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JP-7855573-B2 - Liquid crystal composition, optical element, and light guide element

JP7855573B2JP 7855573 B2JP7855573 B2JP 7855573B2JP-7855573-B2

Inventors

  • 大窪 恵
  • 市橋 光芳
  • 福島 悠貴
  • 小玉 啓祐
  • 加藤 峻也

Assignees

  • 富士フイルム株式会社

Dates

Publication Date
20260508
Application Date
20220322
Priority Date
20210322

Claims (14)

  1. A liquid crystal composition containing a liquid crystal compound, The liquid crystal composition contains a rod-shaped liquid crystal compound and a disc-shaped liquid crystal compound, A liquid crystal composition used for forming a diffraction element , wherein the ratio of the twist elastic constant K22 to the spray elastic constant K11 of the liquid crystal composition satisfies 0.7 ≤ K22/K11.
  2. The liquid crystal composition according to claim 1, wherein the refractive index difference Δn 550 due to the refractive index anisotropy of the liquid crystal composition is 0.2 or more.
  3. The liquid crystal composition according to claim 1 or 2, wherein the content of the disc-shaped liquid crystal compound in the liquid crystal composition is 5 to 25% by mass relative to the total mass of the rod-shaped liquid crystal compound and the disc-shaped liquid crystal compound in the liquid crystal composition.
  4. The liquid crystal composition according to any one of claims 1 to 3, wherein the rod-shaped liquid crystal compound is a compound represented by the following formula (I). Here, in equation (I) above, P1 and P2 each independently represent a hydrogen atom or a substituent. S1 and S2 each independently represent a single bond or a divalent linking group. A1 and A2 each independently represent a non-aromatic ring, aromatic ring, or aromatic heterocycle, which may have substituents. However, if there are multiple A2s , the multiple A2s may be the same or different. Y 1 is -O-, -S-, -OCH 2 -, -CH 2 O-, -CH 2 CH 2 -, -CO-, -COO-, -OCO-, -CO-S-, -S-CO-, -O-CO-O-, -CO-NH-, -NH-CO-, -SCH 2 -, -CH 2 S-, -CF 2 O-, -OCF 2 -, -CF 2 S-, -SCF 2 -, -CH=CH-COO-, -CH=CH-OCO-, -COO-CH=CH-, -OCO-CH=CH-, -COO-CH 2 CH 2 -, -OCO-CH 2 CH 2 -, -CH 2 CH 2 -COO-, -CH 2 CH 2 -OCO-, -COO-CH 2 -, -OCO- CH2- , -CH2 -COO-, -CH2-OCO-, -CH=CH-, -N= N- , -CH=N-N=CH-, -CF=CF-, -C≡C- , -OCH2CH2O- , -SCH2CH2S- , or a single bond. However, if there are multiple Y1s , the multiple Y1s may be the same or different. m1 represents an integer between 1 and 12.
  5. The liquid crystal composition according to any one of claims 1 to 4, wherein the disc-shaped liquid crystal compound is a compound represented by the following formula (II). Here, in equation (II), P3 represents a hydrogen atom or a substituent. However, multiple P3s may be the same or different. S3 represents a single bond or a divalent linking group. However, multiple S3s may be the same or different. A3 represents a non-aromatic ring, aromatic ring, or aromatic heterocycle, which may have substituents. However, multiple A3s may be the same or different. Y 2 is -O-, -S-, -OCH 2 -, -CH 2 O-, -CH 2 CH 2 -, -CO-, -COO-, -OCO-, -CO-S-, -S-CO-, -O-CO-O-, -CO-NH-, -NH-CO-, -SCH 2 -, -CH 2 S-, -CF 2 O-, -OCF 2 -, -CF 2 S-, -SCF 2 -, -CH=CH-COO-, -CH=CH-OCO-, -COO-CH=CH-, -OCO-CH=CH-, -COO-CH 2 CH 2 -, -OCO-CH 2 CH 2 -, -CH 2 CH 2 -COO-, -CH 2 CH 2 -OCO-, -COO-CH 2 -, -OCO- CH2- , -CH2 -COO-, -CH2-OCO-, -CH=CH-, -N= N- , -CH=N-N=CH-, -CF = CF- , -C≡C-, -OCH2CH2O-, -SCH2CH2S- , or represents a single bond. However, multiple Y2s may be the same or different. m² represents an integer between 0 and 5. n represents an integer between 3 and 20. D represents an n-valent disk-shaped core.
  6. The liquid crystal composition according to claim 4, wherein at least one Y1 in formula (I) is -C≡C-.
  7. A diffraction element having an optically anisotropic layer formed using a liquid crystal composition containing a liquid crystal compound, The liquid crystal composition contains a rod-shaped liquid crystal compound and a disc-shaped liquid crystal compound, A diffraction element in which the optical anisotropy layer has a liquid crystal orientation pattern in which the orientation of the optical axis derived from the liquid crystal compound changes while continuously rotating along at least one direction in the plane.
  8. The diffraction element according to claim 7, wherein the liquid crystal composition is the liquid crystal composition according to any one of claims 1 to 6.
  9. The diffraction element according to claim 7 or 8, wherein the optical anisotropy layer has the optical axis orientation aligned in the thickness direction.
  10. The diffraction element according to claim 7 or 8, wherein the optical anisotropy layer has a region in which the orientation of the optical axis twists and rotates in the thickness direction.
  11. A diffraction element according to any one of claims 7 to 10, wherein when the length of one period is defined as the length over which the orientation of the optical axis rotates 180° in the plane, the liquid crystal alignment pattern has regions in which the length of one period is different.
  12. When the length over which the orientation of the optical axis rotates 180° in the plane is defined as one period, The diffraction element according to any one of claims 7 to 11, wherein the period of the liquid crystal alignment pattern gradually shortens in the direction in which the orientation of the optical axis in the liquid crystal alignment pattern changes while continuously rotating.
  13. The diffraction element according to any one of claims 7 to 12, wherein the liquid crystal alignment pattern of the optical anisotropy layer is a concentric pattern having the one direction in which the orientation of the optical axis changes while continuously rotating in a concentric manner from the inside to the outside.
  14. A light guide element comprising a diffracting element and a light guide plate according to any one of claims 7 to 13.

Description

This invention relates to a liquid crystal composition, an optical element, and a light guide element. Polarization is used in many optical devices and systems. In response, development is underway on optical elements that control the reflection, focusing, and divergence of polarized light. For example, Patent Document 1 describes an optical element comprising a plurality of stacked birefringent sublayers configured to change the direction of propagation of light passing through the interior according to the Bragg condition, wherein the stacked birefringent sublayers have local optical axes that change along the respective interfaces between adjacent stacked birefringent sublayers to define their respective lattice periods. The optical element described in Patent Document 1 has an optically anisotropic thin film containing a liquid crystal compound (i.e., a thin liquid crystal layer). Specifically, the optical element described in Patent Document 1 is a diffraction element having a liquid crystal layer that diffracts light by changing the orientation pattern of rod-shaped liquid crystal compounds in one direction within the plane. Diffractive elements using such liquid crystal compounds are expected to be used, for example, as optical components in image projection devices such as AR (Augmented Reality) glasses. As an example, AR glasses work by having an image displayed on a screen enter one end of a light guide plate, propagate through it, and emit it from the other end, thereby superimposing a virtual image onto the scene the user is actually seeing. In AR glasses, a diffracting element is used to diffract (refract) light from the display (projected light) and direct it into one end of a light guide plate. This introduces the light into the light guide plate at an angle, causing it to propagate through total internal reflection within the plate. The light that has propagated through the light guide plate is then diffracted again by a diffracting element at the other end of the light guide plate and emitted from the light guide plate to the user's observation position. Special table 2017/522601 This figure conceptually illustrates an example of the optical element of the present invention.This is a conceptual diagram illustrating the optical element shown in Figure 1.Figure 1 is a plan view of the optical element shown.Figure 1 is a conceptual diagram illustrating the operation of the optical element shown.This is a diagram conceptually illustrating another example of the optical element of the present invention.This is a diagram conceptually illustrating another example of the optical element of the present invention.Figure 6 is a plan view of the optical element shown.Figure 6 is a conceptual diagram illustrating the operation of the optical element shown.Figure 6 is a conceptual diagram illustrating the operation of the optical element shown.Figures 2 and 6 conceptually illustrate an example of an exposure apparatus for exposing the alignment film of the diffraction element.This figure conceptually illustrates another example of the optical anisotropy layer of the optical element of the present invention.This figure conceptually shows an example of an exposure apparatus for exposing an alignment film that forms the optical anisotropy layer shown in Figure 11.This is a conceptual diagram illustrating AR glasses using the light guide element of the present invention, which comprises the optical elements shown in Figure 1. The present invention will be described in detail below. The following description of the constituent elements may be based on typical embodiments of the present invention, but the present invention is not limited to such embodiments. In this specification, a numerical range represented by "~" means a range that includes the numbers written before and after "~" as the lower and upper limits, respectively. In this specification, each component may be represented by a single substance or by a combination of two or more substances. When two or more substances are used in combination for each component, the content of that component refers to the total content of the combined substances unless otherwise specified. In this specification, "(meth)acrylate" means "either acrylate or methacrylate, or both." [Liquid crystal composition] The present invention relates to a liquid crystal composition containing a liquid crystal compound, comprising a rod-shaped liquid crystal compound and a disc-shaped liquid crystal compound, wherein the ratio of the elastic constant of twist (K22) to the elastic constant of spray (K11) satisfies 0.7 ≤ K22/K11. In the present invention, the ratio (K22/K11) of the elastic constant of the twist (K22) to the elastic constant of the spray (K11) is preferably 0.7 to 2.0, and more preferably 0.75 to 1.5. Here, the elastic constant of the liquid crystal composition is the elastic constant of the liquid crystal composition excluding the solvent. Furthermore, the ratio (K22