JP4402429B2 - Optical element - Google Patents

Description

  The present invention relates to an optical element that can be used as a retardation substrate, a color filter, and the like.

  In recent years, optical elements formed using polymerizable liquid crystals have begun to be applied in various fields. A reflection type using a retardation layer formed using a polymerizable nematic liquid crystal, a cholesteric liquid crystal, a chiral nematic liquid crystal, or a discotic liquid crystal, or a layer formed using a polymerizable cholesteric liquid crystal or a chiral nematic liquid crystal. A wide variety of devices such as a polarization separation element and a polarization color filter have been developed.

For example, it is disclosed that a color filter substrate is produced by applying a polymerizable cholesteric liquid crystal composition containing a photoreactive chiral material and curing it by irradiating with ultraviolet rays through a photomask. Here, the formation of the color filter region of each color is performed by irradiating with ultraviolet rays at room temperature, and the transparent partition wall is formed by irradiating with ultraviolet rays while heating until the cholesteric liquid crystal layer becomes isotropic. Forming is also disclosed. (Patent Document 1).
JP2003-66214A.

  In the method disclosed in Patent Document 1, heating is performed at a temperature at which a liquid crystal state can be formed corresponding to the photoreactive chiral material isomerized according to the amount of light irradiation, while irradiating with ultraviolet rays or after irradiation. Although it is possible to control the wavelength characteristics of the liquid crystal layer, measures such as equalizing the thickness and phase difference of each region and adjusting the width of the selective reflection wavelength band are not particularly considered.

  An object of the present invention is to provide an optical element capable of equalizing the thickness and phase difference of each region of an optical element configured using liquid crystal and adjusting the width of a selective reflection wavelength band. It is what.

  According to the inventor's study, it was found that the thickness and phase difference of each region can be controlled by using different liquid crystal materials for forming each region of the optical element. It was also found that the width of the selective reflection wavelength band can be adjusted when using the color filter to selectively reflect each color light, and the present invention has been achieved.

In a first invention for solving the problem, a cross-linked liquid crystal layer having liquid crystal regularity is arranged in a plurality of regions on a substrate, and the liquid crystal layer is a cross-linked cured product of a polymerizable liquid crystal composition that is different for each region. An optical element comprising: a color filter layer stacked on the substrate; and the polymerizable liquid crystal composition is formed by stacking or blending two or more liquid crystal materials having different birefringences. It is about.

  According to a second aspect of the present invention, in the first aspect, the thickness and birefringence of each region of the liquid crystal layer are different from those of central wavelengths in different wavelength bands incident corresponding to the regions. The present invention relates to an optical element that is adjusted to give the same phase difference.

  A third invention relates to the optical element according to the first or second invention, wherein the thickness of each region of the liquid crystal layer is substantially equal.

  A fourth invention relates to an optical element according to the first or second invention, wherein the thickness of each region of the liquid crystal layer is different.

  A fifth invention relates to an optical element according to any one of the first to fourth inventions, wherein the polymerizable liquid crystal composition has nematic regularity.

A sixth invention relates to the optical element according to the first invention, wherein each of the liquid crystal layers has a cholesteric regularity and has a selective reflection wavelength band having a different central wavelength for each region. Is.

  A seventh invention relates to the optical element according to the sixth invention, wherein the widths of the selective reflection wavelength bands for each region are substantially equal.

  According to an eighth invention, in the sixth invention, each of the selective reflection wavelength bands corresponds to each of red light, green light, and blue light, and a blue light selective reflection wavelength band width Δλ (G ) Is smaller than the width Δλ (R) of the selective reflection wavelength band of red light and the width Δλ (B) of the selective reflection wavelength band of blue light.

According to a ninth aspect of the present invention, a plurality of cross-linked liquid crystal layers having liquid crystal regularity are laminated in each of a plurality of regions on a substrate, and the plurality of liquid crystal layers are different in polymerizable liquid crystal in each region. It is composed of a crosslinked cured product of the composition , a color filter layer is laminated on the substrate, and the polymerizable liquid crystal composition is obtained by laminating or blending two or more liquid crystal materials having different birefringences. The present invention relates to an optical element.

According to the first invention, the liquid crystal layer is composed of a cured product of a polymerizable liquid crystal composition that varies from region to region , a color filter layer is laminated on the substrate, and the polymerizable liquid crystal composition is Since two or more types of liquid crystal materials with different birefringence are laminated or blended, an optical element is provided that can make the thickness of the liquid crystal layer constant between each type and the phase difference between each type. can do.

  According to the second invention, in addition to the effect of the first invention, by changing the thickness and birefringence according to the wavelength of incident light, the phase difference is made constant, or the phase difference is desired. The optical element which can be set to the value of can be provided.

  According to the third invention, in addition to the effects of the first or second invention, it is possible to provide an optical element in which the thickness of the liquid crystal layer for each region is substantially constant.

  According to the fourth invention, in addition to the effects of the first or second invention, there is provided an optical element suitable for application to a multi-gap type liquid crystal display element having different thicknesses of liquid crystal driven for each color. be able to.

According to the fifth invention, in addition to the effects of any one of the first to fourth inventions, since the liquid crystal layer has nematic regularity, the position of having the optical axis in the plane of each liquid crystal layer. An optical element that can be used as a phase difference plate can be provided.

According to the sixth invention, in addition to the effect of the invention of claim 1, since the liquid crystal layer has cholesteric regularity, it can be used as a reflection filter having a different selective reflection wavelength band for each region. Possible optical elements can be provided. Moreover, the optical element which can be utilized as a phase difference plate which has an optical axis in the normal line direction in a surface can be provided.

  According to the seventh aspect, in addition to the effect of the sixth aspect, it is possible to provide an optical element capable of improving the white balance when applied to a color display.

  According to the eighth invention, in addition to the effects of the sixth invention, the selective reflection wavelength band of each liquid crystal layer corresponds to each of red light, green light, and blue light, of which blue light is selected. By reducing the width of the reflection wavelength band, it is possible to improve the brightness of red light and blue light with a low visibility coefficient to obtain white balance, and to make the width of the selective reflection wavelength band of each liquid crystal layer constant. In contrast, an optical element that can be manufactured more easily can be provided.

According to the ninth invention, a plurality of liquid crystal layers are laminated for each region , a color filter layer is laminated on the substrate, and the polymerizable liquid crystal composition comprises two or more types having different birefringence indices. Since the liquid crystal material is laminated or blended, it is possible to provide an optical element having a characteristic in which the optical characteristics of the laminated liquid crystal layers are combined. For example, an optical element capable of setting an arbitrary selective reflection wavelength band Can be provided.

  FIG. 1 is a diagram conceptually showing the laminated structure of the optical element of the present invention. As illustrated in FIG. 1A, the optical element 1 of the present invention has a laminated structure in which a liquid crystal layer 4 is laminated on a substrate 2 via an alignment film 3. Among these, the alignment film 3 can be omitted when the liquid crystal layer 4 side of the substrate 2 has orientation, and the upper surface of the layer in contact with the lower surface of the liquid crystal layer 4 also has orientation in the following examples. Can be omitted. The liquid crystal layer 4 is disposed in a plurality of regions, and is composed of a cross-linked cured product of a different polymerizable liquid crystal composition for each region, and is a cross-linked one having liquid crystal regularity, as shown in FIG. As shown, it is composed of two or more types of liquid crystal layers that differ from region to region. For example, as shown with the letters R, G, and B in the figure, it consists of three types of liquid crystal layers. Is. The liquid crystal layer 4 is composed of three types of liquid crystal layers as described above, and is suitable for use in color display for red, green, and blue, respectively. However, the liquid crystal layer 4 includes two types of liquid crystal layers. It may consist of.

  The optical element 1 of the present invention may be combined with an optical element other than the liquid crystal layer 4, and a typical example of the other optical element is a color filter layer. Accordingly, as shown in FIG. 1B, the optical element 1 of the present invention has a laminated structure in which a color filter layer 5, an alignment film 3, and a liquid crystal layer 4 are laminated on a substrate 2 in this order. Alternatively, as shown in FIG. 1C, the substrate may have a laminated structure in which an alignment film 3, a liquid crystal layer 4, and a color filter layer 5 are laminated in this order on the substrate 2.

  Similarly to the liquid crystal layer 4, the color filter layer 5 may also be configured by arranging two or more types of areas. For example, the letters R, G, and B are attached in the drawing. As shown, it consists of three types of areas. The color filter layer 5 having three types of areas is suitable for use in color display as red, green, and blue, respectively. However, the color filter layer 5 has two types of areas. It may consist of.

  In the laminated structure having the color filter layer 5 described with reference to FIGS. 1B and 1C, the color filter layer 5 may be accompanied by a black matrix 6 at the boundary of each area.

  The substrate 2 is made of transparent glass, quartz, or plastic, and is a support that supports the alignment film 3 and the liquid crystal layer 4 and, if necessary, the color filter layer 5 and the black matrix 6.

The alignment film 3 aligns the liquid crystal compound in the liquid crystal layer 4, and typically a resin composition such as a polyamide resin, a polyimide resin, or a polyvinyl alcohol resin is dissolved in the resin composition. After being formed by applying and drying, it is formed by rubbing rubbing in a predetermined direction with a metal roller or the like wrapped with a cloth such as rayon, cotton, polyamide, or polymethyl methacrylate. In addition, the alignment film 3 may be an oblique deposition film such as SiO ₂ or an organic material, a vertical alignment film of an organic material such as organic silane, or a film obtained by rubbing a vertical alignment film. If the film itself has orientation, such as a stretched plastic sheet, the formation of the alignment film 3 can be omitted, and also when a scattering cholesteric layer or nematic layer is desired. The formation of the alignment film 3 can be omitted, and the film can be formed on a substrate having no orientation.

  The liquid crystal layer 4 is disposed in a plurality of regions, is composed of a cross-linked cured product of a polymerizable liquid crystal composition that is different for each region, and is a cross-linked one having liquid crystal regularity, preferably UV curable. A crosslinked cured product of an ionizing radiation curable liquid crystal composition such as a liquid crystal composition or an electron beam curable liquid crystal composition, and more preferably a three-dimensionally crosslinked material while maintaining the liquid crystal regularity of a low molecular liquid crystal However, the polymer liquid crystal may be once crystallized and then rapidly cooled to give liquid crystal regularity, or a mixture of these. Moreover, it is preferable that at least two types of liquid crystal layers are different from each other in the two or more types of liquid crystal layers.

  In order to obtain the liquid crystal layer 4, necessary types of ionizing radiation curable liquid crystal compositions for forming each type of liquid crystal layer are prepared. First, the first ionizing radiation curable liquid crystal composition is formed on the substrate 2. The first ionizing radiation curable liquid crystal composition applied is aligned by heating, etc., and then developed by irradiation with ionizing radiation such as ultraviolet rays or electron beams in a pattern. After forming the liquid crystal layer 1, the ionizing radiation curable liquid crystal composition to be used is changed, and the pattern when the ionizing radiation is irradiated in a pattern is changed to change the position of the liquid crystal layer that has already been formed. May be performed by repeating the same process as that for forming the first liquid crystal layer.

  Each type of ionizing radiation curable liquid crystal composition for forming the liquid crystal layer 4 is any one of a polymerizable liquid crystal monomer having a polymerizable functional group such as an acrylate group, a polymerizable liquid crystal oligomer, or a polymerizable liquid crystal polymer. One group or a combination of two or more liquid crystal compounds selected from two or more groups can be used. The type of liquid crystal can be either nematic liquid crystal, cholesteric liquid crystal, or smectic liquid crystal. May be the type.

Here, since the retardation and the intensity of selective reflection are determined by the birefringence Δn of the liquid crystal molecules and the thickness of the liquid crystal cured layer, Δn is preferably 0.03 or more, more preferably 0.05 or more. It is a preferable thing and can illustrate the compound quoted in following formula (1)-a formula (7).

  The birefringence Δn can be measured by measuring retardation and film thickness. Retardation is measured by an automatic birefringence meter (manufactured by Oji Scientific Instruments, product number; “KOBRA-21 series”). The wavelength of the measurement light is preferably in the visible light range (380 to 780 nm), and the wavelength with the highest specific luminous efficiency is measured with light near 550 nm. Is particularly preferred. For film thickness measurement, it is possible to use a commercially available apparatus such as a stylus type step gauge (manufactured by Sloan, trade name “DEKTAK”).

  In the ionizing radiation-curable liquid crystal composition, it is preferable to add a photopolymerization initiator in a range that does not significantly disturb the alignment of the liquid crystal in addition to the liquid crystal as described above. Benzoin isopropyl ether, benzophenone, benzoylbenzoic acid, methyl benzoylbenzoate, 4-benzoyl-4′-methyldiphenyl sulfide, benzylmethyl ketal, dimethylaminomethylbenzoate, 2-n-butoxyethyl-4-dimethylaminobenzoate, p -Isoamyl dimethylaminobenzoate, 3,3'-dimethyl-4-methoxybenzophenone, methylobenzoyl formate, 2-methyl-1- (4- (methylthio) phenyl) -2-morpholinopropan-1-one, -Benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butan-1-one, 1- (4-dodecylphenyl) -2-hydroxy-2-methylpropan-1-one, 1-hydroxycyclohexyl Phenylketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropan-1-one, 2-chlorothioxanthone, 2,4 -Diethylthioxanthone, 2,4-diisopropylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 1-chloro-4-propoxythioxanthone, etc. can be mentioned. Such a photopolymerization initiator is preferably blended in an amount of about 0.01 to 10%, more preferably 0.1 to 7%, particularly preferably 0. 5 to 5%. In addition to the photopolymerization initiator, a sensitizer can be added within a range that does not impair the object of the present invention.

  In the present invention, the two or more types of liquid crystal layers constituting the liquid crystal layer 4 are composed of cross-linked cured products of different polymerizable liquid crystal compositions. Preferably, the two types of liquid crystal layers have different birefringences. Such a liquid crystal layer 4 is suitable for use as a retardation layer. In general, the retardation amount R representing the degree of phase difference can be represented by R = (n1−n2) · d, where n1 is an ordinary refractive index, n2 is an extraordinary refractive index, and d is a liquid crystal. When the optical element 1 has two or more types of liquid crystal layers, the birefringence index (n1-n2) is different even if each liquid crystal layer has a constant thickness (d). By doing so, the same retardation amount can be realized in a predetermined, for example, each type. For example, when the light incident on the liquid crystal layer has a different wavelength (or wavelength band) depending on the type of the liquid crystal layer, the birefringence (n1-n2) ) Can be realized by adjusting. The birefringence (n1-n2) of the liquid crystal layer can be adjusted by mixing a liquid crystal material having a high birefringence and a liquid crystal material having a low birefringence at a predetermined ratio. Further, when the optical element 1 of the present invention is applied to a multi-gap type liquid crystal display element having different liquid crystal thicknesses driven for each color, it is necessary to change the thickness d of the liquid crystal layer 4 of the optical element 1 for each region. However, a predetermined retardation amount can be realized by making the birefringence (n1-n2) different.

  When the liquid crystal layer 4 is composed of two or more types of liquid crystal layers, the thickness of each liquid crystal layer is determined by, for example, the application conditions of the ionizing radiation curable liquid crystal composition and the shrinkage at the time of curing. Since the thickness of each liquid crystal layer constituting the liquid crystal layer 4 in the optical element 1 of the present invention is constant, the thickness of the liquid crystal layer for each type (average value) )), The maximum value is within -10%.

  In the present invention, the liquid crystal layer 4 may have nematic regularity. The optical element 1 in which the liquid crystal layer 4 has nematic regularity can be used as a retardation plate having an optical axis in the plane of each liquid crystal layer. The liquid crystal layer 4 may also be composed of chiral nematic liquid crystal having cholesteric regularity obtained by adding a chiral agent to nematic liquid crystal. By providing the liquid crystal layer 4 having cholesteric liquid crystal regularity with a selective reflection wavelength band for each type of liquid crystal layer and by making the center wavelength different, such a liquid crystal layer 4 can be used in a reflective liquid crystal display device. Suitable for use as a reflective layer.

  The width of the selective reflection wavelength band (the maximum wavelength minus the minimum wavelength) can be arbitrarily set. For example, three types of liquid crystal layers correspond to red light, green light, and blue light. In some cases, when the widths of the selective reflection wavelength bands are the same, when such a liquid crystal layer 4 is used as a reflection layer, a display with excellent white balance can be achieved. Note that the widths of the selective reflection wavelength bands being the same are considered to be the same if they are within -10% of the maximum standard, considering manufacturing problems. .

  In addition, when the three types of liquid crystal layers correspond to red light (R), green light (G), and blue light (B), the width Δλ of each selective reflection wavelength band is set to each color light. Correspondingly, assuming that Δλ (R), Δλ (G), and Δλ (B), Δλ (G) is preferably smaller than both Δλ (R) and Δλ (B). In this case, it is more preferable that Δλ (R) and Δλ (B) are within -10% of the smaller one based on whichever is larger, and Δλ (G) is Δλ (R) and More preferably, it is about −5% to −20%, whichever is smaller of Δλ (B).

  Thus, when Δλ (G) is smaller than both Δλ (R) and Δλ (B), when such a liquid crystal layer 4 is used as a reflective layer, a display with excellent white balance can be achieved. This is because the luminance of red light (R) and blue light (B) having a low visibility coefficient can be relatively improved, and the design complexity is small. Note that the widths of the selective reflection wavelength bands being the same are considered to be the same if they are within -10% of the maximum standard, considering manufacturing problems. .

As the chiral agent to be added to the nematic liquid crystal, compounds as shown in the following formulas (8) to (11), chiral dopant liquid crystals (product number manufactured by Merck & Co .; “S-811”), and the like can be used. In addition, it is preferable to use what has a polymeric group as a chiral agent from a heat resistant viewpoint of the optical element obtained.

  In the above description, the liquid crystal layer 4 is only one layer in the thickness direction of the optical element 1, but two or more liquid crystal layers may be laminated in the thickness direction. When two or more liquid crystal layers are laminated in the thickness direction, it is possible to provide an optical element having characteristics in which the optical characteristics of the laminated liquid crystal layers are combined. For example, liquid crystals having different selective reflection wavelength bands As a result of the layers being stacked, the selective reflection wavelength bands of both layers are superimposed, and an arbitrary selective reflection wavelength band that is difficult to realize with one liquid crystal layer can be set.

Retardation layers for blue, green, and red colors, for blue, wavelength: retardation value for light of 460 nm is 115 nm, for green, wavelength: retardation for light of 540 nm For the value of 135 nm and for red, a coating composition having the following composition was prepared so that the retardation value for light having a wavelength of 640 nm was 157.5 nm.
Common composition ・ Liquid crystal (below) ………………………………………………………………… 100 parts ・ Photopolymerization initiator (below) ……………… ………………………………………………… 5 parts ・ Polymerization inhibitor (below) ………………………………………………………… … 0.01 part ・ Surfactant (below) ………………………………………………………… 0.1 part ・ Solvent (cyclohexanone) ……………… ……………………………………… 200 copies

Among the above common compositions, as the liquid crystal, the compound A shown in the following formula (12) and the compound B shown in the formula (13) are used by changing the blending ratio for each color, and for blue, A / B = 1 For A / 0, green, A / B = 3/1, and for red, A / B = 1/1. In addition, both the number of parts in a composition and the compounding ratio of a liquid crystal are mass references | standards, and it is the same also after that. In addition, as a photopolymerization initiator, 2-methyl-1 [4- (methylthio) phenyl] -2-morpholinopropan-1-one (manufactured by Ciba Specialty Chemicals Co., Ltd., trade name: “Irgacure 907”) ), Butylhydroxytoluene as a polymerization inhibitor, and fluorine surfactant (manufactured by Sumitomo 3M Co., Ltd., trade name: “Furorad 171”) as a surfactant.

  Prepare a substrate having an alignment film formed by rubbing a polyimide resin thin film on one side of a glass substrate, set this substrate on a spin coater, and apply the blue coating composition of the above composition on the alignment film After the object was spin-coated to form a coating film, it was dried in a vacuum dryer to remove the solvent, and after removal, the film was oriented on a hot plate having a surface temperature of 130 ° C. The orientation was confirmed by observing the state as it was and the state through the polarizing plate.

  The aligned coating film was exposed to ultraviolet rays in a pattern through an ultrahigh pressure mercury lamp and a photomask, and after the exposure, unexposed portions were removed by development using methyl ethyl ketone. After the development, an annealing treatment was further performed in a clean oven at 230 ° C. to form a blue liquid crystal pattern.

  By repeating the above spin coating, drying, orientation, exposure, development, and annealing treatments in place of the coating composition for green and red, the liquid crystal pattern for blue, green, and red is repeated. A retardation layer made of was formed to obtain a retardation substrate.

  When the retardation value and thickness of the liquid crystal pattern for each color of the obtained retardation substrate were measured, the retardation value was 116 nm for blue, 134 nm for green, and 155 nm for red, and the planned retardation. The thickness was 0.93 nm for blue, 0.95 nm for green, and 0.95 nm for red, and there was very little difference between the liquid crystal patterns for each color.

Comparative Example 1
As a phase difference layer for each color for blue, green, and red, the wavelength for blue is 115 nm, the retardation value for light of 460 nm is 115 nm, and the color for green is retardation value for light of 540 nm. For 135 nm and red, only the coating composition having the following composition containing only one type of the compound of formula (14) as a liquid crystal so that the retardation value for light having a wavelength of 640 nm is 157.5 nm. A retardation substrate was obtained in the same manner as in Example 1 except that the coating conditions were changed and the thickness of each retardation layer was changed.
Composition ・ Liquid crystal (Formula (14) below) …………………………………………………… 100 parts ・ Photopolymerization initiator (below) …………………… …………………………………………… 5 parts ・ Polymerization inhibitor ……………………………………………………………………… 0.01 parts ・ Surfactant …………………………………………………………………… 0.1 parts ・ Solvent (cyclohexanone) ……………… ……………………………………… 200 parts Of the above composition, 2,2-dimethoxy-1,2-diphenylethane-1-one (Ciba Specialty Chemicals Co., Ltd., trade name: “Irgacure 651”), and the same polymerization inhibitor and surfactant as those in Example 1 were used.

  When the thickness of the liquid crystal pattern for each color of the obtained retardation substrate was measured, it was 0.92 nm for blue, 1.13 nm for green, and 1.37 nm for red, and 0 for blue and red. A large difference of .45 nm occurred.

A reflective substrate was obtained in the same manner as in Example 1 except that the coating composition having the following composition was used for forming the reflective layer for each color for blue, green, and red.
Composition ・ Liquid crystal (below) ……………………………………………………………………… 100 parts ・ Photopolymerization initiator (below) ………………… ……………………………………………… 5 parts ・ Polymerization inhibitor …………………………………………………………………… … 0.01 parts ・ Surfactant …………………………………………………………………… 0.1 parts ・ Solvent (cyclohexanone) ………… …………………………………… 200 parts Of the above-mentioned common composition, as a liquid crystal, a compound C represented by the following formula (15), a compound D represented by the following formula (16), and The compound E represented by the formula (17) is used by changing the blending ratio for each color. For blue, C / D / E = 0 / 5.5 / 94.5, for green, C / D / E = For 45 / 4.5 / 50.5 and red Was C / D / E = 79/3/18. Compound D is a chiral agent. Moreover, among the above compositions, as a photopolymerization initiator, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1 (manufactured by Ciba Specialty Chemicals Co., Ltd., trade name); “Irgacure 369”) was used, and the same polymerization inhibitor and surfactant as those in Example 1 were used.

  With respect to the obtained liquid crystal pattern for each color of the reflective substrate, the wavelength dependency of the transmittance was obtained. As shown in the graph of FIG. 2, the widths of the selective reflection wavelength bands (wavelength ranges) were almost equal. It was a thing.

For forming a reflective layer for each color for blue, green, and red, the components are the same as those in Example 2, except that the compounding ratio of Compound C, Compound D, and Compound E is changed. A reflective substrate was obtained in the same manner as in Example 1 except that the composition was used. In the coating composition for forming the reflective layer in Example 3, C / D / E = 0 / 5.5 / 94.5 for blue, and C / D / E = 95.5 for green. For /4.5/0 and red, the compounding ratio was C / D / E = 79/3/18.

  When the wavelength dependency of the transmittance was determined for each color liquid crystal pattern of the obtained reflective substrate, the width of the selective reflection wavelength band (wavelength range) was red on both sides as shown in the graph of FIG. For green and blue, it was almost the same, and for green, it was about 30% narrower than red and blue.

Comparative Example 2
For forming a reflective layer for each color for blue, green, and red, it has the same composition as in Example 2, except that only compound C and compound D are used as the liquid crystal, and compound C and compound D A reflective substrate was obtained in the same manner as in Example 1 except that the coating composition having a different blending ratio was used. In the coating composition for forming a reflective layer in Comparative Example 2, C / D = 94.5 / 5.5 for blue, C / D = 95.5 / 4.5 for green, and For red, the compounding ratio was C / D = 97/3.

  Regarding the liquid crystal pattern for each color of the obtained reflective substrate, the wavelength dependence of the transmittance was obtained. As shown in the graph of FIG. 4, the width of the selective reflection wavelength band (wavelength range) is for red. It was the widest, and was narrowed in the order of green and blue.

It is a figure which shows the laminated structure of the optical element of this invention. 4 is a graph showing a “transmittance to wavelength” curve of the optical element obtained in Example 2. FIG. 6 is a graph showing a “transmittance to wavelength” curve of the optical element obtained in Example 3. FIG. 6 is a graph showing a “transmittance to wavelength” curve of an optical element obtained in Comparative Example 2.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Optical element 2 ... Substrate 3 ... Orientation film 4 ... Liquid crystal layer 5 ... Color filter layer 6 ... Black matrix

Claims (9)

A cross-linked liquid crystal layer having liquid crystal regularity is disposed in a plurality of regions on the substrate, and the liquid crystal layer is composed of a cross-linked cured product of a different polymerizable liquid crystal composition for each region , on the substrate, A color filter layer is laminated, and the polymerizable liquid crystal composition is obtained by laminating or blending two or more liquid crystal materials having different birefringences .   The thickness and the birefringence of each region of the liquid crystal layer are adjusted so as to give the same phase difference to the light having the center wavelengths in the different wavelength bands incident corresponding to each region. The optical element according to claim 1.   3. The optical element according to claim 1, wherein the thickness of each region of the liquid crystal layer is substantially equal.   The optical element according to claim 1, wherein the thickness of each region of the liquid crystal layer is different.   The optical element according to claim 1, wherein the polymerizable liquid crystal composition has nematic regularity. Wherein each liquid crystal layer is a layer having a cholesteric regularity, optical element according to claim 1 Symbol mounting, characterized in that it has a selective reflection band center wavelength for each region is different.   The optical element according to claim 6, wherein widths of the selective reflection wavelength bands for each region are substantially equal.   Each of the selective reflection bands corresponds to each of red light, green light, and blue light, and the width Δλ (G) of the selective reflection band of blue light is the width Δλ (R of the selective reflection band of red light. The optical element according to claim 6, wherein the optical element is smaller than a width Δλ (B) of the selective reflection band of blue light. A plurality of cross-linked liquid crystal layers having liquid crystal regularity are disposed in each of a plurality of regions on the substrate, and the plurality of liquid crystal layers are cross-linked cured products of different polymerizable liquid crystal compositions in each region. A color filter layer is laminated on the substrate, and the polymerizable liquid crystal composition is formed by laminating or blending two or more liquid crystal materials having different birefringences. element.

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