JP2016126288A - Liquid crystal cell, light control material, and laminated glass - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to easily drive a liquid crystal layer and reduce defects compared with a prior art.SOLUTION: There is provided a liquid crystal cell 15 that has a laminated structure including a first liquid crystal alignment film 12, a liquid crystal layer 14A composed of liquid crystals having positive dielectric anisotropy, and a second liquid crystal alignment film 13, where the first and second liquid crystal alignment films 12 and 13 have transparent electrodes 22A and 22B and alignment layers 23A and 23B provided respectively on transparent film materials 21A and 21B. The liquid crystal layer 14A has liquid crystals horizontally aligned while a voltage is not applied to between the transparent electrodes 22A and 22B of the first and second liquid crystal alignment films 12 and 13, and the liquid crystals are vertically aligned while a voltage of 6.5 V or more is applied.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a light control material that can be used for, for example, an electronic blind that is attached to a window to control the transmission of extraneous light, a liquid crystal cell used for the light control material, and a laminated glass using the light control material.

  Conventionally, various devices relating to a light control material that can be used for, for example, an electronic blind that is attached to a window to control the transmission of external light have been proposed (Patent Documents 1 and 2). One of such light control materials uses liquid crystal. In the light control material using this liquid crystal, a liquid crystal material is produced by sandwiching a liquid crystal material with a transparent film material on which a transparent electrode is produced, and this liquid crystal cell is produced by sandwiching it with a linear polarizing plate. As a result, in this light control material, the orientation of the liquid crystal is changed by changing the electric field applied to the liquid crystal, thereby blocking or transmitting the extraneous light, and further changing the amount of transmitted light. To control.

  In such a light control material, it is considered that a spacer is provided on the transparent film material constituting the liquid crystal cell, and the liquid crystal layer is held at a desired thickness by the spacer. Moreover, after producing a spacer, it is possible to produce an alignment layer by producing a thin film such as polyimide and performing a rubbing treatment, and restricting the alignment of the liquid crystal material by this alignment layer.

  By the way, it is conceivable that this type of light control material is used for laminated glass and used for a vehicle window. In such a use, it is desired that it can be driven easily.

JP 03-47392 A Japanese Patent Laid-Open No. 08-184273

  The present invention has been made in view of such a situation, and an object thereof is to enable simple driving.

  The present inventor has intensively studied to solve the above-described problems, and has led to the idea that the alignment layer is formed of a photo-alignment layer, and the liquid crystal material is driven to switch between vertical alignment and horizontal alignment. The present invention has been completed.

  Specifically, the present invention provides the following.

(1) A liquid crystal cell having a laminated structure of a first liquid crystal alignment layer film, a liquid crystal layer having liquid crystal having positive dielectric anisotropy, and a second liquid crystal alignment layer film,
The first and second liquid crystal alignment layer films are:
A transparent electrode and an alignment layer are provided on the transparent film material,
The liquid crystal layer is
The liquid crystal is horizontally aligned with no voltage applied between the transparent electrodes of the first and second liquid crystal alignment layer films, and the liquid crystal is vertically aligned with a voltage of 6.5 V or more applied. Liquid crystal cell.

  According to (1), the horizontal alignment and the vertical alignment can be switched by changing the applied voltage between the transparent electrodes. The applied voltage used for this switching can be a relatively high voltage. Thus, the battery can be easily driven, for example, by directly connecting a battery power source.

(2) In (1),
A liquid crystal cell for driving the liquid crystal layer by applying a voltage of 6.5 V or more between the transparent electrodes of the first and second liquid crystal alignment layer films.

  According to (2), it is possible to drive the liquid crystal layer while ensuring vertical alignment.

  (3) The liquid crystal cell in which the alignment layer is a photo-alignment layer in (1) or (2).

  According to (3), by aligning the liquid crystal with the photo-alignment layer, generation of dust in the rubbing treatment can be effectively avoided, and defects can be reduced as compared with the conventional case.

(4) In any one of (1), (2) and (3),
The liquid crystal layer is
A liquid crystal cell having a thickness that imparts a phase difference of ½ wavelength to transmitted light in a state where the liquid crystal is horizontally aligned.

  According to (4), the incident light by the linearly polarized light can be emitted by the circularly polarized light, whereby the utilization efficiency of the incident light can be improved in the light control material.

(5) A light control material in which the liquid crystal cell according to any one of (1), (2), (3), and (4) is sandwiched between linear polarizing plates,
The linear polarizing plate is
Cross Nicol arrangement,
The light control material arrange | positioned so that the absorption-axis direction may make the angle of 40 degree | times or more and 50 degrees or less with respect to the orientation direction which concerns on the horizontal orientation of the said liquid crystal in the said liquid-crystal layer.

  According to (5), it is possible to provide a light control material that can be easily driven using the liquid crystal cell according to any one of (1), (2), (3), and (4). it can.

  (6) A laminated glass in which the light control material according to (5) is sandwiched between plate glasses and integrated.

  According to (6), it is possible to easily drive, and furthermore, it is possible to produce a laminated glass with a light control material that has fewer defects than conventional ones.

  ADVANTAGE OF THE INVENTION According to this invention, it can drive easily regarding the light control material which can be utilized for an electronic blind etc., the liquid crystal cell used for this light control material, and the laminated glass using this light control material.

It is a figure which shows the laminated glass which concerns on 1st Embodiment of this invention. It is a figure which shows the light control material applied to the laminated glass of FIG. It is a figure where it uses for description of each part which concerns on the light modulation material of FIG. It is a figure where it uses for description of the light control material of FIG. It is a flowchart which shows the manufacturing process of the liquid crystal cell applied to the light modulation material of FIG. It is a chart which shows the Example of the light modulation material of FIG.

[First Embodiment]
[Laminated glass]
FIG. 1 is a cross-sectional view showing a laminated glass according to the first embodiment of the present invention. The laminated glass 1 is a laminated glass used for a vehicle window, for example, and is configured by sandwiching a light control material 10 between plate glasses 2 and 3 through intermediate layers 4 and 5, respectively. Here, as the glass plates 2 and 3, various materials applicable to this type of laminated glass can be widely applied. The intermediate layers 4 and 5 are configured to function as an adhesive layer between the light control material 10 and the plate glasses 2 and 3, and various configurations applied to this type of laminated glass can be widely applied. You may make it provide the function as a shielding material.

  In the laminated glass 1, the intermediate layers 4 and 5 are provided on the plate glasses 2 and 3, respectively, and laminated with the light control material 10, and then heated and pressurized, whereby the plate glasses 2 and 3 and the adjustment of the glass plates 2 and 3 are performed. The optical material 10 is integrated, and the whole is formed into a desired curved surface shape. Thereby, the laminated glass 1 is produced so that it can be applied to the rear window of a vehicle, for example, and it is comprised so that transmitted light can be controlled by the light control material 10. FIG. In addition, the manufacturing process of the laminated glass 1 by this has the lamination process which laminates | stacks the plate glass 2 and 3 which each provided the intermediate | middle layers 4 and 5 with the light control material 10, and the heating pressurization process which heats and pressurizes the laminated body by a lamination process. Prepare.

[Light control material]
FIG. 2 is a cross-sectional view showing the light control material. The light control material 10 is formed in a film shape and is used by being attached to, for example, a portion where light control is intended, in addition to the case where it is used for laminated glass. In addition, when sticking to the site | part which aims at such light control, it is the case where it arrange | positions, for example in the window glass of a building, a showcase, an indoor transparent partition etc., and switches transparent and opaque.

  This light control material 10 is a light control material that controls transmitted light using liquid crystal, and a liquid crystal cell 15 is produced by sandwiching a liquid crystal layer 14A of a liquid crystal material 14 between liquid crystal alignment layer films 12 and 13, The liquid crystal cell 15 is formed by being sandwiched between linearly polarizing plates 16 and 17. The light modulating material 10 is provided with a spacer 24 on the liquid crystal alignment layer films 12 and 13 for keeping the thickness of the liquid crystal layer 14A constant. The linear polarizing plates 16 and 17 are respectively provided with retardation films 18 and 19 for optical compensation on the liquid crystal cell 15 side. The liquid crystal alignment layer films 12 and 13 are formed by sequentially forming transparent electrodes 22A and 22B and alignment layers 23A and 23B on film materials 21A and 21B, respectively. The retardation films 18 and 19 may be omitted as necessary.

  As shown in FIG. 3, in the light control material 10, the linearly polarizing plates 16 and 17 are provided so as to sandwich the liquid crystal cell 15 in a crossed Nicols arrangement in which the absorption axis directions L <b> 16 and L <b> 17 are orthogonal. Further, in the light modulating material 10, the absorption axis directions L16 and L17 are set in a direction along the sides of the linearly polarizing plates 16 and 17 having a rectangular shape. Configured to reduce.

  In the liquid crystal cell 15, the orientation directions L23A and L23B due to the orientation layers 23A and 23B are parallel to each other, and the orientation directions L23A and L23B are predetermined with respect to the absorption axis direction L16 of the linear polarizing plate 16. It is configured to tilt by an angle θ. In addition, the inclination θ is set to an angle of 40 degrees or more and 50 degrees or less, which is approximately 45 degrees.

  As a result, as shown in FIG. 4A, in the liquid crystal cell 15, the liquid crystal material 14 is horizontally aligned (homogeneous alignment) in a state where no voltage is applied to the transparent electrodes 22A and 22B. The liquid crystal layer 14A is configured to exhibit optical anisotropy. In addition, the orientation direction of the liquid crystal, which is the slow axis direction related to the optical anisotropy, is set to be at an angle of substantially 45 degrees with respect to the polarization plane of the incident light by the linearly polarized light from the linear polarizing plate 16 or 17. Is done.

  The liquid crystal cell 15 provides optical anisotropy in this way, and imparts a phase difference of approximately ½ wavelength to the incident light from the linearly polarized light from the linearly polarizing plate 16 or 17. The thickness d is set so that incident light by linearly polarized light from 16 or 17 is emitted by circularly polarized light. More specifically, the thickness d is set so that Δn × d = 550 nm / 2 where Δn is the difference in refractive index between the slow axis direction and the fast axis direction in the liquid crystal layer 14A. Here, 550 nm is the central wavelength in the visible light region.

  As a result, as shown in FIG. 4A, the light control material 10 converts the extraneous light into linearly polarized light by the linearly polarizing plate 16 or 17 and enters the liquid crystal layer 14A, and converts it into circularly polarized light by the liquid crystal layer 14A. To do. Further, the light emitted from the liquid crystal layer 14A by the circularly polarized light is emitted by the linearly polarized light through the linearly polarizing plate 17 or 16, and the external light is transmitted through normally white.

  In addition, by configuring the liquid crystal layer 14A by horizontal alignment in this way, the light control material 10 can cause the liquid crystal material to be aligned vertically (homeo) by applying a voltage between the transparent electrodes 22A and 22B, as shown in FIG. In this case, the optical anisotropy in the in-plane direction is lost. Accordingly, in this case, incident light by linearly polarized light from the linearly polarizing plate 16 or 17 is transmitted through the liquid crystal layer 14A while being linearly polarized without any phase difference, and is blocked by the linearly polarizing plate 17 or 16. It will be.

  Thus, when the liquid crystal layer is driven by switching between horizontal alignment and vertical alignment as described above, the liquid crystal layer is driven by a TN (Twisted Nematic) method, an IPS (In-Place-Switching) method, or the like. Thus, it is necessary to apply a large voltage between the transparent electrodes 22A and 22B. However, in a vehicle that is an environment to which a light control material is applied, the power supply voltage of the battery is 12 V, and when the liquid crystal layer is driven by switching between horizontal alignment and vertical alignment as in this embodiment, As a result of the experiment, the liquid crystal layer can be sufficiently driven by applying a voltage of 6.5 V or more. Thereby, in this embodiment, the power source (12V or 24V) of the vehicle battery can be directly applied to the transparent electrodes 22A and 22B to drive the light control member 10, and the drive can be simplified accordingly. Can do. In an environment where a light control material other than such a vehicle is used, the driving voltage used for switching between the horizontal alignment and the vertical alignment can be obtained with a relatively simple configuration. Thus, it can be driven easily.

  Further, in such vertical alignment, the vertical alignment of the liquid crystal can be sufficiently maintained even if the applied voltage between the transparent electrodes changes to some extent, so that it can be driven easily. In this way, in this embodiment, the light control member 10 is switched to the vertical orientation by applying a voltage of 12 or 24 V by being driven by a power supply voltage from a battery of the vehicle on which it is mounted. The vertical alignment may be switched by a voltage of 6.5 V or more.

  For example, when the light control material 10 is used by being attached to, for example, a window glass of a building, a showcase, an indoor transparent partition, or the like, the linearly polarizing plate 16 and / or 17 on the side opposite to the liquid crystal cell 15 is used. A protective layer such as a hard coat layer is provided on the surface.

  Here, various transparent film materials having flexibility applicable to the liquid crystal cell 15 can be applied to the film materials 21A and 21B. In this embodiment, the film materials 21A and 21B are made of polycarbonate having hard coat layers formed on both sides. Film material is applied. The transparent electrodes 22A and 22B can apply a substantially uniform electric field to the liquid crystal layer 14A, and various configurations that are perceived as transparent can be applied. In this embodiment, the transparent electrodes 22A and 22B are made of ITO, which is a transparent electrode material. A transparent conductive film is formed on the entire surface of the film materials 21A and 21B.

  The alignment layers 23A and 23B are formed of a so-called photo-alignment layer. More specifically, the alignment layers 23 </ b> A and 23 </ b> B are prepared by irradiating the photo-alignment material film with ultraviolet rays by linearly polarized light after the photo-alignment material film is formed of the photo-alignment material. Here, the ultraviolet rays applied to the photo-alignment material film are set so that the direction of polarization is the direction of the orientation ability described above with reference to FIG. 3, and thereby the orientation ability is developed by applying the photo-alignment technique. . By applying the photo-alignment layer to the alignment layer in this manner, the alignment layer can be produced without rubbing treatment, and as a result, generation of dust due to rubbing treatment is completely prevented and the occurrence of defects is reduced. be able to.

  In addition, although various materials to which the photo-alignment technique can be applied can be applied as the photo-alignment material, in this embodiment, the alignment is not changed by ultraviolet irradiation after the alignment, for example, a light dimerization type. Use materials. As for this light dimerization type material, “M. Schadt, K. Schmitt, V. Kozinkov and V. Chigrinov: Jpn. J. Appl. Phys., 31, 2155 (1992)”, “M. Schadt, H Seiberle and A. Schuster: Nature, 381, 212 (1996) ".

  As the liquid crystal material 14, various liquid crystal materials having a positive dielectric anisotropy applicable to this type of liquid crystal layer can be widely applied.

  Although various resin materials can be widely applied to the spacer 24, in this embodiment, the spacer 24 is made of a transparent resin using a photoresist. In the liquid crystal cell 15, a sealing agent 25 is arranged in a frame shape surrounding the liquid crystal layer 14A, the leakage of the liquid crystal material 14 is prevented by the sealing agent 25, and the liquid crystal alignment layer films 12 and 13 are held together. The Here, as the sealing agent 25, various materials capable of integrally holding the liquid crystal alignment layer films 12 and 13 can be applied while preventing leakage of the liquid crystal material. In this embodiment, for example, an epoxy resin agent is used. A thermosetting resin is applied.

〔Manufacturing process〕
FIG. 5 is a flowchart showing the manufacturing process of the liquid crystal cell 15. In the liquid crystal cell 15, transparent electrodes 22A and 22B made of ITO are formed on the film materials 21A and 21B in the transparent electrode manufacturing step SP1. In the subsequent spacer manufacturing step SP3, the coating liquid (photoresist) according to the spacer 24 is applied, followed by drying, exposure and development, whereby the spacer 24 is manufactured. In addition, when producing the spacer 24 only in one of the films 12 and 13 for liquid crystal aligning layers, spacer production process SP3 is abbreviate | omitted about the film material of the side which does not produce the spacer 24.

  Subsequently, in the alignment layer manufacturing step SP4, the liquid crystal cell 15 is prepared by applying a coating liquid made of a photo-alignment material and drying it to form a photo-alignment material film. , The alignment layers 23A and 23B are produced.

  Subsequently, in the sealing step SP5, the liquid crystal cell 15 is provided with a sealing agent 25 in a frame shape surrounding the liquid crystal layer 14A on one of the liquid crystal alignment layer films 12 and 13, and a portion surrounded by the sealing agent 25 A liquid crystal material 14 is disposed in the central portion of the. In this state, the liquid crystal cell 15 is laminated so that the other of the liquid crystal alignment layer films 12 and 13 is brought and the liquid crystal alignment layer films 12 and 13 sandwich the liquid crystal material. The sealant is cured. Thereby, the liquid crystal material 15 is sealed to produce the liquid crystal cell 15.

  The liquid crystal cell 15 is provided in the form of a long film in which the film materials 21A and 21B are wound on a roll, and all of these processes SP2 to SP6 or a part of these processes SP2 to SP6 are formed from the roll. 21A and 21B are sequentially executed while being pulled out and conveyed. In this way, each step of the liquid crystal cell 15 is executed by processing a single wafer from an intermediate step as necessary.

〔Experimental result〕
FIG. 6 is a chart showing experimental results. Examples 1 and 2 are examples of the light control material according to the above-described embodiment, and are examples in which the horizontal alignment is switched to the vertical alignment by applying a drive voltage (12 V, 6.5 V). The polarizing plate absorption axis direction is the absorption axis direction of the linear polarizing plates 16 and 17, and the longitudinal direction of the rectangular linear polarizing plate is represented as 0 degree. The cell gap is the thickness of the liquid crystal layer 14A. In Examples 1 and 2, no defects such as generation of defects were observed in 5 sets or more out of 10 sets.

  Comparative Example 1 is an example in which the drive voltage is lowered to 5 V. In this case, reverse tilt occurs in 5 or more sets of 10 sets, thereby blocking light due to in-plane anisotropy due to this reverse tilt. Light and dark unevenness was observed. In Comparative Example 2, the absorption axis directions of the linear polarizing plates above and below the liquid crystal cell are set to 45 degrees and 135 degrees, and the direction in which the alignment ability is expressed in the alignment layer is set to the absorption axis direction of the nearest linear polarizing plate. In this case, the liquid crystal layer is driven by the (Twisted Nematic) method. In Comparative Example 2, the cell gap was 6 μm and the drive voltage was 5V. Also in Comparative Example 2, occurrence of reverse tilt was confirmed in 5 or more sets out of 10 sets. Thus, it was found that the driving voltage of the liquid crystal layer needs to be 6.5 V or more.

[Other Embodiments]
As mentioned above, although the specific structure suitable for implementation of this invention was explained in full detail, this invention can be variously changed in the range which does not deviate from the meaning of this invention.

  That is, in the above-described embodiment, the case where the alignment layer is formed using the photo-alignment layer has been described. However, the present invention is not limited to this, and the alignment layer may be manufactured using a rubbing process. It may be produced by mold processing.

DESCRIPTION OF SYMBOLS 1 Laminated glass 2, 3 Plate glass 4, 5 Intermediate layer 10 Light control material 12, 13 Film 14 for liquid crystal aligning layers Liquid crystal material 14A Liquid crystal layer 15 Liquid crystal cell 16, 17 Linearly-polarizing plate 18, 19 Phase difference film 21A, 21B Film material 22A, 22B Transparent electrodes 23A, 23B Alignment layer 24 Spacer 25 Sealing agent

Claims (6)

A liquid crystal cell having a laminated structure of a first liquid crystal alignment layer film, a liquid crystal layer having liquid crystal having positive dielectric anisotropy, and a second liquid crystal alignment layer film,
The first and second liquid crystal alignment layer films are:
A transparent electrode and an alignment layer are provided on the transparent film material,
The liquid crystal layer is
The liquid crystal is horizontally aligned with no voltage applied between the transparent electrodes of the first and second liquid crystal alignment layer films, and the liquid crystal is vertically aligned with a voltage of 6.5 V or more applied. Liquid crystal cell. The liquid crystal cell according to claim 1, wherein a voltage of 6.5 V or more is applied between the transparent electrodes of the first and second liquid crystal alignment layer films to drive the liquid crystal layer. The liquid crystal cell according to claim 1, wherein the alignment layer is a photo-alignment layer. The liquid crystal layer is
The liquid crystal cell according to claim 1, wherein the liquid crystal cell has a thickness that imparts a phase difference of ½ wavelength to transmitted light in a state where the liquid crystal is horizontally aligned. A light control material in which the liquid crystal cell according to any one of claims 1, 2, 3, and 4 is sandwiched between linear polarizing plates,
The linear polarizing plate is
Cross Nicol arrangement,
The light control material arrange | positioned so that an absorption-axis direction may make the angle of 40 degree | times or more and 50 degrees or less with respect to the orientation direction which concerns on the horizontal orientation of the said liquid crystal in the said liquid-crystal layer. A laminated glass in which the light control material according to claim 5 is sandwiched and integrated by a plate glass.

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