JP2019139080A - Wavelength selection film, video source unit, and display - Google Patents

Abstract

To provide a wavelength selection film for displaying colors with high saturation.SOLUTION: A wavelength selection film (10) is arranged on a display, blocks light with a predetermined wavelength, and has a cholesteric liquid crystal layer (13) provided with a cholesteric liquid crystal structure. The cholesteric liquid crystal layer reflects light in a predetermined wavelength region including 590 nm.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a wavelength selection film for expressing a highly saturated color, a video source unit including the same, and a display device.

A display device such as a liquid crystal display device or an organic electroluminescence (organic EL) display device is provided with a light emission source, and emits light with a spectral distribution having respective characteristics. Further, the color expression in the display device may be performed by a color filter in which regions divided into RGB are arranged as is well known.
In recent years, when various types of light emitting sources have been proposed, the color filters used in the conventional display devices cannot cope with the characteristics of the respective spectral distributions, and color mixing occurs. There was a problem that colors could not be expressed. Also, display devices that do not use a color filter are required to express colors with higher saturation.

  On the other hand, Patent Document 1 discloses a technique of adjusting the spectral transmittance characteristics of each RGB in a color filter using a pigment.

JP 2005-134508 A

  However, the adjustment of the spectral transmittance by using a pigment as in Patent Document 1 has a wide absorption band of the pigment and a limited absorption efficiency, and therefore absorbs a part of light having a wavelength that should be originally used. Or, conversely, the portion to be absorbed is not always transmitted, so that it is not always possible to express a highly saturated color.

  Then, this invention makes it a subject to provide the wavelength selection film for expressing the color of high saturation in view of said problem. In addition, an image source unit and a display device provided with this wavelength selection film are provided.

  The present invention will be described below.

  One aspect of the present invention is a wavelength selection film that is disposed in a display device and blocks light of a predetermined wavelength, and includes a cholesteric liquid crystal layer having a cholesteric liquid crystal structure, and the cholesteric liquid crystal layer includes a predetermined wavelength including 590 nm. It is a wavelength selective film which reflects the light of the wavelength band.

  The cholesteric liquid crystal layer may be formed by laminating two layers of two cholesteric liquid crystals having a spiral structure rotating in opposite directions.

  When producing the wavelength selective film, after applying the composition before curing that constitutes one of the cholesteric liquid crystal layers of the two cholesteric liquid crystal layers, it is aligned and cured, without winding up the formed layer, It can be produced by a method for producing a wavelength selective film in which the composition before curing that constitutes the other cholesteric liquid crystal layer is applied and then oriented and cured.

  The two cholesteric liquid crystal layers may be formed integrally with an adhesive.

  The thickness of the cholesteric liquid crystal layer may be 10 μm or less.

  The cholesteric liquid crystal layer can be formed so as to have a rod-like liquid crystal.

  The wavelength selection film may further include another cholesteric liquid crystal layer, and the other cholesteric liquid crystal layer may reflect light in a predetermined wavelength band including 490 nm.

  When producing the wavelength selective film, the composition that forms the other cholesteric liquid crystal layer without winding up the formed cholesteric liquid crystal layer without applying the orientation and curing after applying the composition before curing constituting the cholesteric liquid crystal layer. It can be produced by a method for producing a wavelength selective film in which the previous composition is applied and then oriented and cured.

  The other cholesteric liquid crystal layer may be formed by laminating two layers of two cholesteric liquid crystals having a spiral structure rotating in opposite directions.

  When producing the wavelength selective film, a layer formed by applying an uncured composition constituting one of the cholesteric liquid crystal layers of the other cholesteric liquid crystal layers and then curing and forming the cholesteric liquid crystal layer. The film can be produced by a method for producing a wavelength-selective film in which the composition before curing that constitutes the layer made of the other cholesteric liquid crystal is applied and then oriented and cured.

  The two cholesteric liquid crystal layers in the other cholesteric liquid crystals may be integrally formed through an adhesive.

  The thickness of other cholesteric liquid crystal layers may be 10 μm or less.

  The other cholesteric liquid crystal layer can be formed to have a rod-like liquid crystal.

  In another aspect of the present invention, the backlight, the wavelength selection film disposed on the light exit side of the backlight, the liquid crystal cell layer disposed on the light exit side of the backlight, and the light exit side of the liquid crystal cell layer are disposed. And a color filter.

  The other aspect of this invention is a laminated body provided with a backlight and the said wavelength selection film arrange | positioned at the light emission side of a backlight.

  The other aspect of this invention is a laminated body provided with the said wavelength selection film and the liquid crystal cell layer arrange | positioned at the light emission side of a wavelength selection film.

  Another aspect of the present invention is a backlight, a wavelength selection film disposed on the light exit side of the backlight, a liquid crystal cell layer disposed on the light exit side of the backlight, and disposed on the light exit side of the liquid crystal cell layer. And a color filter, wherein the wavelength selection film includes a cholesteric liquid crystal layer having a cholesteric liquid crystal structure, and the cholesteric liquid crystal layer reflects light in a predetermined wavelength band including 490 nm.

  Another aspect of the present invention is an image source unit comprising an organic EL display panel and the wavelength selection film disposed on the light output side of the organic EL display panel.

  In addition, a display device in which the video source unit is housed in a housing can be provided.

  According to the present invention, it is possible to make a wide color gamut in the color expression in the display device, and it is also possible to express a color with higher saturation.

1 is an external perspective view of a wavelength selection film 10. FIG. It is a figure showing the example of the transmittance | permeability characteristic of a color filter. 3 is a diagram illustrating a layer configuration of a video source unit 20. FIG. 3 is a diagram illustrating a layer configuration of a video source unit 30. FIG. It is a figure explaining the example of the wavelength intensity characteristic of a light emission source. It is a figure explaining the transmittance | permeability characteristic of a 1st cholesteric liquid crystal layer. It is a figure explaining the transmittance | permeability characteristic of a 2nd cholesteric liquid crystal layer. It is a figure explaining the example of the wavelength intensity characteristic of a light emission source. It is a figure explaining the example of the wavelength intensity characteristic of a light emission source. It is a figure explaining the example of the wavelength intensity characteristic of a light emission source. It is a figure showing the example of the transmittance | permeability characteristic of a color filter. It is a figure explaining the example of the wavelength intensity characteristic of a light emission source.

  Hereinafter, the present invention will be described based on embodiments shown in the drawings. However, the present invention is not limited to these forms.

  FIG. 1 is a perspective view of a wavelength selection film 10 for explaining one embodiment. As can be seen from FIG. 1, the wavelength selection film 10 of this embodiment includes a base material 11, a first cholesteric liquid crystal layer 12, and a second cholesteric liquid crystal layer 13.

The substrate 11 is a layer made of a transparent film that supports the first cholesteric liquid crystal layer 12 and the second cholesteric liquid crystal layer 13. Various materials can be used as the material forming the substrate 11. However, a material that is widely used as a material of a member constituting an optical element and has excellent mechanical characteristics, optical characteristics, stability, workability, and the like and can be used at low cost can be used. For example, a polymer resin having an alicyclic structure, a methacrylic resin, a polycarbonate resin, a polystyrene resin, an acrylonitrile-styrene copolymer, a methyl methacrylate-styrene copolymer, an ABS resin, a polyethersulfone, or the like. And epoxy acrylate and urethane acrylate-based reactive resins (ionizing radiation curable resins and the like), triacetyl cellulose resin, polyethylene terephthalate resin (PET), and glass.
And the thickness can be comprised in the range of 10 micrometers or more and 1000 micrometers or less, Preferably it is 50 micrometers or more and 100 micrometers or less.

  When a stretching material is used for the substrate, the stretching axis can be used for liquid crystal alignment. Moreover, when not using an extending | stretching material, you may laminate | stack an orientation film on a base material layer.

  The 1st cholesteric liquid crystal layer 12 is a layer laminated | stacked on one surface of the base material 11, and consists of a liquid crystalline composition which shows a cholesteric regularity. As a physical molecular arrangement of the liquid crystal molecules, a liquid crystal molecule director is provided with a spiral structure formed by continuously rotating in the layer thickness direction.

The first cholesteric liquid layer 12 selectively reflects light having a wavelength λ ₀ expressed by the following formula based on the physical molecular arrangement of the liquid crystal molecules.
λ ₀ = n _ave · p
Here, p is the helical pitch length in the helical structure of the liquid crystal molecules (the length per pitch of the molecular helix of the liquid crystal molecules), and n _ave is the average refractive index in a plane perpendicular to the helical axis.

Further, the wavelength bandwidth Δλ of the reflected light at this time is expressed by the following equation. Here, Δn is a birefringence value.
Δλ = Δn · p
Here, Δλ can be adjusted by mixing a plurality of materials having different Δn. The number of materials to be mixed is preferably small, and it is preferable to adjust the ratio of two types of materials, but more types of materials may be mixed as necessary.

  Further, the incident light having such a selected wavelength includes both a circularly polarized light component in one direction and a circularly polarized light component in the opposite direction. On the other hand, the first cholesteric liquid crystal layer 12 converts the non-polarized state (a state including both circularly polarized components) incident along the spiral axis into two circularly polarized light (right circularly polarized light and left circularly polarized light). Circularly polarized light), one is transmitted and the other is reflected. This phenomenon is known as circular dichroism, and when a spiral direction in the spiral structure of liquid crystal molecules is appropriately selected, a circularly polarized component having the same optical rotation direction as this spiral direction is selectively reflected.

That is, the non-polarized light incident on the first cholesteric liquid crystal layer 12 belongs to the range of the wavelength bandwidth Δλ centered on the selective reflection center wavelength λ ₀ (selective reflection wavelength region) according to the polarization separation characteristic. One circularly polarized component (for example, right circularly polarized light within the selective reflection wavelength region) is reflected as reflected light, and the other light (for example, left circularly polarized light within the selective reflection wavelength region, and right circularly polarized light and left circularly polarized light outside the selective reflection wavelength region) ) Is transmitted.

  Using such polarization separation characteristics, the first cholesteric liquid crystal layer 12 can be configured to have selective reflectivity of light along the wavelength targeted by the wavelength selection film 10. Therefore, the center wavelength of selective reflection may be configured to be a target wavelength. Specifically, it is as follows.

  FIG. 2 shows an example of transmittance characteristics of a color filter used in a display device. The horizontal axis represents wavelength, and the vertical axis represents transmittance with 100% transmittance being 1.0. In FIG. 2, B represents a blue component, G represents a green component, and R represents a red component. As can be seen from FIG. 2, in this color filter, B and G intersect at 490 nm, and include both B and G at wavelengths before and after that. The light emitted from the light source usually includes this wavelength (see, for example, the light output characteristics of each light source shown in FIGS. 5, 8, 9, 10, and 12 shown later). Therefore, color mixture of B and G occurs with respect to the light incident on the color filter from the light source. Similarly, G and R intersect at 590 nm, and both G and R are included at wavelengths before and after that. Since light emitted from the light source usually includes this wavelength, light incident from the light source In contrast, a color mixture of G and R occurs. Such color mixing hinders expression due to high saturation.

Therefore, in this embodiment, the first cholesteric liquid crystal layer 12 is configured to have a selective reflection characteristic including a wavelength of 490 nm and a predetermined wavelength bandwidth Δλ ₁ . In order to selectively reflect such a wavelength, as described above, the helical pitch length in the helical structure of the liquid crystal molecules may be adjusted, and a material having a predetermined average refractive index and birefringence is used for this.
Here, the specific size of the wavelength bandwidth Δλ ₁ can be set as appropriate, and can be determined by the wavelength characteristics of the backlight and the characteristics of the color filter. For example, if the wavelength bandwidth Δλ ₁ is a half-value width with respect to the center wavelength (the wavelength having the lowest transmittance), the wavelength bandwidth Δλ ₁ is normally in the range of 30 nm to 150 nm, and based on this, the Δn of the material is It is possible to decide.
Further, the center wavelength is not particularly limited, and can be appropriately set depending on the wavelength characteristics of the backlight and the characteristics of the color filter. The center wavelength may be 490 nm or there may be a deviation from 490 nm.

According to this, of the light that has reached the first cholesteric liquid crystal layer 12, for a given wavelength band width △ lambda ₁ light comprises wavelength 490 nm, does not transmit to reflect one circularly polarized component. Accordingly, since at least a part of the light causing the color mixture is not emitted to the observer, high saturation can be expressed.

  The first cholesteric liquid crystal layer 12 is composed of two cholesteric liquid crystal layers, and both layers have selective reflection characteristics of the same wavelength, and the spiral structure of the cholesteric liquid crystal has one of a right-turn structure and the other. If a left-turning structure is used, both circularly polarized light components are reflected and not transmitted, so that higher saturation can be expressed.

  The thickness of the first cholesteric liquid crystal layer 12 is not particularly limited, but can be about 1 μm or more and 10 μm or less. Preferably they are 1 micrometer or more and 3 micrometers or less.

The second cholesteric liquid crystal layer 13 is a layer stacked on the first cholesteric liquid crystal layer 12. The second cholesteric liquid crystal layer 13 can be considered similarly to the first cholesteric liquid crystal layer 12. However, the second cholesteric liquid crystal layer 13 is configured such that the central wavelength of selective reflection is different from that of the first cholesteric liquid crystal layer 12. More specifically, the wavelength of selective reflection of the second cholesteric liquid crystal layer 13 is configured to include a wavelength of 590 nm, which is the intersection of G and R shown in FIG. That is, in this embodiment, the second cholesteric liquid crystal layer 13 is configured to have a selective reflection characteristic including a wavelength of 590 nm and a predetermined wavelength bandwidth Δλ ₂ .
In order to selectively reflect such a wavelength, as described above, the helical pitch length in the helical structure of the liquid crystal molecules may be adjusted, and a material having a predetermined average refractive index and birefringence is used for this.
The concept of wavelength bandwidth and center wavelength is the same as that of the first cholesteric liquid crystal layer.

According to this, of the light reaches the second cholesteric liquid crystal layer 13, for a given wavelength bandwidth △ lambda ₂ light comprises wavelength 590 nm, it does not transmit to reflect one circularly polarized component. Accordingly, since at least a part of the light causing the color mixture is not emitted to the observer, high saturation can be expressed.

  The second cholesteric liquid crystal layer 13 is also composed of two layers of cholesteric liquid crystal, both layers have selective reflection characteristics of the same wavelength, and the cholesteric liquid crystal has a spiral structure, one of which is a right-turn structure. If the other is a left-turn structure, both circularly polarized light components are reflected and not transmitted, so that higher saturation can be expressed.

  The thickness of the second cholesteric liquid crystal layer 13 is not particularly limited, but can be about 1 μm or more and 10 μm or less. Preferably they are 1 micrometer or more and 3 micrometers or less.

  The wavelength selection film 10 as described above can be manufactured, for example, as follows. That is, after applying a liquid crystalline composition exhibiting cholesteric regularity to be the first cholesteric liquid crystal layer to the substrate 11, an alignment treatment and a curing treatment are performed to obtain a first cholesteric liquid crystal layer. Further, after applying the liquid crystalline composition exhibiting cholesteric regularity to be the second cholesteric liquid crystal layer to the first cholesteric liquid crystal layer without winding up the laminate in which the first cholesteric liquid crystal layer is laminated, the alignment is performed. A treatment and a curing treatment are performed to form a second cholesteric liquid crystal layer.

  In addition, as described above, when the first cholesteric liquid crystal layer is composed of two layers of cholesteric liquid crystals having a spiral structure in which the first cholesteric liquid crystal layers are rotated in the opposite directions, and / or in the spiral structure in which the second cholesteric liquid crystal layer is also rotated in the opposite directions. In the case of a layer composed of two layers of cholesteric liquid crystal having the same, it can be similarly produced. That is, the first layer is applied, oriented (dried) and cured, and the next layer is further applied, oriented (dried) and cured without winding. By further repeating this, a layer of cholesteric liquid crystal laminated can be formed without winding up once.

  Thereby, it is possible to prevent the cholesteric liquid crystal layer from being contaminated or scratched due to contact with the back surface of the base material due to winding, or deformation due to winding tension or the like. There is also a method of strengthening the curing of the cholesteric liquid crystal layer to prevent contamination and scratches. However, if the curing is strengthened in this way, the risk of occurrence of repelling, poor alignment, poor adhesion, etc. during application of the composition for lamination Becomes higher. Therefore, it is possible to avoid such a risk by making as described above.

  However, the present invention is not limited to this, and each layer of the first cholesteric liquid crystal layer, each layer of the second cholesteric liquid crystal layer, and lamination of the first cholesteric liquid crystal and the second cholesteric liquid crystal layer may be performed by transfer. At this time, the hardened layers are overlapped and adhered to each other, so that the layers are integrated with an adhesive.

  More details are as follows. First, a base material 11 is prepared, and after applying a liquid crystalline composition exhibiting cholesteric regularity to be a first cholesteric liquid crystal layer on one surface of the base material 11, an alignment treatment and a curing treatment are performed. Then, the first cholesteric liquid crystal layer 12 is laminated. Details are as follows.

  As a method for applying the liquid crystalline composition exhibiting cholesteric regularity to be the first cholesteric liquid crystal layer to the base material 11, any existing method can be used. Specifically, a roll coating method, a gravure coating method, a bar coating method, a slide coating method, a die coating method, a slit coating method, a dipping method, or the like can be used. Moreover, when using a plastic film as the base material 11, the film coating by what is called a roll to roll (Roll to Roll) system etc. can be used.

  In addition, as a liquid crystalline composition to be applied, chiral nematic liquid crystal or cholesteric liquid crystal exhibiting cholesteric regularity can be used. Such a material is not particularly limited as long as it is a liquid crystal material capable of forming a cholesteric liquid crystal structure. In particular, a polymerizable rod-like liquid crystal having a polymerizable functional group at both ends of the molecule. The material is preferable for obtaining the first cholesteric liquid crystal layer 12 which is optically stable after curing.

  Here, a case where a chiral nematic liquid crystal exhibiting cholesteric regularity is used as the liquid crystal composition will be described as an example. The chiral nematic liquid crystal is a mixture of a polymerizable liquid crystal material exhibiting nematic regularity and a chiral agent. Here, the chiral agent is for controlling the helical pitch length of the polymerizable liquid crystal material exhibiting nematic regularity so that the liquid crystalline composition exhibits cholesteric regularity as a whole. Moreover, a polymerization initiator and an additive are suitably added to such a liquid crystalline composition.

  Examples of polymerizable liquid crystal materials exhibiting nematic regularity include, for example, compounds represented by the following general formula (1) and compounds represented by the following formulas (2-i) to (2-xi). Can be mentioned. These compounds can be used alone or in combination.

In the above formula (1), R ¹ and R ² each represent hydrogen or a methyl group, but both R ¹ and R ² are preferably hydrogen because of the wide temperature range showing the liquid crystal phase. X in the formula (1) may be hydrogen, chlorine, bromine, iodine, an alkyl group having 1 to 4 carbon atoms, a methoxy group, a cyano group, or a nitro group, but it may be chlorine or a methyl group. preferable. In the above formula (1), a and b indicating the chain length of the alkylene group which is a spacer between the (meth) acryloyloxy group and the aromatic ring at both ends of the molecular chain are each an arbitrary integer in the range of 2 to 12, respectively. However, it is preferably in the range of 4-10, more preferably in the range of 6-9. The compound of the formula (1) in which a = b = 0 is poor in stability, easily subjected to hydrolysis, and the compound itself has high crystallinity. In addition, the compound of the general formula (1) in which a and b are each 13 or more has a low isotropic transition temperature (TI). For this reason, both of these compounds are not preferable because the temperature range in which the liquid crystal phase is exhibited is narrow.

  In the above, examples of polymerizable liquid crystal monomers have been described as polymerizable liquid crystal materials exhibiting nematic regularity, but not limited thereto, polymerizable liquid crystal oligomers, polymerizable liquid crystal polymers, liquid crystal polymers, etc. It is also possible to use it. Such a polymerizable liquid crystal oligomer, polymerizable liquid crystal polymer and liquid crystal polymer can be appropriately selected from those conventionally proposed.

  On the other hand, a chiral agent is a low molecular compound having an optically active site, and is mainly a compound having a molecular weight of 1500 or less. The chiral agent is mainly used for the purpose of inducing a helical structure in the positive uniaxial nematic regularity expressed by the polymerizable liquid crystal material exhibiting nematic regularity. As long as this purpose is achieved, it is compatible with a polymerizable liquid crystal material exhibiting nematic regularity in a solution state or a molten state, without impairing the liquid crystal property of the polymerizable liquid crystal material exhibiting nematic regularity, The kind of the low molecular compound as the chiral agent is not particularly limited as long as it can induce a desired helical structure.

  In addition, the chiral agent used for inducing a helical structure in the liquid crystal in this way needs to have at least some chirality in the molecule. Therefore, as the chiral agent used here, for example, a compound having one or more asymmetric carbons, a compound having an asymmetric point on a heteroatom such as a chiral amine or a chiral sulfoxide, or cumulene And compounds having an optically active moiety having axial asymmetry such as binaphthol. More specifically, a commercially available chiral nematic liquid crystal (for example, chiral dopant liquid crystal S-811 (manufactured by Merck)) can be mentioned.

  However, depending on the properties of the selected chiral agent, the nematic regularity formed by the polymerizable liquid crystal material exhibiting nematic regularity, the orientation deterioration, or the liquid crystallinity when the chiral agent is non-polymerizable. There exists a possibility of causing the fall of the sclerosis | hardenability of a composition and the reliability of the film after hardening. Furthermore, the use of a large amount of a chiral agent having an optically active site leads to an increase in the cost of the liquid crystal composition. Accordingly, when a liquid crystal layer having a cholesteric regularity with a short helical pitch length is formed, a chiral agent having a large effect of inducing a helical structure is used as a chiral agent having an optically active site to be contained in the liquid crystalline composition. Specifically, it is preferable to use a low molecular compound having axial asymmetry in the molecule, as represented by the following formula (3), (4) or (5).

In the above formula (3) or formula (4), R ⁴ represents hydrogen or a methyl group. Y is any one of formulas (i) to (xxiv) shown above, and among them, any one of formulas (i), (ii), (iii), (v), and (vii) It is preferable that Moreover, although c and d which show the chain length of an alkylene group can each take arbitrary integers in the range of 2-12, it is preferable that it is the range of 4-10, and is the range of 6-9. Is more preferable. The compound of the above formula (3) or (4) in which the value of c or d is 0 or 1 lacks stability, is susceptible to hydrolysis, and has high crystallinity. On the other hand, a compound having a value of c or d of 13 or more has a low melting point (Tm). In these compounds, compatibility with a polymerizable liquid crystal material exhibiting nematic regularity is lowered, and phase separation or the like may occur depending on the concentration.

  In addition, such a chiral agent does not need to have polymerizability in particular. However, when the chiral agent has polymerizability, it is polymerized with a polymerizable liquid crystal material exhibiting nematic regularity, and the cholesteric regularity is stably fixed, so in terms of thermal stability, etc. preferable. In particular, it is preferable to have a polymerizable functional group at both ends of the molecule in order to obtain the first cholesteric liquid crystal layer 12 having good heat resistance.

  The amount of the chiral agent contained in the liquid crystalline composition is determined in consideration of the ability to induce a helical structure, the finally obtained cholesteric liquid crystal structure, and the like.

  The liquid crystalline composition can be applied as it is on the substrate 11, but the viscosity can be adjusted to the application device, or can be dissolved in a solvent such as an organic solvent to obtain an ink for the purpose of obtaining a good alignment state. May be.

  As described above, the liquid crystalline composition is applied to the substrate 11 to form a cholesteric liquid crystal layer, and then the cholesteric liquid crystal layer is maintained at a predetermined temperature at which the cholesteric liquid crystal structure is expressed, and the liquid crystal molecules in the cholesteric liquid crystal layer are aligned. Let me.

  Here, when the laminated cholesteric liquid crystal layer is maintained at a predetermined temperature at which the cholesteric liquid crystal structure is exhibited, the cholesteric liquid crystal layer exhibits a liquid crystal phase, and the liquid crystal molecule director is formed by the self-integration action of the liquid crystal molecules themselves. A spiral structure that is continuously rotated in the thickness direction is formed. And the cholesteric liquid crystal structure expressed in such a liquid crystal phase can be fixed by curing the cholesteric liquid crystal layer by a method as described later.

  Such alignment treatment is usually performed together with a drying treatment for removing the solvent when the applied liquid crystalline composition contains a solvent. In order to remove the solvent, it is carried out at a predetermined drying temperature, and the drying time (heating time) is set appropriately as long as the cholesteric liquid crystal structure is developed and the solvent is substantially removed.

  After aligning the liquid crystal molecules in the cholesteric liquid crystal layer as described above, the cholesteric liquid crystal layer is cured, and the cholesteric liquid crystal structure expressed in the liquid crystal phase is fixed to form the first cholesteric liquid crystal layer 12.

Here, as a method of curing treatment,
(1) Method of drying the solvent in the liquid crystalline composition (2) Method of polymerizing liquid crystal molecules in the liquid crystalline composition by heating (3) Liquid crystallinity by irradiation with ionizing radiation (including electron beams and ultraviolet rays) A method of polymerizing liquid crystal molecules in the composition (4) A method of combining at least two of the above (1) to (3) can be mentioned.

  The second cholesteric liquid crystal layer 13 can be produced following the formation of the first cholesteric liquid crystal layer 12. That is, after applying a liquid crystalline composition exhibiting cholesteric regularity to be the second cholesteric liquid crystal to the first cholesteric liquid crystal layer 12, an alignment treatment and a curing treatment are performed to form a second cholesteric liquid crystal layer.

  By performing the above steps, the wavelength selection film 10 having the first cholesteric liquid crystal layer 12 and the second cholesteric liquid crystal layer 13 can be manufactured.

  Thus, according to the wavelength selection film 10, it is possible to produce a film that can easily transmit light of only a necessary wavelength and block others.

According to the wavelength selection film 10, the first cholesteric liquid crystal layer 12 and the second cholesteric liquid crystal layer 13 selectively reflect light having a specific wavelength that causes color mixing based on the cholesteric liquid crystal structure provided therein. , Other light is transmitted. In particular, selective reflection of the wavelength by the cholesteric liquid crystal layer reflects light of a wavelength in a necessary band with high accuracy, so that light of a necessary wavelength to be transmitted can be efficiently transmitted. Therefore, many colors can be expressed and high saturation can be achieved.
Moreover, according to the wavelength selection film 10, the same wavelength selection film has an effect on many types of light emitting sources.

  Next, a display device to which the wavelength selection film 10 is applied will be described. FIG. 3 shows a layer configuration of the video source unit 20 included in a liquid crystal display device which is a display device according to one example. Such a video source unit 20 is housed in a casing together with other known devices that operate the video source unit 20, and functions as a display device.

  The video source unit 20 is a video source unit for a liquid crystal display device, and a liquid crystal display panel 22 as an optical functional laminate is disposed on the viewer side of a backlight 21 as a light emission source.

  The liquid crystal display panel 22 is provided with a liquid crystal cell layer 23 made of liquid crystal, and a linear polarizing plate 24 is provided on the surface of the liquid crystal cell layer 23 on the backlight 21 side, for example, with a pressure-sensitive adhesive layer (not shown). . The linearly polarizing plate 24 is configured by sandwiching a polarizer that functions as a linearly polarizing plate between two substrates made of a transparent film. In this embodiment, the wavelength selection film 10 is disposed on the backlight 21 side of the surface of the linear polarizing plate 24 with an adhesive layer or the like.

  In this embodiment, the color filter 25 is disposed on the light exit surface side of the liquid crystal cell layer 23, and the linear polarizing plate 26 is disposed on the light exit surface side of the color filter 25. If necessary, a protective layer or other functional layer may be laminated on the light exit surface side of the linearly polarizing plate 26.

  According to such a video source unit 20, the light emitted from the backlight 21 enters the wavelength selection film 10. As described above, the wavelength selection film 10 is configured to reflect light having a wavelength causing color mixing and transmit other light. Therefore, even if the light transmitted through the wavelength selection film 10 reaches the color filter 25, the wavelength causing color mixing is cut, so that an image can be provided with high color purity. Further, the selective reflection of the wavelength by the cholesteric liquid crystal layer accurately reflects the light of the wavelength in the necessary band, so that the light of the necessary wavelength to be transmitted can be efficiently transmitted. Therefore, it is possible to express a color with higher saturation.

  FIG. 4 shows a layer configuration of the video source unit 30 included in an organic EL display device which is a display device according to another example. Such a video source unit 30 is housed in a casing together with other known devices that operate the video source unit 30, and functions as a display device.

  The video source unit 30 is a video source unit for an organic EL display device, and the organic EL display device is a device that provides the observer with video light emitted by the organic EL display panel 31 as a light emission source. The video source unit 30 is configured by laminating an optical functional laminate 32 on the observer side of the organic EL display panel 31.

  Specifically, the optical functional laminate 32 includes, from the organic EL display panel 31 side, a wavelength selection film 10, a color filter 33, a λ / 4 retardation plate 34, a polarizer 35 as a linearly polarizing plate, and a surface material. A material (protective film) 36 is provided. Here, the λ / 4 retardation plate 34 and the polarizer 35 function as a circularly polarizing plate for preventing external light reflection.

  According to such a video source unit 30, the light emitted from the organic EL display panel 31 that is a light emission source enters the wavelength selection film 10. As described above, the wavelength selection film 10 is configured to reflect light having a wavelength causing color mixing and transmit other light. Therefore, even if the light transmitted through the wavelength selection film 10 reaches the color filter 33, the wavelength that causes color mixing is cut, so that an image can be provided with high color purity. Further, the selective reflection of the wavelength by the cholesteric liquid crystal layer accurately reflects the light of the wavelength in the necessary band, so that the light of the necessary wavelength to be transmitted can be efficiently transmitted. Therefore, a highly saturated color can be expressed.

1. Form of specimen <Example 1-1>
In Example 1-1, assuming a video source unit following the example of the video source unit 20 for the liquid crystal display device shown in FIG. 3, three layers of a backlight (light source), a color filter, and a wavelength selection film are provided. The performance of the laminated body was examined. The configuration of each member in Example 1-1 is as follows.

<Backlight>
The backlight as the light emission source in this example is a QD backlight using quantum dots. FIG. 5 shows the light output characteristics of this backlight. The horizontal axis is wavelength and the vertical axis is intensity. As can be seen from FIG. 5, the emission source includes wavelengths of 490 nm and its front and back, and 590 nm and its front and back.

<Color filter>
The color filter in this example has the transmittance characteristic shown in FIG. The thicknesses are R = 3.3 μm, G = 3.4 μm, and B = 3.6 μm.

<Base material of wavelength selective film>
In this example, the wavelength selection film is formed by transferring the first cholesteric liquid crystal layer and the second cholesteric liquid crystal layer to the color filter without using the base material layer.

<First cholesteric liquid crystal layer of wavelength selective film>
In this example, the first cholesteric liquid crystal layer having the transmittance characteristics shown in FIG. 6 is applied. In this figure, the horizontal axis represents wavelength, and the vertical axis represents transmittance when 100% of non-polarized incident light is 1.0.
As can be seen from FIG. 6, in this example, the center wavelength of selective reflection of the first cholesteric liquid crystal layer is 490 nm, the half width is 40 nm, the thickness of the right-handed (right-turned) layer is 1.6 μm, and the left-handed (left-turned) ) Was 1.6 μm.

<Second cholesteric liquid crystal layer of wavelength selective film>
In this example, the second cholesteric liquid crystal layer having the transmittance characteristics shown in FIG. 7 is applied. In this figure, the horizontal axis represents wavelength and the vertical axis represents transmittance when 100% is 1.0.
As can be seen from FIG. 7, in this example, the center wavelength of selective reflection of the second cholesteric liquid crystal layer is 590 nm, the half width is 60 nm, the thickness of the right-handed (right-turned) layer is 2.0 μm, and the left-handed (left-handed) ) Was set to 2.0 μm.

[Example 1-2]
In Example 1-2, the second cholesteric liquid crystal layer was excluded from Example 1-1. Therefore, the cholesteric liquid crystal layer of the wavelength selective film is only the first cholesteric liquid crystal layer.

[Example 1-3]
In Example 1-3, the first cholesteric liquid crystal layer was excluded from Example 1-1. Therefore, the cholesteric liquid crystal layer of the wavelength selective film is only the second cholesteric liquid crystal layer.

[Comparative Example 1]
In Comparative Example 1, the first cholesteric liquid crystal layer and the second cholesteric liquid crystal layer were not provided as compared with Example 1-1.

[Example 2-1]
In Example 2-1, the backlight as the light emission source was changed from Example 1-1. The light emission characteristics are shown in FIG. This backlight is an LED backlight. As can be seen from FIG. 8, this light source includes wavelengths of 490 nm and its front and back, and 590 nm and its front and back.
Other configurations are the same as those of Example 1-1.

[Example 2-2]
In Example 2-2, the second cholesteric liquid crystal layer was excluded from Example 2-1. Therefore, the cholesteric liquid crystal layer of the wavelength selective film is only the first cholesteric liquid crystal layer.

[Example 2-3]
In Example 2-3, the first cholesteric liquid crystal layer was excluded from Example 2-1. Therefore, the cholesteric liquid crystal layer of the wavelength selective film is only the second cholesteric liquid crystal layer.

[Comparative Example 2]
In Comparative Example 2, the first cholesteric liquid crystal layer and the second cholesteric liquid crystal layer were not provided as compared with Example 2-1.

[Example 3-1]
In Example 3-1, the backlight as the light emission source was changed from Example 1-1. The light emission characteristics are shown in FIG. This backlight is a backlight using a C light source which is a CIE standard light source. As can be seen from FIG. 9, the light source includes wavelengths of 490 nm and its front and back, and 590 nm and its front and back.
Other configurations are the same as those of Example 1-1.

[Example 3-2]
In Example 3-2, the second cholesteric liquid crystal layer was excluded from Example 3-1. Therefore, the cholesteric liquid crystal layer of the wavelength selective film is only the first cholesteric liquid crystal layer.

[Example 3-3]
In Example 3-3, the first cholesteric liquid crystal layer was excluded from Example 3-1. Therefore, the cholesteric liquid crystal layer of the wavelength selective film is only the second cholesteric liquid crystal layer.

[Comparative Example 3]
In Comparative Example 3, the first cholesteric liquid crystal layer and the second cholesteric liquid crystal layer were not provided as compared with Example 3-1.

[Example 4-1]
In Example 4-1, each member was configured assuming an image source unit following the example of the image source unit 30 for the liquid crystal display device shown in FIG. The configuration of each member in Example 4-1 is as follows.

<Organic EL panel>
The organic EL panel as a light emission source in this example is a white organic EL panel, and emits white light. FIG. 10 shows the light emission characteristics of the light source. The horizontal axis is wavelength and the vertical axis is intensity. As can be seen from FIG. 10, the light source includes wavelengths of 490 nm and its front and back, and 590 nm and its front and back.

<Color filter>
The color filter in this example has the transmittance characteristic shown in FIG. The thicknesses were R = 3.4 μm, G = 3.7 μm, and B = 3.9 μm.

<Wavelength selection film>
The same wavelength selective film as in Example 1-1 was applied.

[Example 4-2]
In Example 4-2, the second cholesteric liquid crystal layer was excluded from Example 4-1. Therefore, the cholesteric liquid crystal layer of the wavelength selective film is only the first cholesteric liquid crystal layer.

[Example 4-3]
In Example 4-3, the first cholesteric liquid crystal layer was excluded from Example 4-1. Therefore, the cholesteric liquid crystal layer of the wavelength selective film is only the second cholesteric liquid crystal layer.

[Comparative Example 4]
In Comparative Example 4, the first cholesteric liquid crystal layer and the second cholesteric liquid crystal layer were not provided as compared to Example 4-1.

[Example 5-1]
In Example 5-1, the organic EL panel as a light emission source was changed from Example 4-1. The light emission characteristics are shown in FIG. This organic EL panel is a three-color organic EL panel. As can be seen from FIG. 12, the light source includes wavelengths of 490 nm and its front and back, and 590 nm and its front and back.
Other configurations are the same as those of Example 4-1.

[Example 5-2]
In Example 5-2, the second cholesteric liquid crystal layer was excluded from Example 5-1. Therefore, the cholesteric liquid crystal layer of the wavelength selective film is only the first cholesteric liquid crystal layer.

[Example 5-3]
In Example 5-3, the first cholesteric liquid crystal layer was excluded from Example 5-1. Therefore, the cholesteric liquid crystal layer of the wavelength selective film is only the second cholesteric liquid crystal layer.

[Comparative Example 5]
In Comparative Example 5, the first cholesteric liquid crystal layer and the second cholesteric liquid crystal layer were not provided as compared with Example 5-1.

2. Evaluation The evaluation was based on how wide (narrow) the color gamut is with respect to the color gamut according to the NTSC standard. By having a wider color gamut, it means that a color in a highly saturated area can also be expressed. The color gamut according to the NTSC standard is known, but the vertices on the xy chromaticity diagram are R (0.670, 0.330), G (0.210, 0.710), B (0.140, 0). .080) is a triangle.
The xy chromaticity coordinates of each pixel of the color filter were calculated for the laminates of the above examples, thereby obtaining a triangular color gamut having the above coordinates as vertices. This triangle was compared with the triangular color gamut according to the NTSC standard. Specifically, the value obtained by dividing the area of the color gamut according to each of the above examples by the area of the color gamut of the NTSC standard was expressed as a percentage as “ratio to NTSC”.
Here, the measurement for calculating the xy chromaticity coordinates is performed using a spectroradiometer (SR-2, manufactured by TOPCON) under the condition that the distance between the spectroradiometer and the laminate surface is 50 cm and the measurement angle is 2 degrees. It was.

3. Results The results are shown in Table 1 along with the main conditions. In Table 1, the “first” column represents a case where the first cholesteric liquid crystal layer is present, and the “second” column represents a case where the second cholesteric liquid crystal layer is present. In Table 1, “ratio to NTSC” is an area ratio expressed as a percentage as described above. Furthermore, “ratio to comparative example” in Table 1 is the ratio of the ratio of NTSC in each example to Examples 1-1, 1-2, and 1-3, where the ratio of Comparative Example 1 to NTSC is 1.0. It is represented by Examples 2-1, 2-2, and 2-3 are Comparative Example 2, Examples 3-1, 3-2, and 3-3 are Comparative Example 3, and Examples 4-1, 4-2, and 4-3 are Comparative Example 4 and Examples 5-1, 5-2, and 5-3 show ratios in the same manner as Comparative Example 5, respectively.

  As can be seen from Table 1, when the second cholesteric liquid crystal layer is provided alone, and when both the first cholesteric liquid crystal layer and the second cholesteric liquid crystal layer are provided, a wide color gamut can be obtained and high saturation can be obtained. It can be seen that the color of the region can also be expressed.

  In addition, when the first cholesteric liquid crystal is provided alone, it can be seen that a wide color gamut can be obtained particularly in a liquid crystal display device, and colors in a highly saturated area can also be expressed.

  Further, according to the wavelength selection film, the same wavelength selection film has an effect on many types of light emitting sources.

DESCRIPTION OF SYMBOLS 10 Wavelength selection film 11 Base material 12 1st cholesteric liquid crystal layer 13 2nd cholesteric liquid crystal layer 20 Image source unit 21 Backlight 22 Liquid crystal display panel 23 Liquid crystal cell layer 24 Linearly polarizing plate 25 Color filter 26 Linearly polarizing plate 30 Image source unit 31 Organic EL display panel 32 Optical functional laminate 33 Color filter 34 λ / 4 retardation plate 35 Linearly polarizing plate

Claims (19)

A wavelength selection film that is arranged in a display device and blocks light of a predetermined wavelength,
A cholesteric liquid crystal layer having a cholesteric liquid crystal structure;
The cholesteric liquid crystal layer reflects light in a predetermined wavelength band including 590 nm;
Wavelength selective film.   2. The wavelength selective film according to claim 1, wherein the cholesteric liquid crystal layer is formed by laminating two layers of two cholesteric liquid crystals having a spiral structure rotating in opposite directions.   The wavelength-selective film according to claim 2, wherein the two cholesteric liquid crystal layers are integrated with each other via an adhesive.   The wavelength selection film according to claim 1, wherein the cholesteric liquid crystal layer has a thickness of 10 μm or less.   The wavelength-selective film according to claim 1, wherein the cholesteric liquid crystal layer includes a rod-like liquid crystal. Furthermore, it has another cholesteric liquid crystal layer,
6. The wavelength selective film according to claim 1, wherein the other cholesteric liquid crystal layer reflects light in a predetermined wavelength band including 490 nm.   The wavelength-selective film according to claim 6, wherein the other cholesteric liquid crystal layer is formed by laminating two layers of two cholesteric liquid crystals having a spiral structure rotating in opposite directions.   The wavelength-selective film according to claim 7, wherein the two cholesteric liquid crystal layers in the other cholesteric liquid crystal are integrated with each other through an adhesive.   The wavelength selection film according to any one of claims 6 to 8, wherein the thickness of the other cholesteric liquid crystal layer is 10 µm or less.   The wavelength-selective film according to claim 6, wherein the other cholesteric liquid crystal layer has a rod-like liquid crystal. With backlight,
A laminate comprising: the wavelength selective film according to claim 1, which is disposed on a light output side of the backlight. The wavelength selective film according to any one of claims 1 to 10,
And a liquid crystal cell layer disposed on the light output side of the wavelength selective film. With backlight,
The wavelength selective film according to any one of claims 1 to 10, which is disposed on a light output side of the backlight,
A liquid crystal cell layer disposed on the light output side of the backlight;
A color filter disposed on the light output side of the liquid crystal cell layer,
Video source unit. With backlight,
A wavelength selection film disposed on the light output side of the backlight;
A liquid crystal cell layer disposed on the light output side of the backlight;
A color filter disposed on the light output side of the liquid crystal cell layer,
The wavelength selective film has a cholesteric liquid crystal layer having a cholesteric liquid crystal structure, and the cholesteric liquid crystal layer reflects light in a predetermined wavelength band including 490 nm.
Video source unit. An organic EL display panel;
The wavelength selection film according to any one of claims 1 to 10, which is disposed on a light output side of the organic EL display panel,
Video source unit.   A display device comprising the video source unit according to claim 13 housed in a casing. A method for producing the wavelength selective film according to claim 2,
After applying the composition before curing constituting one of the two cholesteric liquid crystal layers, the orientation and curing,
A method for producing a wavelength selective film, in which a composition before curing that constitutes a layer made of the other cholesteric liquid crystal is applied without winding up the formed layer, and then oriented and cured. A method for producing the wavelength selective film according to claim 6,
Orienting and curing after applying the composition before curing constituting the cholesteric liquid crystal layer,
A method for producing a wavelength selective film, wherein a composition before curing that constitutes the other cholesteric liquid crystal layer is applied without winding up the formed cholesteric liquid crystal layer, and then oriented and cured. A method for producing the wavelength selective film according to claim 7,
In the other cholesteric liquid crystal layer, one of the two cholesteric liquid crystal layers and one of the cholesteric liquid crystal layers is coated with an uncured composition, and then oriented and cured.
A method for producing a wavelength selective film, in which a composition before curing that constitutes a layer made of the other cholesteric liquid crystal is applied without winding up the formed layer, and then oriented and cured.

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