JPWO2018043618A1 - Depolarization element - Google Patents

Abstract

It is an object of the present invention to provide a depolarizing element capable of suppressing change in tint due to transmission while maintaining high transparency and providing a plurality of regions having different thicknesses. It has a liquid crystal layer composed of aligned liquid crystals.

Description

  The present invention relates to a depolarizer for depolarizing light in a polarized state and turning it into a non-polarized light as a whole.

  The light in which the phase state is uniform (polarized light) has strong regularity, so that interference may occur or the light may not be transmitted through the polarizing plate such as polarizing sunglasses, which may cause a problem. It is necessary to cancel the state (polarization state).

  As means for that purpose, for example, a technique of applying a film having a high retardation as described in Patent Document 1 and a technique of applying an element having a plurality of regions having different film thicknesses as described in Patent Document 2 is there.

  Further, as described in Patent Document 3, there is also a technique of dispersing light in a random manner by dispersing inorganic particles having birefringence in a transparent resin to eliminate the polarization state.

Patent No. 3105374 JP 2014-2286 A JP 2012-88507 A

  However, a film having a high retardation as described in Patent Document 1 has a large difference in transmittance depending on the wavelength, and therefore, depending on incident light, the color may change due to transmission. Further, in the device described in Patent Document 2, the device becomes thick, and if there are a plurality of regions having different phase differences, the function as a depolarizer is exhibited, but the transmittance by wavelength is biased, and the color tone There is a problem that is attached.

  In the technique of dispersing inorganic particles having birefringence in a transparent resin, since particles having different refractive indexes are dispersed, the transparency is impaired and the haze is increased.

  Therefore, in view of the above problems, the present invention is to provide a depolarizing element capable of reducing the change in tint due to transmission while maintaining high transparency, and capable of suppressing thickening. It will be an issue.

  Hereinafter, the present invention will be described.

  One aspect of the present invention is a depolarizer that emits a plurality of phase differences with respect to incident light and emits the light, and has a liquid crystal layer made of liquid crystal in which a plurality of regions having different thicknesses are arranged. It is an element.

  In the depolarizer, the liquid crystal layer may have a configuration in which a plurality of convex portions and concave portions formed between adjacent convex portions are arranged on at least one surface.

  In the depolarizer, the liquid crystal layer may have a plurality of convex portions formed on at least one surface and a concave portion formed between adjacent convex portions irregularly arranged.

  Moreover, it can also be comprised so that the uneven | corrugated formation layer which consists of transparent resin may be provided in this recessed part.

  Moreover, it can also be set as the depolarizing element by which the said liquid-crystal layer and the said unevenness | corrugation formation layer are laminated | stacked on one surface of a transparent base material.

  In addition, the convex portion has a predetermined cross section and extends in one direction, and a direction in which the convex portion extends with respect to the edge of the outer shape of the depolarization element is inclined in a range larger than 0 ° and smaller than 90 °. You can also

  In addition, the liquid crystal layer may be configured to be made of a polymerizable rod-like liquid crystal material or a disc-like liquid crystal material.

  Also, while the liquid crystal layer is made of a polymerizable rod-like liquid crystal material or a disc-like liquid crystal material, the convex part has a predetermined cross section and extends in one direction, the direction in which the convex part extends, and the polymerizable rod-like liquid crystal material or disc The direction of the slow axis of the liquid crystal material may be configured to be different.

  In the liquid crystal layer, the difference in thickness between the thickest portion and the thinnest portion may be 5 μm or less.

Further, in the depolarization element, when the front phase difference is Re and the thickness phase difference is Rth,
Nz = (Rth / Re) +0.5
For the Nz coefficient represented by the following equation, the Nz coefficient at a wavelength of 450 nm is N ₄₅₀ , and the Nz coefficient at a wavelength of 550 nm is N ₅₅₀ :
N ₄₅₀ <N ₅₅₀ -0.1
Can be established.

Regarding the liquid crystal of the liquid crystal layer described above, the birefringence at a wavelength of 450 nm is Δn ₄₅₀ , the birefringence at a wavelength of 550 nm is Δn ₅₅₀ , and the birefringence at a wavelength of 650 nm is Δn ₆₅₀ ,
Δn ₄₅₀ > Δn ₅₅₀ > Δn ₆₅₀
The relationship between
Here, the “birefringence” of each wavelength was determined by orienting the liquid crystal on a glass substrate, measuring the retardation, and dividing by the liquid crystal film thickness.

  In the depolarization element, the transmittance can be 0.2 or more and 0.8 or less in any wavelength in the wavelength range of 380 nm or more and 780 nm or less.

In addition, when the depolarizing element is disposed between two polarizing plates whose absorption axes are arranged orthogonally or in parallel so that the optical axis is inclined at 45 ° in plan view with respect to the absorption axis, a wavelength of 380 nm or more and 780 nm In the following wavelength range, the depolarizing element can have transmittance of 0.2 or more and 0.8 or less at any wavelength.
And when using this depolarizing element, it is equipped with the display unit which comprises a polarizing plate and radiate | emits an image, and the said depolarizing element arrange | positioned at the image output side of a display unit, The said 2 polarization It is also possible to provide a display device in which one of the plates is a polarizing plate provided in the display unit.

  The thickness of the depolarizer may be 20 μm or less.

  The haze value of the depolarizer may be 5% or less.

  Further, it is possible to provide a display device provided with a display unit for emitting an image and the above-described depolarizing element disposed on the image emission side of the display unit.

  The direction in which the convex portion of the depolarization element extends can be configured to be inclined in a range larger than 0 degrees and smaller than 90 degrees with respect to the direction in which the pixels of the display unit are arranged.

  In addition, it is possible to configure the form of the depolarizing element so as not to generate moire.

  According to the present invention, it is possible to form a plurality of regions having different thicknesses of the liquid crystal layer, to impart a plurality of different phase differences to the transmitted light, and eliminate the polarization state of the transmitted light as a whole. At that time, since the difference in transmittance between each visible light wavelength can be reduced, it is possible to suppress the change in color due to transmission. And since it comprises with a liquid crystal layer, a layer can be made thin.

FIG. 1A is a perspective view of the depolarizer 10, and FIG. 1B is an exploded perspective view of the depolarizer 10. As shown in FIG. FIG. 2 is a cross-sectional view of a depolarizer 10. 5 is a graph illustrating the operation of the depolarizer 10. FIG. 2 is a cross-sectional view of a depolarizer 20. 5 is a graph illustrating the operation of the depolarizer 20. FIG. 2 is a cross-sectional view of a depolarizer 30. FIG. 5 is a cross-sectional view of a depolarizer 40. 8 (a) is a cross-sectional view of the depolarizer 50, and FIG. 8 (b) is a cross-sectional view of the depolarizer 60. As shown in FIG. FIG. 7 is a cross-sectional view of the depolarizer 70. FIG. 1 is an exploded perspective view conceptually showing an image forming apparatus 1; It is a graph showing the relationship between the wavelength in Example 1 and Comparative Example 1, and a front phase difference. It is a graph showing the relationship between the wavelength in Example 1 and Comparative Example 1, and a Nz coefficient. It is a figure explaining the form of Example 2-Example 4. FIG. FIG. 18 is a diagram for explaining the form of Example 5; FIG. 18 is a diagram for explaining the form of Example 6; FIG. 18 is a diagram for explaining the form of Example 7; FIG. 18 is a view for explaining the form of Example 8; It is a figure explaining the form of Example 9-19.

  Hereinafter, the present invention will be described based on the embodiments shown in the drawings. However, the present invention is not limited to these embodiments. In the drawings, even small elements may be deformed or enlarged for the sake of easy understanding, and when the same elements are repeatedly arranged, some of the reference numerals may be omitted.

  FIG. 1 is a view for explaining the first embodiment, and FIG. 1 (a) is a perspective view of the depolarizer 10. FIG. 1 (b) is an exploded perspective view of the depolarizer 10. As shown in FIG. As can be seen from FIGS. 1 (a) and 1 (b), the depolarizer 10 of this embodiment is configured to have a base 11, an asperity-forming layer 12, and a liquid crystal layer 15.

The base material 11 is a transparent layer which becomes a base material for laminating the unevenness forming layer 12 and the liquid crystal layer 15 on one surface thereof. Various materials can be used as the material of the substrate 11. However, it is widely used as a material of a member constituting an optical element, and a material which has excellent mechanical properties, optical properties, stability, processability and the like and can be obtained inexpensively can be used. For example, thermoplastic resins such as polymer resins having an alicyclic structure, methacrylic resins, polycarbonate resins, polystyrene resins, acrylonitrile-styrene copolymers, methyl methacrylate-styrene copolymers, ABS resins, polyether sulfones and the like And epoxy acrylate and urethane acrylate reactive resins (ionizing radiation curable resins etc.), triacetyl cellulose resin, polyethylene terephthalate resin (PET), glass and the like.
And the thickness can be comprised in 10 micrometers or more and 1000 micrometers or less.

The concavo-convex forming layer 12 is a layer for providing a plurality of portions having different thicknesses to the liquid crystal layer 15, and in the present embodiment, a plurality of convex streaks 13 are arranged at intervals. Accordingly, in the region where the ridges 13 are disposed, the ridges 12a and the ridges 13 form recesses 12b, and the ridges 12a and the recesses 12b are repeatedly arranged.
In the present embodiment, the ridges 13 are quadrangular prisms having a quadrangular cross section, and the plurality of ridges 13 are arranged along one surface of the base material 11 so that the axis lines of the columns are parallel. .

  Various materials can be used as the material forming the ridges 13 of the unevenness forming layer 12. However, materials which are widely used as materials of members constituting optical elements and which have excellent mechanical properties, optical properties, stability, processability and the like and can be obtained inexpensively can be used. For example, thermoplastic resins such as polymer resins having an alicyclic structure, methacrylic resins, polycarbonate resins, polystyrene resins, acrylonitrile-styrene copolymers, methyl methacrylate-styrene copolymers, ABS resins, polyether sulfones and the like And epoxy acrylate and urethane acrylate reactive resins (ionizing radiation curable resins and the like), triacetyl cellulose resins and the like.

The base 11 and the concavo-convex forming layer 12 described above may be integrated without a boundary, or the concavo-convex forming layer 12 may be laminated on the surface of the base 11 and another member may be adhered. .
As the manufacturing process, extrusion molding, molding, photolithography and the like can be mentioned. In the case of manufacturing by extrusion molding, the base material 11 and the unevenness forming layer 12 can be integrally formed. Moreover, when manufacturing by forming, it can form by forming the unevenness forming layer 12 on the base material 11, and in this case, the base material layer 11 and the unevenness forming layer 12 are the same resin. It may be a material or a different material.

The liquid crystal layer 15 is a layer made of a liquid crystal material laminated on the unevenness forming layer 12. Therefore, the surface of the liquid crystal layer 15 on the side in contact with the unevenness forming layer 12 has unevenness opposite to the unevenness of the unevenness forming layer 12. That is, the liquid crystal layer 15 includes the convex portion 15 a so as to fill the concave portion 12 b of the concavo-convex forming layer 12 and the concave portion 15 b so as to be filled with the convex portion 12 a of the concavo-convex forming layer 12. Therefore, in the present embodiment, the concavo-convex forming layer 12 and the liquid crystal layer 15 are in contact with each other with a concavo-convex interface.
On the other hand, the surface of the liquid crystal layer 15 opposite to the uneven surface is a smooth surface in this embodiment. However, other uneven surfaces may be formed without being limited to this.

Here, for the liquid crystal constituting the liquid crystal layer 15, when the birefringence at a wavelength of 450 nm is Δn ₄₅₀ , the birefringence at a wavelength of 550 nm is Δn ₅₅₀ , and the birefringence at a wavelength of 650 nm is Δn ₆₅₀ ,
Δn ₄₅₀ > Δn ₅₅₀ > Δn ₆₅₀
The relationship between That is, it is also possible to use a liquid crystal layer having wavelength dispersion (positive dispersion) in which the phase difference decreases in the visible light region from the short wavelength side to the long wavelength side. Here, the “birefringence” of each wavelength was determined by orienting the liquid crystal on a glass substrate, measuring the retardation, and dividing by the liquid crystal film thickness.
Conventionally, polycarbonate using fluorene as a material having reverse dispersive property (that is, wavelength dispersive property in which the phase difference becomes large from the short wavelength side to the long wavelength side in the visible light region) has characteristics reverse to the normal dispersive property. Copolymer resins are known, but when they are used, the members become thick.
As for liquid crystal materials, polymerizable liquid crystal compounds having reverse dispersion may be mentioned. However, although thin film formation is possible with such a polymerizable liquid crystal compound, there is a problem in that the cost is higher than that of the positive dispersion material and the product is widely supplied.
On the other hand, in the present embodiment, by using the above-described configuration, it is possible to use a positive dispersive liquid crystal material, to obtain a thinner depolarizing element without giving a tint while suppressing costs.

  Although the liquid crystal material which comprises the liquid-crystal layer 15 is not specifically limited, For example, rod-like liquid crystal material like (1)-(17) represented by the following chemical formula can be mentioned.

  Among them, those made of a polymerizable rod-like liquid crystal material can be used. As a polymerizable functional group in this case, what superposes | polymerizes by the effect | action of an ionizing radiation, such as an ultraviolet-ray and an electron beam, or a heat can be mentioned, for example. Specific examples include radically polymerizable functional groups. Representative examples of the radically polymerizable functional group include functional groups having at least one addition-polymerizable ethylenic unsaturated double bond, and specific examples thereof include a vinyl group having or not having a substituent and an acrylate group. (A generic name including an acryloyl group, a methacryloyl group, an acryloyloxy group, and a methacryloyloxy group) and the like.

  In addition to the rod-like liquid crystal material, discotic liquid crystal which is a disk-like liquid crystal material can also be used. Therefore, widely known compounds exhibiting discotic liquid crystallinity can be used, which have a disc-like core portion and a structure in which side chains extend radially from the core portion.

  The liquid crystal layer 15 as described above can be formed by applying a liquid crystal material to the base 11 and the unevenness forming layer 12.

The depolarizer 10 having the above-described structure has, for example, the following form. FIG. 2 shows a cross-sectional view for explanation.
In the present embodiment, the unevenness forming layer 12 causes the liquid crystal layer 15 to alternately arrange two different thickness regions. That is, a region having a liquid crystal thickness indicated by d1 in FIG. 2 and a region having a liquid crystal thickness indicated by d2. The liquid crystal thickness indicated by d1 is the thickness of the region of the liquid crystal layer 15 by the convex portion 15a, and the liquid crystal thickness indicated by d2 is the thickness of the region of the liquid crystal layer 15 by the recess 15b. The thickness (d1) of the liquid crystal layer 15 for such a liquid crystal layer to act as described later can be in the range of 1 μm to 10 μm. It is possible to obtain the effect even in the range of 1 μm to 5 μm.
In the liquid crystal layer 15, the difference in thickness between the thickest portion (the portion d1 in the present embodiment) and the thinnest portion (the portion d2 in the present embodiment) is preferably 5 μm or less.

On the other hand, it is preferable that the pitch p of the adjacent convex part 15a shown in FIG. 2 is one to 100 micrometer. If the pitch is less than 1 μm, the cause is not clear but the depolarization effect tends to be small. In addition, when the pitch is larger than 100 μm, there is a possibility that the unevenness may be visually recognized. More preferably, it is 20 μm or less.
Further, the ratio of the convex portion 15a to the concave portion 15b in one pitch is not particularly limited, and can be appropriately set based on the required depolarization and the transmittance characteristic for each wavelength. However, as described later in the examples, the ratio produces a more remarkable effect.

As described above, since the liquid crystal layer is used in this embodiment, the polarization state can be canceled by a very thin element. For example, the thickness of the depolarizer 10 shown by d0 in FIG. 2 can be set to 20 μm or less.
In addition, since the element can be made flexible, it is possible to flexibly correspond to the shape of the object to which the depolarizing element 10 is applied, because the element can be made flexible.

  In addition, in this embodiment, since liquid crystal is used to convert light into a plurality of lights having different phase differences, there is no increase in haze that occurs when inorganic particles are dispersed, and light can be transmitted in the state without increase in haze. It is. Specifically, it is also possible to form a depolarizer having a haze value of 5% or less.

The depolarizer 10 having the above-described configuration operates as follows, for example.
The light in phase (in a predetermined polarization state) is incident on the depolarization element 10. Then, this light passes through the liquid crystal layer 15.
Here, in the depolarizer 10 of this embodiment, in the liquid crystal layer 15, two types of regions having different thicknesses of the region of thickness d1 consisting of the convex portion 15a and the region of thickness d2 consisting of the concave portion 15b are Have.
The retardation (Re: retardation) generated in the light transmitted through the liquid crystal layer is determined by the product of the refractive index difference Δn of the birefringence light depending on the liquid crystal material and the thickness d of the liquid crystal layer. That is,
Re = Δn · d
It is.

Therefore, in the depolarizer 10 of this embodiment, as a result of the light having the same phase (in the predetermined polarization state) being transmitted through the depolarizer 10,
Re1 = Δn · d1
Re2 = Δn · d2
Thus, light having two types of phase differences can be obtained, and a single phase difference (polarization) state can be eliminated.

At this time, as described below, the depolarizer 10 can suppress the difference in transmittance depending on the wavelength, and can transmit light while suppressing the change in color. The figure for description is shown in FIG. FIG. 3 is a graph in which the abscissa represents the wavelength and the ordinate represents the transmittance.
As can be seen from FIG. 3, the total transmittance of the depolarizer 10 is the total transmittance of the characteristic of the transmittance in the region of the convex portion 15 a and the characteristic of the transmittance in the region of the concave portion 15 b. Therefore, if the transmittance characteristics of each region are adjusted so that the transmittance for each wavelength is constant (for example, around 0.5), an element having transmittance characteristics in which the bias of the transmittance due to the wavelength is suppressed as a whole is obtained. be able to.
Thereby, in the depolarizer 10, it is possible to suppress the difference in transmittance due to the wavelength in the visible light range, and to transmit light while suppressing the change in color. That is, even when the depolarizer 10 is used for an image display device, sunglasses, or the like, it is possible to provide the viewer with a change in color relative to the color of the original image. Therefore, in the conventional depolarizer, the change in color in the transmitted light sometimes causes a problem, but such a problem can be solved.

  Similarly, when the light source of the image display device has a sharp emission spectrum, in the conventional depolarizer, the transmittance of a predetermined color is determined by the relationship between the emission spectrum and the wavelength transmittance characteristic of the depolarizer. There is a problem that the color is greatly changed when it is extremely low and the light is transmitted through the depolarization element. Even with such a problem, according to the depolarizer of this embodiment, it is possible to suppress the change in color of the light source light and transmit it, and it becomes possible to cancel the polarization state regardless of the type of the light source. .

In addition, the depolarizer 10 is thin as described above, and by forming the liquid crystal layer 15 as described above, light traveling obliquely in the depolarizer is parallel to the thickness direction in the depolarizer. It is less likely to make a big difference with the light traveling on the As a result, even if there is light traveling obliquely in the depolarization element, it is easy to obtain the designed performance as desired for the depolarization state and color.
In the prior art, light obliquely advancing in the element travels across other retardation regions, so that it may not be possible to obtain a predetermined phase difference state or a color change may occur. The Therefore, the depolarizer of this embodiment can solve the problem of achieving the designed phase difference state and color change with high accuracy.

According to the depolarizing element 10, by providing the liquid crystal layer with the concavo-convex shape, it is possible to give totally different retardation characteristics as a whole to the liquid crystal layer having no asperity (liquid crystal as a simple material) . For example, when the front phase difference is Re and the thickness phase difference is Rth, the Nz coefficient is
Nz = (Rth / Re) +0.5
In but represented in the depolarizer of the present embodiment includes a _{N 450} is a Nz coefficient at a wavelength of 450 nm, with the _{N 550} is a Nz coefficient at a wavelength of 550 nm,
N ₄₅₀ <N ₅₅₀ -0.1
It is also possible. This means that the material properties of the liquid crystal used can be reversed (see the examples below).
As described above, in the depolarizing element, it is possible to control the phase difference beyond the range of the material characteristics by the combination of the concavities and convexities and the liquid crystal material forming the concavities, and the depolarizing element becomes high in design freedom.

The depolarizer 10 described above can be manufactured, for example, as follows. That is, as described above, the base material 11 and the unevenness forming layer 12 can be manufactured by extrusion molding, molding, photolithography and the like. In the case of manufacturing by extrusion molding, the base material 11 and the unevenness forming layer 12 can be integrally formed. Moreover, when manufacturing by forming, it can form by forming the unevenness forming layer 12 on the base material 11, and in this case, the base material 11 and the unevenness forming layer 12 are the same resin material However, different resin materials may be used.
A liquid crystal material to be the liquid crystal layer 15 is coated on the side of the base 11 and the unevenness forming layer 12 formed as described above on which the unevenness forming layer 12 is disposed, whereby a liquid crystal layer 15 is obtained to obtain the depolarizing element 10.

In the technology using a film having a high retardation as described in Patent Document 1 which is a conventional depolarizer, it is necessary to stretch the film in an oblique direction in order to adjust the optical axis, and the optical axis varies. There was a risk of On the other hand, according to the depolarizer 10 and the above manufacturing method, when the alignment film is not used, the direction of the unevenness is the direction of the optical axis, and the direction of the unevenness can be easily controlled with high accuracy. Therefore, when it is an object to provide a depolarizing element that needs to control the optical axis, the depolarizing element is capable of high-volume productivity and accurate optical axis control by doing as described above. The manufacturing method can be provided.
Also, as in the embodiment described later, in the case of using an alignment film, an arbitrary direction determined by the polarization exposure can be used as an optical axis, and also in this case, optical axis control can be performed accurately and easily. .
Therefore, it is preferable that the optical axes are aligned in each of the regions where the thickness of the liquid crystal layer 15 of the depolarizer 10 is different. Specifically, it is preferable that the direction of the slow axis be in the range of ± 1 ° between the respective regions.

FIG. 4 is a view for explaining a depolarization element 20 which is a second embodiment of a modified example of the depolarization element 10, and corresponds to FIG. In the depolarizing element 10 described above, the liquid crystal layer 15 is formed to have two types of thicknesses (d1 and d2), but in the depolarizing element 20, the liquid crystal layer 25 has three types of thicknesses d21, d22, It is configured to be able to d23.
That is, the unevenness forming layer 22 includes the first convex portion 22a, the second convex portion 22b different in height (thickness) from the first convex portion 22a, and the concave portion 22c. Therefore, the recessed part 22c is formed between the 1st convex part 22a and the 2nd convex part 22b. And the liquid crystal layer 25 is provided with the convex part 25a, the 1st recessed part 25b, and the 2nd recessed part 25c corresponding to this. The basic configuration is the same as that of the depolarizer 10.
According to this, as also shown in FIG. 4, in the liquid crystal layer 25, the thickest portion in the region of the convex portion 25 a (thickness d 21), and then the thickened region of the first concave portion 25 b (thickness d 22), And the thinnest (thickness d23) in the area of the second recess 25c.

  According to such a depolarizer 10, since transmitted light has three different phase differences (non-polarization state), depolarization can be performed more reliably. Further, as shown in FIG. 5 corresponding to FIG. 3, when viewed as the whole of the depolarizer 20, substantially the same transmittance (0.5) can be obtained at all wavelengths of visible light, and It is possible to suppress the change significantly.

  In this modification, the liquid crystal layer 25 is configured to obtain three types of thickness, but the convex portion and the concave portion of the liquid crystal layer may be formed so as to obtain more types of thickness. At that time, the arrangement of the asperities may be formed to have regularity or may be irregular. Here, irregular means that the shape of a convex portion of one unit and the shape of a convex portion of another unit adjacent to this are regular, when ten convex portions are one unit. It says that there is not.

  That is, in the wavelength range of 380 nm to 780 nm in which the wavelength is in the visible light range, the transmittance is preferably 0.2 to 0.8 for any wavelength. More preferably, the transmittance at any wavelength is 0.3 or more and 0.7 or less, and most preferably 0.4 or more and 0.6 or less. In this transmittance, the depolarizing element is placed between two polarizing plates (with the transmission axis (or absorption axis) parallel or orthogonal), and the optical axis (the direction in which the unevenness extends when the alignment film is not disposed) is It can define with the transmittance | permeability when inserting in the attitude | position inclined 45 degree | times with respect to the absorption axis of a polarizing plate.

FIG. 6 is a view for explaining the depolarization element 30 of the third embodiment, and is a view corresponding to FIG. The present embodiment differs from the depolarizer 10 in that there is no substrate 11. The other parts are the same as in the depolarizer 10.
According to such a depolarization element 30, the element can be made thinner.
In the depolarizing element 30, the surface of the base 11 on which the concavo-convex forming layer 12 and the liquid crystal layer 15 are laminated is subjected to a treatment (for example, application of a release agent) to facilitate peeling. After the unevenness forming layer 12 is shaped and the liquid crystal layer 15 is applied and formed, the base 11 is peeled off.

FIG. 7 is a view for explaining the depolarization element 40 of the fourth embodiment, and is a view corresponding to FIG. The present embodiment differs from the depolarizing element 10 in that the base 11 and the unevenness forming layer 12 are not present.
According to such a depolarizing element 30, the element can be thinner than the depolarizing element 10.

The depolarizing element 40 is subjected to a treatment (for example, application of a release agent) on the surface of the substrate 11 and the surface on which the liquid crystal layer 15 of the unevenness forming layer 12 is to be laminated easily. After forming the forming layer 12 and applying and forming the liquid crystal layer 15, the base 11 and the unevenness forming layer 12 can be peeled off.
Alternatively, by using a liquid crystal material used for the liquid crystal layer 15 as a material that is easily peeled off from the base material layer 11 and the unevenness forming layer 12, the base material 11 and the unevenness forming layer 12 are peeled off from the liquid crystal layer 15. Can also be made.
According to such a manufacturing method, the liquid crystal layer 15 can be peeled off smoothly even if there are the convex portions 15a and the concave portions 15b which are portions having different thicknesses, and the liquid crystal layer 15 may be broken or wrinkles may occur. Can be prevented, so-called defective products can be reduced, and the yield can be improved and the productivity can be improved. Therefore, it is possible to solve the problem of producing the form such as the depolarizing element 40 with high yield and high productivity by such means.

FIG. 8 (a) is a view for explaining the depolarization element 50 of the fifth embodiment, and FIG. 8 (b) is a view for explaining the depolarization element 60 of the sixth embodiment. The depolarizer 50 and the depolarizer 60 are examples in which the alignment film 51 is provided on the surface of the liquid crystal layer 15 on which the asperities are formed. That is, in the depolarizer 50 shown in FIG. 8A, an example in which the alignment film 51 is provided on the surface of the liquid crystal layer 15 of the depolarizer 10 on which the unevenness is formed, the depolarizer shown in FIG. The element 60 is an example in which an alignment film 51 is provided on the surface of the liquid crystal layer 15 of the depolarizing element 40 on which the unevenness is formed.
Thereby, the alignment state of the liquid crystal molecules in the liquid crystal layer 15 can be made into a desired posture. And since it is possible to set an optical axis to arbitrary directions by this alignment film, optical axis control can be performed with sufficient accuracy easily. For example, when a polymerizable rod-like liquid crystal is used as the liquid crystal layer, the direction of the slow axis of the polymerizable rod-like liquid crystal can be set to be different from the direction in which the convexes of the liquid crystal layer extend using an alignment film. .
The specific aspect of the alignment film 51 can apply the thing of a well-known form as needed. In addition, the alignment film does not necessarily need to be left in the form of being laminated on the liquid crystal layer depending on the type, and even if the alignment film is used in the manufacturing stage, the alignment film may not be finally left. it can.

Here, in the depolarizing element 60, the surface on the side on which the alignment film 51 of the base material 11 and the unevenness forming layer 12 is laminated is subjected to a treatment (for example, application of a release agent) to facilitate peeling. After forming the concavo-convex forming layer 12 on 11 and forming the alignment film 51 and the liquid crystal layer 15, the base 11 and the concavo-convex forming layer 12 can be manufactured by peeling.
In addition, since the releasability can be enhanced by using the alignment film 51, the separation can be smoothly performed without the need for additional processing. Furthermore, it is possible to make the material used for the alignment film 51 easier to peel off by using an additive such as a crosslinking agent or an adhesion aiding agent.

  FIG. 9 is a view for explaining the depolarizer 70 of the seventh embodiment. In the depolarizer 70, a plurality of convex portions 15a (or a plurality of concave portions having different depths in the step shape) having different heights (thicknesses) are formed stepwise in the unevenness of 1 unit shown by p in FIG. It is an example provided. Such a form can also be used as the depolarizer of the present invention.

  The depolarizer 10 described above (as well as the depolarizers in the other embodiments are the same), for example, is disposed in a display device such as a liquid crystal display device, thereby eliminating problems caused by light in a polarization state. Can. As one form, as shown in FIG. 10, the display device 1 includes a display unit 2 for emitting an image, and a depolarizing element 10 disposed on the image emission side of the display unit 2. And these are combined with other required apparatus, and it is set as the display apparatus 1 by accommodating in a housing not shown.

A liquid crystal display device 1 can be mentioned as a specific embodiment of the display device 1, and in that case, the display unit 2 is a liquid crystal display unit 2, where it is disposed on a layer made of liquid crystal to be an image source and its front and back. And a liquid crystal panel having a polarizing plate. The liquid crystal display unit 2 may be a known one and can use an existing form.
In a normal liquid crystal display device, the light emitted from the liquid crystal display device is in a predetermined polarization state due to the nature of the liquid crystal panel. The image may be almost invisible. On the other hand, if the depolarizing element 10 is disposed on the output side of the liquid crystal display unit 2 to form the liquid crystal display device 1, the observer can view the image light whose polarization state has been eliminated. You can still watch the video even if you

When the display device is a liquid crystal display device, it is preferable that the depolarization element provided here has the following configuration.
In the liquid crystal display unit 2, as is known, a layer made of liquid crystal and polarizing plates are disposed on each of the front and back sides (the light source side and the observer side) of the layer made of the liquid crystal. Among these polarizing plates, a polarizing plate disposed on the viewer side is prepared (polarizing plate a), and another polarizing plate having a transmission axis orthogonal to the transmission axis of the polarizing plate a is prepared (polarizing plate b And the polarization removing element 10 is disposed between the polarizing plate a and the polarizing plate b. At this time, the optical axis of the depolarizer 10 is set to 45 degrees viewed from the front with respect to the absorption axis of the polarizing plate a.
When a laminate of such a polarizing plate a, the depolarizing element 10, and the polarizing plate b is irradiated with light from the polarizing plate a side and the light emission side is measured by a spectrophotometer, the wavelength is a visible light region In the range of 380 nm to 780 nm, the transmittance is preferably 0.2 to 0.8 at any wavelength. More preferably, the transmittance at any wavelength is 0.3 or more and 0.7 or less, and most preferably 0.4 or more and 0.6 or less.

In addition, although the case of a liquid crystal display unit was demonstrated here, it can comprise similarly with the display unit of another kind provided with a polarizing plate. This includes, for example, an organic EL display unit. That is, a polarizing plate provided in the organic EL display unit is prepared (polarizing plate a), and another polarizing plate having a transmission axis orthogonal to the transmission axis of the polarizing plate a is prepared (polarizing plate b) The depolarization element 10 is disposed between a and the polarizing plate b. At this time, the optical axis of the depolarizer 10 is set to 45 degrees viewed from the front with respect to the absorption axis of the polarizing plate a.
When a laminate of such a polarizing plate a, the depolarizing element 10, and the polarizing plate b is irradiated with light from the polarizing plate a side and the light emission side is measured by a spectrophotometer, the wavelength is a visible light region In the range of 380 nm to 780 nm, the transmittance is preferably 0.2 to 0.8 at any wavelength. More preferably, the transmittance at any wavelength is 0.3 or more and 0.7 or less, and most preferably 0.4 or more and 0.6 or less.

Furthermore, in such a display unit there are pixels, which form a regular grid pattern. On the other hand, when the depolarizing element is used, interference fringes (moire) may occur due to the regular pattern of the pixels and the regularity of the depolarizing element. In the conventional depolarizer, it is often difficult to change the structure so as to prevent occurrence of moiré while maintaining the basic performance as the depolarizer in response to this.
On the other hand, according to the depolarizer of this embodiment, there are many elements that can be changed, such as the pitch of the asperity, the direction in which the asperity extends, the shape in the extending direction (linear or wavy), the size of the asperity, etc. Therefore, it becomes possible to set it as the form which a moire does not generate, having an effect mentioned above. For example, in a depolarization element whose outer shape (edge shape) is a square, the direction in which the asperities extend is an angle other than an angle parallel to or perpendicular to the side of the edge (an angle larger than 0 ° and smaller than 90 °) To form an angle of more than 0 degrees and less than 90 degrees with respect to the regular arrangement direction of the pixels, so that the occurrence of It can also be done efficiently when pasting.

  In the depolarizer of each form described above, the convexes and the concaves in the concavo-convex forming layer have a predetermined cross section and extend in one direction, and the concavities and convexities are repeated in the other direction. However, the unevenness forming layer is not limited to this, as long as a liquid crystal layer formed of liquid crystal in which a plurality of regions having different thicknesses are arranged is formed. Therefore, a plurality of convex portions may be regularly or irregularly dotted in a plane, and a concave portion may be formed between the convex portions. Examples thereof include so-called dot shapes, island shapes, and staggered arrangement shapes. This can also suppress moire generation.

  About suppressing generation | occurrence | production of a moire, it is possible to consider suitably in consideration of the pixel arrangement of the display unit which applies a depolarization element, and the combination with a pixel shape.

  Further, the example in which the cross-sectional shape of the convex portion and the concave portion of the liquid crystal layer described above is a quadrangle has been described. However, the present invention is not limited to this, and may be, for example, a triangle, a trapezoid, a semicircle, a semielliptic, or the like.

  In addition, in the case where the cross section of the convex portion and the concave portion of the liquid crystal layer is a triangle or a quadrangle, it may be configured to round the portion to be the vertex (edge line) (rounded chamfered shape). According to this, it is possible to suppress the occurrence of moiré due to the edge.

(Example 1, Comparative Example 1)
Here, a depolarizing element was produced as Example 1, and a laminate of a liquid crystal layer without irregularities was produced as Comparative Example 1, and the two were compared.

In the depolarizing element of Example 1, the substrate 11 was made of glass and the unevenness forming layer 12 was formed by photolithography, following the example of the depolarizing element 50 (FIG. 8A). The liquid crystal layer 15 was formed on the unevenness forming layer 12 and the base material 11 with the alignment film 51 interposed therebetween.
The pitch (see p in FIG. 2) of the concavo-convex forming layer 12 is 40 μm, and the thickness including the alignment film is about 2 μm in thickness corresponding to d1 in FIG. 2 and 1 μm in thickness corresponding to d2 It formed so that it might become an extent. Specifically, it was produced as follows.

  The uneven | corrugated formation layer used the curable resin composition, and prepared the copolymer resin solution for that purpose first. That is, 63 parts by mass of methyl methacrylate (MMA), 12 parts by mass of acrylic acid (AA), 6 parts by mass of 2-hydroxyethyl methacrylate (HEMA), and 88 parts by mass of diethylene glycol dimethyl ether (DMDG) in a polymerization tank The mixture was stirred and dissolved. Thereafter, 7 parts by mass of 2,2'-azobis (2-methylbutyronitrile) was added and uniformly dissolved. Then, it stirred at 85 degreeC under nitrogen stream for 2 hours, and also made it react at 100 degreeC for 1 hour. Further, 7 parts by mass of glycidyl methacrylate (GMA), 0.4 parts by mass of triethylamine, and 0.2 parts by mass of hydroquinone are added to the obtained solution, and the mixture is stirred at 100 ° C. for 5 hours to obtain a copolymer resin solution ( 50% solids was obtained.

Next, the following materials containing the copolymer resin solution obtained as described above were stirred and mixed at room temperature to prepare a curable resin composition.
・ 16 parts by mass of copolymer resin solution (solid content: 50%) ・ 24 parts by mass of dipentaerythritol pentaacrylate (Sartmar Japan KK SR399) ・ Orthocresol novolac epoxy resin (Japan Epoxy Resins Co., Ltd. Epicoat 180S70) 4 parts by mass
4 parts by mass of 2-methyl-1- (4-methylthiophenyl) -2-morpholinopropan-1-one 52 parts by mass of diethylene glycol dimethyl ether

Then, the obtained curable resin composition was coated on a substrate by a spin coater and dried at 100 ° C. for 3 minutes to obtain a coating film having a film thickness of about 1 μm. A photomask was placed at a distance of 100 μm from the coating film, and was irradiated with ultraviolet light of 100 mJ / cm ² with an exposure device. Then, it is immersed in a 0.05% by mass aqueous solution of potassium hydroxide for 1 minute for alkali development to remove only the uncured portion, and then heat treated by leaving it in an atmosphere at 200 ° C. for 30 minutes. An uneven layer was formed.

  A polymerizable rod-like liquid crystal material is applied to the liquid crystal layer, and a compound obtained by mixing rod-like compounds of the above-mentioned chemical formula (11) and chemical formula (17) in a mixing ratio of 1: 1 and BASF Japan Irgacure 907 as an initiator And Megafuck (F477, manufactured by DIC Corporation) were dissolved in a 1: 1 mixed solvent of methyl ethyl ketone and methyl isobutyl ketone to prepare and apply a 25 mass% solution.

The alignment film is coated with a photo alignment film (solid content 4.5%) manufactured by JSR Corporation to a film thickness of 0.2 μm, dried at 120 ° C. for 1 minute, and desired by a polarization exposure apparatus. The sample was placed at an angle and manufactured by irradiating 30 mJ / cm ² polarized ultraviolet light.

  On the other hand, the laminate of Comparative Example 1 uses the same base material, alignment film, and liquid crystal as in Example 1, and a liquid crystal layer with a thickness of 1 μm without irregularities is formed on the base through the alignment film.

  In the depolarizer according to the first embodiment, as described above, it is possible to give a plurality of phase differences to the incident light and emit it. On the other hand, in the laminate of Comparative Example 1, since the thickness of the liquid crystal layer is constant, a plurality of phase differences can not be given and the light can not be emitted, and it does not have a function as a depolarizer.

  Then, according to the depolarizer of Example 1, the liquid crystal layer having the concavo-convex shape imparts totally different retardation properties to the liquid crystal layer having no concavo-convex shape of Comparative Example 1 as a whole. It becomes possible. Specifically, it is as follows.

  FIG. 11 is a graph showing the front retardation Re (nm) for each wavelength. The frontal phase difference was measured using KOBRA-WR manufactured by Oji Scientific Instruments.

Furthermore, the thickness retardation Rth (nm) is similarly measured,
Nz = (Rth / Re) +0.5
The result of calculating is shown in FIG. In FIG. 12, the horizontal axis represents wavelength (nm) and the vertical axis represents Nz coefficient.
As can be seen from Figure 12, the _{N 450} is a Nz coefficient at a wavelength of 450 nm, looking at the difference between the _{N 550} is Nz coefficient, the difference in Comparative Example 1 is 0.05 at a wavelength 550nm On the other hand, it is 0.33 in the example. Thus, the depolarization element according to Example 1, the _{N 450} is a Nz coefficient at a wavelength of 450 nm, with the _{N 550} is a Nz coefficient at a wavelength of 550 nm,
N ₄₅₀ <N ₅₅₀ -0.1
Meet.

  As described above, in the depolarizer of this example, it is possible to control the phase difference beyond the range of the material characteristics by the combination of the unevenness and the liquid crystal material forming the unevenness, and the design freedom is high. It becomes a depolarizing element.

(Example 2 to Example 8, Comparative Example 2)
In Examples 2 to 8, the performance was confirmed by changing the thickness of the unevenness, the ratio of the convex portion to the concave portion, and the cross-sectional shape. Further, as Comparative Example 2, in the same manner as Comparative Example 1, the comparison was performed in an example having no unevenness. The materials used for each example are as in Example 1. The form of the liquid crystal layer in each example is shown in FIGS. 13 to 16 and Table 1.

  Example 2 to Example 4 are examples of a liquid crystal layer having one type of convex portion having the same height (thickness) and one type of concave portion having the same depth. The dimensions of the concavo-convex forming layer shown in FIG. 13 were changed to obtain depolarizing elements according to three examples.

  Example 5 is an example of a liquid crystal layer having two types of convex portions having different heights (thicknesses) and one type of concave portion having the same depth. It was set as the dimension of the uneven | corrugated formation layer shown in FIG.

  The sixth embodiment is an example of a liquid crystal layer having two types of convex portions having different heights (thicknesses) as in the fifth embodiment and one type of concave portion having the same depth. However, in this example, a rounded (rounded chamfered shape) is formed at the protruding corner of the convex portion or the inner corner of the concave portion, and the surface extends in the thickness direction forming the convex (slope A). Provided. The shape is shown in FIG. According to this example, the cross section of the convex portion and the concave portion of the liquid crystal layer is trapezoidal, and the corner portion is rounded and chamfered.

  Example 7 is an example of a liquid crystal layer having regions of different thicknesses such that the height (thickness) decreases by 0.15 μm from 1.93 μm to 0.43 μm. The dimensions in the array direction of the regions are as shown in FIG. As can be seen from FIG. 16, in this example, the liquid crystal layer is stepped.

  Example 8 is an example of a liquid crystal layer having one type of convex portion having the same height (thickness) and one type of concave portion having the same depth. In this example, the cross-sectional shape of the convex portion and the concave portion is a triangle. The shape is shown in FIG.

  The laminate of Comparative Example 2 includes an alignment film and a liquid crystal layer with a constant thickness of 2 μm provided in the alignment film.

  The “color reproduction test” and the transmittance measurement for each wavelength were performed on the element and the laminate in each of Examples 2 to 8 and Comparative Example 2 as described above. The details are as follows.

  In the color reproduction test, the device according to each example is attached to a liquid crystal display device, the screen of the liquid crystal display device is in color display, polarized sunglasses are applied (state 1), and polarized sunglasses are removed (state In 2), the screen was observed from the front, and the color reproducibility in state 1 was visually evaluated. The element according to each example was placed on the outermost surface of the liquid crystal display device so that the optical axis was 45 ° as viewed from the front with respect to the absorption axis of the polarizing plate on the viewer side of the liquid crystal display device.

The color difference between the state 1 and the state 2 was scored based on the following determination, and 20 people evaluated them to calculate an average point.
3 points: I do not mind the difference in color.
2 points: There are some differences in color but there is no problem.
1 point: There is a difference in color, but there is no problem in practical use.
0 point: There is a problem that the difference in color is very bad.
And, the average score is "good" particularly 2.5 points or more, the average score is "good" between 1.7 points and less than 2.5 points, and the average score is "more than 1.0 points and less than 1.7 points" And “less than 1.0” were considered “impossible”.

To measure the transmittance for each wavelength, prepare a polarizing plate for use in a liquid crystal display device, and further prepare another polarizing plate disposed so that the absorption axis is orthogonal to the polarizing plate (so-called crossed Nicols). The element of each example was disposed between two polarizing plates. At this time, the element was disposed such that the optical axis was inclined at 45 ° in plan view with respect to the absorption axis of the polarizing plate. Then, the laminate was illuminated with a backlight from the polarizing plate side, and was measured by a spectroradiometer from the other polarizing plate side. Specifically, the transmittance is measured for each wavelength (every 1 nm) in the wavelength range of 380 nm to 780 nm at a measurement angle of 2 ° and a distance of 50 cm from the element with a spectroradiometer (Topcon, SR-2) And got its maximum and minimum.
In this example, the measurement was performed using orthogonal Nicol, which is easier to understand the effect, but the same effect can be obtained by using parallel Nicol.

  The above evaluation results are also shown in Table 1.

  As can be seen from the above, it can be seen that the provision of irregularities in the liquid crystal layer eliminates the problem in color reproducibility. When the transmittance is 0.3 or more and 0.7 or less, and most preferably 0.4 or more and 0.6 or less, the color reproducibility is further improved.

In the sixth embodiment, since the corners of the convex portion and the concave portion are rounded, the occurrence of moiré due to the edge can be further suppressed.
By forming the taper as shown by A in FIG. 15, the rapid change in transmittance at this portion is mitigated, and the variation in transmittance due to each wavelength can be reduced.
In addition, as in the sixth and eighth embodiments, the effect can be obtained even if the convex portion and the concave portion of the liquid crystal layer do not have a square or rectangular cross section.

In Examples 9 to 19, the performance was examined for an example in which the ratio of the width of the asperities was changed based on the liquid crystal layer thickness of Example 5. A diagram for explanation is shown in FIG. In Examples 9 to 19, the width of the thinnest region in the liquid crystal layer is C, the width of the region having an intermediate thickness is B, and the width of the thickest region is A. Then, when C was a ratio of 1.00, each of A and B was expressed as a ratio, and the performance was examined.
The evaluation items and the evaluation method are the same as those in Examples 2 to 8 described above. Table 2 shows the shape and the evaluation results.

As can be seen from Table 2, the performance can be adjusted by adjusting the ratio of the width of the asperities. In consideration of this, while A ≦ B <C,
C-0.4 <A + B <C + 0.4
It is preferable from the viewpoint of color reproduction and transmittance characteristics, more preferably
C-0.25 <A + B <C + 0.25
It is.

10, 20, 30, 40, 50, 60, 70 Depolarization element 11 Base 12 Corrugated layer 13 Convex stripe 15 Liquid crystal layer 15a Convex part 15b Concave part

Claims (19)

A depolarization element that emits a plurality of phase differences with respect to incident light,
A depolarizer having a liquid crystal layer made of liquid crystal in which a plurality of regions having different thicknesses are arranged.   2. The depolarizer according to claim 1, wherein the liquid crystal layer has a plurality of convex portions and concave portions formed between adjacent convex portions arranged on at least one surface.   The depolarizer according to claim 1, wherein the liquid crystal layer has a plurality of convex portions on at least one surface and concave portions formed between the adjacent convex portions irregularly arranged.   The depolarizing element according to claim 2 or 3, wherein the concave portion is provided with an unevenness forming layer made of a transparent resin.   The depolarizing element according to claim 4, wherein the liquid crystal layer and the unevenness forming layer are laminated on one surface of a transparent substrate.   The convex portion has a predetermined cross section and extends in one direction, and a direction in which the convex portion extends with respect to an edge of a rectangular outline of the depolarizer is inclined in a range of more than 0 degree and less than 90 degrees. Item 5. The depolarizing element according to any one of Items 2 to 5. The liquid crystal layer is made of a polymerizable rod-like liquid crystal material or a disc-like liquid crystal material, and the convex portion has a predetermined cross section and extends in one direction.
The depolarizer according to any one of claims 2 to 6, wherein the direction in which the convex portion extends and the direction of the slow axis of the polymerizable rod-like liquid crystal material or the discotic liquid crystal material are different.   The depolarizing element according to any one of claims 1 to 6, wherein the liquid crystal layer comprises a polymerizable rod-like liquid crystal material or a discotic liquid crystal material.   The depolarizer according to any one of claims 1 to 8, wherein a difference in thickness between the thickest portion and the thinnest portion of the liquid crystal layer is 5 μm or less. When the front retardation is Re and the thickness retardation is Rth,
Nz = (Rth / Re) +0.5
For the Nz coefficient represented by the following equation, the Nz coefficient at a wavelength of 450 nm is N ₄₅₀ , and the Nz coefficient at a wavelength of 550 nm is N ₅₅₀ :
N ₄₅₀ <N ₅₅₀ -0.1
The depolarizing element according to any one of claims 1 to 9, wherein Regarding the liquid crystal of the liquid crystal layer, the birefringence at a wavelength of 450 nm is Δn ₄₅₀ , the birefringence at a wavelength of 550 nm is Δn ₅₅₀ , and the birefringence at a wavelength of 650 nm is Δn ₆₅₀ .
Δn ₄₅₀ > Δn ₅₅₀ > Δn ₆₅₀
A depolarizer according to any of the preceding claims, wherein   The depolarizer according to any one of claims 1 to 11, wherein the transmittance is 0.2 or more and 0.8 or less at any wavelength in a wavelength range of 380 nm to 780 nm.   When the depolarizing element is disposed between two polarizing plates whose absorption axes are arranged orthogonally or in parallel so that the optical axis is inclined at 45 ° in plan view with respect to the absorption axis, the wavelength is 380 nm or more and 780 nm or less 13. The depolarizer according to claim 12, wherein the transmittance is 0.2 or more and 0.8 or less at any wavelength in the wavelength range of.   The depolarizing element according to any one of claims 1 to 13, which has a thickness of 20 μm or less.   The depolarizing element according to any one of claims 1 to 14, which has a haze value of 5% or less. A display unit that emits an image;
A depolarizing element according to any one of claims 1 to 15, which is disposed on the image emission side of the display unit. A display unit having a polarizing plate and emitting an image;
The depolarization element according to claim 13, which is disposed on the image emission side of the display unit.
A display device, wherein one of the two polarizing plates according to claim 13 is the polarizing plate provided in the display unit.   The display device according to claim 16 or 17, wherein a direction in which the convex portion of the depolarization element extends is inclined in a range larger than 0 degrees and smaller than 90 degrees with respect to the direction in which the pixels of the display unit are arranged. .   The display device according to claim 16, wherein no moiré occurs.

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