JP3715940B2 - Method for manufacturing circularly polarized light extracting optical element, circularly polarized light extracting optical element, polarized light source device and liquid crystal display device provided with the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a circularly polarized light extracting optical element able to effectively suppress the deterioration of the display quality of a display device due to appearance of a light and dark pattern inside the screen of the display device. SOLUTION: The circularly polarized light extracting optical element 10 is provided with a glass substrate 11, an alignment layer 12 laminated on the glass substrate 11 and a cholesteric layer 13 subjected to planar alignment caused by alignment controllability of the surface of the alignment layer 12. The cholesteric layer 13 has the first surface 13a located on the glass substrate 11 side and the second surface 13b being opposite to the first surface 13a. The director directions of molecules along the first surface 13a in the cholesteric layer 13 practically coincide with each other in the first surface 13a due to the alignment controllability of the surface of the alignment layer 12. Also the chiral pitch of the cholesteric layer 13 varies so as to have the chiral pitch p2 on the second surface 13b side being longer compared with the chiral pitch p1 on the first surface 13a side.

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a circularly polarized light extracting optical element used in a display device such as a liquid crystal display device, and in particular, a method for producing a circularly polarized light extracting optical element having a layer having a cholesteric structure (hereinafter also referred to as “cholesteric layer”), The present invention relates to a circularly polarized light extracting optical element, a polarized light source device including the same, and a liquid crystal display device.
[0002]
[Prior art]
Conventionally, a circularly polarized light extracting optical element having a cholesteric liquid crystal layer is known as an optical element that separates right-handed or left-handed circularly polarized light components contained in incident light and selectively reflects or transmits each circularly polarized light component. ing. In such a circularly polarized light extracting optical element, in order to improve the utilization efficiency of a circularly polarized component in a predetermined optical rotation direction (right-handed circularly polarized light component or left-handed circularly polarized light component) separated by the circularly polarized light extracting optical element, It is desired to increase the bandwidth of the circularly polarized light component separated by the circularly polarized light extracting optical element. For this reason, conventionally, a circularly polarized light extracting optical element formed by laminating a plurality of cholesteric liquid crystal layers having different chiral pitches has been proposed (JP-A-8-271731 and JP-A-11-264907). A polarized light source device and a liquid crystal display device provided with such a circularly polarized light extracting optical element have also been proposed (Japanese Patent Laid-Open No. 9-304770).
[0003]
[Problems to be solved by the invention]
Incidentally, when the circularly polarized light extracting optical element as described above is used in a display device such as a liquid crystal display device, it is important that the in-plane polarization state is uniform. Here, in a liquid crystal display device or the like, as shown in FIG. 8, the circularly polarized light extracting optical element 10 includes a linearly polarizing plate arranged in a crossed Nicols state (a state in which the transmission axes of the polarizing plates are orthogonal to each other) The display device is used in a state of being sandwiched between polarizing plates 31 and 32 such as an elliptical polarizing plate, and depending on the state of a liquid crystal cell (not shown) sandwiched between the polarizing plates 31 and 32. Is changing. In a state where the liquid crystal cell (not shown) completely transmits the polarized light, the incident light is completely blocked by the polarizing plates 31 and 32, and the leakage light to the outside is eliminated.
[0004]
However, in the actual display device, since the polarization state in the plane of the circularly polarized light extracting optical element 10 is not uniform, even when the incident light is expected to be completely blocked by the polarizing plates 31 and 32, It has been found that a bright and dark pattern appears in the surface of the display device, and the display quality of the display device is significantly lowered.
[0005]
As a result of earnest research on the cause of such a phenomenon using experiments and computer simulations, the present inventors have found that the main cause is the direction of molecules on the surface of the circularly polarized light extraction optical element. .
[0006]
The present invention has been made based on such knowledge, and even when a circularly polarized light extracting optical element is sandwiched between a pair of polarizing plates arranged in a crossed Nicol state, a light and dark pattern appears in the plane of the display device. A method of manufacturing a circularly polarized light extracting optical element, a circularly polarized light extracting optical element, a polarized light source device including the same, and a liquid crystal display device capable of effectively suppressing display quality degradation of the display device The purpose is to do.
[0007]
[Means for Solving the Problems]
  The present invention provides, as a first solving means, a step of coating a polymerizable material on a support substrate, and orienting the polymerizable material by an alignment regulating force in substantially the same direction on the surface of the support substrate. A first surface located on the support substrate side by three-dimensionally cross-linking the prepared polymerizable material and changing a chiral pitch of a cholesteric structure formed by the polymerizable material with respect to a thickness direction of the support substrate Compared to the side chiral pitch,Second surface opposite to the first surfaceAnd the second surface where the director direction of the molecules does not match due to the in-plane film thickness distribution of the second surface.And a step of forming a cholesteric layer having a longer side chiral pitch. A method of manufacturing a circularly polarized light extracting optical element is provided.
[0008]
  The present invention provides, as a second solution, a step of coating a polymerizable material on a support substrate, and orienting the polymerizable material by an alignment regulating force in a substantially same direction on the surface of the support substrate, Three-dimensionally crosslinking the polymerizable material formed to form a first cholesteric coating film having a predetermined chiral pitch, and directly coating the polymerizable material for lamination on the first cholesteric coating film, The step of orienting the polymerizable material for lamination by the orientation regulating force on the surface of the first cholesteric coating, and the three-dimensional crosslinking of the polymerizable material for lamination, on the first cholesteric coating,A second cholesteric coating film in which the director direction of molecules on the surface does not match due to the in-plane film thickness distribution,Forming a second cholesteric coating film having a chiral pitch longer than the chiral pitch of the first cholesteric coating film, and providing a method for producing a circularly polarized light extracting optical element.
[0009]
  As a third solution, the present invention includes a step of coating a liquid crystal polymer on a support substrate, and aligning the liquid crystal polymer with an alignment regulating force in substantially the same direction on the surface of the support substrate. The liquid crystal polymer is cooled to a glass state, the chiral pitch of the cholesteric structure formed by the liquid crystal polymer is changed with respect to the thickness direction of the support substrate, and the first surface side located on the support substrate side Compared to the chiral pitch of,Second surface opposite to the first surfaceAnd the second surface where the director direction of the molecules does not match due to the in-plane film thickness distribution of the second surface.And a step of forming a cholesteric layer having a longer side chiral pitch. A method for producing a circularly polarized light extracting optical element is provided.
[0010]
  The present invention provides, as a fourth solution, a step of coating a liquid crystal polymer on a support substrate, and orienting the liquid crystal polymer by an alignment regulating force in substantially the same direction on the surface of the support substrate. Cooling the liquid crystal polymer into a glass state, forming a first cholesteric coating film having a predetermined chiral pitch, directly coating a laminating liquid crystal polymer on the first cholesteric coating film, The step of aligning the liquid crystal polymer for laminating by the orientation regulating force on the surface of 1 cholesteric coating, and cooling the liquid crystal polymer for laminating to a glass state, on the first cholesteric coating,A second cholesteric coating film in which the director direction of molecules on the surface does not match due to the in-plane film thickness distribution,Forming a second cholesteric coating film having a chiral pitch longer than the chiral pitch of the first cholesteric coating film, and providing a method for producing a circularly polarized light extracting optical element.
[0011]
  As a fifth solution, the present invention includes a cholesteric layer oriented by an orientation regulating force on the surface of the supporting substrate, and the cholesteric layer includes a first surface and a second surface facing the first surface. And the director direction of molecules on the first surface of the cholesteric layer substantially matches within the first surface due to the orientation regulating force of the support substrate surface,The director direction of the molecules on the second surface of the cholesteric layer is in a state that does not match due to the in-plane film thickness distribution of the second surface,A circularly polarized light extracting optical element is provided, wherein a chiral pitch on the second surface side of the cholesteric layer is longer than a chiral pitch on the first surface side.
[0012]
In the fifth solution described above, it is preferable that the chiral pitch of the cholesteric layer gradually changes from the first surface side toward the second surface side. Moreover, it is preferable that the said cholesteric layer consists of a laminated body of a some cholesteric coating film. Furthermore, it is preferable that the cholesteric layer partially transmits one circularly polarized light component in a selective reflection wavelength band among right-handed and left-handed circularly polarized light components included in incident light. Furthermore, it is preferable that the chiral pitch on the second surface side in the cholesteric layer is selected so that the selective reflection wavelength on the second surface side is 687 nm or more.
[0013]
The present invention provides, as a sixth solution, the circularly polarized light extraction optical element according to the fifth solution described above, and the light incident from the side surface is emitted from one of the upper surface and the lower surface and projected onto the circularly polarized light extraction optical element. There is provided a polarized light source device comprising: a light guide body that emits light; and a light source that emits light toward the side surface of the light guide body.
[0014]
As a seventh solution, the present invention provides a polarized light source device according to the sixth solution described above, and receives the polarized light emitted from the polarized light source device and changes the transmittance with respect to the polarized light. Provided is a liquid crystal display device comprising a liquid crystal cell that transmits polarized light.
[0015]
According to the present invention, in the cholesteric layer, the chiral pitch on the second surface side where the polarized light is emitted is longer than the chiral pitch on the first surface side where the director directions of the molecules are substantially coincident. Therefore, the unevenness of the twist angle on the second surface side of the cholesteric layer is reduced, and the in-plane polarization state of the circularly polarized light extracting optical element becomes uniform. For this reason, in a display device such as a liquid crystal display device, even when the circularly polarized light extracting optical element is sandwiched between polarizing plates such as a linearly polarizing plate and an elliptically polarizing plate arranged in a crossed Nicol state, the display device It is possible to effectively prevent the display quality of the display device from deteriorating due to the appearance of bright and dark patterns in the surface.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0017]
First embodiment
First, a circularly polarized light extracting optical element according to the first embodiment of the present invention will be described with reference to FIGS. 1 (a) and 1 (b).
[0018]
FIG. 1A is a diagram showing a circularly polarized light extracting optical element according to the first embodiment of the present invention, and FIG. 1B is a schematic diagram enlarging the Ib portion of FIG. As shown in FIGS. 1A and 1B, a circularly polarized light extracting optical element 10 according to the first embodiment of the present invention includes a glass substrate 11, an alignment film 12 laminated on the glass substrate 11, And a layer (cholesteric layer) 13 having a cholesteric structure, which is planarly aligned by the alignment regulating force on the surface of the alignment film 12. The glass substrate 11 and the alignment film 12 constitute a support base material.
[0019]
Here, the cholesteric layer 13 has a helical structure (cholesteric structure) in which the director direction of the molecule is continuously rotated in the thickness direction of the cholesteric layer 13 as a physical molecular arrangement. Based on a specific molecular arrangement, it has an optical rotation selection characteristic (polarization separation characteristic) that separates a circular polarization component in one direction (optical rotation component) and a circular polarization component in the opposite direction. In such a cholesteric layer 13, incident light incident on the helical axis of the cholesteric structure is separated into a right-handed circularly polarized light component (right-handed light) and a left-handed circularly-polarized light component (left-handed light). The polarization component is transmitted and the other circular polarization component is reflected. This phenomenon is widely known as circular dichroism, and the optical rotation direction is the same as the direction of the helical axis of the cholesteric structure of the cholesteric layer 13 by appropriately selecting the optical rotation direction of the circularly polarized component with respect to the incident light. Are selectively reflected.
[0020]
In this case, the maximum optical rotation of the reflected light is expressed by the wavelength λ of the following equation (1).₀It occurs in.
[0021]
λ₀= N_av・ P ... (1)
Here, p is a chiral pitch (helical pitch), n_avIs the average refractive index in a plane perpendicular to the helical axis.
[0022]
The wavelength bandwidth Δλ of the reflected light at this time is expressed by the following equation (2).
[0023]
Δλ = Δn · p (2)
Here, Δn is a birefringence and p is a chiral pitch.
[0024]
That is, in the cholesteric layer 13, the wavelength λ₀One of the right-handed and left-handed circularly polarized light components in the range of the wavelength bandwidth Δλ centered on is reflected, and the other circularly polarized light component and light in other wavelength regions are transmitted. In reflection, right-handed or left-handed circularly polarized light components are reflected as they are without reversing the optical rotation direction, unlike normal reflection.
[0025]
The cholesteric layer 13 has a first surface 13a located on the glass substrate 11 side and a second surface 13b opposite to the first surface 13a, and molecules on the first surface 13a of the cholesteric layer 13 are included. As shown in FIG. 1B, the director direction is substantially matched in the first surface 13a by the alignment regulating force on the surface of the alignment film 12. In FIG.1 (b), the arrow has shown the director direction of a molecule | numerator. In addition, the case where the director direction of the molecule matches includes the case where the director direction of the molecule is shifted by 180 degrees in addition to the case where the director direction of the molecule completely matches. This is because in many cases, the head and the bottom of the molecule cannot be distinguished optically. Whether or not the director directions of the molecules substantially coincide can be determined by observing the cross section of the cholesteric layer 13 with a transmission electron microscope. When the cross section of the cholesteric layer 13 is observed with a transmission electron microscope, a bright and dark pattern corresponding to a pitch peculiar to the cholesteric structure can be observed. Therefore, if the surface portion can be seen at substantially the same density (brightness and darkness), it can be determined that the director directions of the molecules in the plane are substantially the same.
[0026]
The chiral pitch of the cholesteric layer 13 is the chiral pitch p on the first surface 13a side as shown in FIG.₁Compared to the chiral pitch p on the second surface 13b side.₂It has changed to become longer. Thereby, the selective reflection wavelength band of the cholesteric layer 13 can be broadened. Further, the chiral pitch p on the first surface 13a side where the director directions of the molecules substantially coincide.₁As compared with the chiral pitch p on the second surface 13b side from which the polarized light is emitted.₂Because of the longer direction, even when the cholesteric layer 13 is formed by a coating apparatus having an in-plane film thickness distribution of ± 3%, the cholesteric layer 13 is caused by unevenness on the second surface 13b. Unevenness of the twist angle on the second surface 13b side of the cholesteric layer 13 (unevenness of molecular director direction) can be reduced. Note that the chiral pitch of the cholesteric layer 13 is the first surface 13a from the viewpoint that an optical discontinuity is not formed in an intermediate portion of the cholesteric layer 13 between the first surface 13a side and the second surface 13b side. It is preferable to gradually change from the side toward the second surface 13b side.
[0027]
Furthermore, the thickness of the cholesteric layer 13 is sufficiently increased so that one of the right-handed and left-handed circularly polarized light components included in the incident light is completely (with a maximum reflectance of 100%). In addition to reflecting, for example, a polarizing reflection layer of a display device proposed in Japanese Patent Application Laid-Open No. 2000-193962, the thickness thereof is made smaller than a necessary thickness for reflecting with the maximum reflectance. Alternatively, one of the right-handed and left-handed circularly polarized light components included in the incident light may be partially reflected (for example, with a maximum reflectance of less than 95%). In the latter case, the effects of the present invention are remarkably exhibited. This is because, in the selective reflection wavelength band of the cholesteric layer 13, not only the circularly polarized component reverse to the circularly polarized component but also the circularly polarized component itself is transmitted depending on the thickness (thickness). This is because the thinner the film becomes, the more light is transmitted), and the effect appears for one of the circularly polarized light components.
[0028]
Furthermore, the cholesteric layer 13 has a chiral pitch p on the second surface 13b side.₂However, it is preferable that the selective reflection wavelength on the second surface 13b side be selected to be sufficiently long. In this case, the effect of the present invention is remarkably revealed. As described above, when the cholesteric layer 13 is formed by a coating apparatus having an in-plane film thickness distribution of ± 3%, the chiral pitch of the cholesteric layer 13 is made as long as possible with the same film thickness distribution. This is because when the selective reflection wavelength is made as long as possible, the twist angle unevenness (unevenness in the director direction of molecules) on the second surface 13b side can be reduced. In particular, when the selective reflection wavelength on the second surface 13b side of the cholesteric layer 13 is 687 nm or more, when the circularly polarized light extracting optical element 10 including such a cholesteric layer 13 is used in a display device, Compared to 555 nm, which has a maximum spectral visibility, it becomes 1/100 or less and can be almost ignored. In addition, if the selective reflection wavelength on the second surface 13b side of the cholesteric layer 13 is 720 nm or more, the ratio is 1/1000, which is completely negligible. The selective reflection wavelength on the first surface 13a side of the cholesteric layer 13 is 429 nm or less, more preferably 409 nm or less in order to cover the entire visible light region when the circularly polarized light extracting optical element 10 is used in a display device. It is preferable.
[0029]
In addition, as a material of the cholesteric layer 13, a polymerizable monomer molecule or a polymerizable oligomer molecule (polymerizable material) can be used, and a liquid crystal polymer can also be used.
[0030]
Here, when a polymerizable monomer molecule is used as the material of the cholesteric layer 13, liquid crystalline monomers and chiral compounds described in JP-A-7-258638 and JP-A-10-508882 are used. Mixtures can be used. When a polymerizable oligomer molecule is used, a cyclic organopolysiloxane compound having a cholesteric phase as described in JP-A-57-165480 can be used.
[0031]
On the other hand, when a liquid crystal polymer is used as the material of the cholesteric layer 13, a polymer in which a mesogenic group exhibiting liquid crystal is introduced into the main chain, the side chain, or both the main chain and the side chain, and a cholesteryl group are used as the side chain. A high molecular weight cholesteric liquid crystal, a liquid crystalline polymer as described in JP-A-9-133810, a liquid crystalline polymer as described in JP-A-11-293252, or the like is used. it can.
[0032]
Next, a manufacturing method of the circularly polarized light extracting optical element 10 according to the first embodiment of the present invention having such a configuration will be described with reference to FIGS.
[0033]
(First example)
First, a manufacturing method in the case of using a polymerizable monomer molecule or a polymerizable oligomer molecule as the material of the cholesteric layer 13 will be described.
[0034]
In this case, first, the alignment film 12 subjected to the alignment process is formed on the glass substrate 11.
[0035]
Next, a polymerizable monomer molecule or a polymerizable oligomer molecule is coated on the alignment film 12, heated as necessary, and the polymerizable monomer molecule or the polymerizable property by the alignment regulating force in the substantially same direction on the surface of the alignment film 12. Orient oligomer molecules. At this time, the coated polymerizable monomer molecule or polymerizable oligomer molecule is in a liquid crystal phase. The heating here is for holding the polymerizable monomer molecule or polymerizable oligomer molecule for a while in the temperature zone of the liquid crystal phase, and if necessary, several seconds to 5 minutes, preferably 30 seconds to 90 seconds. It is good to do. In addition, when a polymerizable monomer molecule or a polymerizable oligomer molecule is in a liquid crystal phase at a predetermined temperature, a nematic state is obtained. However, if an arbitrary chiral agent is added thereto, a chiral nematic liquid crystal (cholesteric liquid crystal) is obtained. Here, it is preferable to add about several to 10% of a chiral agent. The selective reflection wavelength band resulting from the cholesteric structure of the polymerizable monomer molecule or polymerizable oligomer molecule can be controlled by changing the chiral power by changing the type of the chiral agent or by changing the concentration of the chiral agent. Can do.
[0036]
The oriented polymerizable monomer molecule or polymerizable oligomer molecule is three-dimensionally cross-linked to be polymerized, and the chiral pitch of the cholesteric structure formed by the polymerizable monomer molecule or polymerizable oligomer molecule is converted into the glass substrate 11 (alignment film). 12) with respect to the thickness direction, and the chiral pitch p on the first surface 13a side located on the glass substrate 11 (alignment film 12) side.₁Compared to the chiral pitch p on the second surface 13b side facing the first surface 13a.₂A cholesteric layer 13 having a longer side is formed. At this time, as a method for three-dimensionally crosslinking the polymerizable monomer molecule or the polymerizable oligomer molecule, in addition to a method of adding a photoinitiator to these materials and curing them by ultraviolet irradiation, an electron beam is applied to these materials. A method of curing by direct irradiation can be used. Here, “three-dimensional crosslinking” means that polymerizable monomer molecules or polymerizable oligomer molecules are polymerized three-dimensionally to form a network (network) structure. By adopting such a state, the state of the cholesteric liquid crystal can be optically fixed, and a film-like film that is easy to handle as an optical film and stable at room temperature can be obtained. Further, as a method of changing the chiral pitch in the cholesteric layer 13, the polymerized cholesteric layer 13 is immersed in a toluene solution or the like, and a larger amount of the chiral agent is extracted from the first surface 13a side of the cholesteric layer 13, thereby cholesteric. A method such as providing a gradient in the component concentration in the layer 13 can be used. In addition, methods described in JP-A-6-281814, JP-A-10-316755, and the like can be used.
[0037]
In the case of such a manufacturing method, the polymerizable monomer molecule or polymerizable oligomer molecule for the cholesteric layer 13 may be dissolved in a solvent to form a coating liquid. In that case, the solvent for evaporating the solvent before three-dimensional crosslinking is used. It is necessary to perform a drying process.
[0038]
Further, in such a manufacturing method, in particular, if the direction of the alignment regulating force on the surface of the alignment film 12 is substantially matched in the surface of the alignment film 12, the first surface 13 a of the cholesteric layer 13 that is in contact therewith. The director directions of the molecules can be substantially matched. The alignment film 12 may be formed by a conventionally known method. For example, (1) a method of forming a polyimide film on a glass substrate 11 and rubbing, or (2) a photo-alignment method on the glass substrate 11. For example, a method of forming a polymer compound to be a film and irradiating with ultraviolet rays which are polarized light, and (3) a method of using a stretched PET film can be used.
[0039]
(Second example)
Next, a manufacturing method when a liquid crystal polymer is used as the material of the cholesteric layer 13 will be described.
[0040]
In this case, first, the alignment film 12 subjected to the alignment process is formed on the glass substrate 11.
[0041]
Next, a liquid crystal polymer is coated on the alignment film 12 and heated as necessary to align the liquid crystal polymer by the alignment regulating force in the substantially same direction on the surface of the alignment film 12. At this time, the coated liquid crystal polymer is in a liquid crystal phase. In addition, the heating here is for hold | maintaining a liquid crystal polymer in the temperature zone of a liquid crystal phase for a while. As the liquid crystal polymer, a cholesteric liquid crystal polymer itself having a chiral ability may be used, or a mixture of a nematic liquid crystal polymer and a cholesteric liquid crystal polymer may be used. Here, as a method of controlling the selective reflection wavelength band resulting from the cholesteric structure of the liquid crystal polymer, when a cholesteric liquid crystal polymer is used, the content of a bent chain having a chiral component is adjusted, or a mesogenic monomer and a chiral mesogen. The chiral power in the molecule may be adjusted by a known method such as adjusting the composition ratio of copolymerization with the monomer (Literature (Naideyuki Koide, Kunisuke Sakamoto, “Liquid Crystal Polymer”, Kyoritsu Publishing Co., Ltd., 1998). Year)). Moreover, what is necessary is just to adjust the mixing ratio, when using the mixture of a nematic liquid crystal polymer and a cholesteric liquid crystal polymer.
[0042]
Then, the aligned liquid crystal polymer is cooled to a glass state, and the chiral pitch of the cholesteric structure formed by the liquid crystal polymer is changed with respect to the thickness direction of the glass substrate 11 (alignment film 12). Chiral pitch p on the first surface 13a side located on the alignment film 12) side₁The chiral pitch p on the second surface 13b side facing the first surface 13a compared to₂A cholesteric layer 13 having a longer side is formed. Here, the state of the liquid crystal polymer changes depending on the temperature. For example, when the glass transition temperature is 90 ° C. and the isotropic transition temperature is 200 ° C., the temperature of the cholesteric liquid crystal is between 90 ° C. and 200 ° C. If it exhibits a state and is cooled to room temperature, it is fixed in a glass state while having a cholesteric structure. As a method for changing the chiral pitch in the cholesteric layer 13, a method described in JP-A-10-319235 can be used.
[0043]
In such a manufacturing method, the liquid crystal polymer for the cholesteric layer 13 may be dissolved in a solvent to form a coating liquid. In that case, it is necessary to perform a drying step for evaporating the solvent before cooling.
[0044]
Further, in such a manufacturing method, in particular, if the direction of the alignment regulating force on the surface of the alignment film 12 is substantially matched in the surface of the alignment film 12, the first surface 13 a of the cholesteric layer 13 that is in contact therewith. The director directions of the molecules can be substantially matched. The alignment film 12 may be formed by a conventionally known method. For example, (1) a method of forming a polyimide film on a glass substrate 11 and rubbing, or (2) a photo-alignment method on the glass substrate 11. For example, a method of forming a polymer compound to be a film and irradiating with ultraviolet rays which are polarized light, and (3) a method of using a stretched PET film can be used.
[0045]
As described above, according to the first embodiment of the present invention, in the cholesteric layer 13, the chiral pitch p on the first surface 13a side where the director directions of the molecules substantially coincide with each other.₁As compared with the chiral pitch p on the second surface 13b side from which the polarized light is emitted.₂Since this is made longer, the twist angle unevenness on the second surface 13b side of the cholesteric layer 13 is reduced, and the in-plane polarization state of the circularly polarized light extracting optical element 10 becomes uniform. Therefore, as shown in FIG. 8, in a display device such as a liquid crystal display device, the circularly polarized light extracting optical element 10 is sandwiched between polarizing plates 31 and 32 such as a linearly polarizing plate and an elliptically polarizing plate arranged in a crossed Nicol state. Even in the case of being used in such a state, it is possible to effectively suppress the appearance of a bright and dark pattern in the surface of the display device and the deterioration of the display quality of the display device.
[0046]
Further, according to the first embodiment of the present invention, the cholesteric layer 13 partially converts one circularly polarized component in the selective reflection wavelength band of right-handed or left-handed circularly polarized light components included in the incident light. It is also possible to transmit light depending on the thickness (in this case, it is effective for the bright and dark pattern caused by the one circularly polarized light component that transmits depending on the thickness (transmits as the thickness decreases). Can be suppressed.
[0047]
Furthermore, according to the first embodiment of the present invention, the chiral pitch p on the second surface 13b side of the cholesteric layer 13 is determined.₂Is selected so that the selective reflection wavelength on the second surface 13b side is sufficiently long, the chiral pitch on the second surface 13b side of the cholesteric layer 13 is sufficiently long, so on the second surface 13b side. The twist angle unevenness (unevenness of the director direction of molecules) can be reduced. In particular, when the selective reflection wavelength on the second surface 13b side of the cholesteric layer 13 is 687 nm or more, when the circularly polarized light extracting optical element 10 including such a cholesteric layer 13 is used in a display device, Compared to 555 nm, which has a maximum spectral visibility, it becomes 1/100 or less and can be almost ignored.
[0048]
In the first embodiment described above, the cholesteric layer 13 laminated on the glass substrate 11 (alignment film 12) is used as the circularly polarized light extracting optical element 10. However, the present invention is not limited to this. The cholesteric layer 13 peeled from 11 (alignment film 12) may be used alone.
[0049]
Second embodiment
Next, a second embodiment of the present invention will be described with reference to FIGS. The second embodiment of the present invention is the same as the first embodiment shown in FIGS. 1 (a) and 1 (b) except that the cholesteric layer 13 is composed of a laminate of a plurality of cholesteric coating films 13 'and 13' '. In the second embodiment of the present invention, the same parts as those in the first embodiment shown in FIGS. Is omitted.
[0050]
FIG. 2 is a diagram showing a circularly polarized light extracting optical element according to the second embodiment of the present invention, and FIG. 3 is a schematic diagram enlarging the III part of FIG. As shown in FIGS. 2 and 3, the circularly polarized light extracting optical element 10 according to the second embodiment of the present invention includes a glass substrate 11, an alignment film 12 laminated on the glass substrate 11, and an alignment film 12. And a layer (cholesteric layer) 13 having a cholesteric structure, which is planar-aligned by a surface alignment regulating force. The glass substrate 11 and the alignment film 12 constitute a support base material.
[0051]
Here, the cholesteric layer 13 is composed of a laminate of a plurality of cholesteric coatings 13 'and 13 "having different chiral pitches. As shown in FIG. 3, adjacent cholesteric coatings 13' and 13" The director direction of the molecules is substantially coincident with the adjacent surface. Further, the chiral pitch of the cholesteric coating film 13 ″ located on the side opposite to the glass substrate 11 (alignment film 12) is longer than the chiral pitch of the cholesteric coating film 13 ′ located on the glass substrate 11 (alignment film 12) side. ing.
[0052]
Next, a method for manufacturing the circularly polarized light extracting optical element 10 according to the second embodiment of the present invention having such a configuration will be described.
[0053]
(First example)
First, a manufacturing method in the case of using a polymerizable monomer molecule or a polymerizable oligomer molecule as the material of the cholesteric layer 13 will be described with reference to FIGS. 4 (a) (b) (c) (d) (e).
[0054]
In this case, first, the alignment film 12 subjected to the alignment process is formed on the glass substrate 11 (FIG. 4A).
[0055]
Next, as in the case of the first embodiment described above, a polymerizable monomer molecule or polymerizable oligomer molecule is coated on the alignment film 12 and heated as necessary, so that the surface of the alignment film 12 is substantially covered. The polymerizable monomer molecules or polymerizable oligomer molecules are aligned by the alignment regulating force in the same direction (FIG. 4 (b)).
[0056]
Then, as in the case of the first embodiment described above, the first cholesteric coating film 13 having a predetermined chiral pitch is obtained by three-dimensionally cross-linking the oriented polymerizable monomer molecules or polymerizable oligomer molecules to form a polymer. 'Is formed (FIG. 4 (c)).
[0057]
Thereafter, a polymerizable monomer molecule or polymerizable oligomer molecule for laminating is directly coated on the formed first cholesteric coating film 13 ', and heated as necessary to align the surface of the first cholesteric coating film 13'. The polymerizable monomer molecules or polymerizable oligomer molecules for lamination are oriented by the regulating force (FIG. 4 (d)).
[0058]
Finally, as in the case of the first cholesteric coating film 13 ', the polymerizable monomer molecules or polymerizable oligomer molecules for lamination are three-dimensionally cross-linked, and the first cholesteric coating film 13' is coated with the first cholesteric coating film 13 '. A second cholesteric coating film 13 ″ having a chiral pitch longer than that of the cholesteric coating film 13 ′ is formed (FIG. 4E). Note that the chiral pitch (selective reflection) in the cholesteric coating films 13 ′ and 13 ″ is formed. The wavelength band) can be controlled by changing the concentration of the chiral agent in the polymerizable monomer molecule or polymerizable oligomer molecule for lamination.
[0059]
In such a production method, the polymerizable monomer molecules or polymerizable oligomer molecules for the cholesteric coating films 13 ′ and 13 ″ may be dissolved in a solvent to form a coating liquid. In this case, the solvent is used before three-dimensional crosslinking. It is necessary to perform a drying process for evaporating the water.
[0060]
Further, in such a manufacturing method, in particular, if the direction of the alignment regulating force on the surface of the alignment film 12 is substantially matched within the surface of the alignment film 12, the cholesteric layer 13 (cholesteric coating film 13 ') in contact therewith The director direction of the molecules in the first surface 13a can be substantially matched. The alignment film 12 may be formed by a conventionally known method. For example, (1) a method of forming a polyimide film on a glass substrate 11 and rubbing, or (2) a photo-alignment method on the glass substrate 11. For example, a method of forming a polymer compound to be a film and irradiating with ultraviolet rays which are polarized light, and (3) a method of using a stretched PET film can be used.
[0061]
(Second example)
Next, a manufacturing method in the case where a liquid crystal polymer is used as the material of the cholesteric layer 13 will be described with reference to FIGS.
[0062]
In this case, first, an alignment film 12 subjected to an alignment process is formed on the glass substrate 11 (FIG. 5A).
[0063]
Next, as in the case of the first embodiment described above, the alignment film 12 is coated with a liquid crystal polymer, heated as necessary, and by the alignment regulating force in the substantially same direction on the alignment film 12 surface. Align the liquid crystal polymer.
[0064]
Then, as in the case of the first embodiment described above, the aligned liquid crystal polymer is cooled to a glass state to form a first cholesteric coating film 13 'having a predetermined chiral pitch (FIG. 5 ( b)).
[0065]
Thereafter, a liquid crystal polymer for laminating is directly coated on the formed first cholesteric coating film 13 ′, heated as necessary, and liquid crystal for laminating is formed by the alignment regulating force on the surface of the first cholesteric coating film 13 ′. Orient the polymer.
[0066]
Finally, as in the case of the first cholesteric coating film 13 ', the liquid crystal polymer for lamination is cooled to a glass state, and the first cholesteric coating film 13' is formed on the first cholesteric coating film 13 '. The second cholesteric coating film 13 ″ having a longer chiral pitch than the chiral pitch (FIG. 5 (c)) is formed. The chiral pitch (selective reflection wavelength band) in the cholesteric coating films 13 ′ and 13 ″ is: It is controlled by changing the chiral power in the liquid crystal polymer molecule by a known method such as adjusting the content of the bent chain with a chiral component or adjusting the composition ratio of copolymerization of mesogenic monomer and chiral mesogenic monomer. (See literature (Naoko Koide, Kunisuke Sakamoto, “Liquid Crystal Polymer”, Kyoritsu Publishing Co., Ltd., 1998)).
[0067]
In such a production method, the liquid crystal polymer for the cholesteric coating films 13 'and 13 "may be dissolved in a solvent to form a coating liquid. In that case, a drying step for evaporating the solvent is performed before cooling. There is a need.
[0068]
Further, in such a manufacturing method, in particular, if the direction of the alignment regulating force on the surface of the alignment film 12 is substantially matched within the surface of the alignment film 12, the cholesteric layer 13 (cholesteric coating film 13 ') in contact therewith The director direction of the molecules in the first surface 13a can be substantially matched. The alignment film 12 may be formed by a conventionally known method. For example, (1) a method of forming a polyimide film on a glass substrate 11 and rubbing, or (2) a photo-alignment method on the glass substrate 11. For example, a method of forming a polymer compound to be a film and irradiating with ultraviolet rays which are polarized light, and (3) a method of using a stretched PET film can be used.
[0069]
As described above, according to the second embodiment of the present invention, since the cholesteric layer 13 is composed of a laminate of a plurality of cholesteric coating films 13 'and 13 ", the operational effects of the first embodiment described above. In addition, the circularly polarized light extracting optical element 10 having a wide selective reflection wavelength band can be easily manufactured by laminating a plurality of cholesteric coating films 13 ′ and 13 ″ having different chiral pitches.
[0070]
The circularly polarized light extracting optical element 10 according to the first and second embodiments described above is used by being incorporated in a polarized light source device 20 as shown in FIG. 6 and a liquid crystal display device 30 as shown in FIG. Can do. Thereby, a polarized light source device and a liquid crystal display device having a uniform in-plane polarization state can be obtained.
[0071]
As shown in FIG. 6, the polarized light source device 20 includes a light guide 23 that emits light incident from the side surface from one of the upper surface and the lower surface and projects it onto the circularly polarized light extracting optical element 10, and A light source 21 that emits light toward the light source and a reflection plate 24 that reflects light emitted from the lower surface of the light guide 23 are provided. Here, the circularly polarized light extracting optical element 10 is provided on the upper surface of the light guide 23 so that the light emitted from the light source 21 can be emitted as polarized light. A phase difference plate 25 and a polarizing plate 26 are provided on the upper surface of the circularly polarized light extracting optical element 10.
[0072]
As shown in FIG. 7, the liquid crystal display device 30 includes a polarized light source device 20 as described above, and a liquid crystal cell that receives the polarized light emitted from the polarized light source device 20 and transmits the polarized light while changing the transmittance for the polarized light. 27. A polarizing plate 28 is provided on the upper surface of the liquid crystal cell 27.
[0073]
【Example】
Next, specific examples of the above-described first and second embodiments will be described.
[0074]
Example 1
92 parts of monomer molecules having a polymerizable acrylate at both ends and a spacer between the mesogen in the central part and the acrylate and having a nematic-isotropic transition temperature of 110 ° C., and a polymerizable acrylate at one end A toluene solution was prepared by dissolving 8 parts of a chiral agent molecule having The toluene solution was added with 2% by weight of photoinitiator based on the monomer molecules. (For the liquid crystal obtained in this way, it was confirmed that the director direction of the molecules was aligned in the range of the rubbing direction ± 5 degrees on the alignment film.)
On the other hand, a polyimide dissolved in a solvent was coated on a transparent glass substrate by a spin coating method, and after drying, a film was formed at 200 ° C. (film thickness 0.1 μm), and an alignment film was formed by rubbing in a certain direction. .
[0075]
Then, such a glass substrate with an alignment film was set on a spin coater, and the toluene solution was spin-coated on the alignment film.
[0076]
Next, toluene in the toluene solution was evaporated at 80 ° C., and it was visually confirmed by selective reflection that the coating film formed on the alignment film exhibited a cholesteric phase.
[0077]
Then, the coating film was irradiated with ultraviolet rays, and acrylates of monomer molecules were three-dimensionally cross-linked by radicals generated from the photoinitiator in the coating film to form a cholesteric coating film on the alignment film. At this time, the film thickness of the cholesteric coating film was 2 μm ± 3%. Further, when measured with a spectrophotometer, the selective reflection wavelength band was 600 to 670 nm.
[0078]
(Example 2)
The cholesteric coating film (circularly polarized light extraction optical element) obtained in Example 1 was immersed in a toluene solution in a state where one surface was in close contact with a glass substrate with an alignment film, pulled up after a while, and 80 ° C. And dried. At this time, the film thickness of the cholesteric coating film was 2 μm ± 3%. Further, when measured with a spectrophotometer, the selective reflection wavelength band was 600 to 690 nm.
[0079]
(Example 3)
The cholesteric coating film (circularly polarized light extraction optical element) obtained in Example 1 was dipped in a toluene solution for a longer time than Example 2 and dried at 80 ° C. At this time, when measured with a spectrophotometer, the selective reflection wavelength band was 600 to 720 nm.
[0080]
In addition, when the cross section of the cholesteric layer (cholesteric coating film) of the circularly polarized light extracting optical element according to Example 1 to Example 3 was observed with a transmission electron microscope, the light and dark pattern (corresponding to the pitch) on the surface of the glass substrate side. Are parallel to each other(From this, it can be seen that the directions of the helical axes coincide. The chiral pitch was shorter than the chiral pitch on the opposite surface. From this, it is considered that the selective reflection wavelength band is shifted to the longer wavelength side due to the extraction of the chiral agent having a crosslinking strength weaker than that of the nematic monomer by the toluene solution in which the circularly polarized light extracting optical element is immersed.
[0081]
Example 4
90 parts of a monomer molecule having a polymerizable acrylate at both ends and a spacer between the central mesogen and the acrylate and having a nematic-isotropic transition temperature of 110 ° C., and a polymerizable acrylate at one end A toluene solution was prepared by dissolving 10 parts of a chiral agent molecule containing In addition, 5 weight% photoinitiator with respect to the said monomer molecule was added to the said toluene solution. (For the liquid crystal obtained in this way, it was confirmed that the director direction of the molecules was aligned in the range of the rubbing direction ± 5 degrees on the alignment film.)
On the other hand, a polyimide dissolved in a solvent was coated on a transparent glass substrate by a spin coating method, and after drying, a film was formed at 200 ° C. (film thickness 0.1 μm), and an alignment film was formed by rubbing in a certain direction. .
[0082]
Then, such a glass substrate with an alignment film was set on a spin coater, and the toluene solution was spin-coated on the alignment film under conditions such that the film thickness was as constant as possible.
[0083]
Next, toluene in the toluene solution was evaporated at 80 ° C., and it was visually confirmed by selective reflection that the coating film formed on the alignment film exhibited a cholesteric phase.
[0084]
Then, the coating film was irradiated with ultraviolet rays, and the acrylate of the monomer molecule was three-dimensionally cross-linked by radicals generated from the photoinitiator in the coating film to form a first cholesteric coating film on the alignment film. At this time, the film thickness of the cholesteric coating film was 2 μm ± 3%. Further, when measured with a spectrophotometer, the center wavelength of the selective reflection wavelength band was around 600 nm.
[0085]
Furthermore, the rotational speed of the spin coater is increased as compared with the case where the first cholesteric coating film is formed, and the same toluene solution as the above toluene solution is formed on the first cholesteric coating film except that the chiral agent molecule is 6 parts. Spin coated.
[0086]
Next, toluene in the toluene solution was evaporated at 80 ° C., and it was visually confirmed by selective reflection that the coating film formed on the alignment film exhibited a cholesteric phase.
[0087]
Then, the coating film was irradiated with ultraviolet rays, and the acrylate of the monomer molecule was three-dimensionally crosslinked and polymerized by radicals generated from the photoinitiator in the coating film to form a second cholesteric coating film on the alignment film. . At this time, the film thickness of the second cholesteric coating film was 3.5 μm ± 3%. Further, when measured with a spectrophotometer, the central wavelength of the selective reflection wavelength band of the second-layer cholesteric coating film was around 690 nm.
[0088]
(Example 5)
A toluene solution in which an acrylic side chain 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 liquid crystal obtained in this way, it was confirmed that the director direction of the molecules is aligned in the range of ± 5 degrees in the rubbing direction on the alignment film.)
On the other hand, a polyimide dissolved in a solvent was coated on a transparent glass substrate by a spin coating method, and after drying, a film was formed at 200 ° C. (film thickness 0.1 μm), and an alignment film was formed by rubbing in a certain direction. .
[0089]
Then, such a glass substrate with an alignment film was set on a spin coater, and the toluene solution was spin-coated on the alignment film under conditions such that the film thickness was as constant as possible.
[0090]
Next, the toluene in the toluene solution is evaporated at 90 ° C., and the coating film formed on the alignment film is held at 150 ° C. for 10 minutes, so that the coating film formed on the alignment film exhibits a cholesteric phase. Was visually confirmed by selective reflection. Furthermore, the said coating film was cooled to room temperature, the liquid crystal polymer was made into the glass state, and the 1st cholesteric coating film was formed. At this time, the film thickness of the cholesteric coating film was 2 μm ± 3%. Further, when measured with a spectrophotometer, the center wavelength of the selective reflection wavelength band was around 600 nm.
[0091]
Further, the rotational speed of the spin coater is increased as compared with the case where the first cholesteric coating film is formed, and the acrylic transition material having a glass transition temperature of 83 ° C. and an isotropic transition temperature of 210 ° C. is formed on the first cholesteric coating film. A toluene solution in which a side chain type liquid crystal polymer was dissolved was spin-coated.
[0092]
Next, toluene in the toluene solution was evaporated at 80 ° C., and it was visually confirmed by selective reflection that the coating film formed on the alignment film exhibited a cholesteric phase.
[0093]
Next, the toluene in the toluene solution is evaporated at 90 ° C., and the coating film formed on the alignment film is held at 130 ° C. for 10 minutes, so that the coating film formed on the alignment film exhibits a cholesteric phase. Was visually confirmed by selective reflection. Furthermore, the said coating film was cooled to room temperature, the liquid crystal polymer was made into the glass state, and the 2nd-layer cholesteric coating film was formed. At this time, the film thickness of the cholesteric coating film was 3.5 μm ± 3%. Further, when measured with a spectrophotometer, the central wavelength of the selective reflection wavelength band of the second-layer cholesteric coating film was around 690 nm.
[0094]
In addition, when the cross section of the cholesteric layer (cholesteric coating film) of the circularly polarized light extracting optical element according to Example 4 and Example 5 was observed with a transmission electron microscope, the light-dark pattern between the surfaces of each polymerized cholesteric coating film was as follows. In the state parallel to each other (from this it can be seen that the directions of the helical axes coincide), there were no faults. From this, it can be seen that the director directions of the molecules between the surfaces of the adjacent cholesteric coating films are the same. Further, when measured with a spectrophotometer, no optical singularity was observed in the transmittance.
[0095]
(Evaluation results)
As shown in FIG. 8, polarizing plates 31 and 32 such as a linear polarizing plate and an elliptical polarizing plate are arranged in a crossed Nicols state, and the circularly polarized light extraction optical element 10 is sandwiched between the polarizing plates 31 and 32 and visually observed. However, the bright and dark patterns appearing in the plane were less in Example 2 than in Example 1, less in Example 3 than in Example 2, and less in Example 4 than in Example 1. In Example 5, the light and dark pattern appearing in the plane was equivalent to Example 4.
[0096]
【The invention's effect】
As described above, according to the present invention, even when a circularly polarized light extraction optical element is sandwiched between a pair of polarizing plates arranged in a crossed Nicol state, a bright and dark pattern appears in the plane of the display device, and the display of the display device is displayed. It can suppress effectively that a quality falls.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view for explaining a first embodiment of a circularly polarized light extracting optical element according to the present invention.
FIG. 2 is a schematic sectional view for explaining a second embodiment of a circularly polarized light extracting optical element according to the present invention.
3 is a schematic cross-sectional view showing a state between the surfaces of adjacent coating films of the circularly polarized light extracting optical element shown in FIG.
4 is a schematic cross-sectional view for explaining a first example of a manufacturing method of the circularly polarized light extracting optical element shown in FIG.
5 is a schematic cross-sectional view for explaining a second example of the method for manufacturing the circularly polarized light extracting optical element shown in FIG. 2. FIG.
FIG. 6 is a schematic sectional view showing an example of a polarized light source device including a circularly polarized light extracting optical element according to the present invention.
FIG. 7 is a schematic sectional view showing an example of a liquid crystal display device including a circularly polarized light extracting optical element according to the present invention.
FIG. 8 is a diagram for explaining a usage mode of a circularly polarized light extracting optical element;
[Explanation of symbols]
10 Circularly polarized light extraction optical element
11 Glass substrate
12 Alignment film
13 Cholesteric layer
13 ', 13 "cholesteric coating
13a First surface
13b Second surface
20 Polarized light source device
21 Light source
23 Light guide
24 reflector
25 Retardation plate
26, 28 Polarizer
27 Liquid crystal cell
30 Liquid crystal display device
31, 32 Polarizer

Claims (13)

Coating a polymerizable material on a support substrate, and orienting the polymerizable material by an orientation regulating force in substantially the same direction on the surface of the support substrate;
The oriented polymerizable material is three-dimensionally cross-linked, and the chiral pitch of the cholesteric structure formed by the polymerizable material is changed with respect to the thickness direction of the support substrate, and the first material positioned on the support substrate side compared to the chiral pitch of the surface, a second surface side of director direction of thickness molecules due to the distribution of the second a surface plane of the second surface opposite the first surface does not match Forming a cholesteric layer having a longer chiral pitch than that of the circularly polarized light extracting optical element. Coating a polymerizable material on a support substrate, and orienting the polymerizable material by an orientation regulating force in substantially the same direction on the surface of the support substrate;
Three-dimensionally cross-linking the oriented polymerizable material to form a first cholesteric coating film having a predetermined chiral pitch;
Coating the polymerizable material for lamination directly on the first cholesteric coating film, and orienting the polymerizable material for lamination by the orientation regulating force on the surface of the first cholesteric coating film;
The polymerizable material for lamination is three-dimensionally cross-linked, and the second cholesteric coating on the first cholesteric coating film in which the director directions of molecules on the surface are not coincident due to the in- plane film thickness distribution. And forming a second cholesteric coating film having a chiral pitch longer than the chiral pitch of the first cholesteric coating film. Coating a liquid crystal polymer on a support substrate, and orienting the liquid crystal polymer by an alignment regulating force in substantially the same direction on the support substrate surface;
The aligned liquid crystal polymer is cooled to a glass state, and the chiral pitch of the cholesteric structure formed by the liquid crystal polymer is changed with respect to the thickness direction of the support substrate, and the liquid crystal polymer positioned on the support substrate side is changed. compared to the chiral pitch of the first surface side, the second surface director direction due molecule does not match the film thickness distribution of a opposing second surface plane of the second surface to the first surface And a step of forming a cholesteric layer having a longer side chiral pitch. Coating a liquid crystal polymer on a support substrate, and orienting the liquid crystal polymer by an alignment regulating force in substantially the same direction on the support substrate surface;
Cooling the aligned liquid crystal polymer into a glass state and forming a first cholesteric coating film having a predetermined chiral pitch; and
Directly coating a liquid crystal polymer for lamination on the first cholesteric coating film, and orienting the liquid crystal polymer for lamination by an alignment regulating force on the surface of the first cholesteric coating film;
The liquid crystal polymer for laminating is cooled to a glass state, and the second cholesteric molecules on the first cholesteric coating film whose molecular director directions on the surface do not coincide due to the in- plane film thickness distribution. a coating method of the first, characterized in that it comprises a step of forming a second cholesteric coating having a long chiral pitch than the chiral pitch of the cholesteric coating, circular polarization extraction optical element . Provided with a cholesteric layer oriented by the orientation regulating force of the support substrate surface,
The cholesteric layer has a first surface and a second surface opposite to the first surface, and the director direction of molecules on the first surface of the cholesteric layer is determined by the orientation regulating force of the support substrate surface. The first surface is substantially matched, and the director direction of molecules on the second surface of the cholesteric layer is not matched due to the in-plane film thickness distribution of the second surface. There, the chiral pitch of the second surface of the cholesteric layer, circularly polarized light extracting optical element characterized in longer than the chiral pitch of the first surface.   6. The circularly polarized light extracting optical element according to claim 5, wherein the chiral pitch of the cholesteric layer gradually changes from the first surface side toward the second surface side.   The circularly polarized light extraction optical element according to claim 5 or 6, wherein the cholesteric layer comprises a laminate of a plurality of cholesteric coating films.   6. The cholesteric layer partially transmits one circularly polarized light component in a selective reflection wavelength band among right-handed and left-handed circularly polarized light components included in incident light. 8. The circularly polarized light extracting optical element as described in any one of 7 above.   9. The chiral pitch on the second surface side of the cholesteric layer is selected so that a selective reflection wavelength on the second surface side is 687 nm or more. Circularly polarized light extraction optical element. The circularly polarized light extracting optical element according to any one of claims 5 to 9,
A light guide that emits light incident from the side surface from one of the upper surface and the lower surface and projects it onto the circularly polarized light extracting optical element;
A polarized light source device, comprising: a light source that emits light toward the side surface of the light guide. 11. The polarized light source according to claim 10, wherein the second surface of the cholesteric layer of the circularly polarized light extracting optical element is disposed on a side from which light projected by the light guide is emitted. apparatus. The polarized light source device according to claim 10 or 11 ,
A liquid crystal display device comprising: a liquid crystal cell that receives polarized light emitted from the polarized light source device and transmits the polarized light while changing a transmittance of the polarized light. The second surface of the cholesteric layer of the circularly polarized light extracting optical element included in the polarized light source device is disposed on a side from which light projected by the light guide is emitted. Item 13. A liquid crystal display device according to item 12.

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