KR102486855B1 - Optical Device - Google Patents

Abstract

This application relates to an optical device. The present application provides an optical device capable of varying transmittance, and such an optical device includes eyewear such as sunglasses, eyewear for AR (Argumented Reality) or VR (Virtual Reality), outer walls of buildings or cables for vehicles. It can be used for various purposes such as loops.

Description

Optical Device {Optical Device}

This application relates to an optical device.

Various optical devices designed to vary transmittance using a liquid crystal compound are known. Such a variable transmittance device is applied to various applications including eyewear such as sunglasses or glasses, an outer wall of a building, or a sunroof of a vehicle.

This application provides an optical device.

Among the physical properties mentioned in this specification, if the measurement temperature affects the result, the corresponding physical property is a physical property measured at room temperature unless otherwise specified. The term room temperature is a natural temperature that is not heated or cooled, and is usually a temperature in the range of about 10 ° C to 30 ° C or about 23 ° C or about 25 ° C. In addition, unless specifically stated otherwise in the present specification, the unit of temperature is °C.

Among the physical properties mentioned in this specification, when the measured pressure affects the result, the corresponding physical property is a physical property measured at normal pressure unless otherwise specified. The term normal pressure refers to a natural temperature that is not pressurized or reduced, and usually refers to about 1 atm.

The present application relates to an optical device capable of adjusting transmittance, for example, an optical device capable of switching between at least a transmission mode and a blocking mode. The transmissive mode is a state in which the optical device exhibits a relatively high transmittance, and the blocking mode is a state in which the optical device exhibits a relatively low transmittance.

In one example, the optical device has a transmittance of about 10% or more, about 15% or more, about 20% or more, about 25% or more, about 30% or more, about 35% or more, about 40% or more, It may be about 45% or more or about 50% or more. In addition, the optical device may have a transmittance of about 20% or less, about 15% or less, about 10% or less, or about 5% or less in the blocking mode.

The upper and lower limits are not particularly limited because the higher the transmittance in the transmission mode and the lower the transmittance in the blocking mode, the more advantageous the value. In one example, the upper limit of the transmittance in the transmission mode may be about 100, about 95%, about 90%, about 85%, about 80%, about 75%, about 70%, about 65%, or about 60%. The lower limit of the transmittance in the blocking mode is about 0%, about 1%, about 2%, about 3%, about 4%, about 5%, about 6%, about 7%, about 8%, about 9% or about may be 10%.

The transmittance may be a straight light transmittance. The term straight light transmittance may be a ratio of light incident through the optical device in a predetermined direction to light transmitted through the optical device in the same direction as the incident direction (straight light). In one example, the transmittance may be a result of measuring light incident in a direction parallel to the surface normal of the optical device (normal light transmittance).

The light whose transmittance is controlled in the optical device of the present application may be ultraviolet rays in the UV-A region, visible light, or near infrared rays. According to commonly used definitions, ultraviolet light in the UV-A region is used to mean radiation having a wavelength within the range of 320 nm to 380 nm, and visible light means radiation having a wavelength within the range of 380 nm to 780 nm. Infrared is used to mean radiation having a wavelength within the range of 780 nm to 2000 nm.

The optical device of the present application is designed to be able to switch between at least the transmission mode and blocking mode. If necessary, the optical device may exhibit other modes other than the transmission and blocking modes, for example, any transmittance between the transmittance of the transmission and blocking modes, or may exhibit scattering, reflection or refraction or other polarization characteristics. It can be designed to implement a third mode as well.

Switching between such modes can be achieved by including an active liquid crystal film element and/or a polarizing film in the optical device. In the above, the active liquid crystal film element is a liquid crystal film element capable of switching between alignment states of at least two or more optical axes, for example, a first alignment state and a second alignment state. In the above, the optical axis may mean a long axis direction when the liquid crystal compound included in the liquid crystal film device is rod-shaped, and may mean a normal direction of the disk plane when the liquid crystal compound is in a discotic shape. In addition, when the liquid crystal film element includes a plurality of liquid crystal compounds having different optical axes in different directions in a certain alignment state, the optical axis of the liquid crystal film element may be defined as an average optical axis. It can mean vector sum.

The alignment state in an active liquid crystal film device can be changed by application of energy, for example, application of voltage. For example, the liquid crystal film element may have one alignment state among the first and second alignment states in a state in which voltage is not applied, and may be switched to another alignment state when voltage is applied.

The blocking mode may be implemented in any one of the first and second alignment states, and the transmission mode may be implemented in another orientation state. For convenience, in this specification, it is described that the blocking mode is implemented in the first state.

The liquid crystal film element may include a liquid crystal layer containing at least a liquid crystal compound. In the liquid crystal layer, the liquid crystal compound may be included in the liquid crystal layer such that an alignment state thereof may be switched depending on whether external energy is applied and/or whether external energy is applied. The liquid crystal layer may be a liquid crystal layer including the liquid crystal compound or an anisotropic dye together with the liquid crystal compound.

The liquid crystal layer including the liquid crystal compound and the anisotropic dye is a liquid crystal layer using a so-called guest host effect, and the anisotropic dye is aligned according to the orientation direction of the liquid crystal compound (hereinafter referred to as a liquid crystal host). . Alignment direction of the liquid crystal host can be adjusted according to whether the aforementioned external energy is applied.

The type of liquid crystal host used in the liquid crystal layer is not particularly limited, and a general type of liquid crystal compound applied to implement a guest host effect may be used.

For example, as the liquid crystal host, a smectic liquid crystal compound, a nematic liquid crystal compound, or a cholesteric liquid crystal compound may be used. In general, a nematic liquid crystal compound can be used. The term nematic liquid crystal compound refers to a liquid crystal compound that has no regularity in the location of liquid crystal molecules, but can be arranged in an orderly manner in the direction of the molecular axis, and these liquid crystal compounds are rod-shaped or discotic-shaped. can be

Such a nematic liquid crystal compound may have, for example, about 40°C or more, about 50°C or more, about 60°C or more, about 70°C or more, about 80°C or more, about 90°C or more, about 100°C or more, or about 110°C or more. One having a clearing point or a phase transition point within the above range, that is, a phase transition point from a nematic phase to an isotropic phase may be selected. In one example, the clearing point or phase transition point may be about 160°C or less, about 150°C or less, or about 140°C or less.

The liquid crystal compound may have a negative or positive dielectric anisotropy. The absolute value of the dielectric anisotropy may be appropriately selected in consideration of the purpose. For example, the dielectric constant anisotropy may be greater than 3 or greater than 7, or less than -2 or less than -3.

The liquid crystal compound may also have an optical anisotropy (Δn) of about 0.01 or more or about 0.04 or more. Optical anisotropy of the liquid crystal compound may be about 0.3 or less or about 0.27 or less in another example.

Liquid crystal compounds that can be used as the liquid crystal host of the guest host liquid crystal layer are known to experts in the art and can be freely selected from them.

The liquid crystal layer includes an anisotropic dye together with the liquid crystal host. The term "dye" may refer to a material capable of intensively absorbing and/or transforming at least a portion or the entire range of light in the visible light region, for example, a wavelength range of 380 nm to 780 nm, and the term "anisotropic Dye” may refer to a material capable of anisotropic absorption of light in at least a part or the entire range of the visible light region.

As the anisotropic dye, for example, a known dye known to have a characteristic that can be aligned according to the alignment state of the liquid crystal host may be selected and used. For example, as the anisotropic dye, an azo dye or an anthraquinone dye may be used, and the liquid crystal layer may contain one or more dyes in order to achieve light absorption in a wide wavelength range.

The dichroic ratio of the anisotropic dye may be appropriately selected in consideration of the purpose. For example, the anisotropic dye may have a dichroic ratio of 5 or more to 20 or less. The term "dichroic ratio" may mean, for example, in the case of a p-type dye, a value obtained by dividing absorption of polarized light parallel to the major axis direction of the dye by absorption of polarized light parallel to the direction perpendicular to the major axis direction. The anisotropic dye may have the dichroic ratio in at least some wavelengths or any one wavelength or the entire range within a wavelength range of the visible light region, for example, within a wavelength range of about 380 nm to 780 nm or about 400 nm to 700 nm. there is.

The content of the anisotropic dye in the liquid crystal layer may be appropriately selected in consideration of the purpose. For example, the content of the anisotropic dye based on the total weight of the liquid crystal host and the anisotropic dye may be selected within the range of 0.1 to 10% by weight. The ratio of the anisotropic dye may be changed in consideration of the desired transmittance and the solubility of the anisotropic dye in the liquid crystal host.

The liquid crystal layer basically includes the liquid crystal host and the anisotropic dye, and may further include other optional additives according to known forms, if necessary. Examples of additives include, but are not limited to, chiral dopants or stabilizers.

The liquid crystal layer may have an anisotropy (R) of about 0.5 or more. The anisotropy (R) is the absorbance of light polarized parallel to the alignment direction of the liquid crystal host (E(p)) and the absorbance of light polarized perpendicular to the alignment direction of the liquid crystal host (E(s)) It is measured according to the following formula.

<Anisotropy formula>

Anisotropy (R) = [E(p)-E(s)] / [E(p) + 2*E(s)].

The criterion used above is another identical device containing no dye in the liquid crystal layer.

Specifically, the anisotropy (R) is obtained from the absorbance value (E(p)) of the liquid crystal layer in which the dye molecules are horizontally aligned and the absorbance value (E(s)) of the same liquid crystal layer in which the dye molecules are vertically aligned. can be measured The absorbance is measured by comparison with a liquid crystal layer that contains no dye but has an otherwise identical composition. This measurement is performed using a polarized light beam in which the vibrating plane oscillates in a direction parallel to the orientation direction (E(p)) in one case and in a direction perpendicular to the orientation direction (E(s)) in subsequent measurements. It can be. The liquid crystal layer is not switched or rotated during measurement, and therefore, the measurement of E(p) and E(s) can be performed by rotating the vibration plane of polarized incident light.

An example of a detailed procedure is as described below. Spectra for measuring E(p) and E(s) can be recorded using a spectrometer such as a Perkin Elmer Lambda 1050 UV spectrometer. The spectrometer is equipped with Glan-Thompson polarisers for the wavelength range from 250 nm to 2500 nm in both the measurement and reference beams. The two polarizing films are controlled by a stepping motor and oriented in the same direction. A change in the direction of the polarizing film, for example, from 0 degrees to 90 degrees, is always performed synchronously and in the same direction with respect to the measurement beam and the reference beam. The orientation of the individual polarizers was studied at the University of Wurzburg, T. It can be measured using the method described in T. Karstens' 1973 thesis.

In this method, the polarizing film is rotated stepwise by 5 degrees relative to the oriented dichroic sample, and the absorbance is recorded at a fixed wavelength, for example in the region of maximum absorption. A new baseline zero line is run for each polarizer position. For the measurement of the two dichroic spectra E(p) and E(s), an antiparallel-rubbed test cell coated with polyimide AL-1054 from JSR is placed in both the measurement and reference beams. The two test cells can be selected with the same layer thickness. A test cell containing a pure host (liquid crystal compound) is placed within the reference beam. A test cell containing a solution of dye in liquid crystal is placed within the measuring beam. Two test cells for the measurement beam and the reference beam are installed in the ray path in the same orientation direction. In order to ensure the maximum possible precision of the spectrometer, E(p) must be in the range of its maximum absorption wavelength, for example in the range of wavelengths from 0.5 to 1.5. This corresponds to a transmittance of 30% to 5%. This is set by correspondingly adjusting the layer thickness and/or the dye concentration.

The degree of anisotropy (R) is given by E(p) and E(s) according to the above equation as shown in "Polarized Light in Optics and Spectroscopy", D. S. Kliger et al., Academic Press, 1990. can be calculated from the measured values for

The anisotropy (R) may be about 0.55 or more, 0.6 or more, or 0.65 or more in another example. The anisotropy (R) may be, for example, about 0.9 or less, about 0.85 or less, about 0.8 or less, about 0.75 or less, or about 0.7 or less.

Such anisotropy (R) can be achieved by controlling the type of liquid crystal layer, for example, the type of liquid crystal compound (host), the type and ratio of anisotropic dye, and the thickness of the liquid crystal layer.

Through the anisotropy (R) within the above range, it is possible to provide an optical device in which a contrast ratio is increased due to a large difference in transmittance between a transmissive state and a blocked state while using a lower energy.

The thickness of the liquid crystal layer may be appropriately selected in consideration of a purpose, for example, a desired anisotropy. In one example, the thickness of the liquid crystal layer is about 0.01 μm or more, 0.05 μm or more, 0.1 μm or more, 0.5 μm or more, 1 μm or more, 1.5 μm or more, 2 μm or more, 2.5 μm or more, 3 μm or more, 3.5 μm or more, or 4 μm or more. , 4.5 μm or more, 5 μm or more, 5.5 μm or more, 6 μm or more, 6.5 μm or more, 7 μm or more, 7.5 μm or more, 8 μm or more, 8.5 μm or more, 9 μm or more, or 9.5 μm or more. By controlling the thickness in this way, an optical device having a large difference between the transmittance in the transmissive state and the transmittance in the blocking state, that is, a device having a large contrast ratio, can be implemented. The thickness is not particularly limited since a higher contrast ratio can be implemented as the thickness is thicker, but may be generally about 30 μm or less, 25 μm or less, 20 μm or less, or 15 μm or less.

The active liquid crystal layer or a liquid crystal film device including the same may switch between a first alignment state and a second alignment state different from the first alignment state. The switching may be controlled through application of external energy such as voltage. For example, one of the first and second alignment states may be maintained in a state where no voltage is applied, and then switched to another alignment state by application of voltage.

The first and second alignment states, in one example, may be selected from horizontal alignment, vertical alignment, twisted nematic alignment, or cholesteric alignment, respectively. For example, in the blocking mode, the liquid crystal film element or liquid crystal layer is at least horizontally aligned, twisted nematic orientation, or cholesteric orientation, and in the transmissive mode, the liquid crystal film element or liquid crystal layer is vertically aligned or horizontally aligned in the blocking mode. It may be in a horizontal alignment state having an optical axis in a direction different from that of the optical axis. The liquid crystal film device may be a normally black mode device in which the blocking mode is implemented in a voltage-free state or a normally transparent mode in which the transparent mode is implemented in a voltage-free state.

A method for confirming in which direction an optical axis is formed in an alignment state of a liquid crystal layer or a liquid crystal film element is known. For example, the direction of the optical axis of the liquid crystal layer can be measured using another polarizer whose optical axis direction is known, which can be measured using a known measuring device, for example, a polarimeter such as Jascp's P-2000. can

A method of implementing a liquid crystal film device in a normal transmissive or blocking mode as described above by adjusting the dielectric anisotropy of the liquid crystal host and/or the alignment direction of an alignment film for orienting the liquid crystal host is known.

The liquid crystal film element may include two film substrates disposed opposite to each other and the active liquid crystal layer existing between the two film substrates.

In addition, the liquid crystal film device may include a spacer maintaining a distance between the two film substrates and/or attaching the film substrate while maintaining a distance between the two film substrates disposed opposite to each other, A sealant may be additionally included. A known material may be used as the spacer and/or sealant without particular limitation.

As the film substrate, for example, an inorganic film made of glass or the like or a plastic film can be used, and a plastic film is applied appropriately. That is, as will be described later, the optical device of the present application may include the active liquid crystal film element encapsulated between outer substrates having a curved shape. In this structure, it is effective to apply a plastic film. As the plastic film, a known film can be applied, and for example, a TAC (triacetyl cellulose) film; COP (cyclo olefin copolymer) films such as norbornene derivatives; Acrylic film such as poly(methyl methacrylate) (PMMA); polycarbonate (PC) film; polyethylene (PE) film; polypropylene (PP) film; polyvinyl alcohol (PVA) film; diacetyl cellulose (DAC) film; polyacrylate (Pac) film; Polyether sulfone (PES) film; polyetheretherketon (PEEK) film; polyphenylsulfone (PPS) film, polyetherimide (PEI) film; polyethylenemaphthatlate (PEN) film; polyethyleneterephtalate (PET) film; polyimide (PI) film; polysulfone (PSF) film; A PAR (polyarylate) film or a fluororesin film may be used, but is not limited thereto.. On the film substrate, if necessary, a coating layer of a silicon compound such as gold, silver, silicon dioxide or silicon monoxide, or a coating layer such as an antireflection layer may exist.

As the film substrate, a film having a retardation within a predetermined range may be used. In one example, the film substrate may have a frontal retardation of 100 nm or less. In another example, the front retardation is about 95 nm or less, about 90 nm or less, about 85 nm or less, about 80 nm or less, about 75 nm or less, about 70 nm or less, about 65 nm or less, about 60 nm or less, about 55 nm or less, about 50 nm or less, about 45 nm or less. , about 40 nm or less, about 35 nm or less, about 30 nm or less, about 25 nm or less, about 20 nm or less, about 15 nm or less, about 10 nm or less, about 5 nm or less, about 4 nm or less, about 3 nm or less, about 2 nm or less, about 1 nm or less or about 0.5 nm or less. In another example, the front retardation is about 0 nm or more, about 1 nm or more, about 2 nm or more, about 3 nm or more, about 4 nm or more, about 5 nm or more, about 6 nm or more, about 7 nm or more, about 8 nm or more, about 9 nm or more, or about 9.5 nm or more.

The absolute value of the retardation in the thickness direction of the film substrate may be, for example, 200 nm or less. In another example, the absolute value of the retardation in the thickness direction is 190 nm or less, 180 nm or less, 170 nm or less, 160 nm or less, 150 nm or less, 140 nm or less, 130 nm or less, 120 nm or less, 110 nm or less, 100 nm or less, 90 nm or less, 85 nm or less, 80 nm or less. , 70 nm or less, 60 nm or less, 50 nm or less, 40 nm or less, 30 nm or less, 20 nm or less, 10 nm or less, 5 nm or less, 4 nm or less, 3 nm or less, 2 nm or less, 1 nm or less, or 0.5 nm or less, 0 nm or more, 10 nm or more, 20 nm It may be 30 nm or more, 40 nm or more, 50 nm or more, 60 nm or more, 70 nm or more, or 75 nm or more. The thickness direction retardation may be a negative number or a positive number if the absolute value is within the above range, for example, it may be a negative number.

In the present specification, the front retardation (Rin) is a value calculated by Equation 2 below, and the thickness direction retardation (Rth) is a value calculated by Equation 3 below, unless otherwise specified, the reference wavelength of the front and thickness direction retardation. is about 550 nm.

[Equation 2]

Front phase difference (Rin) = d × (nx - ny)

[Formula 3]

Thickness direction phase difference (Rth) = d × (nz - ny)

In Equations 2 and 3, d is the thickness of the film substrate, nx is the refractive index in the slow axis direction of the film substrate, ny is the refractive index in the fast axis direction of the film substrate, and nz is the refractive index in the thickness direction of the film substrate.

When the film substrate is optically anisotropic, the angle formed by the slow axes of the film substrates disposed opposite to each other is, for example, within the range of about -10 degrees to 10 degrees, within the range of -7 degrees to 7 degrees, and -5 degrees to 5 degrees. degrees or within the range of -3 degrees to 3 degrees or approximately parallel.

In addition, the angle between the slow axis of the film substrate and the light absorption axis of the polarizing film described later is, for example, within the range of about -10 degrees to 10 degrees, within the range of -7 degrees to 7 degrees, and -5 degrees to 5 degrees. within the range or within the range of -3 degrees to 3 degrees or approximately parallel, or within the range of about 80 degrees to 100 degrees, within the range of about 83 degrees to 97 degrees, within the range of about 85 degrees to 95 degrees or within the range of about 87 degrees to It may be in the range of 92 degrees or approximately vertical.

Optically excellent and uniform transmission and blocking modes may be realized through the phase difference adjustment or the arrangement of the slow axis as described above.

The film substrate may have a thermal expansion coefficient of 100 ppm/K or less. The thermal expansion coefficient is, in another example, 95 ppm / K or less, 90 ppm / K or less, 85 ppm / K or less, 80 ppm / K or less, 75 ppm / K or less, 70 ppm / K or less, or 65 ppm / K or less, or 10 ppm / K or more, 20 ppm/K or more, 30 ppm/K or more, 40 ppm/K or more, 50 ppm/K or more, or 55 ppm/K or more. The coefficient of thermal expansion of the film substrate can be measured, for example, according to the rules of ASTM D696, and the coefficient of thermal expansion can be calculated by cutting the film in the form provided by the standard and measuring the change in length per unit temperature, It can be measured by a known method such as TMA (ThermoMechanic Analysis).

As the film substrate, a film substrate having an elongation at break of 90% or more can be used. The elongation at break is 95% or more, 100% or more, 105% or more, 110% or more, 115% or more, 120% or more, 125% or more, 130% or more, 135% or more, 140% or more, 145% or more, 150% 155% or more, 160% or more, 165% or more, 170% or more, or 175% or more, 1,000% or less, 900% or less, 800% or less, 700% or less, 600% or less, 500% or less, 400% It may be less than or equal to 300% or less than or equal to 200%. The elongation at break of a film substrate can be measured according to the ASTM D882 standard, cut the film into the shape provided by the standard, and use equipment that can measure the Stress-Strain curve (which can measure force and length at the same time). can be measured using

A more durable optical device can be provided by selecting the film substrate to have the above coefficient of thermal expansion and/or elongation at break.

The thickness of the film substrate as described above is not particularly limited, and may be, for example, within a range of about 50 μm to about 200 μm.

In a liquid crystal film device, a conductive layer and/or an alignment layer may be present on one surface of the film substrate, for example, on a surface facing the active liquid crystal layer.

The conductive layer present on the surface of the film substrate is a component for applying a voltage to the active liquid crystal layer, and a known conductive layer may be applied without particular limitation. As the conductive layer, for example, conductive polymers, conductive metals, conductive nanowires, or metal oxides such as indium tin oxide (ITO) may be applied. Examples of the conductive layer that can be applied in the present application are not limited to the above, and all types of conductive layers known to be applicable to liquid crystal film elements in this field can be used.

In one example, an alignment layer is present on the surface of the film substrate. For example, a conductive layer may be first formed on one surface of a film substrate, and an alignment layer may be formed thereon.

The alignment layer is a component for controlling alignment of liquid crystal compounds included in the active liquid crystal layer, and a known alignment layer may be applied. As an alignment layer known in the industry, there is a rubbing alignment layer or an optical alignment layer, and such an alignment layer may be used in the present application.

The alignment direction of the alignment layer may be controlled to achieve a desired alignment of the optical axis. For example, the orientation direction of the two alignment films formed on each side of two film substrates disposed opposite to each other is an angle within the range of about -10 degrees to 10 degrees, an angle within the range of -7 degrees to 7 degrees, -5 degrees to They may form an angle within the range of 5 degrees or within the range of -3 degrees to 3 degrees or be approximately parallel to each other. In another example, the orientation direction of the two alignment films is within an angle within the range of about 80 degrees to 100 degrees, an angle within the range of about 83 degrees to 97 degrees, an angle within the range of about 85 degrees to 95 degrees, or within the range of about 87 degrees to 92 degrees. They may be angled or approximately perpendicular to each other.

Since the direction of the optical axis of the active liquid crystal layer is determined according to the alignment direction, the alignment direction can be confirmed by checking the direction of the optical axis of the active liquid crystal layer.

The shape of the liquid crystal film element having the above structure is not particularly limited and may be determined according to the application of the optical device, and is generally in the form of a film or sheet.

The optical device may further include a polarizing film alone or together with the active liquid crystal film element. As the polarizing film, for example, an absorption type linear polarizing film, that is, a polarizing film having a light absorption axis formed in one direction and a light transmission axis formed substantially perpendicular thereto may be used.

The polarizing film has an average optical axis (optical axis) in the first alignment state when it is assumed that the polarizing film is applied together with the active liquid crystal film element and the blocking state is implemented in the first alignment state of the active liquid crystal layer of the film element. It is arranged in the optical device so that the angle formed by the vector of) and the light absorption axis of the polarizing film is 80 degrees to 100 degrees or 85 degrees to 95 degrees, or is approximately perpendicular, or is 35 degrees to 55 degrees or about 40 degrees. degrees to 50 degrees or approximately 45 degrees.

In addition, as described above, the orientation direction of the alignment films formed on each side of the two film substrates of the liquid crystal film elements disposed opposite to each other is an angle within the range of about -10 degrees to 10 degrees, an angle within the range of -7 degrees to 7 degrees, - When an angle within the range of 5 degrees to 5 degrees, or an angle within the range of -3 degrees to 3 degrees, or substantially parallel to each other, the angle between the alignment direction of any one of the two alignment films and the light absorption axis of the polarizing film is It may be 80 to 100 degrees or 85 to 95 degrees, or it may be approximately vertical.

In another example, the orientation direction of the two alignment films is within an angle within the range of about 80 degrees to 100 degrees, an angle within the range of about 83 degrees to 97 degrees, an angle within the range of about 85 degrees to 95 degrees, or within the range of about 87 degrees to 92 degrees. In the case of forming an angle or being substantially perpendicular to each other, the angle formed between the alignment direction of the alignment film disposed closer to the polarizing film among the two alignment films and the light absorption axis of the polarizing film is 80 to 100 degrees or 85 to 95 degrees. Or, it can be approximately vertical.

For example, in a state where the liquid crystal film element and the polarizing film are stacked with each other, an optical axis (average optical axis) of the liquid crystal film element in the first alignment direction and a light absorption axis of the polarizing film 20 are arranged in the above relationship. can

In one example, when the polarizing film is a polarizing coating layer described later, a structure in which the polarizing coating layer exists inside the liquid crystal film device as a so-called inner polarizing layer may be implemented. In this case, a structure in which the polarization coating layer is present between at least one of the film substrates of the liquid crystal film device and the active liquid crystal layer may be implemented. For example, the aforementioned conductive layer, the polarization coating layer 201, and the alignment layer may be sequentially formed on a film substrate.

The type of the polarizing film that can be applied in the optical device of the present application is not particularly limited. For example, as a polarizing film, a conventional material used in conventional LCDs, such as a poly(vinyl alcohol) (PVA) polarizing film, a lyotropic liquid cystal (LLC), or a reactive liquid crystal ( A polarizing film realized by a coating method, such as a polarizing coating layer containing reactive mesogen (RM) and a dichroic dye, may be used. In the present specification, the polarizing film implemented by the coating method as described above may be referred to as a polarizing coating layer. A known liquid crystal may be used as the lyotropic liquid crystal without particular limitation, and for example, a lyotropic liquid crystal capable of forming a lyotropic liquid crystal layer having a dichroic ratio of about 30 to 40 may be used. On the other hand, when the polarization coating layer includes a reactive mesogen (RM) and a dichroic dye, a linear dye or a discotic dye may be used as the dichroic dye. may be

The optical device of the present application may include only one active liquid crystal film element and polarizing film as described above, or may include two or more of any one of the active liquid crystal film element and polarizing film. Accordingly, in one example, the optical device may include only one active liquid crystal film element and may include only one polarizing film, but is not limited thereto.

The optical device may further include two outer substrates disposed opposite to each other. In this specification, for convenience, one of the two outer substrates may be referred to as a first outer substrate and the other may be referred to as a second outer substrate. It is not stipulating. The active liquid crystal film element and/or the polarizing film may be encapsulated between the two outer substrates. Such encapsulation may be achieved using an adhesive film as an encapsulant. In the above, that the active liquid crystal film element and/or the polarizing film is encapsulated with an encapsulant means a case in which the upper, lower, left and right front surfaces of the active liquid crystal film element and/or the polarizing film are surrounded by the encapsulant. However, as long as the top, bottom and left and right front surfaces of the active liquid crystal film element and/or polarizing film are surrounded by an encapsulant, the encapsulant and the top, bottom and left and right front surfaces of the active liquid crystal film element and/or polarizing film do not necessarily need to be in contact with each other. , another layer may be interposed therebetween. In addition, in the case of a device requiring application of external energy to change its state, such as an active liquid crystal film device, when a terminal portion for applying energy to the device is exposed to the outside of the encapsulant, it may also be included in the scope of the encapsulation. .

For example, as shown in FIG. 1, the active liquid crystal film element or polarizing film 200 is present between the two outer substrates 101 and 102 disposed opposite to each other, and the upper, lower, left and right front surfaces thereof are covered with the encapsulant. (300) may surround. When an active liquid crystal film element is encapsulated, as shown in FIG. 2 , the active liquid crystal includes two opposite film substrates 201 and 202 and a sealant 203 sealing the edges of the film substrates 201 and 202 . The front surface of the film element may be surrounded by an encapsulant 303 between the two outer substrates 101 and 102 on top, bottom and left and right front surfaces. Although not shown in the drawings, the above-described conductive layer, alignment layer, and/or internal polarizing coating layer are formed on the inner surface of at least one of the film substrates 201 and 202 of the active liquid crystal film device, that is, on the surface facing the other substrate. can exist

FIG. 3 shows a case where both the active liquid crystal film element and the polarizing film 400 as shown in FIG. 2 are encapsulated with the encapsulant 300 between the outer substrates 101 and 102 . In this case, as shown in the drawing, the encapsulant is between the active liquid crystal device film and the outer substrate 101, between the polarizing film 400 and the outer substrate 102, and all sides of the active liquid crystal film device and the polarizing film 400. may encapsulate the above, and the encapsulant may also exist between the active liquid crystal film element and the polarizing film 400 .

As the outer substrate, for example, an inorganic substrate made of glass or a plastic substrate may be used. As the plastic substrate, TAC (triacetyl cellulose) film; COP (cyclo olefin copolymer) films such as norbornene derivatives; Acrylic film such as poly(methyl methacrylate) (PMMA); polycarbonate (PC) film; polyethylene (PE) film; polypropylene (PP) film; polyvinyl alcohol (PVA) film; diacetyl cellulose (DAC) film; polyacrylate (Pac) film; Polyether sulfone (PES) film; polyetheretherketon (PEEK) film; polyphenylsulfone (PPS) film, polyetherimide (PEI) film; polyethylenemaphthatlate (PEN) film; polyethyleneterephtalate (PET) film; polyimide (PI) film; polysulfone (PSF) film; A PAR (polyarylate) film or a fluorine resin film may be used, but is not limited thereto.. On the outer substrate, if necessary, a coating layer of a silicon compound such as gold, silver, silicon dioxide or silicon monoxide, or a coating layer such as an antireflection layer may exist.

The thickness of the outer substrate is not particularly limited, and may be, for example, about 0.3 mm or more. In another example, the thickness may be about 0.5 mm or more, about 1 mm or more, about 1.5 mm or more, or about 2 mm or more, and about 10 mm or less, 9 mm or less, 8 mm or less, 7 mm or less, 6 mm or less, 5 mm or less, 4 mm or less, or 3 mm or less.

The outer substrate may be a flat substrate or a substrate having a curved shape. For example, the two outer substrates may be flat substrates simultaneously, or simultaneously have a curved shape, or one may be a flat substrate and the other may be a curved substrate.

In addition, in the case of simultaneously having a curved surface shape, each curvature or radius of curvature may be the same or different.

In this specification, the curvature or radius of curvature may be measured by a method known in the industry, for example, a 2D Profile Laser Sensor (laser sensor), a Chromatic confocal line sensor (confocal sensor), or a non-contact method such as 3D Measuring Conforcal Microscopy. It can be measured using the instrument. Methods of measuring curvature or radius of curvature using such equipment are known.

In addition, in relation to the substrate, for example, when the curvature or radius of curvature is different between the front surface and the rear surface, the curvature or radius of curvature of the facing surface, that is, in the case of the first outer substrate, the surface facing the second outer substrate The curvature or radius of curvature of and the curvature or radius of curvature of the surface facing the first outer substrate in the case of the second outer substrate may be references. In addition, when the curvature or radius of curvature on the corresponding surface is not constant and there are different portions, the largest curvature or radius of curvature, the smallest curvature or radius of curvature, or the average curvature or average radius of curvature may be used as a criterion.

The substrate has a difference in curvature or radius of curvature of both within 10%, within 9%, within 8%, within 7%, within 6%, within 5%, within 4%, within 3%, within 2% or 1 It can be within %. The difference in curvature or radius of curvature is a numerical value calculated as _100Х (CL -CS )/CS when a _large curvature or radius of curvature is C _L and a _small curvature or radius of curvature is C _S . In addition, the lower limit of the difference in curvature or radius of curvature is not particularly limited. Since the difference in curvature or radius of curvature of the two outer substrates may be the same, the difference in curvature or radius of curvature may be greater than or equal to 0% or greater than 0%.

Control of the curvature or radius of curvature as described above is useful in a structure in which an active liquid crystal film element and/or a polarizing film are encapsulated with an adhesive film, such as in the optical device of the present application.

When both the first and second outer substrates are curved surfaces, the curvatures of both may have the same sign. In other words, both of the two outer substrates may be curved in the same direction. That is, in the above case, both the center of curvature of the first outer substrate and the center of curvature of the second outer substrate exist in the same part among the upper and lower portions of the first and second outer substrates.

4 is an example of a side surface in which an encapsulation region 400 including an active liquid crystal device or the like is present between the first and second outer substrates 30. In this case, both the first and second outer substrates 30 The center of curvature of is the case at the bottom in the drawing.

A specific range of each curvature or radius of curvature of the first and second outer substrates is not particularly limited. In one example, the radius of curvature of each substrate is 100R or more, 200R or more, 300R or more, 400R or more, 500R or more, 600R or more, 700R or more, 800R or more or 900R or more, or 10,000R or less, 9,000R or less, 8,000R 7,000R or less, 6,000R or less, 5,000R or less, 4,000R or less, 3,000R or less, 2,000R or less, 1,900R or less, 1,800R or less, 1,700R or less, 1,600R or less, 1,500R or less, 1,400R or less, 1,300R or less, 1,200R or less, 1,100R or less, or 1,050R or less. In the above, R means the curved hardness of a circle having a radius of 1 mm. Thus, in the above, for example, 100R is the degree of curvature of a circle having a radius of 100 mm or the radius of curvature for such a circle. Of course, when the substrate is flat, the curvature is zero and the radius of curvature is infinite.

The first and second outer substrates may have the same or different radii of curvature within the above range. In one example, when the curvatures of the first and second outer substrates are different from each other, the radius of curvature of the substrate having the greater curvature may be within the above range.

In one example, when the curvatures of the first and second outer substrates are different from each other, a substrate having a greater curvature among them may be a substrate disposed in a direction of gravity more when an optical device is used.

That is, for the encapsulation, as will be described later, an autoclave process using an adhesive film may be performed, and high temperature and high pressure are usually applied in this process. However, in some cases, such as when an adhesive film applied to encapsulation is stored at a high temperature for a long time after such an autoclave process, some re-melting may occur, causing a problem in that the outer substrate is opened. When this phenomenon occurs, force acts on the encapsulated active liquid crystal device and/or the polarizing film, and bubbles may be formed therein.

However, if the curvature or radius of curvature between the substrates is controlled as described above, even if the bonding force by the adhesive film is reduced, the net force, which is the sum of restoring force and gravity, acts to prevent unfolding, and can withstand process pressure such as autoclave well. can

The optical device may further include an adhesive film as an encapsulant encapsulating the active liquid crystal film element and/or the polarizing film in the outer substrate. The form of the encapsulation has already been described. Therefore, the adhesive film may be present, for example, between the outer substrate and the active liquid crystal film element, between the active liquid crystal film element and the polarizing film, and/or between the polarizing film and the outer substrate, and between the active liquid crystal film element and the outer substrate. It may also exist on the side of the polarizing film, appropriately on all sides.

The adhesive film may encapsulate the active liquid crystal film element and the polarizing film while adhering the outer substrate and the active liquid crystal film element, the active liquid crystal film element and the polarizing film, and the polarizing film and the outer substrate to each other.

For example, the structure may be implemented by laminating an outer substrate, an active liquid crystal film element, a polarizing film, and an adhesive film according to a desired structure and then compressing the outer substrate in a vacuum state.

A known material may be used as the adhesive film without particular limitation, for example, a known thermoplastic polyurethane (TPU) adhesive film, a thermoplastic starch (TPS), a polyamide adhesive film, a polyester adhesive film, An appropriate one may be selected from an EVA (Ethylene Vinyl Acetate) adhesive film, a polyolefin adhesive film such as polyethylene or polypropylene, or a polyolefin elastomer film (POE film).

The thickness of the adhesive film is not particularly limited, and may be, for example, within a range of about 200 μm to about 600 μm. The thickness of the adhesive film is the thickness of the adhesive film between the outer substrate and the active liquid crystal film element, for example, the distance between the two, the thickness of the adhesive film between the active liquid crystal film element and the polarizing film, for example, the thickness of the adhesive film between the two The distance and/or the thickness of the adhesive film between the polarizing film and the outer substrate, for example, may be the distance between the two.

The optical device may also further include a buffer layer. Such a buffer layer may be present on one side or both sides of the liquid crystal film element.

The buffer layer, in a structure in which an active liquid crystal film device is encapsulated by an adhesive film, can alleviate sound pressure generated by a difference in thermal expansion coefficient between layers, and can enable a more durable device to be implemented.

In one example, as the buffer layer, a layer having a Young's modulus of 1 MPa or less may be used. In another example, the Young's modulus of the buffer layer may be 0.9 MPa or less, 0.8 MPa or less, 0.7 MPa or less, 0.6 MPa or less, 0.6 MPa or less, 0.1 MPa or less, 0.09 MPa or less, 0.08 MPa or less, 0.07 MPa or less, or 0.06 MPa or less. In another example, the Young's modulus is about 0.001 MPa or more, 0.002 MPa or more, 0.003 MPa or more, 0.004 MPa or more, 0.005 MPa or more, 0.006 MPa or more, 0.007 MPa or more, 0.008 MPa or more, 0.009 MPa or more, 0.01 MPa or more, or 0.02 MPa or more. , 0.03 MPa or more, 0.04 MPa or more, or 0.045 MPa or more. The method for measuring the Young's modulus is the same as the method for measuring the adhesive film described above.

As a specific type of the buffer layer, a transparent material exhibiting the above-described Young's modulus may be used without particular limitation. For example, an acrylate-based, urethane-based, rubber-based, or silicon-based oligomer or polymeric material may be used.

The thickness of the buffer layer is not particularly limited, and may be selected within a range capable of effectively alleviating sound pressure or the like generated inside the device by exhibiting a Young's modulus within the above range.

In addition to the above components, the optical device may further include necessary optional components, and for example, known components such as a retardation layer, an optical compensation layer, an antireflection layer, and a hard coating layer may be included at appropriate locations.

In the present application, an optical device having excellent durability, particularly durability at high temperatures, can be provided by controlling the moisture content of the active liquid crystal film element and/or the polarizing film encapsulated with the encapsulant between the outer substrates as described above. Such durability is particularly advantageous when the optical device of the present application is in a structure exposed to the external environment, such as for vehicles or for construction. Accordingly, in one example, the total moisture content included in the encapsulant, the active liquid crystal film element, and the polarizing film in the optical device may be 1.5% by weight or less. In another example, the moisture content may be about 1.4% by weight or less, about 1.3% by weight or less, about 1.2% by weight or less, about 1.1% by weight or less, about 1.0% by weight or less, about 0.9% by weight or less, or about 0.85% by weight or less. there is. Since the lower the moisture content is advantageous in terms of high temperature durability, the moisture content is 0% by weight or more, 0.1% by weight or more, 0.2% by weight or more, 0.3% by weight or more, 0.4% by weight or more, 0.5% by weight or more, 0.6% by weight or more. , 0.7% by weight or more or 0.8% by weight or more.

Each of the above water contents can be measured according to the method disclosed in Korean Patent Publication No. 2017-0122552.

The present inventors have found that elements used for fabrication of the above-mentioned structure, that is, an adhesive film as an encapsulant, a polarizing film, and/or a substrate as a plastic film, always contain moisture above a certain level, and therefore such moisture is high-temperature durability. was found to have a negative effect on Therefore, it was possible to achieve the above-described moisture content by controlling the moisture content of each element of the optical device through necessary processing and manufacturing the optical device using the same, thereby ensuring excellent durability.

Thus, in one example, the moisture content of each element constituting the optical device may be controlled to achieve a desired moisture content.

For example, in the optical device, the water content of the encapsulant is 0.7% or less, 0.65% or less, 0.6% or less, 0.55% or less, 0.5% or less, 0.45% or less, 0.4% or less, 0.35% or less, 0.3% or less, 0.25% or less, 0.2% or less, 0.15% or less, 0.1% or less, 0.09% or less, 0.08% or less, 0.07% or less, 0.06% or less, or 0.05 wt% or less, or 0 wt% or more, 0.01 wt% or more, 0.02 wt% or more, 0.03 wt% or more, or 0.04 wt% or more.

In addition, in the optical device, the film substrate, which is a plastic film, or the outer substrate has a moisture content of 0.7% by weight or less, 0.65% by weight or less, 0.6% by weight or less, 0.55% by weight or less, 0.5% by weight or less, 0.45% by weight or less, 0.4% by weight or less. or less than or equal to 0.35%, or greater than or equal to 0%, greater than or equal to 0.05%, greater than or equal to 0.1%, greater than or equal to 0.15%, greater than or equal to 0.2%, greater than or equal to 0.25% or greater than or equal to 0.3% by weight.

In addition, in the optical device, the water content of the polarizing film is 0.7% by weight or less, 0.65% by weight or less, 0.6% by weight or less, 0.55% by weight or less, or 0.5% by weight or less, or 0% by weight or more, 0.05% by weight or more, or 0.1% by weight or more. % or more, 0.15 wt% or more, 0.2 wt% or more, 0.25 wt% or more, 0.3 wt% or more, 0.35 wt% or more, or 0.4 wt% or more.

The generally known encapsulant (adhesive film), polarizing film, plastic film, etc. have a water content higher than the above-mentioned range. Therefore, appropriate pretreatment is required to control the moisture content of each element.

Accordingly, each of the above elements may be elements maintained at a temperature within a range of approximately 18° C. to 50° C. and a relative humidity of 2% or less. In the above, the drying temperature or humidity may be changed according to the purpose, and the holding time may also be controlled within a range in which a desired moisture content can be achieved. The relative humidity may be about 0.5% or more, 0.7% or more, 0.9% or more, or about 1% or more in another example.

In the case of the above pretreatment, it may be performed separately for each of the plastic film, the polarizing film and the adhesive film, or may be performed in a state in which the optical device or active liquid crystal film element is formed as a whole, but effectively, the above treatment is performed for each Afterwards, the optical device can be manufactured under low humidity conditions.

In addition, even when the pretreated elements are used to achieve the desired moisture content (moisture content), it is necessary to assemble the optical device under low humidity conditions as much as possible in order to block the inflow of moisture during the assembly process. .

By the above adjustment, the optical device can exhibit excellent durability, particularly high-temperature durability. For example, the optical device may have a variation ΔE of 10 or less according to Equation 1 below. In another example, the variation ΔE may be about 9.5 or less, 9 or less, 8.5 or less, 8 or less, 7.5 or less, 7 or less, 6.5 or less, or 6 or less. Since this variation ΔE is more effective as the value is lower, the lower limit thereof is not particularly limited, and is, for example, about 0 or more, about 0.5 or more, about 1 or more, about 1.5 or more, about 2 or more, about 2.5 or more, about 3 or greater, about 3.5 or greater, about 4 or greater, about 4.5 or greater, about 5 or greater, or about 5.5 or greater.

[Equation 1]

ΔE ^* = [(L ^* ₂ -L ^* ₁ ) ² +(a ^* ₂ -a ^* ₁ ) ² +(b ^* ₂ -b ^* ₁ ) ² ] ^1/2

In Equation 1, L ^* ₂ , a ^* ₂ and b ^* ₂ are L ^* , a ^* 2 and b ^* 2 values in the CIE L*a*b* color system after maintaining the optical device at 85° C. for 1,000 hours, respectively, and L ^* ₁ , a ^* ₁ and b ^* ₁ are L ^* , a ^* and b ^* values in the CIE L*a*b* color system of the optical device before being maintained at 85° C. for 1,000 hours, respectively.

That is, in the present application, it is possible to provide an optical device with minimal or no change in its optical characteristics even under severe high temperature conditions through the control of the above conditions (moisture content).

In the above, the L ^* , a ^* and b ^* values in the CIE L * a * b * color system of the optical device are measured according to the standard method using measuring equipment (eg, Konica Minolta's Hunter Lab Vista equipment). can be saved

A method of manufacturing the optical device of the present application is not particularly limited. In one example, the optical device may be manufactured through an autoclave process for the aforementioned encapsulation.

For example, the manufacturing method of the optical device includes the step of encapsulating an active liquid crystal film element and/or a polarizing film positioned between first and second outer substrates that are opposed to each other through an autoclave process using an adhesive film. can do.

The moisture content of each of the applied active liquid crystal film element, polarizing film and adhesive film (encapsulating agent) may be controlled within the above-mentioned range. In this case, the moisture content of the active liquid crystal film device may be the moisture content of the aforementioned plastic film. In other words, among the components of an active liquid crystal film device, since there is not much moisture in other elements except for the film substrate, the moisture content in the active liquid crystal film device is approximately similar to that in the plastic film substrate of the device.

The autoclave process may be performed by disposing an adhesive film, an active liquid crystal film element and/or a polarizing film between outer substrates according to a desired encapsulation structure, and heating/pressing the outer substrate.

For example, a laminate in which an outer substrate, an adhesive film, an active liquid crystal film element, an adhesive film, a polarizing film, an adhesive film, and an outer substrate are disposed in the above order, and an adhesive film is disposed on the side surface of the active liquid crystal film element and the polarizing film. When heated/pressurized in an autoclave process, an optical device as shown in FIG. 3 can be formed.

The conditions of the autoclave process are not particularly limited, and may be carried out, for example, under appropriate temperature and pressure depending on the type of adhesive film applied. The temperature of a typical autoclave process is about 80° C. or higher, 90° C. or higher, or 100° C. or higher, and the pressure is 2 atmospheres or higher, but is not limited thereto. The upper limit of the process temperature may be about 200 ° C or less, 190 ° C or less, 180 ° C or less, or 170 ° C or less, and the upper limit of the process pressure is about 10 atm or less, 9 atm or less, 8 atm or less, 7 atm or less, or 6 atm. It may be less than or equal to.

In order to achieve a desired moisture content (moisture content), an assembly process of an optical device such as the autoclave process may be performed under a low humidity condition. For example, the process may be performed under a relative humidity condition of at least 2% or less. The relative humidity may be about 0.5% or more, 0.7% or more, 0.9% or more, or about 1% or more in another example.

The optical device as described above can be used for various purposes, and for example, eyewear such as sunglasses, AR (Argumented Reality) or VR (Virtual Reality) eyewear, an outer wall of a building or a sunroof for a vehicle, etc. can be used

In one example, the optical device itself may be a vehicle sunroof.

For example, in an automobile including a body in which at least one opening is formed, the optical device or a vehicle sunroof mounted on the opening may be installed and used.

In this case, when the curvature or radius of curvature of the outer substrates is different from each other, a substrate having a smaller radius of curvature, that is, a substrate having a larger curvature may be disposed in the direction of gravity.

The present application provides an optical device capable of varying transmittance, and such an optical device includes eyewear such as sunglasses, eyewear for AR (Argumented Reality) or VR (Virtual Reality), outer walls of buildings or cables for vehicles. It can be used for various purposes such as loops.

1 to 4 are schematic diagrams of the optical device of the present application.
5 to 7 are diagrams showing results of evaluation of high-temperature durability of the optical devices of Example 1 and Comparative Examples 1 and 2, respectively.

The present application will be specifically described through examples and comparative examples below, but the scope of the present application is not limited to the following examples.

1. How to measure the radius of curvature

In the embodiment, the radius of curvature of the outer substrate was measured using a 2D Profile Laser Sensor (laser sensor). In addition, the radius of curvature of each outer substrate is the radius of curvature of the surface facing each other, and when the radius of curvature is not constant and there are different portions, the largest radius of curvature is taken as the basis.

2. How to measure moisture content

The moisture content (plastic film substrate, adhesive film, and polarizing film) in Examples or Comparative Examples was determined by using a moisture measuring device (MASS, Moisture Analyzer for Solid Sample) disclosed in Korean Patent Publication No. 2017-0122552 measured. As described in the Korean Patent Publication, 1% K/F oven standard (Na ₂ WO ₄ .2H ₂ O) was used as a furnace part, and helium was used as a moisture transfer gas. The environment was controlled by flowing helium gas (He gas) into the measurement space at a flow rate of about 100 mL/min, and moisture in the air was removed by ventilation from room temperature to approximately 50 °C. Thereafter, the temperature of the measurement object (sample) was constantly raised from 50 ° C to 200 ° C for 30 minutes, and the internal moisture content was measured. Calibration of the analysis equipment was confirmed by creating a calibration curve in the range of 30 mg to -700 mg for Na ₂ WO ₄ ·2H ₂ O (standard product, water content 1% by weight). The water content calibration curve of the standard product confirmed that the R ² value was 0.9999, confirming the reliability of the measuring equipment.

Example 1.

Guest-host liquid crystal film element as an active liquid crystal film element (cell gap: about 12㎛, film substrate type: PET (poly(ethylene terephthalate) film), liquid crystal/dye mixture type: Merck's MAT-16-969 liquid crystal and anisotropic dye (BASF Co., X12)) and PVA (polyvinylalcohol)-based polarizing film are encapsulated with a thermoplastic polyurethane adhesive film (thickness: about 0.38 mm, manufacturer: Argotec, product name: ArgoFlex) between two outer substrates and encapsulated in an optical device. was manufactured.

In the above, the PET film, PVA polarizing film, and polyurethane adhesive film of the active liquid crystal film device are all maintained for about 24 hours in a storage chamber at a temperature of about 25° C. and a relative humidity of 1%, respectively, and each moisture content is 0.34% by weight (PET film × 2), 0.43% by weight (PVA polarizing film) and 0.05% by weight (adhesive film). Therefore, the water content inside the final optical device is about 0.82% by weight.

As the outer substrate, a glass substrate having a thickness of about 3 mm was used, and a substrate having a radius of curvature of about 1030R (first outer substrate) and a substrate having a radius of curvature of about 1000R (second outer substrate) were used.

The first outer substrate, the adhesive film, the active liquid crystal film element, the adhesive film, the polarizing film, the adhesive film, and the second outer substrate are laminated in the above order, and the adhesive is applied to all sides of the active liquid crystal film element. A laminate was manufactured by disposing the film (the second outer substrate was disposed in the direction of gravity compared to the first outer substrate).

Thereafter, an autoclave process was performed at a temperature of about 110° C. and a pressure of about 2 atm to manufacture an optical device. At this time, the temperature of the chamber in which the autoclave process proceeds was set to approximately 25° C., and the relative humidity was maintained at approximately 50%. The chamber in which the autoclave proceeds is a closed system and is a space blocked from the outside, and the laminate was introduced into the chamber while maintaining a low vacuum condition using an aluminum bag.

Thereafter, after maintaining the manufactured optical device at a temperature of about 85° C. for 1,000 hours, the change amount ΔE ^* before and after holding was measured according to Equation 1 above. 5 is a photograph of the optical device after maintaining at the high temperature, and the amount of change ΔE ^* was about 5.59.

Example 2.

Except for maintaining the PET film of the active liquid crystal film element in a storage chamber at a temperature of 25° C. and a relative humidity of 1% for about 3 hours so that the moisture content is about 0.82% by weight (PET film × 2). A final optical device was manufactured in the same manner as in Example 1. Therefore, the water content inside the final optical device is about 1.3% by weight.

After maintaining the optical device at a temperature of about 85° C. for 1,000 hours, the amount of change ΔE ^* before and after the maintenance was measured according to Equation 1, and the amount of change ΔE ^* was about 8.73. 6 is a photograph of the optical device after holding at the high temperature.

Comparative Example 1.

An optical device was fabricated in the same manner as in Example 1, but only the PVA polarizing film was dried, and the adhesive film and the PET film were not dried. The water contents of the applied PET film, PVA polarizing film, and polyurethane adhesive film were 0.4 wt% (PET film), 0.49 wt% (PVA polarizing film), and 1.34 wt% (adhesive film), respectively. Therefore, the water content inside the final optical device is about 2.23% by weight. As a result of measuring the variation ΔE* in the same manner for the optical device, it was about 11.3, and FIG. 7 is a photograph of the optical device after maintaining at the high temperature.

Comparative Example 2.

An optical device was manufactured in the same manner as in Example 1, but the PVA polarizing film, the adhesive film and the PET film were not dried. The water contents of the applied PET film, PVA polarizing film, and polyurethane adhesive film were 0.42 wt% (PET film), 2.6 wt% (PVA polarizing film), and 1.2 wt% (adhesive film), respectively. Therefore, the water content inside the final optical device is about 4.21% by weight. Although the change amount ΔE* was measured in the same way for the optical device, the change amount was very large and it was difficult to digitize.

Claims (18)

first and second outer substrates disposed opposite to each other;
An active liquid crystal film element and a polarizing film encapsulated with an encapsulant between the first and second outer substrates;
The active liquid crystal film element includes two plastic film substrates disposed opposite to each other and an active liquid crystal layer present between the two plastic film substrates,
An optical device wherein the total water content contained in the encapsulant, the two plastic film substrates of the active liquid crystal film element, and the polarizing film is 1.5% by weight or less. The optical device according to claim 1, wherein a variation ΔE ^* according to Equation 1 below is 10 or less:
[Formula 1]
ΔE ^* = [(L ^* ₂ -L ^* ₁ ) ² +(a ^* ₂ -a ^* ₁ ) ² +(b ^* ₂ -b ^* ₁ ) ² ] ^1/2
In Equation 1, L ^* ₂ , a ^* ₂ and b ^* ₂ are L ^* , a ^* 2 and b ^* 2 values in the CIE L*a*b* color system after maintaining the optical device at 85° C. for 1,000 hours, respectively, and L ^* ₁ , a ^* ₁ and b ^* ₁ are L ^* , a ^* and b ^* values in the CIE L*a*b* color system of the optical device before holding at 85° C. for 1,000 hours, respectively. The optical device according to claim 1, wherein curvatures of the first and second outer substrates are different from each other, and the difference is within 10%. The optical device according to claim 1, wherein both the first and second outer substrates are glass substrates. The optical device of claim 1, wherein one of the first and second outer substrates is a flat substrate and the other is a curved substrate. The optical device of claim 1, wherein both the first and second outer substrates are curved substrates. The optical device according to claim 3, wherein a radius of curvature of a substrate having a large curvature among the first and second outer substrates is within a range of 100R to 10,000R. 7. The optical device according to claim 6, wherein the centers of curvature of the first and second outer substrates are located at the same part of the top or bottom of the first and second outer substrates. The method of claim 1, wherein the active liquid crystal device film and the active liquid crystal device film and An optical device in which a polarizing film is encapsulated. The optical device of claim 1, wherein the encapsulant has a water content of less than or equal to 0.7% by weight. The optical device of claim 1, wherein the encapsulant is a thermoplastic polyurethane adhesive film, a polyamide adhesive film, a polyester adhesive film, an EVA (Ethylene Vinyl Acetate) adhesive film, a polyolefin adhesive film, or a thermoplastic starch (TPS). The optical device of claim 1, wherein the active liquid crystal layer includes a liquid crystal host and an anisotropic dye guest, and is capable of switching between a first alignment state and a second alignment state. The optical device according to claim 1, wherein the active liquid crystal film element further comprises an alignment film present on the side facing the active liquid crystal layer of the two plastic film substrates. 14. The optical device according to claim 13, wherein an angle formed by the alignment directions of the alignment films of the two plastic film substrates is within a range of -10 degrees to 10 degrees or within a range of 80 degrees to 90 degrees. The optical device according to claim 1, wherein the water content of the two plastic film substrates is 0.7% by weight or less. The optical device according to claim 1, wherein the water content of the polarizing film is 0.7% by weight or less. The optical system of claim 1 , wherein the polarizing film is arranged so that an angle formed between an average optical axis of the first alignment state of the active liquid crystal layer and a light absorption axis of the polarizing film is within a range of 80 degrees to 100 degrees or 35 degrees to 55 degrees. device. a vehicle body in which one or more openings are formed; and the optical device of claim 1 mounted in the opening.

Images