KR102382553B1 - Optical Device - Google Patents

Abstract

This application relates to an optical device. In the optical device of the present application, transmittance is variable, and even when negative pressure is generated in the optical device in an environment that changes between high and low temperatures, bubble generation is reduced, thereby improving the appearance of the optical device. Such an optical device may be used for various purposes such as sunglasses, eyewear such as AR (Argumented Reality) or VR (Virtual Reality) eyewear, exterior walls of buildings, or sunroofs for vehicles.

Description

Optical Device

This application relates to an optical device.

Various optical devices designed to vary transmittance using liquid crystal compounds are known.

For example, a transmittance variable device using a so-called GH cell (Guest host cell) to which a mixture of a host material and a dichroic dye guest is applied is known, and in the device, mainly a liquid crystal compound as a host material this is used

Such a transmittance variable device is applied to various uses, including eyewear such as sunglasses or glasses, exterior walls of buildings, or sunroofs of vehicles.

SUMMARY OF THE INVENTION An object of the present application is to provide an optical device in which transmittance is variable, and bubble generation is reduced even when negative pressure is generated in an environment that changes between high and low temperatures, thereby improving the appearance of the optical device.

This application relates to an optical device. The optical device includes a liquid crystal element having a structure in which a first base layer, a liquid crystal layer, and a second base layer are sequentially stacked.

1 exemplarily shows a liquid crystal device according to an embodiment of the present application. 1 , the liquid crystal device 10 may have a structure in which a first base layer 11a, a liquid crystal layer 12, and a second base layer 11b are sequentially stacked. On the other hand, the above-mentioned first and second expressions do not prescribe the precedence or the vertical relationship of the base layer.

As an example, at least one of the first base layer 11a and the second base layer 11b constituting the liquid crystal device 10 has an oxygen transmission rate of 100 cm ³ /m ² *day* may be less than atm.

As another example, at least one of the first substrate layer and the second substrate layer has an oxygen permeability of less than about 90 cm ³ /m ² *day*atm, less than 80 cm ³ /m ² *day*atm, or 60 cm ³ /m ² may be less than *day*atm or less than about 40 cm ³ /m ² *day*atm, the lower limit is not particularly limited, but greater than or equal to about 0 cm ³ /m ² *day*atm or about 1 cm ³ /m ² * It can be more than day*atm.

The oxygen transmittance may be measured at a temperature of 23° C. and a relative humidity of 0% according to ASTM D 3985 method. The measuring device is not particularly limited and it can be measured using a known oxygen transmittance measuring device, for example, OX-TRAN manufactured by MOCON.

When the base layer satisfies the oxygen transmittance within the above range, the optical device including the base layer may generate a negative pressure inside the optical device in an environment that changes between high and low temperatures, but the outside flowing into the optical device The amount of air is reduced. Accordingly, it is possible to reduce the appearance defect of the optical device due to the generation of air bubbles due to the inflow of external air. Meanwhile, in the present application, the term negative pressure means a pressure lower than atmospheric pressure, and the atmospheric pressure means a pressure of about 1 atmosphere.

As an example, the first base layer and the second base layer may each have an oxygen transmittance of less than 100 cm ³ /m ² *day*atm. When the oxygen transmittance of the first and second base layers satisfies the above ranges, it is possible to more efficiently reduce appearance defects caused by internal negative pressure of the optical device.

As an example, each of the first base layer and the second base layer may have a thickness of about 10 μm to about 1,000 μm. As another example, the thickness of the base layer may be about 20 μm or more, 30 μm or more, 40 μm or more, 50 μm or more, 60 μm or more, or about 70 μm or more, and about 900 μm or less, 800 μm or less, 700 μm or less, It may be 600 μm or less, 500 μm or less, or about 400 μm or less.

When the thickness of the base layer satisfies the above range, it is advantageous for the oxygen transmittance of the base layer to have a range of less than 100 cm ³ /m ² *day*atm. Accordingly, it is possible to more efficiently reduce appearance defects caused by internal negative pressure of the optical device.

As an example, the first base layer and the second base layer may each have a crystallinity of about 40% or more. As another example, the crystallinity of the base layer may be about 45% or more, 50% or more, 55% or more, 60% or more, or about 65% or more, and the upper limit is not particularly limited, but about 100% or less, about 99% or less, or about 98% or less.

The term crystallinity refers to the percentage (by weight) of the crystalline region included in the base layer, which may be measured by differential scanning calorimetry. In this process, the temperature increase rate is set to 10° C. per minute, the heat of fusion (ΔHf) is measured in the second temperature increase process, and the heat of fusion of polyvinylidene fluoride having 100% crystallinity (ΔHf = 105 J/g), the crystallinity of each substrate layer can be obtained.

As an example, the first base layer and the second base layer are not particularly limited as long as the oxygen permeability is less than about 100 cm ³ /m ² *day*atm and may be used as the base layer of the present application. In one embodiment, the first base layer and the second base layer are each independently PEN (polyethylene-naphthalate) film, PI (polyimide) film, COP (cyclo-olefin polymer) film, TAC (tri-acetyl-cellulose) film or A polyethyleneterephtalate (PET) film may be used, but is not limited thereto.

The liquid crystal device may include a liquid crystal layer including at least a liquid crystal compound. In one example, the liquid crystal layer is a so-called guest host liquid crystal layer, and may be a liquid crystal layer including a liquid crystal compound and a dichroic dye guest.

The liquid crystal layer is a liquid crystal layer using a so-called guest host effect, and is a liquid crystal layer in which the dichroic dye guest is aligned according to the alignment direction of the liquid crystal compound (hereinafter, may be referred to as a liquid crystal host).

The orientation refers to the alignment of the optical axis, and the optical axis may refer to, for example, the long axis direction of the liquid crystal compound when the liquid crystal compound is of a rod type, and in the case of a discotic type, the normal direction of the plane of the disk. can mean On the other hand, when a plurality of liquid crystal compounds having different optical axis directions are included in an arbitrary alignment state, the optical axis may be defined as an average optical axis, and in this case, the average optical axis may mean a vector sum of the optical axes of the liquid crystal compounds. The orientation direction may be controlled by application of energy, which will be described later.

The type of the liquid crystal host used in the liquid crystal layer is not particularly limited, and a general type of liquid crystal compound applied to realize the 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 may be used. The term nematic liquid crystal compound refers to a liquid crystal compound that has no regularity with respect to the positions of liquid crystal molecules, but can be arranged in an orderly manner in the molecular axis direction, and the liquid crystal compound may be in the form of a rod or a disc can

Such a nematic liquid crystal compound has, for example, a clearing point of about 40°C or more, 50°C or more, 60°C or more, 70°C or more, 80°C or more, 90°C or more, 100°C or more, or about 110°C or more. 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 the phase transition point may be about 160 °C or less, 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 anisotropy may be greater than about 3 or greater than about 7, or less than about -2 or less than about -3.

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

A liquid crystal compound that can be used as a liquid crystal host of the guest host liquid crystal layer is known to those skilled in the art, and can be freely selected from them.

The liquid crystal layer includes a dichroic dye guest together with the liquid crystal host. The term dye may mean a material capable of intensively absorbing and/or modifying light in the visible light region, for example, at least part or all within the wavelength range of 380 nm to 780 nm, the term dichroic dye guest being It may refer to a material capable of absorbing light in at least a part or the entire range of the visible light region.

As the dichroic dye guest, for example, a known dye known to have a property that can be aligned according to the alignment state of the liquid crystal host may be selected and used. In one embodiment, an azo dye or an anthraquinone dye may be used as the dichroic dye guest, and in order to achieve light absorption in a wide wavelength range, the liquid crystal layer may include one or two or more dyes.

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

The content of the dichroic dye guest in the liquid crystal layer may be appropriately selected in consideration of the purpose of use of the dichroic dye guest. For example, based on the total weight of the liquid crystal host and the dichroic dye guest, the content of the dichroic dye guest may be selected within the range of about 0.1 wt% to about 10 wt%. The ratio of the dichroic dye guest may be changed in consideration of the transmittance of the liquid crystal device, which will be described later, and the solubility of the dichroic dye guest in the liquid crystal host.

The liquid crystal layer basically includes the liquid crystal host and the dichroic dye guest, and, if necessary, may further include other optional additives according to a known form. Examples of the additive may include, but are not limited to, a chiral dopant or a stabilizer.

The liquid crystal device includes a spacer that maintains a gap between the first base layer and the second base layer and/or the first base layer and the second base layer in a state where the gap between the first base layer and the second base layer is maintained. 2 It may further include a sealant capable of attaching the base layer. As the material of the spacer and/or sealant, a known material may be used without any particular limitation.

The liquid crystal device may further include a conductive layer and/or an alignment layer. 2 exemplarily shows a liquid crystal device according to an embodiment including a conductive layer and an alignment layer. As shown in FIG. 2 , the liquid crystal element 10 includes a first base layer ( 11a ), a conductive layer ( 13 ), an alignment layer ( 14 ), a liquid crystal layer ( 12 ), an alignment layer ( 14 ), and a conductive layer ( 13 ). And it may have a structure in which the second base layer 11b is sequentially stacked.

The conductive layer 13 may be formed on the first base layer and the second base layer 11a and 11b, respectively. In addition, the conductive layer 13 may be formed on the surface facing the liquid crystal layer 12 . The conductive layer 13 present on the surface of the base layer is a configuration for applying a voltage to the liquid crystal layer 12, and a known conductive layer may be applied without any particular limitation. As the conductive layer, for example, a conductive polymer, a conductive metal, a conductive nanowire, or a metal oxide such as indium tin oxide (ITO) may be applied. Examples of the conductive layer applicable in the present application are not limited to the above, and all types of conductive layers known to be applicable to liquid crystal devices in this field may be used.

The alignment layer 14 may be present on the surfaces of the first and second base layers 11a and 11b. For example, the conductive layer 13 may be first formed on one surface of the base layer, and the alignment layer 14 may be formed thereon.

The alignment layer 14 is configured to control the alignment of the liquid crystal host included in the liquid crystal layer 12 , and a known alignment layer may be applied without any particular limitation. As the alignment layer known in the industry, there is a rubbing alignment layer or a photo alignment layer, and the alignment layer that can be used in the present application is the known alignment layer, which is not particularly limited.

In order to achieve the above-described alignment of the optical axis, the alignment direction of the alignment layer 14 may be controlled. For example, the orientation direction of the two alignment films formed on each surface of the first base layer and the second base layer facing each other is in the range of about -10 degrees to about 10 degrees, and about -7 degrees to about 7 degrees. an angle within a range, an angle within a range of about -5 degrees to about 5 degrees, or an angle within a range of about -3 degrees to about 3 degrees, or approximately parallel to each other. In another example, the alignment direction of the two alignment layers is an angle within a range of about 80 degrees to about 100 degrees, an angle within a range of about 83 degrees to about 97 degrees, an angle within a range of about 85 degrees to about 95 degrees, or an angle within a range of about 87 degrees to about 92 degrees. may be at an angle within the range of degrees or approximately perpendicular to each other.

Since the direction of the optical axis of the liquid crystal layer is determined according to the alignment direction, the alignment direction can be known by confirming the direction of the optical axis of the liquid crystal layer. A method of confirming in which direction the optical axis of the liquid crystal layer is formed is known. For example, the direction of the optical axis of the liquid crystal layer can be measured using another polarizing plate that knows the optical axis direction, which can be measured using a known measuring device, for example, a polarimeter such as Jasco's P-2000. there is.

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

The liquid crystal element may switch between alignment states of at least two optical axes, for example, first and second alignment states. In the liquid crystal device as described above, the alignment state may be changed by application of energy, for example, application of voltage. That is, the liquid crystal device may have one alignment state among the first and second alignment states in a state where no voltage is applied, and may be switched to another alignment state when a voltage is applied. Meanwhile, the transmittance may be adjusted according to the alignment state of the liquid crystal element. For example, the blocking mode may be implemented in one of the first and second orientation states, and the transmission mode may be implemented in the other orientation state.

The transmission mode is a state in which the liquid crystal element exhibits a relatively high transmittance, and the blocking mode is a state in which the liquid crystal element exhibits a relatively low transmittance.

In one example, the transmittance of the liquid crystal device in the transmission mode may be about 20%, 25%, 30% or more, 35% or more, 40% or more, 45% or more, or about 50% or more. In addition, the transmittance of the liquid crystal device in the blocking mode may be less than about 20%, less than 15%, or less than about 10%.

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

The transmittance may be a straight light transmittance. The term "straight light transmittance" may be a ratio of light incident through the liquid crystal element in a predetermined direction to light passing through the liquid crystal element 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 a surface normal of the liquid crystal element (normal light transmittance).

In the liquid crystal device of the present application, the light whose transmittance is controlled may be ultraviolet light, visible light, or near infrared light in the UV-A region. According to a commonly used definition, 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. and near-infrared is used to mean radiation having a wavelength in the range of 780 nm to 2000 nm.

If necessary, the liquid crystal device may be designed to implement other modes in addition to the transmission mode and the blocking mode. For example, it may be designed so that a third mode capable of exhibiting an arbitrary transmittance between transmittances of the transmission mode and the blocking mode may also be implemented.

The optical device of the present application may include first and second outer substrates. The first and second expressions do not stipulate a precedence or an up-and-down relationship. In an example, the liquid crystal device may be positioned between the first and second outer substrates. For example, as shown in FIG. 3 , the liquid crystal device 10 may be positioned between the first and second outer substrates 20 disposed to face each other.

As the first and second outer substrates 20 , for example, an inorganic substrate such as glass or a plastic substrate may be independently used. Examples of the plastic substrate include cellulose films such as triacetyl cellulose (TAC) or diacetyl cellulose (DAC); COP (cyclo olefin copolymer) films such as norbornene derivatives; Acrylic film such as PAR (Polyacrylate) or PMMA (poly(methyl methacrylate); PC (polycarbonate) film; PE (polyethylene) or PP (polypropylene), etc. Polyolefin film; PVA (polyvinyl alcohol) film; PI (polyimide) film; PSF (polysulfone) film; PPS (polyphenylsulfone) film; PES (polyethersulfone) film; PEEK (polyetheretherketon) film; PEI (polyetherimide) film; PEN (polyethylenenaphthatlate) film; PET (polyethyleneterephtalate) film; or a fluororesin film may be used In the first and second outer substrates 20 , if necessary, a coating layer of a silicon compound such as gold; silver; there is.

The thickness of the first and second outer substrates 20 as described above is not particularly limited, and may be, for example, about 0.3 mm or more, respectively. In another example, the thickness may be about 0.5 mm or more, 1 mm or more, 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 about 3 mm or less.

The first and second outer substrates 20 may be a flat substrate or a substrate having a curved shape. For example, the first and second outer substrates may be flat substrates at the same time, have a curved shape at the same time, or one may be a flat substrate and the other may be a curved substrate.

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

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

In addition, in relation to the first and second outer substrates, for example, when the curvature or radius of curvature on the front surface and the rear surface are different, the curvature or radius of curvature of the opposite surfaces, that is, in the case of the first outer substrate, the second The curvature or radius of curvature of the surface facing the outer substrate and the second outer substrate may be based on the curvature or radius of curvature of the surface facing the first outer substrate. In addition, if 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 may be the reference, or the smallest curvature or radius of curvature may be the reference, or the average curvature or average A radius of curvature may be a criterion.

The first and second outer substrates have a difference in curvature or radius of curvature of about 10% or less, 9% or less, 8% or less, 7% or less, 6% or less, 5% or less, 4% or less, 3% or less within, within 2%, or within about 1%. The difference in the curvature or radius of curvature is a numerical value calculated as 100×( _{C L} -CS )/CS _S when a large curvature or radius of curvature is C _L and a small radius or radius of curvature is C _S . In addition, the lower limit of the difference between the curvature or the radius of curvature is not particularly limited. Since the difference between the curvature or the radius of curvature of the first and second outer substrates may be the same, the difference between the curvature or the radius of curvature may be greater than or equal to about 0% or greater than about 0%.

When both the first and second outer substrates have curved surfaces, both curvatures may have the same sign. In other words, both the first and second outer substrates may be curved in the same direction. That is, in this 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 portion among the upper and lower portions of the first and second outer substrates.

A specific range of each curvature or radius of curvature of the first and second outer substrates is not particularly limited. In one example, each of the first and second outer substrates has a radius of curvature of about 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 about 900R or more, or about 10,000R or less. , 9,000R or less, 8,000R or less, 7,000R or less, 6,000R or less, 5,000R or less, 4,000R or less, 3,000R or less, 2,000R or less, 1900R or less, 1800R or less, 1,700R or less, 1,600R or less, 1,500 R or less, 1,400R or less, 1,300R or less, 1,200R or less, 1,100R or less, or about 1,050R or less. In the above, R means the degree of curvature of a circle having a radius of 1 mm. Thus, for example in the above, 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 first and second outer substrates have different curvatures, 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 larger curvature among them may be a substrate disposed in a direction of gravity rather than when an optical device is used.

If the curvature or radius of curvature of the first and second substrates is controlled as described above, even if the bonding force by the adhesive film to be described later falls, a net force that is the sum of the restoring force and gravity acts to prevent the opening, and autoclave (Autoclave) ) can withstand process pressures such as

The optical device of the present application may further include a polarizer and/or an adhesive film. 4 exemplarily shows an optical device according to an embodiment including a polarizer and an adhesive film. 4 , the optical device 100 includes a first outer substrate 20 , an adhesive film 40 , a liquid crystal element 10 , an adhesive film 40 , a polarizer 30 , and an adhesive film 40 . And it may have a structure in which the second outer substrate 20 is sequentially stacked.

As the polarizer 30, for example, an absorption-type linear polarizer, that is, a polarizer having a light absorption axis formed in one direction and a light transmission axis formed substantially perpendicular to the polarizer 30 may be used.

When it is assumed that the blocking state is implemented in the first alignment state of the liquid crystal element 10 of the polarizer 30, the average optical axis (vector sum of optical axes) of the first alignment state and the light absorption axis of the polarizer are The angle is between about 80 degrees and about 100 degrees, or between about 85 degrees and about 95 degrees, or is disposed in the optical device such that it is generally perpendicular, or between about 35 degrees and about 55 degrees or between about 40 degrees and about 50 degrees; It may be positioned on the optical device to be approximately 45 degrees.

Based on the alignment direction of the alignment layer, as described above, the alignment direction of the alignment layer formed on each side of the first and second substrate layers is an angle within the range of about -10 degrees to about 10 degrees, about -7 degrees to about The orientation direction of any one of the two alignment layers when an angle within a range of 7 degrees, an angle within a range of about -5 degrees to about 5 degrees, or an angle within a range of about -3 degrees to about 3 degrees, or approximately parallel to each other An angle between the polarizer and the light absorption axis of the polarizer may be about 80 degrees to about 100 degrees, or about 85 degrees to about 95 degrees, or may be substantially perpendicular.

In another example, the alignment directions of the two alignment layers are an angle within a range of about 80 degrees to about 100 degrees, an angle within a range of about 83 degrees to about 97 degrees, an angle within a range of about 85 degrees to about 95 degrees, or an angle of about 87 degrees to about 92 degrees. When the angle is within the range of degrees or is substantially perpendicular to each other, the angle between the alignment direction of the alignment layer disposed closer to the polarizer among the two alignment layers and the light absorption axis of the polarizer is about 80 degrees to about 100 degrees or about 85 degrees to about 95 degrees, or approximately vertical.

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

The optical device of the present application may include only one each of the liquid crystal element and the polarizer as described above. Accordingly, the optical device may include only one liquid crystal element and only one polarizer.

The adhesive film 40 is, for example, between the outer substrate 20 and the liquid crystal element 10, between the liquid crystal element 10 and the polarizer 30, and the polarizer 30, as shown in FIG. It may be present between the outer substrate 20 , and may be present on the side surfaces of the liquid crystal element 10 and the polarizer 30 , suitably on all sides.

Meanwhile, between the outer substrate 20 and the liquid crystal element 10 , between the liquid crystal element 10 and the polarizer 30 , between the polarizer 30 and the outer substrate 20 , and/or the liquid crystal element 10 . ) and the adhesive film positioned on the side of the polarizer 30 may be the same or different adhesive films.

The adhesive film 40 adheres the outer substrate 20 and the liquid crystal element 10 , the liquid crystal element 10 and the polarizer 30 , and the polarizer 30 and the outer substrate 20 to each other, and the liquid crystal element (10) and the polarizer 30 may be encapsulated. In the present application, the term encapsulation (or encapsulation) may mean covering the entire surface of the liquid crystal element and/or the polarizer with an adhesive film. For example, the structure may be implemented by laminating an outer substrate, a liquid crystal device, a polarizer, and an adhesive film according to a desired structure and then compressing in a vacuum state.

As the adhesive film 40, a known material may be used without particular limitation, for example, a known thermoplastic polyurethane adhesive film (TPU: Thermoplastic Polyurethane), TPS (Thermoplastic Starch), polyamide adhesive film, polyester It may be selected from an adhesive film, 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 as described above is not particularly limited, and may be, for example, in the range of about 200 μm to about 600 μm. In the above, the thickness of the adhesive film may include the thickness of the adhesive film between the outer substrate 20 and the liquid crystal device 10 , for example, an interval between the two; the thickness of the adhesive film between the liquid crystal element 10 and the polarizer 30, for example, the distance between the two; And the thickness of the adhesive film between the polarizer 30 and the outer substrate 20, for example, may be the distance between the two.

The optical device may further include any necessary configuration in addition to the above configuration, and for example, a known configuration such as a buffer layer, a retardation layer, an optical compensation layer, an antireflection layer or a hard coating layer may be included in an appropriate position.

The 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 method of manufacturing the optical device may include encapsulating a liquid crystal element and/or a polarizer between the first and second outer substrates disposed opposite to each other through an autoclave process using an adhesive film. there is.

The autoclave process may be performed by disposing an adhesive film, a liquid crystal device and/or a polarizer between the outer substrates according to a desired encapsulation structure, and heating/pressurizing.

As an example, the outer substrate 20 , the adhesive film 40 , the liquid crystal device 10 , the adhesive film 40 , the polarizer 30 , the adhesive film 40 , and the outer substrate 20 are disposed in the above order And, when the laminate in which the adhesive film 40 is disposed on the side surfaces of the liquid crystal element 10 and the polarizer 30 is also heated/pressurized in an autoclave process, an optical device as shown in FIG. 5 can be formed.

The conditions of the autoclave process are not particularly limited, and, for example, may be performed under an appropriate temperature and pressure depending on the type of the applied adhesive film. The temperature of a typical autoclaving process is about 80 °C or more, 90 °C or more, or about 100 °C or more, and the pressure is about 2 atmospheres or more, 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 about 170 °C or less, and the upper limit of the process pressure is about 10 atmospheres or less, 9 atmospheres or less, 8 atmospheres or less, 7 It may be below atmospheric pressure or about 6 atmospheres or less.

The optical device as described above may be used for various purposes, and for example, eyewear such as sunglasses or eyewear for AR (Argumented Reality) or VR (Virtual Reality), exterior walls of buildings or sunroofs for vehicles, etc. can be used

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

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

According to the present application, it is possible to provide an optical device in which transmittance is variable, and bubble generation is reduced even when an internal negative pressure is generated in an environment that changes between high and low temperatures, thereby improving appearance defects. Such an optical device may be used for various purposes such as sunglasses, eyewear such as AR (Argumented Reality) or VR (Virtual Reality) eyewear, exterior walls of buildings, or sunroofs for vehicles.

1 to 2 are exemplary cross-sectional views of liquid crystal elements that can be used in the optical device of the present application.
3 to 5 are exemplary cross-sectional views illustrating exemplary optical devices of the present application.
6 is an image taken using a digital camera after applying the optical devices manufactured according to Examples and Comparative Examples to a high-temperature long-term durability test.

Hereinafter, the present application will be described in detail through Examples and Comparative Examples, but the scope of the present application is not limited by the following Examples.

oxygen permeability

The oxygen transmittance was measured at a temperature of 23° C. and a relative humidity of 0% by the ASTM D 3985 method using an OX-TRAN manufactured by MOCON for the base layer used for manufacturing the liquid crystal device of Examples and Comparative Examples.

Visual defects Occurrence

Appearance defects were measured in a state in which the liquid crystal devices manufactured in Examples and Comparative Examples were encapsulated between the first and second outer substrates after the autoclave process. If the liquid crystal element encapsulated between the first and second outer substrates is subjected to a high-temperature long-term durability test (maintained for about 168 hours at a temperature of 100°C) and left at room temperature for more than 24 hours, whether bubbles are generated on the exterior of the optical device to measure the appearance defect of the optical device.

<Evaluation criteria>

○: bubble generation

X: No bubble generation

Example

liquid crystal element

A polyethylene terephthalate (PET) film having a thickness of about 100 μm to about 200 μm and an oxygen permeability of about 14.6 cm ³ /m ² *day*atm was used as the first and second substrate layers, and the first substrate layer and on the second base layer, each indium-tin-oxide (ITO) was deposited to a thickness of 200 nm to form a conductive layer. A horizontal alignment layer (SE-7492, Nissan Chemical) was coated on the conductive layer to a thickness of 100 nm to 300 nm and cured to form first and second alignment layers.

A liquid crystal device was manufactured by applying a sealant to the outer periphery of the first alignment layer, applying liquid crystal (MDA 14-4145, manufactured by Merck) to the inner region of the sealant, and laminating the second alignment layer. The area of the prepared liquid crystal device was 600 mmХ300 mm, and the cell gap was 12 μm.

optics device

The first outer substrate, the adhesive film, the liquid crystal element, the adhesive film, and the second outer substrate were laminated in the above order, and adhesive films were also placed on all sides of the liquid crystal element to prepare a laminate. (On the first outer substrate In contrast, the second outer substrate is placed in the direction of gravity)

A glass substrate having a thickness of about 3 mm was used as the first and second outer substrates, and a substrate having a radius of curvature of about 2,470R (first outer substrate) and a substrate having a radius of curvature of about 2,400R (second outer substrate) were used. ) was used. Meanwhile, as the adhesive film, a thermoplastic polyurethane adhesive film (thickness: about 0.38 mm, manufacturer: Argotec, product name: ArgoFlex) was used.

An optical device was manufactured by performing an autoclave process on the laminate at a temperature of about 100° C. and a pressure of about 2 atmospheres.

comparative example

As the first and second substrate layers of the liquid crystal element, the liquid crystal element and the optical device are the same as in Example except that polycarbonate (PC) films having an oxygen transmittance of about 1,048 cm ³ /m ² *day*atm are used, respectively. was prepared.

Table 1 below shows the oxygen transmittance for the base layer used for manufacturing the liquid crystal device of Examples and Comparative Examples and the measurement results of poor appearance of optical devices prepared in Examples and Comparative Examples.

Oxygen transmittance of the base layer
(cm ³ /m ² *day*atm) of optical devices
Whether there is an appearance defect Example about 14.6 X comparative example about 1,048 ○

6 is a photograph of the optical device after the durability test, on the left is a photograph of a device of an Example, and on the right is a photograph of a device of a comparative example. In the optical device of the embodiment, it can be confirmed that the optical device is stably manufactured without an appearance defect because bubbles are not generated on the appearance of the device even when an internal negative pressure is generated according to the temperature change. In contrast, the device of the comparative example has an appearance It can be confirmed that the appearance defect has occurred due to the generation of air bubbles.

10: liquid crystal element
11a: first base layer
11b: second base layer
12: liquid crystal layer
13: conductive layer
14: alignment layer
20: outer substrate
30: polarizer
40: adhesive film
100: optical device

Claims (14)

first and second outer substrates;
It is positioned between the first and second outer substrates, has a structure in which a first base layer, a liquid crystal layer, and a second base layer are sequentially stacked, and includes a conductive layer formed on the first base layer and the second base layer, respectively a liquid crystal device; and
An adhesive film positioned between the first outer substrate and the liquid crystal element and between the second outer substrate and the liquid crystal element and encapsulating the liquid crystal element,
At least one of the first base layer and the second base layer has an oxygen transmission rate of less than 100 cm ³ /m ² *day*atm,
An optical device in which the first base layer and the second base layer are each PET (polyethyleneterephtalate) film. The optical device of claim 1 , wherein the first substrate layer and the second substrate layer each have an oxygen transmission rate of less than 100 cm ³ /m ² *day*atm. The optical device according to claim 1, wherein the first base layer and the second base layer each have a thickness of 10 μm to 1,000 μm. The optical device according to claim 1, wherein the first base layer and the second base layer each have a crystallinity of 40% or more. delete The optical device of claim 1 , wherein the liquid crystal layer comprises a dichroic dye guest. delete The optical device according to claim 1, wherein the liquid crystal element includes an alignment film formed on the conductive layer. The optical device of claim 1, wherein the liquid crystal element is capable of switching first and second alignment states. delete The optical device of claim 1 , further comprising a polarizer positioned between the first and second outer substrates. delete The optical device of claim 11 , further comprising an adhesive film positioned between the first outer substrate and the liquid crystal element, between the liquid crystal element and the polarizer, and between the second outer substrate and the polarizer. a vehicle body in which one or more openings are formed; and the optical device of claim 1 mounted in the opening.

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