JP2007240628A - Optical element and method of manufacturing same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical element which has a refractive index distribution based upon alignment of liquid crystal molecules and also has the refractive index distribution fixed, and to provide a method of manufacturing the same. <P>SOLUTION: The optical element at least includes a liquid crystal material and pigment; and the refractive index distribution is formed by irradiating a polymerizable composition having polymerization property with light and aligning liquid crystal molecules through the light irradiation and the refractive index distribution is fixed by polymerizing the polymerizable composition. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical element having a refractive index distribution based on the orientation of liquid crystal molecules and having the refractive index distribution fixed, and a method for manufacturing the same.

  The present invention can be applied to an optical element (for example, a lens, a prism, a mirror, a filter, etc.) that uses a refractive index distribution without any particular limitation. Background art related to a certain “lens” will be mainly described.

  The lens has a condensing / diffusing function and is one of the most widely used optical elements.

  In recent years, along with the general trend of so-called lightness, thinness, and miniaturization of devices have been desired also in the optical field. For this reason, for example, lenses of the order of micrometers (μm) have attracted attention, and many methods for producing such lenses have been reported.

  One of such attention techniques is a method using a liquid crystal material. This is because when a liquid crystal material is used, it can be applied to the production of a microlens by precisely controlling the orientation of liquid crystal molecules.

  Regarding microlens fabrication, in particular, micrometer-order microlenses to be used in optical pickups, optical communication devices, and the like, and microlens arrays in which they are periodically arranged, have attracted attention, and many fabrication methods have been proposed. Yes. For example, Sato et al. (Masuda, S .; Fujioka, S .; Honma, m .; Nose, T .; Sato, S. Jpn. J. Appl. Phys. 1996, 35, 4668; Non-Patent Document 1) By using a material and a non-uniform electric field, a focus variable type flat microlens having a large numerical aperture has been successfully produced.

  However, even if alignment of liquid crystal molecules suitable for an optical element such as a metaphor lens is obtained, such a “preferable molecular alignment” is temporary, and gradually, when the supply of energy such as an electric field is stopped, It had returned to the original distribution. The details of various phenomena related to the alignment of the liquid crystal molecules are described in Non-Patent Documents 2 to 4.

Masuda, S .; Fujioka, S .; Honma, m .; Nose, T .; Sato, S. Jpn. J. Appl. Phys. 1996, 35, 4668 Zhang, H. et al. Adv. Mater. 2000, 12, 1336. Yaegashi, M. et al. Chem. Mater. 2005, 17, 4304. Nose, T .; Sato, S. Liq. Cryst. 1989, 5, 1425.

  The objective of this invention is providing the optical element which can eliminate the fault of the above-mentioned prior art, and its manufacturing method.

  Another object of the present invention is to provide an optical element having a refractive index distribution based on the orientation of liquid crystal molecules and having the refractive index distribution fixed, and a method for producing the same.

  As a result of diligent research, the present inventor achieved the above object by irradiating a composition having at least a liquid crystal material and a dye and having a polymerizable property to align liquid crystal molecules based on the light irradiation. And found it extremely effective.

The optical element of the present invention is based on the above knowledge. More specifically, the optical element includes at least a liquid crystal material and a dye, and has a refractive index distribution based on the orientation of liquid crystal molecules. The distribution is fixed.
In the case of using an electric field, it has the following characteristics.
(1) The orientation changes due to the interaction between the dielectric anisotropy of the liquid crystal and the electric field.
(2) A dielectric anisotropy material is essential.
(3) Since an electrode is used, patterning is essential for producing a desired lens.
(4) An alignment film is essential for producing a polarizing lens.
On the other hand, the production of an optical element using light has the following characteristics.
(1) The orientation of the whole system (liquid crystal) changes due to the change in the orientation of the pigment based on the light irradiation.
(2) A pigment that undergoes photophysical alignment is essential.
(3) A desired polarizing lens can be produced simply by changing the polarization direction of the irradiation light source to an arbitrary direction.
(4) Since light is used, a lens can be produced from a remote location in a contactless manner.
Therefore, when light irradiation is used, not only the number of process steps can be simplified, but an optical element such as a polarizing lens array can be easily produced.

  As described above, according to the present invention, an optical element having a refractive index distribution based on the orientation of liquid crystal molecules and having the refractive index distribution fixed, and a method for manufacturing the same are provided.

  Hereinafter, the present invention will be described more specifically with reference to the drawings as necessary. In the following description, “parts” and “%” representing the quantity ratio are based on mass unless otherwise specified.

(Optical element)
The optical element of the present invention is an optical element containing at least a liquid crystal material and a dye, and has a refractive index distribution based on the orientation of liquid crystal molecules, and the refractive index distribution is fixed. is there.

(Dye)
As long as orientation based on light irradiation is possible, the type of the dye is not particularly limited. Examples of the dye capable of orientation based on such light irradiation include the following.

(Preferred example)
Terthiophene-based liquid crystalline conjugated dye. For example, what is shown to a following formula is mentioned.

(Liquid crystal material)
The type of the liquid crystal material is not particularly limited as long as the liquid crystal molecules around the dye molecules can be aligned based on the alignment of the dye molecules based on the light irradiation. Examples of liquid crystal materials that can be aligned based on such light irradiation include the following.

(Preferred example)

(Refractive index distribution)
The optical element of the present invention has a refractive index distribution based on the orientation of liquid crystal molecules, and the refractive index distribution is fixed. The alignment mechanism of the liquid crystal molecules in this case is not particularly limited as long as the alignment suitable for the optical element can be obtained.

(Fixed refractive index distribution)
In the optical element of the present invention, the above refractive index distribution is fixed. This immobilization can be obtained by polymer formation during the production of the optical element, but the mechanism of the polymer formation is not particularly limited. The polymerizable material that should contribute to the formation of the polymer may have the above-described dye and / or liquid crystal material itself polymerizable, and the polymer formation may be performed by a polymerizable material different from the dye or the liquid crystal material. May be achieved.

(Preferred embodiment)
As a preferred embodiment of the optical element formation of the present invention, the system of “Example 1” described later will be described in detail.

(Orientation of dye molecules)
That is, in this system, by irradiating a system of (specific dye + nematic liquid crystal molecule + polymerization monomer) with laser light (polarized light), the dye molecules are aligned in response to light irradiation. In this case, in the portion where the light is relatively strong, the dye molecules are aligned parallel to the cell (that is, the pair of substrates sandwiching the molecule layer of the nematic liquid crystal material), while in the portion where the light is relatively weak. The dye molecules are oriented perpendicular to the cell. As a result, a lens shape based on the refractive index distribution is formed by the light irradiation. In the present invention, the formation of a lens shape based on such a refractive index distribution is fundamental, but if necessary, a refractive index distribution based on the shape may be combined, such as a shape (for example, a convex lens). .

(Alignment of liquid crystal molecules)
As a result of the above-described alignment of the dye molecules, the liquid crystal molecules present around the dye molecules are also aligned with the alignment of the dye molecules. That is, when strong light is irradiated to the center of the cell, the refractive index at the center of the cell increases. In this way, a lens based on the internal refractive index distribution is formed. In the present invention, when a lens based on the internal refractive index distribution is formed, the thickness of the lens material may be constant.

(Fixed refractive index distribution)
The refractive index distribution based on the orientation of the dye molecules (and liquid crystal molecules) as described above is usually temporary, and gradually returns to the original distribution when the light irradiation that caused the orientation is eliminated. The present invention is characterized in that the refractive index distribution based on light irradiation is fixed.

(Constituent materials)
Hereinafter, each constituent element or material constituting the optical element of the present invention (or used in the manufacturing method thereof) will be described in detail.

(Liquid crystal molecule + dye combination)
The production method of the present invention is characterized by irradiating light to a polymerizable composition having at least a liquid crystal material and a dye and having polymerizability. In the system of Example 1 described later, (nematic liquid crystal molecule + dye) + polymerization monomer = a new system of the present invention. As described above, the liquid crystal material is not limited to the nematic liquid crystal material.

  As described above, in the present invention, the polymerizable material that should contribute to the formation of the polymer may have the above-described dye and / or liquid crystal material itself polymerizable, and is separate from the dye or liquid crystal material. The above polymer formation may be achieved by the polymerizable material.

(Polymerizable material)
In the present invention, when a polymerizable material different from the dye or liquid crystal material is used, the type of the polymerizable material, the polymerization mechanism, the amount ratio, etc. are as long as the target optical element can be formed. There is no particular limitation. The polymerizable material is required to have a polymerizable group and is not particularly limited as long as it has liquid crystallinity as the whole system (pigment + liquid crystal material + polymerizable material). In the present invention, the following materials (for example, compounds having a vinyl group) can be suitably used as the polymerizable material.

(Preferred example)

(Polymerizable composition)
In the polymerizable composition to be used in the present invention, the following ratios of elements can be preferably used.

Liquid crystal material: 100 parts (standard)
Dye: 0.0001 to 10 parts (further 0.001 to 1 part)
Polymerizable material (when used): 1 to 100 parts (further 5 to 30 parts)
As described above, in the present invention, the liquid crystal material may also serve as the polymerizable material.
(Sub-materials or additives)
In addition to the above, various auxiliary materials or additives may be added to the polymerizable composition to be used in the present invention as necessary. Examples of such auxiliary materials or additives include those shown below.

(Suitable polymerizable composition)
In the present invention, the polymerizable composition to be used for forming the optical element preferably has, for example, the following properties.
In the present invention, it is essential that the polymerizable composition exhibits liquid crystal in the entire system (pigment + liquid crystal material + polymerizable material) upon light irradiation. For example, in the examples described later, those showing a nematic liquid crystal phase near room temperature are used.
The wider the liquid crystal temperature range of the entire system, the better. From the viewpoint of ease of handling, those that exhibit a liquid crystal phase near room temperature (20 ° C.) are preferred (the type of liquid crystal phase is not particularly limited).
More specifically, for example, those that exhibit a liquid crystal phase at about -50 to 50 ° C (further about -20 to 40 ° C) are preferable. In the examples to be described later, those that exhibit a nematic liquid crystal phase at room temperature of 20 ° C. are used.
Regarding identification of liquid crystals and phases, “Liquid Crystal Handbook”, pages 1 to 448, edited by Liquid Crystal Handbook Editorial Committee (Maruzen, 2000) can be referred to as necessary.

(Formed optical element)
The optical element (lens or the like) formed according to the present invention usually has anisotropy (that is, polarization) based on the orientation of the dye molecules. That is, the optical element formed according to the present invention is usually a polarizing optical element (for example, a polarizing lens). By changing the direction of polarization of the irradiated light, it is possible to manufacture polarizing optical elements having various directions of polarization. In the present invention, when circularly polarized light or omnidirectional light is used, it is possible to form a normal “non-anisotropic” optical element.

(Cooperative effect of liquid crystal molecules)
Since liquid crystal molecules usually have a cooperative effect, if a certain liquid crystal molecule is aligned, the surrounding liquid crystal molecules also tend to be aligned. Therefore, when the light intensity to be irradiated to the polymerizable composition is increased, the range of liquid crystal molecular alignment is expanded (that is, the diameter of the optical element such as the lens diameter is increased).

(Preferable optical element shape)
Since the optical element of the present invention has a refractive index distribution inside the element, even if the surface of the optical element is flat, a lens such as a planoconvex lens, a biconvex lens, a planoconcave lens, a biconcave lens, a Fresnel lens, etc. It can be set as the optical element which has these optical functions. According to the present invention, an optical element that is thin and has a short focal length can be obtained even in a flat shape, which is useful in terms of workability and design.

  The light-emitting device of the present invention includes the optical element and the light-emitting element of the present invention. Examples of the light emitting element include an organic EL element, an inorganic EL element, and a compound semiconductor light emitting element. From the viewpoint of emission color, a white LED, a blue LED, a red LED, a green LED, and the like can be given. When an organic EL element is used as the light-emitting element, the light-emitting device of the present invention is a preferable embodiment because it can be efficiently taken out while suppressing total reflection of light emitted from the organic EL element. In the light emitting device of the present invention, the optical element may be present inside the light emitting element or may be disposed outside. Examples of a light-emitting device in the case where an organic EL element is used as the light-emitting element are shown in FIGS.

(Preferred optical element, optical element array)
According to the present invention, various optical elements can be created. From the viewpoint of using the present invention as a member of a light emitting device, the diameter of the optical element is preferably 0.5 μm to 3 mm, and more preferably 1 μm to 0.5 mm. If the diameter is smaller than 0.5 μm, the above optical function may not be obtained, and if it exceeds 3 mm, the obtained optical image depends on the viewing angle and the image may not be uniform. Also, the present invention can be suitably applied to an aspect in which a plurality of optical elements are regularly arranged in a certain range, that is, an optical element array (for example, a lens array). The degree of integration of the optical elements in the array is preferably 10 to 4 × 10 ⁸ optical elements regularly arranged within a range of 1 cm × 1 cm, more preferably 400 to 1 × 10 ^8. It is.

(Characteristics of suitable optical elements)
The optical element of the present invention preferably has the following physical properties (1) to (3).
(1) Total light transmittance When used as a member of a light-emitting device, the total light transmittance is preferably 70% or more, more preferably 80% or more, from the viewpoint of efficiently extracting emitted light to the outside.
(2) Surface flatness From the viewpoint of using the optical element of the present invention as a member of a light-emitting device, the surface of the optical element is preferably a flat shape, and a centerline average indicating the degree of flatness of the surface The roughness (Ra) is preferably 100 nm or less, and more preferably 50 nm or less.
(3) Thickness When used as a member of a light-emitting device, the thickness is preferably 5 mm or less, more preferably 3 mm or less, and even more preferably 1 mm or less in terms of being lightweight and compact.

  Hereinafter, the present invention will be described more specifically with reference to examples.

Example 1
(Preparation of micro lens using argon ion laser / mercury lamp)
The compounds used in this example are shown in FIG.
Referring to FIG. 3, acrylate monomer A6CB having a similar skeleton and a crosslinking agent (HDDA and HDDMA) are mixed in nematic liquid crystal material (host liquid crystal material) 5CB at a ratio (composition ratio) shown in Table 1 below to obtain a liquid crystal A material / monomer mixture (13 types) was prepared.

  In the following description, a sample obtained by mixing 5CB: A6CB: crosslinking agent at a composition ratio of X: Y: Z is expressed as X / Y / Z). A and M at the end represent the type of polymerized group, which means acrylate (HDDA) and methacrylate (HDDA), respectively.

  A cell having a cell thickness of 60 μm, in which 0.1 mol% of oligothiophene TD (guest dye) and 0.5 mol% of photopolymerization initiator Irgacure 184 are added to each liquid crystal material / monomer mixture described above, and the cell thickness is 60 μm. To be a measurement sample (in addition, the clearing point of “Sample No. 84/12 / 4A” in Table 1 above was 28.3 ° C.).

  The experimental system used here is shown in the schematic perspective view of FIG. A more detailed optical system is shown in the block diagram of FIG.

Referring to FIG. 5 (a), the sample was irradiated with horizontally polarized light having a wavelength of 488 nm of a focused argon ion laser to induce realignment of the liquid crystal material. After confirming that the light transmitted through the sample forms an interference pattern on the screen, a 366-nm bright line of a high-pressure mercury lamp was irradiated at a light intensity of 0.5 mW / cm ² to perform photopolymerization.

The meaning of each symbol in FIG. 5A is as follows.
BS: Beam splitter CF: Color filter (except 505 nm or less)
L: Lens (f = 200, 60)
M: Mirror ND: ND filter P: Polarizer PH: Pinhole WP: 1/2 wavelength version (Horizontal polarization)
Whether or not a microlens could be produced by the above procedure was determined by the following method.
That is, as shown in FIG. 5A, horizontal polarized light of a wavelength of 633 nm of a helium-neon laser was used as the probe light. The probe light was incident on the sample coaxially with the argon ion laser light, and the probe light transmitted through the sample was observed on a distant screen.

  Since the sample does not have an absorption band in this wavelength region, even if helium-neon laser light is incident on the sample, it does not affect the microlens fabrication. Therefore, even when a more simplified optical system (FIG. 5B) is used, the microlens can be manufactured.

  When a microlens is formed by irradiation with argon ion laser light, an interference pattern appears on the screen (FIG. 5A or FIG. 5B). The interference pattern was observed 10 minutes after the argon ion laser beam irradiation was stopped, and it was determined whether or not a microlens could be produced.

Example 2
(Confirmation of optical properties)
When the sample is irradiated with light, the light transmitted through the sample forms such an annular interference pattern on the screen. The formed interference pattern is shown in the photograph of FIG.

  This annular interference pattern appears when light passes through a refractive index gradient formed on the basis of realignment of the liquid crystal. That is, the appearance of interference fringes indicates that the liquid crystal molecules have been reoriented to form microlenses. The number of observed fringes depends on the refractive index modulation induced by the light, ie, the difference in refractive index between the center of the spot and the edge, as shown in this equation (for such measurements, if necessary Reference can be made to the document Durbin, SD et al. Opt. Lett. 1981, 6, 411).

Δn: Refractive index difference N: Number of rings d: Cell thickness λ: Wavelength of laser beam In the present invention, this interference fringe was evaluated as a degree of refractive index difference induced by light. The relationship between the number of interference fringes and light intensity is shown. It was found that a light intensity of a certain level or more is necessary for forming a microlens, and a threshold value exists. In the region where the light intensity is 8 W / cm ² or less, the number of interference fringes changes greatly depending on the light intensity, that is, the refractive index difference changes greatly. On the other hand, the change was small in the region with high light intensity.

Example 3
(Confirmation of immobilization)
When the microlens was formed, ultraviolet light irradiation was performed to attempt photopolymerization. A sample composed only of 5CB and a dye was irradiated with argon ion laser light to form a lens, and then irradiated with ultraviolet light, and then the argon ion laser light and ultraviolet light were turned off, and left at room temperature in a dark place for 10 minutes. When the weak argon ion laser light below the threshold was irradiated again, the previous interference fringes disappeared (FIG. 7).

  This is because orientation relaxation occurs and the initial state is restored. Subsequently, the same operation was performed on the sample in which the monomer was dispersed, and when a weak argon ion laser beam below the threshold value was irradiated again, interference fringes almost the same as those immediately before the light irradiation was stopped appeared. Since similar interference fringes appear even without continuous light irradiation, it was revealed that the microlens can be fixed by photopolymerization.

Example 4
(Confirmation of polarization)
FIG. 8 shows a polarizing microscope photograph of the obtained microlens. Regardless of the intensity of the argon ion laser beam, a clear spot was observed when the polarizer / analyzer was at plus or minus 45 degrees with respect to the plane of polarization. On the other hand, when the polarizer / analyzer was 0 ° / 90 °, a dark field was observed on the spot. This suggests that the microlens is fixed while maintaining the uniaxial alignment state induced by the argon ion laser light irradiation.

Example 5
(Confirmation of light intensity dependency)
Subsequently, the diameter of the obtained microlens was plotted against the intensity of the argon ion laser beam, and the light intensity dependency was examined (FIG. 9). As a result, it was found that the diameter of the microlens increases as the light intensity increases. This is thought to be due to the fact that alignment changes are induced even in the non-irradiated portion based on the cooperative effect, which is one of the properties of liquid crystals.

Example 6
(Confirm focal length)
The focal length of the obtained microlens was measured using a polarizing microscope and a CCD camera. The dependence of the focal length on the light intensity is shown. In the region where the light intensity is 8 W / cm ² or less, it has been found that the focal length decreases as the light intensity increases. On the other hand, in the region where the light intensity is 8 W / cm ² or more, it was found that the focal length increases as the light intensity increases (FIG. 10). The focal length of the liquid crystal lens depends on the radius r of the lens, the thickness d, and the difference in refractive index Δn between the center and the end, and is expressed by the following relationship.

That is, as the lens radius increases, the focal length increases, and as the refractive index difference increases, the focal length decreases. As described above, the diameter of the microlens increases as the light intensity increases. On the other hand, the refractive index difference Δn, that is, the number of interference fringes greatly changes even in a slight difference in light intensity in a region where the light intensity is 8 W / cm ² or less. Therefore, in this region, the contribution of the increase in the refractive index difference is greater than the increase in the lens diameter, so the focal length is considered to be shortened. On the other hand, in the region where the light intensity is high, the change in the refractive index difference with respect to the light intensity is small.

  As described above, it has been clarified that by combining the light-induced reorientation of the dye-doped liquid crystal and photopolymerization, the molecular orientation of the liquid crystal can be fixed and the microlens can be produced. However, in this method, since photopolymerization is performed on the entire surface of the sample, one sample is required to obtain one microlens. If lens formation and photopolymerization can be performed simultaneously with only the irradiation spot of argon ion laser light, a plurality of microlenses can be produced for a single sample by a simple method, and microlenses can be arranged freely Can be deployed to arrays.

Example 7
(Realignment and photopolymerization of liquid crystal molecules)
Therefore, such a method was attempted with the aim of producing a microlens only by irradiation with an argon ion laser beam. 0.5 mol% of a photopolymerization initiator Irgacure 369 having absorption in the visible region was added to the same material as above to prepare a sample (FIG. 11). Using the same optical system, light was irradiated for 55 seconds at a light intensity of 8.3 W / cm ² . When light irradiation was stopped and weak light was incident again 20 minutes later, interference fringes almost the same as those immediately before the light irradiation was stopped were observed. This is thought to be because only the microlens portion can be fixed as a result of realignment of liquid crystal and photopolymerization occurring simultaneously with the irradiation of argon ion laser light.

Example 8
(Formation of microlens array)
Next, light irradiation for 55 seconds and periodic movement of the sample, these two operations were repeated several times. Finally, the entire surface was irradiated with ultraviolet light to quench the remaining photopolymerization initiator. Observation of the obtained sample with a polarizing microscope revealed that a microlens array in which microlenses were arranged in a hexagonal lattice shape was formed (FIG. 12). In addition, when the polarizer / analyzer is rotated, light / darkness is shown every 45 degrees, so that it is found that liquid crystal molecules are uniaxially aligned in all the microlenses.

Example 9
(Polarization characteristics of microlens array)
Subsequently, the polarization characteristics of the microlens array were examined. When light parallel to the plane of polarization of the argon ion laser light was incident and observed with a microscope, it was found that it worked as a lens in this way (FIG. 13). On the other hand, when light perpendicular to the plane of polarization of the argon ion laser light is incident, the lens effect does not appear, and it has been clarified that the microlens array has polarization selectivity.

Example 10
(Formation of various microlens arrays)
The micrograph of the various microlens arrays produced at the end is shown. Using this method, it is possible to produce microlens arrays arranged in various lattice shapes such as face-centered rectangular lattices and square lattices by moving the sample periodically in addition to the above hexagonal lattice shape. Became clear (FIG. 14). Further, in this sample, the first, third, and fifth stages were manufactured using horizontal polarization, and the second and fourth stages were manufactured using vertical polarization. As a result, it was found that when light perpendicular to each polarization plane is incident, it does not work as a lens. That is, it was clarified that the polarization characteristics of the microlens array can be controlled by changing the polarization plane of the argon ion laser beam. It is considered that the microlens array having such characteristics can be applied to a polarizing plate-free liquid crystal panel element.

Example 11
(Examination of UV light irradiation time)
Using the polymerizable composition sample “85: 12: 3M” shown in Table 1 above, the photopolymerization conditions were examined by changing the ultraviolet light irradiation time.

  In this experimental system, when the ultraviolet light irradiation time was 3-5 minutes, the alignment during the argon ion laser light irradiation could not be fixed, and the liquid crystal material returned to the initial state (FIGS. 15A and 15B). )). On the other hand, when the ultraviolet light irradiation time was 6 minutes or more, the orientation during the irradiation with the argon ion laser light was fixed and could be obtained as a microlens (FIG. 15C). When the irradiation time was 8 minutes or longer, light scattering gradually occurred (FIG. 15 (d)).

  From the above, in the experimental system used in this example, it was found that ultraviolet light irradiation for a certain time or longer was necessary to produce a microlens, and that the lens characteristics deteriorated if the irradiation time was too long. did. Therefore, when the polymerizable composition sample “85: 12: 3M” was used, it was judged that an ultraviolet light irradiation time of 6 minutes was appropriate.

Example 3
(Examination of monomer composition ratio)
About the sample mixed by the composition ratio shown in Table 1, light irradiation was carried out for arbitrary time and the influence of the monomer composition ratio was examined.

  When the polymerizable composition sample “90/10/0” was used, the alignment could not be fixed even after 60 minutes of light irradiation, and the liquid crystal material returned to the initial state.

  In the case of using the polymerizable composition sample “90/8 / 2M”, the orientation at the time of argon ion laser light irradiation could be slightly fixed by light irradiation for 60 minutes, but it was unstable and light scattering. Was produced.

  When the polymerizable composition sample “89/8 / 3M” was used, the alignment at the time of argon ion laser irradiation could be fixed by irradiating with light for 8 minutes, but it was unstable and caused light scattering. It was. When the irradiation time was shorter than that, immobilization could not be performed, and a stable microlens could not be obtained even when the irradiation time was longer than that.

  When the polymerizable composition sample “87/10 / 3M” is used, the orientation at the time of argon ion laser light irradiation is fixed by irradiating with light for 7 minutes, and can be obtained as a microlens, and the irradiation time is less than that. It was not obtained in the case of.

  When the polymerizable composition sample “84/12 / 4M” is used, the orientation at the time of argon ion laser light irradiation is fixed by light irradiation for 5.5 minutes, and can be obtained as a microlens. It was not obtained in the case of less than that.

  When the polymerizable composition sample “82/14 / 4M” is used, the orientation upon irradiation with argon ion laser light is fixed by irradiating with light for 5 minutes, and can be obtained as a microlens, and the irradiation time is less than that. In the case of, it was not obtained.

  From the above, it has been found that if the monomer and cross-linking agent content is large, a microlens can be produced by short-time ultraviolet irradiation.

Example 4
(Influence of polymerized groups in the crosslinking agent)
A micro-lens formation behavior was examined by adding a crosslinking agent having acrylate as a polymerization group.

  When the polymerizable composition sample “90/8 / 2A” is used, the orientation upon irradiation with argon ion laser light is fixed by irradiating with light for 5 minutes, and can be obtained as a microlens, and the irradiation time is less than that. In the case of, it was not obtained.

  When the polymerizable composition sample “9/8 / 3A” is used, the orientation at the time of argon ion laser light irradiation is fixed by irradiating with light for 3.5 minutes, and it can be obtained as a microlens, and the irradiation time is It was not obtained in the case of less than that.

  When the polymerizable composition sample “87/10 / 3A” is used, the orientation at the time of argon ion laser light irradiation is fixed by irradiating with light for 3 minutes, and can be obtained as a microlens, and the irradiation time is less than that. In the case of, it was not obtained.

  When the polymerizable composition sample “85/12 / 3A” is used, the alignment at the time of argon ion laser irradiation is fixed by irradiating with light for 2.5 minutes, and can be obtained as a microlens, and the irradiation time is It was not obtained in the case of less than that.

  When the polymerizable composition sample “84/12 / 4A” is used, the orientation during irradiation with argon ion laser light is fixed by irradiating with light for 2 minutes, and can be obtained as a microlens, and the irradiation time is less than that. In the case of, it was not obtained.

  When the polymerizable composition sample “82/14 / 4A” is used, the alignment at the time of irradiation with argon ion laser light is fixed by irradiating with light for 1.5 minutes, and can be obtained as a microlens. It was not obtained in the case of less than that.

  From the above, it was found that microlenses can be obtained by light irradiation for a short time by using HDDA as a crosslinking agent. On the other hand, it has been found that light irradiation occurs when light irradiation is performed for several tens of seconds longer than the above irradiation time, and the resulting microlens is unstable.

  From the results obtained in Examples 1 to 4 described above, when producing a microlens using an argon ion laser / mercury lamp, a polymerizable composition sample “85: 12: 3M” was used for 6 minutes of ultraviolet light irradiation. It was judged that the conditions for performing Therefore, what was produced on these conditions was used for the physical-property evaluation of the obtained microlens.

Example 5
(Preparation of microlens array by argon ion laser irradiation)
Cell thickness obtained by adding 0.1 mol% of dye TD and 0.5 mol% of photopolymerization initiator Irgacure 369 to each of the liquid crystal material / monomer mixture mixed at the composition ratio shown in Table 1 and performing vertical alignment treatment. A measurement sample was sealed in a 60 μm cell. The optical system used is shown in FIG. The sample was irradiated with horizontally polarized light having a wavelength of 488 nm of a focused argon ion laser. The microlens fabrication determination was performed using the same method as described above. Accordingly, the microlens can be manufactured even in a more simplified optical system (FIG. 16B).

Example 6
(Examination of light irradiation time)
Using the polymerizable composition sample “85: 12: 3M”, photopolymerization conditions were examined at an arbitrary light intensity and an arbitrary light irradiation time.

  The results obtained are summarized in Table 2 below.

The meanings of the symbols in Table 2 are as follows.
○: obtained as a microlens;
×: Returned to the initial state;
Light scattering: The orientation is slightly fixed, but it causes light scattering and cannot be used as a microlens;
-: Not performed

From the above experimental results, it has been found that to produce a microlens, it is necessary to irradiate light with a certain intensity or more for a certain period of time (FIG. 17 (a)). (FIG. 17B). Therefore, when the polymerizable composition sample “85: 12: 3M” was used, it was determined that the conditions of light irradiation for 55 seconds at a light intensity of 8.3 W / cm ² were appropriate.

Example 7
(Examination of monomer composition ratio)
About the sample mixed by the composition ratio shown in the said Table 1, light irradiation was carried out at arbitrary light intensity and arbitrary time, and the influence of the monomer composition ratio was examined.

When the polymerizable composition sample “90/10/0” was used, when light irradiation was performed for 45 minutes at a light intensity of 11 W / cm ² , the alignment could not be fixed, and the liquid crystal material returned to the initial state.

When the polymerizable composition sample “90/8 / 2M” is used, a microlens is obtained when argon ion laser light irradiation is performed at a light intensity of 7.0-9.8 W / cm ² for 3-10 minutes. I could not.

  Details of the results obtained are summarized in Table 3 below. Irrespective of the light intensity, the alignment could not be fixed by light irradiation for a short time, and the liquid crystal material returned to the initial state. On the other hand, it was found that light scattering occurs when light irradiation is performed for a long time.

The meanings of the symbols in Table 3 are as follows.
×, returned to the initial state;
Light scattering, orientation is slightly fixed, but light scattering occurs and cannot be used as a microlens;
-: Not performed

When the polymerizable composition sample “89/8 / 3M” is used, a microlens is obtained by performing irradiation with argon ion laser light for 90 to 210 seconds at a light intensity of 7.0 to 9.8 W / cm ^2. I could not.

  Details of the results obtained are summarized in Table 4 below. The alignment could not be fixed by light irradiation for a short time, and the liquid crystal material returned to the initial state. On the other hand, it was found that light scattering occurs when light irradiation is performed for a long time.

The meanings of the symbols in Table 4 are as follows.
×: Returned to the initial state;
Light scattering: The orientation is slightly fixed, but it causes light scattering and cannot be used as a microlens;
-: Not performed

When the polymerizable composition sample “87/10 / 3M” is used, a microlens is obtained by performing irradiation with an argon ion laser beam for 50 to 90 seconds at a light intensity of 5.6 to 9.8 W / cm ^2. I could not.

  Details of the results obtained are summarized in Table 5 below. The alignment could not be fixed by light irradiation for a short time, and the liquid crystal material returned to the initial state. On the other hand, it was found that light scattering occurs when light irradiation is performed for a long time.

The meanings of the symbols in Table 5 are as follows.
×: Returned to the initial state;
XX: Microlens was not formed Light scattering: Orientation is slightly fixed, but light scattering occurs and cannot be used as a microlens;-: Not implemented

When the polymerizable composition sample “84/12 / 4M” was used, argon ion laser irradiation was performed at a light intensity of 5.6 to 9.8 W / cm ² for 30 to 60 seconds.

  Details of the results obtained are summarized in Table 6 below. When the light intensity was low, no microlens was formed. As the light intensity was increased, microlenses were formed, and the alignment could not be fixed by light irradiation for a short time, and the liquid crystal material returned to the initial state. On the other hand, it was found that light scattering occurs when light irradiation is performed for a long time. When this sample is used, it is necessary to precisely control the light irradiation time.

The meanings of the symbols in Table 6 are as follows.
○: obtained as a microlens;
×: Returned to the initial state;
XX: Microlens was not formed Light scattering: Orientation is slightly fixed, but light scattering occurs and cannot be used as a microlens;-: Not implemented

When the polymerizable composition sample “82/14 / 4M” was used, argon ion laser light irradiation was performed at a light intensity of 7.0-14 W / cm ² for 20-60 seconds.

  Details of the results obtained are summarized in Table 7. When the light intensity was low, no microlens was formed. As the light intensity was increased, microlenses were formed, and the alignment could not be fixed by light irradiation for a short time, and the liquid crystal material returned to the initial state. On the other hand, it was found that light scattering occurs when light irradiation is performed for a long time. When this sample is used, it is necessary to precisely control the light irradiation time.

The meanings of the symbols in Table 7 are as follows.
○: obtained as a microlens;
×: Returned to the initial state;
XX: Microlens was not formed Light scattering: Orientation is slightly fixed, but light scattering occurs and cannot be used as a microlens;-: Not implemented

  From the above results, it was found that a certain amount or more of monomers and a crosslinking agent are necessary for the production of the microlens, and if the content is large, the microlens can be produced by short-time light irradiation. On the other hand, when the content of the monomer and the crosslinking agent is large, light scattering is likely to occur. Therefore, it is necessary to precisely control the light irradiation time.

Example 8
(Influence of polymerized groups in the crosslinking agent)
A micro-lens formation behavior was examined by adding a crosslinking agent having acrylate as a polymerization group.

When the polymerizable composition sample “90/8 / 2A” was used, irradiation with argon ion laser light for 90 to 150 seconds was performed at a light intensity of 5.6 to 17 W / cm ² .

  The results obtained are summarized in Table 8 below. When the light intensity was low, no microlens was formed. As the light intensity was increased, microlenses were formed, and the alignment could not be fixed by light irradiation for a short time, and the liquid crystal material returned to the initial state. On the other hand, it was found that light scattering occurs when light irradiation is performed for a long time. Furthermore, the obtained microlens was unstable.

The meanings of the symbols in Table 8 are as follows.
○: obtained as a microlens;
×: Returned to the initial state;
XX: Microlens was not formed Light scattering: Orientation is slightly fixed, but light scattering occurs and cannot be used as a microlens;-: Not implemented

When the polymerizable composition sample “89/8 / 3A” was used, irradiation with argon ion laser light at a light intensity of 5.6-17 W / cm ² did not form a microlens and could not be obtained. It was.

When the polymerizable composition sample “87/10 / 3A” was used, irradiation with argon ion laser light at a light intensity of 5.6-14 W / cm ² did not form a microlens and could not be obtained. It was.

When the polymerizable composition sample “85/12 / 3A” was used, irradiation with an argon ion laser beam with a light intensity of 4.2-12 W / cm ² failed to form a microlens. It was.

  From the above results, it was found that when HDDA is used as the cross-linking agent, microlenses can be obtained only when the monomer content is low. When the monomer content was high, microlenses could not be formed by argon ion laser light irradiation.

In the case of producing a microlens by irradiation with argon ion laser light, it was determined that the condition of using 85: 12: 3M and performing light irradiation for 55 seconds at a light intensity of 8.3 W / cm ² was most appropriate.

  Based on the obtained knowledge, light irradiation under these conditions, periodic movement of the sample, repeating these two operations several tens of times, irradiating ultraviolet light on one side and quenching the remaining photopolymerization initiator A microlens array was produced.

It is a schematic cross section which shows an example of the light-emitting device which has the optical element of this invention, and a light emitting element (this example organic EL element). It is a schematic cross section which shows the other example of the light-emitting device which has the optical element of this invention, and a light emitting element (this example organic EL element). 1 is a diagram showing compound materials used in Example 1. FIG. 1 is a schematic perspective view showing an experimental system used in Example 1. FIG. FIG. 5 is a block diagram (a) showing the optical system of FIG. 4 in more detail, and a block diagram (b) showing a simplified optical system of the optical system of (a). It is an example of the photograph which shows the cyclic | annular interference pattern formed on the screen. It is an example of the photograph which shows disappearance of an interference fringe. 6 is an example of a polarizing microscope photograph of the microlens obtained in Example 4. FIG. It is a graph which shows an example of the light intensity dependence of a micro lens diameter. It is a graph which shows an example of the relationship between light intensity and a focal distance. 10 is a schematic diagram showing an experimental system used in Example 7. FIG. 10 is a photograph showing an example of a microlens array having a hexagonal lattice arrangement formed in Example 8. FIG. 10 is a photograph showing an example of polarization characteristics of the microlens array formed in Example 9. FIG. 10 is a photomicrograph showing examples of various microlens arrays formed in Example 10. FIG. The interference fringes ((a), (b)) of the microlens that have returned to the initial state, the interference fringes (c) of the lens that can be obtained as a microlens, with the orientation at the time of argon ion laser light irradiation fixed, and It is a photograph which shows the interference fringe (d) of the lens which light scattering produced gradually. FIG. 10 is a block diagram (a) showing an optical system used in Example 5 and a block diagram (b) showing a simplified optical system of the optical system of (a). It is a photograph which shows the interference fringe (a) at the time of producing a microlens successfully, and the interference fringe (b) when an irradiation time is too long and a lens characteristic falls.

Claims (9)

  An optical element comprising at least a liquid crystal material and a dye, wherein the optical element has a refractive index distribution based on the orientation of liquid crystal molecules, and the refractive index distribution is fixed.   The optical element according to claim 1, having an optical function of a lens.   The optical element according to claim 1, which has the form of an optical element array.   The optical element according to claim 1, wherein the surface has a flat shape. Irradiating light to a polymerizable composition containing at least a liquid crystal material and a dye and having polymerizability, aligning liquid crystal molecules based on the light irradiation, forming a refractive index distribution, and
A method for producing an optical element, wherein the polymerizable composition is polymerized to fix the refractive index distribution.   The method for producing an optical element according to claim 5, wherein the polymerization of the polymerizable composition occurs at least partially simultaneously with the alignment of liquid crystal molecules.   The method for producing an optical element according to claim 4, wherein polymerization of the polymerizable composition does not occur simultaneously with alignment of liquid crystal molecules.   A light emitting device comprising the optical element according to claim 1 and a light emitting element.   The light emitting device according to claim 8, wherein the light emitting element is an organic EL element.