JP2004110003A - Retardation optical element, manufacturing method therefor, and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a retardation optical element including a negative C-plate (retardation layer) and an A-plate (retardation layer), which does not produce bright-dark pattern on a display image to thereby effectively suppress a degradation in display quality even when disposed between a liquid crystal cell and a polarizing plate. <P>SOLUTION: The retardation optical element 10 is provided with a C-plate type retardation layer 12 which has a planar-aligned structure of cholesteric regularity and functions as a negative C-plate layer and an A-plate type retardation layer 14 which has a structure of nematic regularity and functions as an A-plate. The directions of directors Cb of liquid crystal molecules in a surface 12B on the A-plate type retardation layer 14 side of the C-plate type retardation layer 12 and the directions of directors Na of liquid crystal molecules in a surface 14A on the C-plate type retardation layer 12 side of the A-plate type retardation layer 14 coincide with each other. The C-plate type retardation layer 14 has a spiral pitch of the structure adjusted. <P>COPYRIGHT: (C)2004,JPO

Description

The present invention relates to a retardation optical element incorporated and used in a liquid crystal display device or the like, and more particularly, to a liquid crystal cell including a retardation layer acting as a negative C plate and a retardation layer acting as an A plate. A phase difference optical element for compensating a polarization state of light emitted in a direction inclined from a normal line of the liquid crystal cell among light incident and / or emitted from the liquid crystal cell, a method for manufacturing the same, and a phase difference optical element Liquid crystal display device.

FIG. 9 is a schematic exploded perspective view showing a conventional general liquid crystal display device.

As shown in FIG. 9, the conventional liquid crystal display device 100 includes a polarizing plate 102A on the incident side, a polarizing plate 102B on the emitting side, and a liquid crystal cell 104.

Among these, the polarizing plates 102A and 102B are configured to selectively transmit only linearly polarized light having a vibration surface in a predetermined vibration direction, and the respective vibration directions are perpendicular to each other. Are arranged opposite to each other in a crossed Nicols state. The liquid crystal cell 104 includes many cells corresponding to pixels, and is disposed between the polarizing plates 102A and 102B.

Here, in such a liquid crystal display device 100, the liquid crystal cell 104 is formed by a VA (Vertical Alignment) method in which a nematic liquid crystal having a negative dielectric anisotropy is sealed (in FIG. For example, linearly polarized light transmitted through the polarizing plate 102A on the incident side is phase-shifted when transmitted through the non-driven cell portion of the liquid crystal cell 104. And is blocked by the polarizing plate 102B on the emission side. On the other hand, when the light passes through the portion of the liquid crystal cell 104 that is driven, the linearly polarized light is phase-shifted, and an amount of light corresponding to this phase shift is transmitted through the exit-side polarizing plate 102B. Is emitted. Thus, by appropriately controlling the driving voltage of the liquid crystal cell 104 for each cell, a desired image can be displayed on the polarizing plate 102B on the emission side. In addition, the liquid crystal display device 100 is not limited to the above-described mode of transmitting and blocking light, and the light emitted from the non-driven cell portion of the liquid crystal cell 104 emits the polarizing plate on the emission side. There is also a liquid crystal display device configured so that light emitted from a cell portion in a driven state while being transmitted through and emitted through 102B is blocked by a polarizing plate 102B on the emission side.

By the way, in consideration of the case where the linearly polarized light passes through the non-driven cell portion of the VA type liquid crystal cell 104 as described above, the liquid crystal cell 104 has birefringence and refraction in the thickness direction. Since the refractive index and the refractive index in the plane direction are different, the light incident along the normal to the liquid crystal cell 104 out of the linearly polarized light transmitted through the polarizing plate 102A on the incident side is transmitted without being phase-shifted. Of the linearly polarized light transmitted through the polarizing plate 102A, light incident in a direction inclined from the normal line of the liquid crystal cell 104 has a phase difference when transmitted through the liquid crystal cell 104, and becomes elliptically polarized light. This phenomenon is caused when liquid crystal molecules vertically aligned in the liquid crystal cell 104 function as a positive C plate when a certain cell in the VA liquid crystal cell 104 is not driven. is there. The magnitude of the phase difference generated with respect to the light (transmitted light) transmitted through the liquid crystal cell 104 depends on the birefringence value of the liquid crystal molecules sealed in the liquid crystal cell 104, the thickness of the liquid crystal cell 104, and the transmitted light. It is also affected by wavelength and the like.

Due to the above phenomenon, a certain cell in the liquid crystal cell 104 is in a non-driving state, and even if linear polarization is originally transmitted as it is and should be cut off by the polarizing plate 102B on the output side, the liquid crystal cell 104 is not driven. A part of the light emitted in the direction inclined from the normal line will leak from the polarizing plate 102B on the emission side.

Therefore, in the conventional liquid crystal display device 100 as described above, the display quality of an image viewed from a direction inclined from the normal line of the liquid crystal cell 104 is more likely to be deteriorated than an image viewed from the front. (A problem of viewing angle dependence).

Various techniques have been developed so far to improve the viewing angle dependence problem in the conventional liquid crystal display device 100 as described above, and as one of them, for example, as described in Patent Document 1, Using a retardation optical element provided with a retardation layer having a cholesteric regularity structure (a retardation layer exhibiting birefringence), and disposing such retardation optical element between a liquid crystal cell and a polarizing plate. There has been known a liquid crystal display device which performs optical compensation by using a liquid crystal display device.

Here, in a phase difference optical element having a cholesteric regularity structure, λ = nav · p (p: a helical (helical) pitch in a helical structure of liquid crystal molecules, nav: an average refractive index in a plane perpendicular to a helical axis. ) Is adjusted so as to be smaller or larger than the wavelength of the transmitted light, as described in Patent Document 2, for example.

In the retardation optical element as described above, as in the case of the liquid crystal cell described above, linearly polarized light incident in a direction inclined from the normal to the retardation layer causes a phase difference when passing through the retardation layer. And becomes elliptically polarized light. This phenomenon is attributable to the fact that the structure of the cholesteric regularity acts as a negative C plate. Note that the magnitude of the phase difference generated with respect to light transmitted through the phase difference layer (transmitted light) depends on the birefringence value of liquid crystal molecules in the phase difference layer, the thickness of the phase difference layer, the wavelength of transmitted light, and the like. Is also affected.

Therefore, when the above-described retardation optical element is used, the phase difference generated in the VA type liquid crystal cell acting as a positive C plate and the phase difference generated in the retardation layer of the retardation optical element acting as a negative C plate are obtained. By appropriately designing the retardation layer of the retardation optical element so that the retardation cancels out, the problem of the viewing angle dependence of the liquid crystal display device can be significantly reduced.

Incidentally, such a problem of the viewing angle dependence of the liquid crystal display device is caused by a retardation layer acting as a negative C plate (that is, the refractive index in the plane direction is set to Nx, Ny) as described in Patent Document 3, for example. When the refractive index in the thickness direction is Nz, a retardation layer having a relationship of Nx = Ny> Nz) and a retardation layer acting as an A plate (that is, the refractive indices in the plane direction are Nx, Ny, When the refractive index in the thickness direction is set to Nz, the use of a retardation layer having a relationship of Nx> Ny = Nz) can further improve the characteristics.

However, when the above-mentioned conventional retardation optical element (a retardation layer having a cholesteric regularity structure and acting as a negative C plate) is disposed between the liquid crystal cell and the polarizing plate, the visual dependence Although the problem (1) can be improved, it has been found that a light and dark pattern or the like may be generated in a display image and display quality may be significantly reduced. In particular, as described above, it has been found that when the retardation layer acting as a negative C plate and the retardation layer acting as an A plate are used together in the retardation optical element, the display quality is significantly reduced. did.

The inventor of the present invention conducted an experiment on the cause of the occurrence of a light and dark pattern or the like by such a retardation optical element (having a retardation layer acting as a negative C plate and a retardation layer acting as an A plate). As a result of intensive research using computer simulations, it was found that one of the causes was in the direction of the director of the liquid crystal molecules on the surface of the retardation layer.

Note that the present inventors have already found that in a circularly polarized light extraction optical element provided with one or more liquid crystal layers having cholesteric regularity, the direction of the director of liquid crystal molecules on the surface of the liquid crystal layer and the vicinity of the interface between adjacent liquid crystal layers. Various proposals have been made with respect to the direction of the director of the liquid crystal molecules (Patent Documents 4 and 5). However, these proposals are based on a single liquid crystal layer having cholesteric regularity or a plurality of liquid crystal layers laminated on each other. The present invention relates to a circularly polarized light extraction optical element provided, and is suitable for a phase difference optical element as described above (one having a phase difference layer acting as a negative C plate and a phase difference layer acting as an A plate). Was not always clear.
JP-A-3-67219 JP-A-4-322223 JP-A-11-258605 JP 2002-189124 A Japanese Patent Application No. 2001-60392 (refer to JP-A-2002-258053)

The present invention has been made under such a background, and even when the liquid crystal cell is disposed between the liquid crystal cell and the polarizing plate, the display image does not generate a light and dark pattern or the like, and the display quality is reduced. Optical element comprising a retardation layer acting as a negative C plate and a retardation layer acting as an A plate, capable of effectively suppressing It is an object to provide a liquid crystal display device.

According to a first aspect of the present invention, there is provided a C-plate type retardation layer having a cholesteric regularity structure with a planar orientation and acting as a negative C-plate, and selectively reflecting light generated by the structure. A C-plate type retardation layer in which the helical pitch of the structure is adjusted so that the selective reflection wavelength is in a range different from the wavelength of the incident light; and a lamination adjacent to the C-plate type retardation layer; And an A-plate type retardation layer acting as an A-plate, and a liquid crystal on a surface on the A-plate type retardation layer side of two main surfaces of the C-plate type retardation layer facing each other. The direction of the molecular director and the direction of the liquid crystal molecules on the C-plate type retardation layer side surface of the two main surfaces of the A-plate type retardation layer facing each other. The direction of the coater to provide a retardation optical element, characterized in that substantially matches.

In the first solution, the direction of the director of the liquid crystal molecules on the surface on the side of the A-plate type retardation layer, out of the two main surfaces of the C-plate type retardation layer, It is preferable that the direction of the director of the liquid crystal molecules on the surface on the side away from the mold retardation layer is substantially parallel.

Further, in the first solution described above, the direction of the director of the liquid crystal molecules on the surface of the C plate type retardation layer on the side separated from the A plate type retardation layer, and the A plate type retardation layer It is preferable that the direction of the director of the liquid crystal molecules on the surface of the phase difference layer on the side away from the C-plate type phase difference layer is substantially parallel.

Furthermore, in the first solution described above, of the two main surfaces of the C-plate type retardation layer, the surface on the A-plate type retardation layer side and the surface apart from the A-plate type retardation layer are separated from each other. It is preferable to have a helical structure with a pitch number substantially equal to 0.5 × an integer multiple between the helical structure and the surface on the other side.

Further, in the first solution described above, the C-plate type retardation layer has a structure in which a chiral nematic liquid crystal is three-dimensionally cross-linked and fixed, or a structure in which a polymer cholesteric liquid crystal is fixed in a glass state. It is preferable to have

Further, in the first solution described above, the A-plate type retardation layer has a structure in which a nematic liquid crystal is three-dimensionally cross-linked and fixed, or a structure in which a polymer nematic liquid crystal is fixed in a glass state. It is preferred to have.

The present invention provides, as a second solution, a first liquid crystal having cholesteric regularity on an alignment film in which the direction of the alignment control force is substantially the same over the entire range on the film, Coating the first liquid crystal whose selective reflection wavelength is adjusted to be in a range different from the wavelength of the incident light; and aligning the direction of the director of the liquid crystal molecules on one surface of the coated first liquid crystal. Solidifying in a state regulated by the orientation regulating force of the film to form a C-plate type retardation layer acting as a negative C-plate; and forming nematic regularity directly on the formed C-plate type retardation layer. Coating the second liquid crystal having the C liquid crystal molecules on the surface of the coated second liquid crystal on the side of the C-plate type retardation layer. Forming an A-plate type retardation layer acting as an A-plate by solidifying in a state where the surface is regulated by the orientation regulating force on the surface of the G-type retardation layer. I will provide a.

In the second solution described above, the first liquid crystal is a liquid crystal containing at least one of a polymerizable monomer molecule having cholesteric regularity and a polymerizable oligomer molecule having cholesteric regularity. The direction of the director of the liquid crystal molecules on one surface of one liquid crystal is solidified by three-dimensional crosslinking in a state where the direction of the director is regulated by the alignment regulating force of the alignment film, and the second liquid crystal is polymerizable monomer molecules having nematic regularity. And a liquid crystal containing at least one of polymerizable oligomer molecules having nematic regularity, and the direction of the director of the liquid crystal molecule on the surface of the second liquid crystal on the side of the C plate type retardation layer is the C plate type. It is preferable that the surface of the retardation layer is solidified by three-dimensional crosslinking while being regulated by the orientation regulating force.

In the above-mentioned second solution, the first liquid crystal is a liquid crystal containing a liquid crystal polymer having cholesteric regularity, and a direction of a director of liquid crystal molecules on one surface of the first liquid crystal is equal to the orientation film. The liquid crystal is solidified into a glass state by cooling in a state where the liquid crystal is regulated by the alignment regulating force, and the second liquid crystal is a liquid crystal containing a liquid crystal polymer having nematic regularity, and the second liquid crystal is on the side of the C plate type retardation layer. It is preferable that the liquid crystal molecules be solidified into a glass state by cooling in a state where the direction of the director of the liquid crystal molecules on the surface is regulated by the orientation regulating force on the surface of the C-plate type retardation layer.

Here, in the above-mentioned second solution, the first liquid crystal molecules are arranged so that the directions of the directors of the liquid crystal molecules on both of the two main surfaces of the C-plate type retardation layer that are opposed to each other are substantially parallel. It is preferable to adjust the thickness of the liquid crystal coating.

Further, in the above-mentioned second solution, the liquid crystal is solidified in a state where the directions of the directors of the liquid crystal molecules on both of the two main surfaces of the C-plate type retardation layer opposite to each other are regulated. It is preferable that another alignment film is brought into contact with the surface on the side that is separated from the surface of the alignment film.

Further, in the above-mentioned second solution, the liquid crystal is solidified in a state in which the directions of the directors of the liquid crystal molecules on both of the two main surfaces of the A-plate type retardation layer opposite to each other are regulated. It is preferable that another alignment film is brought into contact with the surface of the C plate type retardation layer that is separated from the surface.

The present invention provides, as a third solution, a step of coating a first liquid crystal having nematic regularity on an alignment film in which the direction of the alignment control force is substantially the same over the entire area of the film; Forming a A-plate type retardation layer that acts as an A-plate by solidifying in a state where the direction of the director of the liquid crystal molecules on one surface of the first liquid crystal is regulated by the orientation regulating force of the orientation film. A second liquid crystal having cholesteric regularity directly on the formed A-plate type retardation layer, the second liquid crystal being adjusted so that the selective reflection wavelength upon solidification exists in a range different from the wavelength of incident light. (2) coating the liquid crystal, and changing the direction of the director of the liquid crystal molecules on the surface of the coated second liquid crystal on the side of the A-plate type retardation layer by the A-plate Forming a C-plate type retardation layer acting as a negative C-plate by solidifying the surface of the retardation layer in a state regulated by the orientation regulating force, thereby producing a retardation optical element. I will provide a.

In the third solution described above, the first liquid crystal is a liquid crystal containing at least one of a polymerizable monomer molecule having a nematic regularity and a polymerizable oligomer molecule having a nematic regularity. The direction of the director of the liquid crystal molecules on one surface of one liquid crystal is solidified by three-dimensional crosslinking in a state where the direction of the director is regulated by the alignment regulating force of the alignment film, and the second liquid crystal is polymerizable monomer molecules having cholesteric regularity. And a liquid crystal containing at least one of polymerizable oligomer molecules having cholesteric regularity, and the direction of the director of the liquid crystal molecules on the surface of the second liquid crystal on the side of the A plate type retardation layer is the A plate type. It is preferable that the surface of the retardation layer is solidified by three-dimensional crosslinking while being regulated by the orientation regulating force.

Further, in the third solution described above, the first liquid crystal is a liquid crystal containing a liquid crystal polymer having nematic regularity, and a direction of a director of liquid crystal molecules on one surface of the first liquid crystal is equal to the orientation film. The second liquid crystal is a liquid crystal containing a liquid crystal polymer having cholesteric regularity, which is solidified into a glassy state by cooling in a state where the second liquid crystal is regulated by the alignment regulating force of the A-plate type retardation layer side of the second liquid crystal. It is preferable that the liquid crystal molecules are solidified into a glass by cooling in a state where the direction of the director of the liquid crystal molecules on the surface is regulated by the orientation regulating force on the surface of the A-plate type retardation layer.

Here, in the third solution, the direction of the director of the liquid crystal molecules on both of the two main surfaces of the C-plate type retardation layer facing each other is substantially parallel. It is preferable to adjust the thickness of the liquid crystal coating.

In the third solution, the second liquid crystal is solidified in a state where the directions of the directors of the liquid crystal molecules on both of the two main surfaces of the C-plate type retardation layer opposite to each other are regulated. It is preferable that another alignment film is brought into contact with the surface of the A-plate type retardation layer that is separated from the surface.

Further, in the above-described third solution, the second liquid crystal is solidified in a state where the directions of the directors of the liquid crystal molecules on both of the two main surfaces of the A-plate type retardation layer opposite to each other are regulated. It is preferable that another alignment film is brought into contact with the surface on the side that is separated from the surface of the alignment film.

The present invention provides, as a fourth solution, a liquid crystal cell, a pair of polarizing plates disposed so as to sandwich the liquid crystal cell, and a liquid crystal cell disposed between at least one of the liquid crystal cell and the pair of polarizing plates. And the phase difference optical element according to the first solution means, wherein the phase difference optical element is a liquid crystal of light having a predetermined polarization state incident on the liquid crystal cell and / or emitted from the liquid crystal cell. Provided is a liquid crystal display device, which compensates for a polarization state of light emitted in a direction inclined from a normal line of a cell.

According to the retardation optical element according to the first solution of the present invention, the C-plate type retardation layer having a cholesteric regularity structure which is planarly oriented and acting as a negative C plate is provided with a nematic regularity. In a retardation optical element having a structure and having an A-plate type retardation layer acting as an A-plate laminated adjacently, the selective reflection wavelength of the selective reflection light caused by the structure of the C-plate type retardation layer is higher than that of the incident light. The helical pitch of the structure is adjusted so as to be in a range different from the wavelength, and the direction of the director of the liquid crystal molecules on the surfaces on the adjacent sides of the C-plate type retardation layer and the A-plate type retardation layer is substantially changed. , The display image does not have a light and dark pattern, and the display quality is degraded even when the display image is disposed between the liquid crystal cell and the polarizing plate. It can be effectively suppressed and.

Here, in the retardation optical element according to the first solution of the present invention, the directions of the directors of the liquid crystal molecules on the two main surfaces of the C-plate type retardation layer are substantially parallel. Thereby, the occurrence of a light and dark pattern or the like can be more effectively suppressed, and the deterioration of the display quality can be further suppressed.

Further, in the phase difference optical element according to the first solution of the present invention, the liquid crystal molecules on two main surfaces of the C plate type phase difference layer and the A plate type phase difference layer which are stacked adjacent to each other are separated from each other. By making the directions of the directors substantially parallel, the occurrence of a light and dark pattern or the like can be more effectively suppressed.

Further, in the retardation optical element according to the first solution of the present invention, a spiral structure having a pitch number of substantially 0.5 × an integral multiple between two main surfaces of the C-plate type retardation layer is provided. With such a configuration, the directions of the directors of the liquid crystal molecules on the two main surfaces of the C-plate type retardation layer can be made to exactly coincide with each other. Thus, a decrease in display quality can be further suppressed.

According to the method for manufacturing a retardation optical element according to the second solution of the present invention, the direction of the alignment regulating force has a cholesteric regularity on the alignment film substantially the same in the entire range on the film. The first liquid crystal is coated to form a C-plate type retardation layer acting as a negative C-plate, and then a second liquid crystal having nematic regularity is directly formed on the formed C-plate type retardation layer. A phase difference optical element comprising a phase difference layer acting as a negative C plate and a phase difference layer acting as an A plate because the coating forms an A plate type retardation layer acting as an A plate. Therefore, it is possible to easily manufacture a phase difference optical element that does not generate a light and dark pattern in a display image and that can effectively suppress a decrease in display quality.

According to the method for manufacturing a retardation optical element according to the third solution of the present invention, the alignment regulating force has a nematic regularity on an alignment film in which the direction of the alignment regulating force is substantially the same in the entire range on the film. The first liquid crystal is coated to form an A-plate type retardation layer acting as an A-plate, and then the second liquid crystal having cholesteric regularity is directly coated on the formed A-plate type retardation layer. Since the C-plate type retardation layer acting as a negative C-plate is formed, a retardation optical element including a retardation layer acting as a negative C-plate and a retardation layer acting as an A-plate Therefore, it is possible to easily manufacture a phase difference optical element that does not generate a light and dark pattern in a display image and that can effectively suppress a decrease in display quality.

According to the fourth solution of the present invention, a phase difference optical element is arranged between a liquid crystal cell and a polarizing plate of a liquid crystal display device, and a predetermined polarization state incident on the liquid crystal cell and / or emitted from the liquid crystal cell is determined. Of the light emitted from the liquid crystal cell in a direction inclined from the normal line of the liquid crystal cell, it is possible to suppress the occurrence of bright and dark patterns in the liquid crystal display device and improve the contrast, thereby improving the display quality. The decrease can be suppressed.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

First, the phase difference optical element according to the present embodiment will be described with reference to FIG.

As shown in FIG. 1, a retardation optical element 10 is formed by laminating a C-plate type retardation layer 12 having a cholesteric regular structure with a planar orientation and a C-plate type retardation layer 12, and An A-plate type retardation layer 14 having a regular structure.

Among them, the C-plate type retardation layer 12 has two main surfaces (wider surfaces) 12A and 12B opposed to each other and arranged to be orthogonal to the thickness direction (the direction of the normal 15). I have. The C-plate type retardation layer 12 has anisotropy, that is, birefringence due to the structure of the cholesteric regularity, and the refractive index in the thickness direction and the refractive index in the plane direction are different. Act as a C-plate. That is, in the three-dimensional orthogonal coordinate system, when the refractive index in the plane direction of the C-plate type retardation layer 12 is Nx and Ny and the refractive index in the thickness direction is Nz, the relationship is Nx = Ny> Nz.

Further, the A-plate type retardation layer 14 has two main surfaces (wider surfaces) 14A and 14B opposed to each other and arranged orthogonal to the thickness direction (direction of the normal 15). . The A-plate type retardation layer 12 has anisotropy, that is, birefringence due to the nematic regularity structure, and has a different refractive index in the plane direction, and thus acts as a (positive) A-plate. . That is, in the three-dimensional orthogonal coordinate system, when the refractive index in the plane direction of the A-plate type retardation layer 14 is Nx and Ny, and the refractive index in the thickness direction is Nz, the relationship is Nx> Ny = Nz.

Here, the direction of the director Cb of the liquid crystal molecules on the surface 12B of the C-plate type retardation layer 12 on the side of the A-plate type retardation layer 14 and the C-plate type retardation layer 12 of the A-plate type retardation layer 14 The direction of the director Na of the liquid crystal molecules on the side surface 14A substantially matches. Note that the range of variation between the direction of the director Cb of the liquid crystal molecules on the surface 12B of the C-plate type retardation layer 12 and the direction of the director of the liquid crystal molecules on the surface 14A of the A-plate type retardation layer 14 is within ± 10 °. , Preferably within ± 5 °, more preferably within ± 1 °.

Note that “substantially coincide” here includes the case where the directions of the directors of the liquid crystal molecules are displaced by approximately 180 degrees, that is, the case where the heads and buttocks of the liquid crystal molecules are in the same direction. This is because, in many cases, the head and tail of the liquid crystal molecules cannot be optically distinguished. This relationship will be described later (when the directions of the directors Ca and Cb of the liquid crystal molecules on the two main surfaces 12A and 12B of the C-plate type retardation layer 12 are “substantially parallel”, The same applies to the case where the directions of the directors Ca and Nb of the liquid crystal molecules on the two spaced surfaces 12A and 14B of the type retardation layer 12 and the A-plate type retardation layer 14 are "substantially parallel".

Further, the term “liquid crystal molecule” is generally used to mean a molecule having both fluidity of liquid and anisotropy of crystal, but in the present specification, the term “liquid crystal molecule” refers to a molecule having fluidity. For the sake of convenience, the term “liquid crystal molecules” will be used for molecules that have been solidified while maintaining the anisotropy. As a method of solidifying the molecules while maintaining the anisotropy that the molecules have in a fluid state, for example, a liquid crystal molecule having a polymerizable group (polymerizable monomer molecule or polymerizable oligomer molecule) is cross-linked. And a method of cooling a polymer liquid crystal (liquid crystal polymer) to a glass transition temperature or lower.

Note that, of the two main surfaces of the C-plate type retardation layer 12, the direction of the director Ca of the liquid crystal molecules on one surface 12A substantially coincides in that surface, and the direction of the liquid crystal molecules on the other surface 12B. It is preferable that the direction of the director Cb substantially coincides in that plane. The range of the variation in the direction of the directors Ca and Cb of the liquid crystal molecules on one surface 12A and the other surface 12B of the C-plate type retardation layer 12 is within ± 10 °, preferably within ± 5 °, and more preferably. It is preferable that it is within ± 1 °.

Here, on the surfaces 12A and 12B of the C-plate type retardation layer 12, it is determined whether or not the directions of the directors Ca and Cb of the liquid crystal molecules substantially coincide with each other through the cross section of the C-plate type retardation layer 12. It can be determined by observing with a scanning electron microscope. More specifically, when a cross section of the C-plate type retardation layer 12 solidified in a cholesteric regular liquid crystal structure is observed with a transmission electron microscope, it corresponds to a helical pitch of molecules specific to a cholesteric regular liquid crystal structure. Light and dark patterns are observed. Therefore, at this time, if the light and dark densities appear to be substantially the same on the surfaces 12A and 12B without any variation along the surfaces, the directions of the directors of the liquid crystal molecules in these surfaces are substantially the same. Can be determined.

In the retardation optical element 10 shown in FIG. 1, the C-plate type retardation layer 12 having a cholesteric regularity structure and acting as a negative C-plate has birefringence, and has a thickness direction. Is different from the refractive index in the plane direction. Therefore, when linearly polarized light is incident on the C-plate type retardation layer 12, the linearly polarized light incident in the direction of the normal 15 of the C-plate type retardation layer 12 is transmitted without being phase-shifted, Linearly polarized light incident in a direction inclined from the normal line 15 of the mold phase difference layer 12 has a phase difference when passing through the C-plate type phase difference layer 12 and becomes elliptically polarized light. Conversely, when elliptically polarized light is incident in a direction inclined from the normal 15 of the C-plate type retardation layer 12, the incident elliptically polarized light can be converted to linearly polarized light.

On the other hand, the A-plate type retardation layer 14 having a nematic regular structure and acting as an A-plate also has birefringence, but has a different refractive index in the plane direction. That is, even in the directions along the surfaces 14A and 14B, the refractive indexes in the directions of the directors Na and Nb are different from the refractive indexes in the directions perpendicular to the directors Na and Nb. The refractive index in the direction perpendicular to the directors Na and Nb is equal to the refractive index in the thickness direction.

Accordingly, a phase difference optical element is constituted by using two kinds of phase difference layers (C-plate type phase difference layer 12 and A-plate type phase difference layer 14) having different birefringence modes in different directions. As a result, both the light transmitted in the direction of the normal 15 and the light transmitted in the direction inclined from the normal 15 can be subjected to a phase shift effect, and various optical compensations can be realized.

At this time, the C-plate type phase difference layer 12 and the A-plate type phase difference layer 14 are laminated adjacent to each other, and the C-plate type phase difference layer 12 and the A-plate type phase difference layer 14 Since the directions of the directors Cb and Na of the liquid crystal molecules on the surfaces 12B and 14A substantially coincide with each other, even when the liquid crystal display device is disposed between the liquid crystal cell and the polarizing plate, a light and dark pattern or the like is generated on the display image. Therefore, it is possible to effectively prevent the display quality from deteriorating.

In the C-plate type retardation layer 12, the selective reflection wavelength of the selective reflection light due to the cholesteric regularity structure is different from the wavelength of the incident light (the selective reflection wavelength is smaller than the wavelength of the incident light or The helical pitch of the structure is adjusted so as to exist in the range where the structure becomes larger. Thus, even if the incident light is a visible light, for example, the incident light (visible light) is not reflected by the selective reflection by the helical structure of the liquid crystal molecules, and there is no problem such as coloring.

Here, the phenomenon of selective reflection in the C-plate type retardation layer 12 having a cholesteric regularity structure will be briefly described.

In general, a cholesteric regularity structure has an optical rotation selection characteristic (polarization separation characteristic) for separating an optical rotation component in one direction (a circularly polarized light component) and an optical rotation component in the opposite direction based on the planar arrangement of the liquid crystal. Have.

現象 This phenomenon is known as circular dichroism, and when the direction of rotation in the helical structure of liquid crystal molecules is appropriately selected, a circularly polarized light component having the same optical rotation direction as this direction of rotation is selectively reflected.

最大 In this case, the maximum optical rotation polarized light scattering (peak of selective reflection) occurs at the selective reflection wavelength λ0 of the following equation (1).

λ0 = nav · p (1)
Here, p is a helical pitch in a helical structure of liquid crystal molecules, and nav is an average refractive index in a plane orthogonal to the helical axis.

On the other hand, the wavelength bandwidth Δλ of the selectively reflected light at this time is expressed by the following equation (2).

Δλ = Δn · p (2)
Here, Δn is a birefringence value expressed as a difference between the refractive index for ordinary light and the refractive index for extraordinary light.

That is, in such a cholesteric regularity structure, the incident non-polarized light has a right-handed or left-handed rotation of light in a wavelength bandwidth △ λ centered on the selective reflection wavelength λ0 according to the polarization separation characteristics as described above. One of the circularly polarized light components is reflected, and the other circularly polarized light component and light (non-polarized light) in a wavelength region other than the selective reflection wavelength are transmitted. The reflected right-handed or left-handed circularly polarized light component is reflected without reversing the turning direction, unlike normal reflection.

Here, since the wavelength band width of visible light in which coloring is a problem is 380 to 780 nm, the cholesteric rule is set so that the selective reflection wavelength of the selective reflection light resulting from the structure of cholesteric regularity is 380 nm or less or 780 nm or more. It is good to constitute a sex structure. This can prevent problems such as coloring due to reflection of incident light (visible light) while allowing the C-plate type retardation layer 12 to function as a negative C-plate. It is more preferable that the selective reflection wavelength of the selective reflection light is smaller than the wavelength of the incident light because the optical rotation is reduced.

Next, a modified example of the phase difference optical element according to the present embodiment will be described with reference to FIG.

As shown in FIG. 2, the retardation optical element 20 includes a C-plate type retardation layer 22 having a cholesteric regular structure in a planar orientation, and a lamination adjacent to the C-plate type retardation layer 22. An A-plate type retardation layer 14 having a regular structure.

Among them, the C-plate type retardation layer 22 functions as a negative C-plate similarly to the C-plate type retardation layer 12 of the retardation optical element 10 shown in FIG. ), Two main surfaces (wider surfaces) 22A and 22B opposed to each other and arranged to be orthogonal to (i.

Here, of the two main surfaces 22A and 22B of the C-plate type retardation layer 22, the direction of the director Cb of the liquid crystal molecule on the surface 22B on the side of the A-plate type retardation layer 14, and the A-plate type retardation layer 14 Is substantially parallel to the direction of the director Ca of the liquid crystal molecules on the surface 22 </ b> A on the side away from the liquid crystal molecules. The angle between the direction (average direction) of the director Cb of the liquid crystal molecules on one surface 22B of the C-plate type retardation layer 22 and the direction (average direction) of the director Ca of the liquid crystal molecules on the other surface 22A is It is preferably within ± 10 °, preferably within ± 5 °, and more preferably within ± 1 °.

The direction of the director Ca of the liquid crystal molecules on the surface 22A on the side of the C-plate type retardation layer 22 that is separated from the A-plate type retardation layer 14, and the C-plate type retardation layer 14 The direction of the director Nb of the liquid crystal molecules on the surface 14B on the side separated from the retardation layer 22 is substantially parallel. The direction (average direction) of the director Ca of liquid crystal molecules on the surface 22A of the C-plate type retardation layer 22 and the direction (average direction) of the director Nb of liquid crystal molecules on the surface 14B of the A-plate type retardation layer 14 It is preferable that the angle formed is within ± 10 °, preferably within ± 5 °, and more preferably within ± 1 °.

Here, in the retardation optical element 20 shown in FIG. 2, the directions of the directors Ca and Cb of the liquid crystal molecules on the two main surfaces 22A and 22B of the C-plate type retardation layer 22 exactly match (ie, in parallel). In this case, the thickness of the C-plate type retardation layer 22 is set to 0.5 × integer multiple of the helical pitch p of the cholesteric regularity structure (spiral structure), and is substantially equal to 0.1 mm between the surfaces 22A and 22B. It is preferable that a spiral structure having a pitch number of 5 × an integral multiple is formed. By doing so, the thickness is optically divisible by half the distance of the helical pitch p of the cholesteric regularity of the liquid crystal molecules, as schematically shown in, for example, FIGS. Thus, the optical deviation from the simplified equation (1), particularly the disturbance of the polarization state due to the phase shift difference with respect to the incident light incident along the helical axis is suppressed.

The phase difference optical element 20 shown in FIG. 2 has the same configuration as the phase difference optical element 10 shown in FIG. 1 except that the configuration of a C-plate type phase difference layer acting as a negative C plate is different. Since they are substantially the same, detailed description of the other components is omitted.

Here, as a material of the C-plate type retardation layers 12 and 22 and the A-plate type retardation layers 14 of the retardation optical elements 10 and 20, a three-dimensionally crosslinkable liquid crystal monomer or liquid crystal oligomer (polymerizable monomer molecule) is used. Alternatively, a polymer liquid crystal (liquid crystal polymer) that can be solidified into a glass by cooling can be used.

Among them, when a polymerizable monomer molecule capable of three-dimensionally cross-linking is used as a material of the C-plate type retardation layers 12 and 22 and the A-plate type retardation layer 14, Japanese Patent Application Laid-Open No. A mixture of a liquid crystalline monomer and a chiral compound as disclosed in JP-A-508882 can be used. When a polymerizable oligomer molecule capable of three-dimensional cross-linking is used, a cyclic organopolysiloxane compound having a cholesteric phase as disclosed in JP-A-57-165480 is desirable. The term “three-dimensional crosslinking” means that polymerizable monomer molecules or polymerizable oligomer molecules are three-dimensionally polymerized with each other to form a network structure. In such a state, the liquid crystal molecules can be optically fixed with the cholesteric regular structure or the nematic regular structure, and the film is easy to handle as an optical film and is stable at room temperature. Can be formed into a membrane.

Here, taking a case where a polymerizable monomer molecule capable of three-dimensional cross-linking is used as an example, a nematic liquid crystal is obtained when a liquid crystal monomer is converted into a liquid crystal phase at a predetermined temperature. By adding a chiral agent to this liquid crystalline monomer, a chiral nematic liquid crystal (cholesteric liquid crystal) can be obtained. More specifically, for example, liquid crystalline monomers represented by general formulas (1) to (11) can be used. In the case of the liquid crystalline monomer represented by the general formula (11), X is preferably 2 to 5 (integer).

Further, as the chiral agent, for example, it is preferable to use a chiral agent represented by any of the general formulas (12) to (14). In the case of the chiral agents represented by the general formulas (12) and (13), X is preferably 2 to 12 (integer), and in the case of the chiral agent represented by the general formula (14), X is It is preferably 2 to 5 (integer). In the general formula (12), R ⁴ represents hydrogen or a methyl group.

On the other hand, when a liquid crystal polymer is used as a material of the C-plate type retardation layers 12 and 22 and the A-plate type retardation layer 14, a mesogen group presenting a liquid crystal has a main chain, a side chain, or a main chain and a side chain. A polymer introduced at both positions, a polymer cholesteric liquid crystal having a cholesteryl group introduced into a side chain, a liquid crystalline polymer as disclosed in JP-A-9-133810, and disclosed in JP-A-11-293252. A liquid crystalline polymer as described above can be used.

Next, a method for manufacturing the retardation optical element 10 (20) according to the present embodiment having such a configuration will be described.

(First manufacturing method)
First, referring to FIGS. 4A to 4E, a production method in which a polymerizable monomer molecule or a polymerizable oligomer molecule is used as a material of the C-plate type retardation layer 12 (22) and the A-plate type retardation layer 14 is shown. Will be described.

(1) Formation of C-plate type retardation layer In this case, as shown in FIG. 4A, an alignment film 17 is formed on a glass substrate or a polymer film 16 such as a TAC (cellulose triacetate) film. Then, as shown in FIG. 4B, a polymerizable monomer molecule (or polymerizable oligomer molecule) 18 having cholesteric regularity is coated thereon, and the alignment is performed by the alignment control force of the alignment film 17. . At this time, the coated polymerizable monomer molecules (or polymerizable oligomer molecules) 18 constitute a liquid crystal layer.

When the polymerizable monomer molecules (or polymerizable oligomer molecules) 18 are formed into a liquid crystal layer at a predetermined temperature, the liquid crystal layer becomes a nematic liquid crystal. However, if an arbitrary chiral agent is added thereto, a chiral nematic liquid crystal (cholesteric liquid crystal) is obtained. ). Specifically, for example, it is preferable to add a chiral agent to the polymerizable monomer molecule or the polymerizable oligomer molecule in a proportion of several% to 10%. In addition, it is possible to control the selective reflection wavelength caused by the molecular structure of the polymerizable monomer molecule or the polymerizable oligomer molecule by changing the chiral power by changing the type of the chiral agent, or by changing the concentration of the chiral agent. it can. The polymerizable monomer molecules (or polymerizable oligomer molecules) 18 are adjusted so that the selective reflection wavelength at the time of solidification thereof is in a range different from the wavelength of the incident light.

The polymerizable monomer molecule (or polymerizable oligomer molecule) 18 may be dissolved in a solvent such as toluene or MEK to form a coating solution, if necessary, in order to lower the viscosity so as to facilitate coating. In this case, a drying step for evaporating the solvent is required before three-dimensional crosslinking is performed by irradiation with ultraviolet rays or electron beams. Preferably, after performing a coating step of coating a coating liquid, a drying step of evaporating a solvent is performed, and then, after maintaining a temperature for forming a liquid crystal layer, an alignment step of aligning liquid crystal is performed.

Next, in this alignment state, that is, the direction of the director of the liquid crystal molecule on the surface of the polymerizable monomer molecule (or polymerizable oligomer molecule) 18 on the side of the alignment film 17 is changed by the alignment regulating force of the surface of the alignment film 17. In the regulated state, as shown in FIG. 4 (C), polymerization of the polymerizable monomer molecule (or polymerizable oligomer molecule) 18 is carried out by a photopolymerization initiator added in advance and ultraviolet light irradiated from the outside. If the polymerization is started or the polymerization is started directly by an electron beam to solidify by three-dimensional crosslinking (polymerization), the C-plate type retardation layer 12 acting as a negative C-plate as described above is formed. You.

Here, if the direction of the alignment regulating force of the alignment film 17 is substantially matched in the entire range on the alignment film 17, the liquid crystal molecules on the surface 12 A of the C-plate type retardation layer 12 which is in contact with the alignment film 17 are formed. The directions of the directors can be substantially matched in the contact area.

In this case, in order to make the direction of the director of the liquid crystal molecules on the surface 12B on the side of the C-plate type retardation layer 12 that is apart from the alignment film 17 substantially coincide with the entire range of the surface 12B, It is preferable to make the film thickness of the C-plate type retardation layer 12 uniform. Further, as shown in FIGS. 5A to 5D, in the steps shown in FIGS. 4A to 4C, the polymerizable monomer molecules (polymerizable oligomer molecules) 18 are placed on the alignment film 17. After the coating, and before the polymerizable monomer molecules (polymerizable oligomer molecules) 18 are three-dimensionally crosslinked, the second alignment film 17A is overlaid on the coated polymerizable monomer molecules (polymerizable oligomer molecules) 18. (FIG. 5C). Thereby, the direction of the director of the liquid crystal molecules on the surface 12B of the C-plate type retardation layer 12 can be more surely substantially matched in the entire range of the surface 12B.

In this state, as in FIG. 4C, the polymerizable monomer molecules (polymerizable oligomer molecules) 18 are three-dimensionally cross-linked between the alignment film 17 and the second alignment film 17A by irradiation with ultraviolet rays or electron beams. As a result, the C-plate type retardation layer 12 acting as a negative C-plate as described above is formed (FIG. 5D).

The second alignment film 17A may be separated from the C-plate type retardation layer 12 in a step after irradiation with ultraviolet rays or electron beams.

Here, the alignment film 17 and / or the second alignment film 17A can be manufactured by a conventionally known method. For example, a method in which PI (polyimide) or PVA (polyvinyl alcohol) is formed and rubbed on a glass substrate or a polymer film 16 such as a TAC film as described above, or a polymer film 16 such as a glass substrate or a TAC film is used. In addition to using a method of forming a polymer compound to be a photo-alignment film thereon and irradiating polarized UV (ultraviolet), a stretched PET (polyethylene terephthalate) film or the like can also be used.

When a polymer film (organic material) such as a TAC film is used as the base material on which the alignment film 17 is formed, a solvent in a coating solution in which polymerizable monomer molecules (or polymerizable oligomer molecules) 18 are dissolved is used. It is preferable to provide a barrier layer having a solvent resistance such as PVA (polyvinyl alcohol) on the polymer film so that the base material is not damaged, and coat the coating liquid thereon. When PVA is used as a barrier layer, if PVA is rubbed, it also serves as an alignment film.

(2) Formation of A-plate type retardation layer Thereafter, as shown in FIG. 4 (D), separately prepared directly on the C-plate type retardation layer 12 formed as described above. Another polymerizable monomer molecule (or polymerizable oligomer molecule) 19 having a nematic regularity and exhibiting a nematic liquid crystal phase at a predetermined temperature is coated, and is aligned by the alignment regulating force of the surface 12B of the C-plate type retardation layer 12. . At this time, the coated polymerizable monomer molecules (or polymerizable oligomer molecules) 19 constitute a liquid crystal layer.

The polymerizable monomer molecule (or polymerizable oligomer molecule) 19 lowers the viscosity so as to be easily coated. Therefore, like the polymerizable monomer molecule (or polymerizable oligomer molecule) 18, toluene and / or It may be dissolved in a solvent such as MEK to form a coating liquid. In this case, a drying step for evaporating the solvent is required before three-dimensional crosslinking is performed by irradiation with ultraviolet rays or electron beams. Preferably, after performing a coating step of coating a coating liquid, a drying step of evaporating a solvent is performed, and then, after maintaining a temperature for forming a liquid crystal layer, an alignment step of aligning liquid crystal is performed.

Next, in this alignment state, that is, the direction of the director of the liquid crystal molecules on the surface of the polymerizable monomer molecule (or the polymerizable oligomer molecule) 19 on the C-plate type retardation layer 12 side is changed to the C-plate type retardation layer. As shown in FIG. 4 (E), the polymerizable monomer molecules (or polymerizable oligomer molecules) 19 are added to the photopolymerization initiator, which has been added in advance, and the external polymerization initiator in a state where it is regulated by the orientation regulating force on the surface of the substrate 12. If the polymerization is initiated by ultraviolet rays irradiated from the surface or by direct initiation of polymerization by an electron beam and then solidified by three-dimensional crosslinking (polymerization), the A-plate type position acting as an A-plate as described above is obtained. The phase difference layer 14 is formed.

Here, the directions of the directors of the liquid crystal molecules on the surface 14B on the side of the A-plate type retardation layer 14 that is separated from the C-plate type retardation layer 12 are made substantially the same in the entire range of the surface 14B. For this purpose, the thickness of the C-plate type retardation layer 12 is made uniform and then the thickness of the A-plate type retardation layer 14 is made uniform, or the C-plate type retardation layer 14 is three-dimensionally crosslinked. When solidifying by using the second alignment film 17A shown in FIGS. 5A to 5D and further solidifying the A-plate type retardation layer 14 by three-dimensionally crosslinking, The second alignment film 17A shown in FIGS. 5C and 5D is provided on the surface of the polymerizable monomer molecule (polymerizable oligomer molecule) 19 on the side away from the surface 12B of the C-plate type retardation layer 12. So that a second alignment film similar to that described above is provided. It may be.

In the case where the retardation optical element 20 as shown in FIG. 2 is manufactured, the director Cb of the liquid crystal molecules on the surface 22B of the C-plate type retardation layer 22 on the side away from the alignment film 17 is used. The direction is made to coincide with the direction of the director Ca of the liquid crystal molecules on the surface 22A of the C-plate type retardation layer 22 on the alignment film 17 side, or from the C-plate type retardation layer 22 of the A-plate type retardation layer 14. The direction of the director Nb of the liquid crystal molecules on the surface 14B on the separated side is adjusted to the direction of the director of the liquid crystal molecules on the surface 22A of the C plate type retardation layer 22 on the side separated from the A plate type retardation layer 14. It is necessary to match the direction of Ca. In this case, the thickness of the C-plate type retardation layer 22 and the A-plate type retardation layer 14 is 0.5 × integer multiple of the helical pitch in the helical structure of the liquid crystal molecules, so that the liquid crystal to be coated is The thickness may be adjusted, or a second alignment film 17A as shown in FIGS. 5C and 5D may be used. When the second alignment film 17A is used, the surface 22B of the C-plate type retardation layer 22 opposite to the alignment film 17 or the A-plate type retardation layer 14 opposite to the C-plate type retardation layer 22 is used. The second alignment film 17A is brought into contact with the surface 14B of the second alignment film.

As described above, the retardation optical element 10 (20) in which the C-plate retardation layer 12 (22) and the A-plate retardation layer 14 are laminated adjacent to each other is manufactured.

(Second manufacturing method)
Next, a manufacturing method in the case of using a liquid crystal polymer as a material of the C-plate type retardation layer 12 (22) and the A-plate type retardation layer 14 will be described with reference to FIGS.

(1) Formation of C-plate type retardation layer In this case, as shown in FIG. 6A, an alignment film 17 is formed on a polymer film 16 such as a glass substrate or a TAC film, and As shown in FIG. 6B, a liquid crystal polymer 32 having cholesteric regularity is coated, and is aligned by the alignment controlling force of the alignment film 17. At this time, the coated liquid crystal polymer 32 constitutes a liquid crystal layer.

As the liquid crystal polymer 32, a cholesteric liquid crystal polymer itself having a chiral ability in the liquid crystal polymer itself may be used, or a mixture of a nematic liquid crystal polymer and a cholesteric liquid crystal polymer may be used. Specifically, for example, a polymer in which a mesogen group presenting a liquid crystal is introduced into a main chain, a side chain or both positions of a main chain and a side chain; a polymer cholesteric liquid crystal in which a cholesteryl group is introduced into a side chain; A liquid crystalline polymer as disclosed in JP-A-133810, a liquid crystalline polymer as disclosed in JP-A-11-293252, and the like can be used.

Such a liquid crystal polymer 32 changes its state depending on the temperature. For example, when the glass transition temperature is 90 ° C. and the isotropic transition temperature is 200 ° C., the liquid crystal polymer 32 exhibits a cholesteric liquid crystal state between 90 ° C. and 200 ° C. Is cooled to room temperature, it can be solidified into a glass while maintaining the cholesteric structure.

As a method of adjusting the selective reflection wavelength of incident light due to the cholesteric regularity structure of the liquid crystal polymer 32, when a cholesteric liquid crystal polymer is used, the chiral power in the liquid crystal molecules is adjusted by a known method. do it. When a mixture of a nematic liquid crystal polymer and a cholesteric liquid crystal polymer is used, the mixing ratio may be adjusted.

The liquid crystal polymer 32 may be dissolved in a solvent such as toluene or MEK to form a coating liquid, if necessary, in order to reduce the viscosity so as to facilitate coating. In this case, a drying step for evaporating the solvent is required before cooling. Preferably, after performing the coating step of coating the coating liquid, a drying step of evaporating the solvent is performed, and then an alignment step of aligning the liquid crystal is performed.

Next, in this alignment state, that is, in a state where the direction of the director of the liquid crystal molecules on the surface of the liquid crystal polymer 32 on the side of the alignment film 17 is regulated, as shown in FIG. When cooled below the glass transition temperature (Tg) and solidified into a glass, the C-plate type retardation layer 12 acting as a negative C-plate as described above is formed.

Here, if the direction of the alignment regulating force of the alignment film 17 is substantially matched in the entire range on the alignment film 17, the liquid crystal molecules on the surface 12 A of the C-plate type retardation layer 12 which is in contact with the alignment film 17 are formed. The directions of the directors can be substantially matched in the contact area.

In this case, in order to make the direction of the director of the liquid crystal molecules on the surface 12B on the side of the C-plate type retardation layer 12 that is apart from the alignment film 17 substantially coincide with the entire range of the surface 12B, It is preferable to make the film thickness of the C-plate type retardation layer 12 uniform. Also, a second alignment film 17A as shown in FIGS. 5C and 5D may be provided on the surface of the liquid crystal polymer 32 on the side separated from the alignment film 17. Thereby, the direction of the director of the liquid crystal molecules on the surface 12B of the C-plate type retardation layer 12 can be more surely substantially matched in the entire range of the surface 12B. Note that the second alignment film 17A may be separated from the C-plate type retardation layer 12 in a later step after cooling.

Here, as the alignment film 17 and / or the second alignment film 17A, the same one as in the first manufacturing method described above can be used. When a polymer film (organic material) such as a TAC film is used as the base material on which the alignment film 17 is formed, the base material is not affected by the solvent in the coating solution in which the liquid crystal polymer 32 is dissolved. As in the first manufacturing method, a barrier layer having solvent resistance such as PVA (polyvinyl alcohol) may be provided on the polymer film, and the coating liquid may be coated thereon.

(2) Formation of A-plate type retardation layer Thereafter, as shown in FIG. 6 (D), separately prepared directly on the C-plate type retardation layer 12 formed as described above. Another liquid crystal polymer 34 having a nematic regularity and exhibiting a nematic liquid crystal phase at a predetermined temperature is coated, and is aligned by the alignment controlling force of the surface 12B of the C-plate type retardation layer 12. At this time, the coated liquid crystal polymer 34 constitutes a liquid crystal layer.

As the liquid crystal polymer 34, for example, a nematic liquid crystal polymer described in the above-mentioned Japanese Patent Application Laid-Open No. 11-293252 is used.

液晶 Such a liquid crystal polymer 34 changes its state depending on the temperature, exhibits a nematic liquid crystal state within a predetermined temperature range, and when cooled to room temperature, can be solidified into a glass state while having a nematic structure.

In addition, the liquid crystal polymer 34 may be dissolved in a solvent such as toluene or MEK as needed to form a coating liquid, as in the case of the liquid crystal polymer 32, in order to reduce the viscosity so as to facilitate coating. In this case, a drying step for evaporating the solvent is required before cooling. Preferably, after performing the coating step of coating the coating liquid, a drying step of evaporating the solvent is performed, and then an alignment step of aligning the liquid crystal is performed.

Next, in this alignment state, that is, the direction of the director of the liquid crystal molecules on the surface of the liquid crystal polymer 34 on the side of the C plate type retardation layer 12 is regulated by the alignment regulating force of the surface of the C plate type retardation layer 12. In this state, as shown in FIG. 6 (E), when the liquid crystal polymer 34 is cooled to a glass transition temperature (Tg) or less and solidified into a glassy state, the liquid crystal polymer 34 functions as an A plate as described above. The plate type retardation layer 14 is formed.

Here, the directions of the directors of the liquid crystal molecules on the surface 14B on the side of the A-plate type retardation layer 14 that is separated from the C-plate type retardation layer 12 are made substantially the same in the entire range of the surface 14B. For this purpose, the thickness of the C-plate type retardation layer 12 is made uniform and then the thickness of the A-plate type retardation layer 14 is made uniform, or the C-plate type retardation layer 14 is cooled and solidified. In this case, the second alignment film 17A shown in FIGS. 5A to 5D is used, and the A-plate type retardation layer 14 is further cooled and solidified. A second alignment film similar to the second alignment film 17A shown in FIGS. 5C and 5D is provided on the surface of the C plate type retardation layer 12 on the side remote from the surface 12B. May be.

In the case where the retardation optical element 20 as shown in FIG. 2 is manufactured, the director Cb of the liquid crystal molecules on the surface 22B of the C-plate type retardation layer 22 on the side away from the alignment film 17 is used. The direction is made to coincide with the direction of the director Ca of the liquid crystal molecules on the surface 22A of the C-plate type retardation layer 22 on the alignment film 17 side, or from the C-plate type retardation layer 22 of the A-plate type retardation layer 14. The direction of the director Nb of the liquid crystal molecules on the surface 14B on the separated side is adjusted to the direction of the director of the liquid crystal molecules on the surface 22A of the C plate type retardation layer 22 on the side separated from the A plate type retardation layer 14. It is necessary to match the direction of Ca. In this case, the thickness of the C-plate type retardation layer 12 and the A-plate type retardation layer 14 is 0.5 × an integer multiple of the helical pitch in the helical structure of the liquid crystal molecules, so that the liquid crystal to be coated is The thickness may be adjusted, or a second alignment film 17A as shown in FIGS. 5C and 5D may be used. When the second alignment film 17A is used, the surface 22B of the C-plate type retardation layer 12 opposite to the alignment film 17 or the A-plate type retardation layer 14 opposite to the C-plate type retardation layer 12 is used. The second alignment film 17A is brought into contact with the surface 14B of the second alignment film.

As described above, the retardation optical element 10 (20) in which the C-plate retardation layer 12 (22) and the A-plate retardation layer 14 are laminated adjacent to each other is manufactured.

In each of the above-described embodiments, the C-plate type having a cholesteric regular structure is first formed on an alignment film 17 formed on a glass substrate or a polymer film 16 such as a TAC film. After the formation of the retardation layer 12 (22), the A-plate type retardation layer 14 having a nematic regular structure is formed on the C-plate type retardation layer 12 (22). However, the present invention is not limited to this. After first forming the A-plate type retardation layer 14 having a nematic regular structure, the cholesteric regular structure is formed on the A-plate type retardation layer 14. May be formed to have the C-plate type retardation layer 12 (22). In this case, a liquid crystal having cholesteric regularity is directly coated on the A-plate type retardation layer 14, and the direction of the director of the liquid crystal molecules on the surface of the liquid crystal on the A-plate type retardation layer 14 side is changed. The liquid crystal is solidified in a state where the liquid crystal is regulated by the alignment regulating force on the surface of the A-plate type retardation layer 14, and the C-plate type retardation layer 12 (22) is formed. Other procedures and conditions in such a manufacturing method are basically the same as those in the above-described manufacturing method, and therefore, detailed description is omitted.

In any of the above-described embodiments, in any case, the retardation optical element has a two-layer structure including one C-plate retardation layer 12 (22) and one A-plate retardation layer 14. However, the present invention is not limited to this. At least one of the C-plate type retardation layer and the A-plate type retardation layer described above has two or more layers, and has a configuration of three or more layers. May be. As a result, various types of optical compensation can be realized.

Furthermore, the phase difference optical elements 10 and 20 according to the above-described embodiment can be used by being incorporated in a liquid crystal display device 60 as shown in FIG. 7, for example.

The liquid crystal display device 60 shown in FIG. 7 includes a polarizing plate 102A on the incident side, a polarizing plate 102B on the emitting side, and a liquid crystal cell 104.

Among these, the polarizing plates 102A and 102B are configured to selectively transmit only linearly polarized light having a vibration surface in a predetermined vibration direction, and the respective vibration directions are perpendicular to each other. Are arranged opposite to each other in a crossed Nicols state. The liquid crystal cell 104 includes many cells corresponding to pixels, and is disposed between the polarizing plates 102A and 102B.

Here, in the liquid crystal display device 60, the liquid crystal cell 104 employs a VA method in which a nematic liquid crystal having negative dielectric anisotropy is sealed, and linearly polarized light transmitted through the incident side polarizing plate 102A is: When the light passes through the non-driven cell portion of the liquid crystal cell 104, the light passes without phase shift and is blocked by the polarizing plate 102B on the emission side. On the other hand, when the light passes through the portion of the liquid crystal cell 104 that is driven, the linearly polarized light is phase-shifted, and an amount of light corresponding to this phase shift is transmitted through the exit-side polarizing plate 102B. Is emitted. Thus, by appropriately controlling the driving voltage of the liquid crystal cell 104 for each cell, a desired image can be displayed on the polarizing plate 102B on the emission side.

In the liquid crystal display device 60 having such a configuration, between the liquid crystal cell 104 and the exit-side polarizing plate 102B (a polarizing plate that selectively transmits light of a predetermined polarization state emitted from the liquid crystal cell 104). The phase difference optical element 10 (20) according to the above-described embodiment is provided, and the phase difference optical element 10 (20) allows the liquid crystal in the light of a predetermined polarization state emitted from the liquid crystal cell 104 The polarization state of light emitted in a direction inclined from the normal line of the cell 104 can be compensated.

Here, in the phase difference optical element 10 (20), the C-plate type phase difference layer 12 (22) included in the phase difference optical element 10 (20) faces the liquid crystal cell 104 side, and the phase difference optical element 10 (20) It is preferable that the A-plate type retardation layer 14 included in the above is disposed so as to face the polarizing plate 102B side, whereby desired performance can be effectively obtained.

As described above, according to the liquid crystal display device 60 having the above-described configuration, between the liquid crystal cell 104 of the liquid crystal display device 60 and the polarizing plate 102B on the emission side, the retardation optical element 10 ( 20) is arranged to compensate for the polarization state of the light emitted from the liquid crystal cell 104 in the direction inclined from the normal line of the liquid crystal cell 104, so that the viewing angle dependence problem can be effectively improved. However, it is possible to suppress the occurrence of light and dark patterns in the liquid crystal display device 60 and to improve the contrast, and to suppress a decrease in display quality.

Note that the liquid crystal display device 60 illustrated in FIG. 7 is a transmission type in which light transmits from one side in the thickness direction to the other side; however, the present embodiment is not limited to this, and is described above. The retardation optical element 10 (20) according to the embodiment can be similarly incorporated and used in a reflection type liquid crystal display device or a reflection / transmission type liquid crystal display device.

In the liquid crystal display device 60 shown in FIG. 7, the retardation optical element 10 (20) according to the above-described embodiment is disposed between the liquid crystal cell 104 and the polarizing plate 102B on the emission side. In some embodiments, the phase difference optical element 10 (20) may be arranged between the liquid crystal cell 104 and the polarizing plate 102A on the incident side. Further, the phase difference optical element 10 (20) is arranged on both sides of the liquid crystal cell 104 (between the liquid crystal cell 104 and the polarizing plate 102A on the incident side and between the liquid crystal cell 104 and the polarizing plate 102B on the emitting side). Is also good. The number of retardation optical elements disposed between the liquid crystal cell 104 and the polarizing plate 102A on the incident side or between the liquid crystal cell 104 and the polarizing plate 102B on the output side is not limited to one, but a plurality of retardation optical elements are disposed. Is also good. However, in any case, in the phase difference optical element 10 (20), the C-plate type phase difference layer 12 included in the phase difference optical element 10 (20) faces the liquid crystal cell 104 side, and the phase difference optical element 10 (20). It is preferable that the A-plate type retardation layer 14 included in 20) is disposed so as to face the polarizing plate 102A or the polarizing plate 102B.

Next, examples of the above-described embodiment will be described with reference to comparative examples.

(Example 1)
In Example 1, the thickness of the retardation layer acting as a negative C plate and the thickness of the retardation layer acting as an A plate were fixed, and the directions of the directors of the liquid crystal molecules on the surface of each retardation layer were matched.

A monomer molecule having a nematic isotropic transition temperature of 110 ° C. having a polymerizable acrylate at both terminals and a spacer between the mesogen in the center and the acrylate (molecular structure represented by the above chemical formula (11)) (A chiral nematic liquid crystal) in which 90 parts of a chiral nematic liquid crystal and 90 parts of a chiral agent molecule having a polymerizable acrylate at both terminals (having a molecular structure represented by the chemical formula (14)) are dissolved. Solution). To the toluene solution, a photopolymerization initiator (Irgacure (registered trademark) 907, manufactured by Ciba Specialty Chemicals Co., Ltd.) was added at 5% by weight based on the monomer molecules. (For the chiral nematic liquid crystal thus obtained, it has been confirmed that the directors of the liquid crystal molecules are aligned on the alignment film within a range of ± 5 degrees in the rubbing direction.)

On the other hand, a polyimide (Optomer (registered trademark) AL1254, manufactured by JSR Corporation) dissolved in a solvent is spin-coated on a transparent glass substrate by a spin coater, dried, and then formed into a film at 200 ° C. (film thickness: 0.1 μm). Rubbed in a certain direction to function as an alignment film.

{Circle around (1)} Then, the glass substrate provided with such an alignment film was set on a spin coater, and spin-coated with a toluene solution in which the monomer molecules and the like were dissolved under the condition that the film thickness was as constant as possible.

Next, the toluene in the toluene solution is evaporated at 80 ° C., and further prepared separately on the surface of the coated film opposite to the glass substrate with the alignment film (first alignment film). The glass substrate provided with the alignment film (second alignment film) was placed, and the coating film was sandwiched from both sides. At this time, the rubbing directions of the first alignment film and the second alignment film were made to coincide.

Then, the coating film is irradiated with ultraviolet light, and the acrylate of the monomer molecule is three-dimensionally cross-linked and solidified (polymerized) by radicals generated from a photopolymerization initiator in the coating film to form a layer having a cholesteric regular structure. Formed. At this time, the glass substrate provided with the alignment film (second alignment film) prepared separately was peeled off. The thickness of the coating film at this time was 2.0 μm ± 1.5%. In addition, as measured by a spectrophotometer, the center wavelength of the selective reflection band of the coating film was 280 nm.

When the thus formed layer having the cholesteric regularity structure was measured with an automatic birefringence measuring device (KOBRA (registered trademark) 21ADH manufactured by Oji Scientific Instruments Co., Ltd.), the negative C plate was measured. (A retardation layer).

Next, on the layer having the cholesteric regularity structure formed as described above, a toluene solution (nematic liquid crystal solution) containing the same components as described above except that no chiral agent is contained is formed as much as possible. Spin coating was performed under the condition that the thickness was constant.

Thereafter, the toluene in the toluene solution is evaporated at 80 ° C. to form a coating film. Further, the coating film is irradiated with ultraviolet light, and the acrylate of the monomer molecule is generated by radicals generated from a photopolymerization initiator in the coating film. Was solidified (polymerized) by three-dimensional cross-linking to form a layer having a nematic regular structure.

に よ り Thus, finally, a retardation optical element in which a layer having a cholesteric regular structure and a layer having a nematic regular structure were laminated adjacent to each other was manufactured. The total film thickness at this time was 3.5 μm ± 1.5%.

When the thus manufactured retardation optical element was measured using an automatic birefringence measuring apparatus (KOBRA (registered trademark) 21ADH manufactured by Oji Scientific Instruments), a negative C plate and an A plate were measured. It was confirmed that and acted in a composite state.

Furthermore, cross-sections of a layer having a cholesteric regular structure (a retardation layer acting as a negative C plate) and a layer having a nematic regular structure (a retardation layer acting as an A plate) are observed with a transmission electron microscope. As a result, the light and dark patterns in the phase difference layer acting as the negative C plate were in parallel with each other (therefore, the directions of the helical axes in the phase difference layer acting as the negative C plate coincided with each other). Understand that). Further, there was no bright and dark pattern in the retardation layer acting as the A plate (this indicates that the directions of the directors of the liquid crystal molecules coincide in the retardation layer acting as the A plate). Also, the contrasts of the two main surfaces of the phase difference layer acting as the A-plate were the same, and the contrasts of the two main surfaces of the phase difference layer acting as the negative C-plate were also the same. It can be seen that the directions of the directors of the liquid crystal molecules on the two main surfaces of the phase difference layer acting as the A plate coincide with each other, and the directors of the liquid crystal molecules on the two main surfaces of the phase difference layer acting as the negative C plate It can be seen that the directions also match.)

Further, as shown in FIG. 8, when the linear polarizing plates 70A and 70B were placed in a crossed Nicols state, and the produced phase difference optical element 10 was interposed therebetween and visually observed, a bright and dark pattern observed in the plane was obtained. Was negligible.

(Comparative Example 1)
In Comparative Example 1, in Example 1, the thickness of the retardation layer acting as a negative C plate was made nonuniform, and the direction of the director of the liquid crystal molecules was disturbed.

That is, the thickness of the layer having a cholesteric regularity structure (a retardation layer acting as a negative C plate) is changed to 2.0 μm ± 5% by changing the conditions of the spin coater, and the second alignment film is used. When the retardation optical element produced in the same manner as in Example 1 except for the absence was not observed, a clear bright and dark pattern was observed in the plane.

(Comparative Example 2)
In Comparative Example 2, in Example 1, the rubbing direction of the alignment film on which the retardation layer acting as a negative C plate was formed was made non-uniform, and the direction of the director of the liquid crystal molecules was disturbed.

That is, when the retardation optical element manufactured in the same manner as in Example 1 except that the rubbing direction of the alignment film was made non-uniform in the plane was observed in the same manner, a clear bright and dark pattern was observed in the plane.

(Example 2)
In Example 2, the thickness of the retardation layer acting as a negative C-plate is made constant and the helical pitch is adjusted so that the direction of the director of the liquid crystal molecules on the two main surfaces of the layer facing each other is changed. Made parallel.

In other words, except that the thickness of the retardation layer acting as a negative C plate was made such that the direction of the director of the cholesteric regularity structure was parallel to the direction of the director from the refractive index of the material used. When the phase difference optical element manufactured in the same manner as in Example 1 was observed in the same manner, the bright and dark patterns observed in the plane were clearly reduced as compared with the case where the same was not performed.

As shown in FIG. 8, when the linear polarizers 70A and 70B were placed in a crossed Nicols state and the produced phase difference optical element 20 was interposed therebetween and visually observed, a bright and dark pattern observed in the plane was obtained. Was negligible. Further, by rotating each of the linear polarizers 70A and 70B (see FIG. 8) disposed on both sides of the produced retardation optical element 20, the die of the start and end points of the cholesteric regularity structure in the retardation optical element 20 is rotated. When the angle formed by the direction of the collector was visually observed by transmitted light intensity, it was within ± 5 degrees.

(Comparative Example 3)
In Comparative Example 3, in Example 2, the thickness of the retardation layer acting as a negative C plate was made non-uniform, and the direction of the director of the liquid crystal molecules was disturbed.

That is, the thickness of the layer having a cholesteric regularity structure (a retardation layer acting as a negative C plate) is changed to 2.0 μm ± 5% by changing the conditions of the spin coater, and the second alignment film is used. When the retardation optical element manufactured in the same manner as in Example 2 except that the optical element was not provided was observed in the same manner, a clear light and dark pattern was observed in the plane.

(Example 3)
In Example 3, a liquid crystal polymer was used as the material of the retardation layer acting as a negative C plate and the retardation layer acting as an A plate, and the thickness of each of the retardation layers was fixed. The direction of the director of the liquid crystal molecules on the surface was matched.

(4) A toluene solution (polymer cholesteric liquid crystal solution) in which an acrylic side-chain type liquid crystal polymer having a glass transition temperature of 80 ° C. and an isotropic transition temperature of 200 ° C. was dissolved was prepared. (For the polymer cholesteric liquid crystal thus obtained, it has been confirmed that the directors of the liquid crystal molecules are aligned within a range of ± 5 degrees in the rubbing direction on the alignment film.)

On the other hand, a polyimide (Optomer (registered trademark) AL1254, manufactured by JSR Corporation) dissolved in a solvent is spin-coated on a transparent glass substrate by a spin coater, dried, and then formed into a film at 200 ° C. (film thickness: 0.1 μm). Rubbed in a certain direction to function as an alignment film.

Then, the glass substrate having such an alignment film was set on a spin coater, and a toluene solution in which the liquid crystal polymer was dissolved was spin-coated under the condition that the film thickness was as constant as possible.

Next, the toluene in the toluene solution is evaporated at 90 ° C., and further prepared separately on the surface of the coated film opposite to the glass substrate with the alignment film (first alignment film). The glass substrate provided with the alignment film (second alignment film) was placed, and the coating film was sandwiched from both sides. At this time, the rubbing directions of the first alignment film and the second alignment film were made to coincide.

Then, the coating film was kept at 150 ° C. for 10 minutes, and it was visually confirmed by selective reflection that a cholesteric phase was exhibited. Further, the coating film was cooled to room temperature to solidify the liquid crystal polymer into a glass, thereby forming a layer having a cholesteric regular structure. At this time, the glass substrate provided with the alignment film (second alignment film) prepared separately was peeled off. The thickness of the coating film at this time was 2.0 μm ± 1.5%. Further, as measured by a spectrophotometer, the center wavelength of the selective reflection band of the coating film was 280 nm.

When the thus formed layer having the cholesteric regularity structure was measured with an automatic birefringence measuring device (KOBRA (registered trademark) 21ADH manufactured by Oji Scientific Instruments Co., Ltd.), the negative C plate was measured. (A retardation layer).

Next, a toluene solution containing a nematic liquid crystal polymer (polymer nematic liquid crystal solution) was formed on the layer having the cholesteric regularity structure formed as described above under such conditions that the film thickness was as constant as possible. Was spin coated.

Then, after evaporating the toluene in the toluene solution at 90 ° C., the coating film thus obtained is cooled to room temperature to solidify the liquid crystal polymer in a glassy state, thereby forming a layer having a nematic regular structure. Formed.

に よ り Thus, finally, a retardation optical element in which a layer having a cholesteric regular structure and a layer having a nematic regular structure were laminated adjacent to each other was manufactured. The total film thickness at this time was 3.5 μm ± 1.5%.

When the thus manufactured retardation optical element was measured using an automatic birefringence measuring apparatus (KOBRA (registered trademark) 21ADH manufactured by Oji Scientific Instruments), a negative C plate and an A plate were measured. It was confirmed that and acted in a composite state.

Furthermore, cross-sections of a layer having a cholesteric regular structure (a retardation layer acting as a negative C plate) and a layer having a nematic regular structure (a retardation layer acting as an A plate) are observed with a transmission electron microscope. As a result, the light and dark patterns in the phase difference layer acting as the negative C plate were in parallel with each other (therefore, the directions of the helical axes in the phase difference layer acting as the negative C plate coincided with each other). Understand that). Further, there was no bright and dark pattern in the retardation layer acting as the A plate (this indicates that the directions of the directors of the liquid crystal molecules coincide in the retardation layer acting as the A plate). Also, the contrasts of the two main surfaces of the phase difference layer acting as the A-plate were the same, and the contrasts of the two main surfaces of the phase difference layer acting as the negative C-plate were also the same. It can be seen that the directions of the directors of the liquid crystal molecules on the two main surfaces of the phase difference layer acting as the A plate coincide with each other, and the directors of the liquid crystal molecules on the two main surfaces of the phase difference layer acting as the negative C plate It can be seen that the directions also match.)

Further, as shown in FIG. 8, when the linear polarizing plates 70A and 70B were placed in a crossed Nicols state, and the produced phase difference optical element 10 was interposed therebetween and visually observed, a bright and dark pattern observed in the plane was obtained. Was negligible.

(Comparative Example 4)
In Comparative Example 4, in Example 3, the thickness of the retardation layer acting as a negative C plate was made non-uniform, and the direction of the director of the liquid crystal molecules was disturbed.

That is, the thickness of the layer having a cholesteric regularity structure (a retardation layer acting as a negative C plate) is changed to 2.0 μm ± 5% by changing the conditions of the spin coater, and the second alignment film is used. When the retardation optical element produced in the same manner as in Example 3 except for the absence was observed in the same manner, a clear bright and dark pattern was observed in the plane.

FIG. 1 is an enlarged perspective view schematically showing a part of a phase difference optical element according to an embodiment of the present invention. FIG. 4 is a perspective view schematically showing an enlarged part of a modification of the phase difference optical element according to the embodiment of the present invention. FIG. 4 is a schematic diagram showing a relationship between a helical pitch in a helical structure of liquid crystal molecules having cholesteric regularity and a director of the liquid crystal molecules on the surface of a retardation layer. FIG. 4 is a schematic cross-sectional view for explaining a first method for manufacturing a phase difference optical element according to one embodiment of the present invention. FIG. 9 is a schematic cross-sectional view for explaining a modification of the first method for manufacturing a phase difference optical element according to one embodiment of the present invention. FIG. 4 is a schematic cross-sectional view for explaining a second method for manufacturing a phase difference optical element according to one embodiment of the present invention. FIG. 1 is a schematic exploded perspective view showing a liquid crystal display device including a retardation optical element according to one embodiment of the present invention. FIG. 2 is a schematic exploded perspective view showing a configuration in the case of observing a phase difference optical element sandwiched between polarizing plates. FIG. 9 is a schematic exploded perspective view showing a conventional liquid crystal display device.

Explanation of reference numerals

10, 20 phase difference optical element 12 phase difference layer acting as negative C plate (C plate type phase difference layer)
14 Retardation layer acting as A plate (A-plate type retardation layer)
12A, 12B, 14A, 14B, 22A, 22B Surface 15 Normal 16 Glass substrate or polymer film 17 Alignment film 17A Second alignment film 18, 19 Polymerizable monomer molecule (polymerizable oligomer molecule)
32, 34 Liquid crystal polymer 60, 100 Liquid crystal display devices 70A, 70B, 102A, 102B Polarizing plate 104 Liquid crystal cells Ca, Cb, Na, Nb Director

Claims (21)

A C-plate type retardation layer having a cholesteric regularity structure with a planar orientation and acting as a negative C-plate, wherein a selective reflection wavelength of selective reflection light caused by the structure is different from a wavelength of incident light. A C-plate type retardation layer in which the helical pitch of the structure is adjusted to exist in
An A-plate type retardation layer that is stacked adjacent to the C-plate type retardation layer, has a nematic regularity structure, and acts as an A-plate;
Of the two main surfaces of the C-plate type retardation layer facing each other, the direction of the director of the liquid crystal molecules on the surface on the side of the A-plate type retardation layer and the two opposite surfaces of the A-plate type retardation layer A phase difference optical element, wherein a direction of a director of liquid crystal molecules substantially coincides with a surface of the main surface on the side of the C plate type phase difference layer. Of the two main surfaces of the C-plate type retardation layer, the direction of the director of liquid crystal molecules on the surface on the side of the A-plate type retardation layer and the direction of the side separated from the A-plate type retardation layer The phase difference optical element according to claim 1, wherein the direction of the director of the liquid crystal molecules on the surface is substantially parallel. The direction of directors of liquid crystal molecules on the surface of the C-plate type retardation layer on the side remote from the A-plate type retardation layer; and the C-plate type retardation layer of the A-plate type retardation layer. 3. The phase difference optical element according to claim 1, wherein the direction of the director of the liquid crystal molecules on the surface on the side away from the substrate is substantially parallel. 4. Of the two main surfaces of the C-plate type retardation layer, substantially between the surface on the A-plate type retardation layer side and the surface on the side separated from the A-plate type retardation layer The phase difference optical element according to any one of claims 1 to 3, wherein the phase difference optical element has a helical structure having a pitch number of 0.5 x an integer multiple. The retardation optical element according to any one of claims 1 to 4, wherein the C-plate type retardation layer has a structure in which a chiral nematic liquid crystal is three-dimensionally cross-linked and fixed. The retardation optical element according to any one of claims 1 to 4, wherein the C-plate type retardation layer has a structure in which a polymer cholesteric liquid crystal is fixed in a glass state. The retardation optical element according to any one of claims 1 to 6, wherein the A-plate type retardation layer has a structure in which a nematic liquid crystal is three-dimensionally cross-linked and fixed. The retardation optical element according to any one of claims 1 to 6, wherein the A-plate type retardation layer has a structure in which a polymer nematic liquid crystal is fixed in a glass state. A first liquid crystal having cholesteric regularity on an alignment film in which the direction of the alignment control force is substantially the same in the entire range on the film, wherein the selective reflection wavelength at the time of solidification is different from the wavelength of incident light. Coating the first liquid crystal adjusted to be present in;
The direction of the director of the liquid crystal molecules on one surface of the coated first liquid crystal is solidified while being regulated by the orientation regulating force of the orientation film to form a C-plate type retardation layer acting as a negative C-plate. The process of
Coating a second liquid crystal having nematic regularity directly on the formed C-plate type retardation layer;
The direction of the director of the liquid crystal molecules on the surface of the coated second liquid crystal on the side of the C-plate type retardation layer is solidified in a state where the direction is regulated by the alignment regulating force on the surface of the C-plate type retardation layer. Forming an A-plate type retardation layer functioning as a plate. The first liquid crystal is a liquid crystal including at least one of a polymerizable monomer molecule having cholesteric regularity and a polymerizable oligomer molecule having cholesteric regularity, and a die of the liquid crystal molecule on one surface of the first liquid crystal. Solidified by three-dimensional cross-linking in a state where the direction of the collector is regulated by the orientation regulating force of the orientation film,
The second liquid crystal is a liquid crystal containing at least one of a polymerizable monomer molecule having a nematic regularity and a polymerizable oligomer molecule having a nematic regularity, and the second liquid crystal is on the C-plate type retardation layer side of the second liquid crystal. 10. The method according to claim 9, wherein the direction of the director of the liquid crystal molecules on the surface of the C-plate type retardation layer is solidified by three-dimensional crosslinking while being regulated by the alignment regulating force of the surface of the C-plate type retardation layer. . The first liquid crystal is a liquid crystal containing a liquid crystal polymer having cholesteric regularity, and is cooled in a state where the direction of the director of the liquid crystal molecules on one surface of the first liquid crystal is regulated by the alignment regulating force of the alignment film. Is solidified into a glass by
The second liquid crystal is a liquid crystal containing a liquid crystal polymer having nematic regularity, and the direction of the director of the liquid crystal molecules on the surface of the second liquid crystal on the side of the C plate type retardation layer is the same as that of the C plate type retardation layer. The method according to claim 9, wherein the glass is solidified by cooling in a state where the surface is regulated by an orientation regulating force of the surface. The thickness of the coating of the first liquid crystal is adjusted so that the directions of the directors of the liquid crystal molecules on both of the two main surfaces facing each other of the C-plate type retardation layer are substantially parallel. The method according to any one of claims 9 to 11, wherein The first liquid crystal is separated from the surface of the alignment film so as to solidify the first liquid crystal in a state where the directions of the directors of the liquid crystal molecules on both of the two main surfaces facing each other of the C-plate type retardation layer are regulated. The method according to claim 9, wherein another alignment film is brought into contact with the side surface. From the surface of the C-plate type retardation layer, the second liquid crystal is solidified in a state where the directions of the directors of the liquid crystal molecules on both of the two main surfaces facing each other of the A-plate type retardation layer are regulated. The method according to any one of claims 9 to 11, wherein another alignment film is brought into contact with the surface on the side that is separated. Coating a first liquid crystal having nematic regularity on an alignment film in which the direction of the alignment control force is substantially the same over the entire range on the film;
Forming an A-plate type retardation layer that acts as an A-plate by solidifying in a state where the direction of the director of the liquid crystal molecules on one surface of the coated first liquid crystal is regulated by the orientation regulating force of the orientation film. When,
A second liquid crystal having cholesteric regularity directly on the formed A-plate type retardation layer, wherein the second liquid crystal is selectively adjusted so that the selective reflection wavelength at the time of solidification is in a range different from the wavelength of incident light. A step of coating the liquid crystal;
The direction of the director of the liquid crystal molecules on the surface of the coated second liquid crystal on the side of the A-plate type retardation layer is solidified in a state where it is regulated by the alignment regulating force of the surface of the A-plate type retardation layer, and the negative Forming a C-plate type retardation layer acting as a C-plate. The first liquid crystal is a liquid crystal including at least one of a polymerizable monomer molecule having a nematic regularity and a polymerizable oligomer molecule having a nematic regularity, and a die of the liquid crystal molecule on one surface of the first liquid crystal. Solidified by three-dimensional cross-linking in a state where the direction of the collector is regulated by the orientation regulating force of the orientation film,
The second liquid crystal is a liquid crystal including at least one of a polymerizable monomer molecule having cholesteric regularity and a polymerizable oligomer molecule having cholesteric regularity, and the second liquid crystal is on the side of the A-plate type retardation layer. 16. The method according to claim 15, wherein the direction of the director of the liquid crystal molecules on the surface of the liquid crystal layer is solidified by three-dimensional crosslinking while being regulated by the alignment regulating force of the surface of the A-plate type retardation layer. . The first liquid crystal is a liquid crystal containing a liquid crystal polymer having a nematic regularity, and is cooled in a state where the direction of the director of the liquid crystal molecules on one surface of the first liquid crystal is regulated by the alignment regulating force of the alignment film. Is solidified into a glass by
The second liquid crystal is a liquid crystal containing a liquid crystal polymer having cholesteric regularity, and the direction of the director of the liquid crystal molecules on the surface of the second liquid crystal on the side of the A-plate type retardation layer is the same as that of the A-plate type retardation layer. The method according to claim 15, characterized in that the surface is solidified into a glass by cooling while being regulated by the orientation regulating force of the surface. The thickness of the coating of the second liquid crystal is adjusted such that the directions of the directors of the liquid crystal molecules on both of the two main surfaces facing each other of the C-plate type retardation layer are substantially parallel. The method according to any one of claims 15 to 17, wherein From the surface of the A-plate type retardation layer, the second liquid crystal is solidified in a state where the directions of the directors of the liquid crystal molecules on both of the two main surfaces facing each other of the C-plate type retardation layer are regulated. The method according to any one of claims 15 to 17, wherein another alignment film is brought into contact with the surface on the side that is separated. The first liquid crystal is separated from the surface of the alignment film so as to solidify the first liquid crystal in a state where the directions of the directors of the liquid crystal molecules on both of the two main surfaces facing each other of the A-plate type retardation layer are regulated. The method according to any one of claims 15 to 17, wherein another alignment film is brought into contact with the surface on the side. A liquid crystal cell,
A pair of polarizing plates arranged to sandwich the liquid crystal cell,
The retardation optical element according to any one of claims 1 to 8, which is disposed between the liquid crystal cell and at least one of the pair of polarizing plates,
The phase difference optical element compensates for the polarization state of light that is incident on the liquid crystal cell and / or is emitted in a predetermined polarization state from the liquid crystal cell and that is emitted in a direction inclined from the normal line of the liquid crystal cell. A liquid crystal display device characterized in that:

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