflected by the upper and lower interfaces of the antireflection layer 14.
Here, the light reflected by the upper and lower interfaces of the antireflection layer 14 is reduced by the antireflection action of the antireflection layer 14.
Therefore, even if these reduced reflected lights are reflected again by the light emitting layer 23 and emitted from the transparent substrate 11 to the viewer as reflected lights L23 and L24, the reflected lights L23 and L24 are more than conventional. It has been reduced.

  Therefore, according to the present invention, it is possible to reduce the reflected lights L23 and L24 generated from the external light L21 without using a circularly polarizing plate.

In addition, when using a circularly polarizing plate, transmission of light emitted from the organic EL element substrate is hindered, and in order to compensate for this, emission intensity is increased, power consumption is increased, The element lifetime of the organic EL element substrate may be shortened.
On the other hand, according to the present invention, such a problem can be solved.

  As mentioned above, although each embodiment was described about the color filter which concerns on this invention, and a display apparatus, this invention is not limited to the said embodiment. The above-described embodiment is an exemplification, and the present invention has substantially the same configuration as the technical idea described in the claims of the present invention and exhibits the same function and effect regardless of the case. Are included in the technical scope.

Hereinafter, the present invention will be described more specifically with reference to examples.
Here, a color filter according to the present invention having an antireflection layer (Examples 1 and 2) and a color filter having a conventional overcoat layer (Comparative Example 1) were manufactured, and the reflectance was evaluated.

Example 1
A glass substrate is used as a transparent substrate, and a colored layer of three colors of red, green, and blue is formed on the glass substrate as in the color filter 1 shown in FIG. A color filter using an antireflection film having a multilayer structure was produced. The film thickness of this antireflection layer was about 3.0 μm.
The color filter was cut into a 10 cm square to obtain a sample of Example 1.

(Example 2)
In the same manner as in Example 1, a glass substrate is used as a transparent substrate, and three colored layers of red, green, and blue are formed, and a photosensitive material constituting the antireflection layer of Example 2 is applied thereon. Then, a color filter having an antireflection layer having a single layer structure was produced by performing steps such as exposure, development, drying, and baking. The film thickness of this antireflection layer was about 3.0 μm.
The color filter was cut into a 10 cm square to obtain a sample of Example 2.

(Comparative Example 1)
In the same manner as in Examples 1 and 2, a glass substrate is used as a transparent substrate, a colored layer of three colors of red, green and blue is formed, and a photosensitive material constituting a conventional overcoat layer is applied thereon. Then, steps such as exposure, development, drying and baking were performed to produce a color filter having a conventional overcoat layer. The film thickness of this overcoat layer was about 3.0 μm.
The color filter was cut into a 10 cm square to obtain a sample of Comparative Example 1.

(Evaluation method)
FIG. 5 is a diagram showing a color filter evaluation method according to the present invention.
In this evaluation method, as shown in FIG. 5, Examples 1 and 2 were formed on a black substrate 32 such that the antireflection layer for Examples 1 and 2 and the overcoat layer for Comparative Example 1 were on the upper side. And each sample of the comparative example 1 was arrange | positioned, the light of the wavelength of 360 nm or more and 740 nm or less was irradiated from the antireflection layer or the overcoat layer, and each reflectance was measured.
CM-2600d manufactured by Konica Minolta Co., Ltd. was used as a measuring apparatus, and measurement was performed using an SCI (Special Components Included) method under the condition of an observation visual field of 2 °.

(Evaluation results)
FIG. 6 is a diagram illustrating the evaluation result of Comparative Example 1, and more specifically, is a diagram illustrating the reflectance measurement result of Comparative Example 1 with respect to light having a wavelength of 360 nm to 740 nm.
FIG. 7 is a diagram showing the evaluation results of Example 1, and more specifically shows the reflectance measurement results of Example 1 with respect to light having a wavelength of 360 nm or more and 740 nm or less.
FIG. 8 is a diagram showing the evaluation results of Example 2, more specifically, the results of measuring the reflectance of Example 2 with respect to light having a wavelength of 360 nm or more and 740 nm or less.

As shown in FIG. 7, Example 1 having an antireflection layer having a multilayer structure was able to significantly reduce the reflectance as compared with Comparative Example 1 having a conventional overcoat layer shown in FIG.
In Example 1, the reflectance is suppressed to 5.5% or less with respect to light having a wavelength of 360 nm or more and 740 nm or less, and in particular, the reflectance is 2 with respect to light having a wavelength of 410 nm or more and 740 nm or less. It was suppressed to 0.0% or less and exhibited an excellent reduction effect.

As shown in FIG. 8, Example 2 having an antireflection layer having a single layer structure was also able to reduce the reflectance as compared with Comparative Example 1 having a conventional overcoat layer shown in FIG.
In Example 2, the reflectance was suppressed to 5.5% or less with respect to light having a wavelength of 360 nm or more and 740 nm or less, and a sufficient reduction effect was exhibited.

DESCRIPTION OF SYMBOLS 1 Color filter 2 Display apparatus 11 Transparent substrate 12 Black matrix layer 13 Colored layer 20 Organic EL element substrate 21 Support substrate 22 Back electrode 23 Light emitting layer 24 Transparent electrode 25 Bonding layer 31 Reflectance measuring device 32 Black substrate L11 Incident light L12 1st Reflected light L13 Second reflected light L21 Outside light L22, L23, L24 Reflected light

Claims (5)

A color filter for an organic EL display device having a light emitting layer of a plurality of colors,
A colored layer of a plurality of colors is provided on the transparent substrate according to the arrangement of the light emitting layers of the plurality of colors of the organic EL display device,
An antireflection layer is provided on the colored layers of the plurality of colors. The antireflection layer comprises
First reflected light reflected on the upper surface of the antireflection layer;
The color filter according to claim 1, wherein the color filter is a transparent layer that reduces reflection by causing interference with second reflected light reflected at an interface between the antireflection layer and the colored layer. The antireflection layer comprises
The color filter according to claim 1, wherein the color filter has a multilayer structure including a plurality of layers having different refractive indexes.   The reflectance is 5.5% or less for light having a wavelength of 360 nm or more and 740 nm or less incident on the antireflection layer from the upper surface side of the antireflection layer provided on the colored layers of the plurality of colors. The color filter according to any one of claims 1 to 3, wherein the color filter is characterized in that: An organic EL element substrate having a light emitting layer of a plurality of colors;
The color filter according to any one of claims 1 to 4, wherein the color filter is disposed so that an upper surface of the antireflection layer faces the organic EL element substrate.
An organic EL display device comprising:

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