KR20200019350A - Optical Device - Google Patents

Abstract

The present application relates to an optical device. The optical device of the present application is variable in transmittance, and the bubble generation is reduced to improve an appearance defect of the optical device even when the negative pressure is generated in the optical device in an environment changed between the high temperature and the low temperature. The optical device can be used for various applications such as sunglasses, eyewear such as eyewear for argument reality (AR) or virtual reality (VR), sunroofs for exterior walls of buildings or vehicles, or the like.

Description

Optical device

The present application relates to an optical device.

Various optical devices designed to vary the transmittance using a liquid crystal compound are known in various ways.

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

The variable transmittance device is applied to various applications including eyewear such as sunglasses and glasses, exterior walls of buildings, or sunroofs of vehicles.

An object of the present application is to provide an optical device capable of varying transmittance and reducing bubble generation even when negative pressure is generated in an environment that varies between high and low temperatures, thereby improving appearance defects.

The present 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 illustrates a liquid crystal device according to an exemplary embodiment of the present application. As illustrated in FIG. 1, the liquid crystal device 10 may have a structure in which the first base layer 11a, the liquid crystal layer 12, and the second base layer 11b are sequentially stacked. In addition, the said 1st and 2nd expression does not prescribe | regulate the relationship of the base material layer up-and-down.

As one example, at least one of the first base layer 11a and the second base layer 11b constituting the liquid crystal element 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 and second substrate layers has an oxygen transmission rate of less than about 90 cm ³ / m ² * day * atm, less than 80 cm ³ / m ² * day * atm, 60 cm ³ / m ^It may be less than ² * day * atm or less than about 40 cm ³ / m ² * day * atm, and the lower limit is not particularly limited, but about 0 cm ³ / m ² or more * day * atm or about 1 cm ³ / m ² * It may be more than day * atm.

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

When the substrate layer satisfies the oxygen transmittance in the above range, the optical device including the substrate layer is externally introduced into the optical device even if negative pressure is generated inside the optical device in an environment that varies between a high temperature and a low temperature. The amount of air is reduced. Therefore, it is possible to reduce appearance defects of the optical device due to bubble generation 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 one example, the first substrate layer and the second substrate layer may each have an oxygen transmittance of less than 100 cm ³ / m ² * day * atm. When the oxygen transmittances of the first and second base layers satisfy the above ranges, appearance defects due to internal negative pressure of the optical device may be more efficiently reduced.

As one example, the first substrate layer and the second substrate layer may each have a thickness of about 10 μm to about 1,000 μm. As another example, the thickness of the substrate 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, about 900 μm or less, 800 μm or less, 700 μm or less, 600 μm or less, 500 μm or less, or about 400 μm or less.

When the thickness of the base material layer satisfies the above range, it is advantageous to have an oxygen transmittance of the base material layer in a range of less than 100 cm ³ / m ² * day * atm. Therefore, appearance defects caused by internal negative pressure of the optical device can be more efficiently reduced.

As one example, the first substrate layer and the second substrate layer may each have a crystallinity of about 40% or more. In another example, the degree of 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 may be about 100% or less, about 99% or less, or about It may be up to 98%.

The term crystallinity refers to the percentage (by weight) of the crystalline region included in the base layer, which can be measured by differential scanning calorimetry (Differential Scanning Calorimetry). In this process, the temperature increase rate was set at 10 ° C. per minute, the heat of fusion (ΔHf) was measured during the second temperature increase, and the polyvinylidene fluoride having a 100% crystallinity (ΔHf = Based on 105 J / g), the crystallinity of each base material layer can be calculated | required.

As one example, the first substrate layer and the second substrate layer is not particularly limited as long as the oxygen transmittance is less than about 100 cm ³ / m ² * day * atm and may be used as the substrate layer of the present application. In one embodiment, each of the first base layer and the second base layer is independently a polyethylene-naphthalate (PEN) film, a polyimide (PI) film, a cyclo-olefin polymer (COP) film, a tri-acetyl-cellulose (TAC) film, or PET (polyethyleneterephtalate) 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 embodiment, 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 guests are aligned according to an alignment direction of the liquid crystal compound (hereinafter, may be referred to as a liquid crystal host).

The orientation refers to the orientation of the optical axis, which may mean, for example, the long axis direction when the liquid crystal compound is rod-shaped, and the normal direction of the disc plane when the discotic shape is discotic. Can mean. On the other hand, when the optical axis includes a plurality of liquid crystal compounds having different optical axis directions in any alignment state, the optical axis may be defined as an average optical axis, in which case the average optical axis may mean a vector sum of the optical axes of the liquid crystal compounds. The orientation direction can be adjusted by the application of energy described below.

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

For example, a smectic liquid crystal compound, a nematic liquid crystal compound, or a cholesteric liquid crystal compound may be used as the liquid crystal host. In general, a nematic liquid crystal compound may be used. The term nematic liquid crystal compound has no regularity with respect to the position of the liquid crystal molecules, but all refers to liquid crystal compounds that can be arranged in order in the direction of the molecular axis, and such liquid crystal compounds may be in rod form or discotic form. Can be.

Such nematic liquid crystal compounds have a clearing point of, for example, 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. It may be selected to have a phase transition point in the above range, that is, a phase transition point from the nematic phase to the isotropic phase. In one example, the clearing point or 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 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 optical anisotropy (Δn) of about 0.01 or more or about 0.04 or more. The 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 those skilled in the art and can be freely selected from them.

 The liquid crystal layer contains 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 region, for example, in the wavelength range from 380 nm to 780 nm, at least in part or in full, and the term dichroic dye guest It may mean a material capable of absorbing light in at least 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 can be selected and used. In one embodiment, an azo dye or an anthraquinone dye may be used as the dichroic dye guest, and the liquid crystal layer may include one or two or more dyes in order to achieve light absorption in a wide wavelength range.

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 or more 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 the absorption of the polarization parallel to the long axis direction of the dye by the absorption of the polarization parallel to the direction perpendicular to the long axis direction. The dichroic dye guest is at least one wavelength, some range of wavelengths, or full range within the wavelength range of the visible region, for example within the wavelength range of about 380 nm to about 780 nm, or about 400 nm to about 700 nm. It may have the dichroic ratio at the wavelength.

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, the content of the dichroic dye guest based on the total weight of the liquid crystal host and 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 can be changed in consideration of the transmittance of the liquid crystal element described later, the solubility of the dichroic dye guest in the liquid crystal host, and the like.

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 known forms. Examples of the additive may include, but are not limited to, chiral dopants or stabilizers and the like.

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

The liquid crystal device may further include a conductive layer and / or an alignment layer. 2 exemplarily illustrates a liquid crystal device according to an exemplary 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 the second base layer 11b are 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 a surface facing the liquid crystal layer 12. The conductive layer 13 present on the surface of the base layer is configured to apply a voltage to the liquid crystal layer 12, and a known conductive layer may be applied without 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 that can be applied in the present application are not limited to the above, and any kind of conductive layer known in the art to be applied to the liquid crystal device 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 first be formed on one surface of the substrate layer, and the alignment layer 14 may be formed on the conductive layer 13.

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 particular limitation. Examples of the alignment film known in the art include a rubbing alignment film, a photoalignment film, and the like, and the alignment film that can be used in the present application is the above known alignment film, which is not particularly limited.

In order to achieve the alignment of the optical axis described above, the alignment direction of the alignment layer 14 may be controlled. For example, the alignment directions of the two alignment films formed on the respective surfaces of the first substrate layer and the second substrate layer that are disposed opposite each other are at an angle within the range of about -10 degrees to about 10 degrees, and about -7 degrees to about 7 degrees. 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 directions of the two alignment layers may be at 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 about 87 degrees to about 92 degrees. It may be at an angle within the range of the figures or approximately perpendicular to each other.

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

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

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

The higher the numerical value, the more advantageous the transmittance in the transmission mode, and the lower the transmittance in the blocking mode, the more advantageous the 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 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 linear light transmittance. The term linear light transmittance may be a ratio of light (direct light) transmitted through the liquid crystal device in the same direction as the incident direction to light incident on the liquid crystal device in a predetermined direction. In one example, the transmittance may be a result (normal light transmittance) measured with respect to light incident in a direction parallel to the surface normal of the liquid crystal device.

The light whose transmittance is controlled in the liquid crystal device of the present application may be ultraviolet rays, visible light or near infrared rays in the UV-A region. According to the definition generally used, ultraviolet rays in the UV-A region are used to mean radiation having a wavelength in the range of 320 nm to 380 nm, and visible light means radiation having a wavelength in the range of 380 nm to 780 nm. 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 can be designed such that a third mode can also be implemented which can exhibit any transmittance between the transmission modes of the transmission mode and the blocking mode.

The optical device of the present application may comprise a first and a second outer substrate. The above first and second expressions do not define the relationship between the top and bottom. In one 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, inorganic substrates such as glass or plastic substrates may be used independently. 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 films such as polyacrylate (PAR) or poly (methyl methacrylate), polycarbonate (PC) films, polyolefin films such as polyethylene (PE) or polypropylene (PP), polyvinyl alcohol (PVA) films, and polyimide (PI) films; Polysulfone (PSF) film; polyphenylsulfone (PPS) film; polyethersulfone (PES) film; polyetheretherketon (PEEK) film; polyetherimide (PEI) film; polyethylenenaphthatlate (PEN) film; polyethyleneterephtalate (PET) film; or fluorine resin film However, the present invention is not limited thereto, and the first and second outer substrates 20 may include a coating layer of gold, silver, or a silicon compound such as silicon dioxide or silicon monoxide, or a functional layer such as an antireflection layer. have.

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. In another example the thickness may be at least about 0.5 mm, at least 1 mm, at least 1.5 mm or at least about 2 mm, and at most about 10 mm, at most 9 mm, at most 8 mm, at most 7 mm, at most 6 mm, at most 5 mm. 4 mm or less, or about 3 mm or less.

The first and second outer substrates 20 may be flat substrates or curved substrates. For example, the first and second outer substrates may be simultaneously flat substrates, simultaneously curved surfaces, 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.

The curvature or radius of curvature herein can be measured in a manner known in the art, for example, a non-contact type such as a 2D Profile Laser Sensor, a Chromatic confocal line sensor, or a 3D Measuring Conforcal Microscopy. Can be measured with the instrument. Methods of measuring the curvature or radius of curvature using such equipment are well known.

Further, in relation to the first and second outer substrates, for example, when the curvature or the radius of curvature at the surface and the rear surface are different, respectively, the curvature or the radius of curvature of the opposing surfaces, that is, the second outer substrate, the second In the case of the curvature or curvature radius of the surface facing the outer substrate and the second outer substrate, the curvature or curvature radius of the surface facing the first outer substrate may be a reference. In addition, if the curvature or curvature radius on the surface is not constant and different portions exist, 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 The radius of curvature may be a reference.

The first and second outer substrates have a difference in curvature or radius of curvature of about 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%. Within 2% or within about 1%. The difference between the curvature or the radius of curvature is a numerical value calculated as 100 × (C _L -C _S ) / C _S when a large curvature or a radius of curvature is referred to as C _L and a small curvature or radius of curvature is referred to as 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 in curvature or radius of curvature of the first and second outer substrates may be the same, the difference in curvature or radius of curvature may be at least about 0% or greater than about 0%.

If both the first and second outer substrates are curved, the curvature of both may be the same. In other words, both the first and second outer substrates may be curved in the same direction. That is, in this case, the center of curvature of the first outer substrate and the center of curvature of the second outer substrate are both present at the same portion among upper and lower portions of the first and second outer substrates.

The specific range of each curvature or radius of curvature of the first and second outer substrates is not particularly limited. In one example, the first and second outer substrates each have 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, 1,900R or less, 1,800R or less, 1,700R or less, 1,600R or less, 1,500 It may be 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 bending of a circle having a radius of 1 mm. Thus, for example, 100R is the degree of curvature of a circle with a radius of 100 mm or the radius of curvature for that circle. Of course, if 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 radius of curvature in 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 larger 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 large curvature may be a substrate disposed in a gravity direction when the optical device is used.

By controlling the curvature or the radius of curvature of the first and second substrates as described above, even if the bonding force is reduced by the adhesive film to be described later, the net force that is the sum of the restoring force and the gravity can act to prevent the gap, and autoclave (Autoclave) It 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. As shown in FIG. 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 a second outer substrate 20 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 thereto may be used.

When the polarizer 30 assumes that the blocking state is implemented in the first alignment state of the liquid crystal device 10, the average optical axis (vector sum of the optical axes) of the first alignment state and the light absorption axis of the polarizer An angle of about 80 degrees to about 100 degrees or about 85 degrees to about 95 degrees, or disposed in the optical device to be approximately perpendicular, or about 35 degrees to about 55 degrees or about 40 degrees to about 50 degrees May be disposed in the optical device to be approximately 45 degrees.

Based on the alignment direction of the alignment film, as described above, the alignment directions of the alignment films formed on the respective surfaces of the first and second substrate layers are each in the range of about -10 degrees to about 10 degrees, about -7 degrees to about Orientation direction of any one of the two alignment films when the angle is in the range of 7 degrees, the angle is in the range of about -5 degrees to about 5 degrees, or the angle is in the range of about -3 degrees to about 3 degrees or is substantially parallel to each other. And an angle formed by 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 approximately vertical.

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

The kind of the polarizer which can be applied in the optical device of the present application is not particularly limited. For example, the polarizer may be a conventional material used in conventional LCDs, for example, a PVA (poly (vinyl alcohol)) polarizer, a lyotropic liquid crystal (LLC), or a reactive liquid crystal (RM). A polarizer implemented by a coating method, such as a polarizing coating layer including a mesogen and a dichroic dye, may be used. In the present specification, the polarizer implemented as a coating method as described above may be referred to as a polarizing coating layer. As the breast liquid crystal, a known liquid crystal may be used without particular limitation. For example, a breast liquid crystal capable of forming a breast liquid crystal layer having a dichroic ratio of about 30 to about 40 may be used. have. Meanwhile, when the polarizing coating layer includes a reactive liquid crystal (RM) and a dichroic dye, a linear dye or a discotic dye may be used as the dichroic dye. It may be.

The optical device of the present application may include only one liquid crystal element and one polarizer, respectively. Thus, the optical device may include only one liquid crystal element and only one polarizer.

For example, the adhesive film 40 may be disposed 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. 4. It may be present between the outer substrate 20, and may exist on the sides of the liquid crystal element 10 and the polarizer 30, and preferably 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 film.

The adhesive film 40 bonds the outer substrate 20 and the liquid crystal element 10, the liquid crystal element 10, the polarizer 30, and the polarizer 30 and the outer substrate 20 to each other. 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 device and / or polarizer with an adhesive film. For example, according to the desired structure, the structure can be implemented by laminating the outer substrate, the liquid crystal device, the polarizer, and the adhesive film and then compressing the same in a vacuum state.

As the adhesive film 40, a known material may be used without particular limitation, and 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 a range of about 200 μm to about 600 μm. Wherein the thickness of the adhesive film is the thickness of the adhesive film between the outer substrate 20 and the liquid crystal element 10, for example, the gap between the two; Thickness of the adhesive film between the liquid crystal element 10 and the polarizer 30, for example, the gap between the two; And a thickness of the adhesive film between the polarizer 30 and the outer substrate 20, for example, the gap between the polarizer 30 and the outer substrate 20.

In addition to the above configuration, the optical device may further include any necessary configuration, and may include, 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 at an appropriate position.

The method for 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 encapsulation described above.

For example, the method of manufacturing the optical device may include encapsulating the liquid crystal element and / or polarizer between the first and second outer substrates disposed oppositely through an autoclave process using an adhesive film. have.

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

As an example, the outer substrate 20, the adhesive film 40, the liquid crystal element 10, the adhesive film 40, the polarizer 30, the adhesive film 40, and the outer substrate 20 are arranged in the above order. In addition, 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 heated / pressurized by an autoclave process, an optical device as shown in FIG. 5 may be formed.

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

Such an optical device may be used for various purposes, for example, sunglasses, eyewear such as AR (Argumented Reality) or VR (Virtual Reality) eyewear, building exterior walls, vehicle sunroofs, etc. Can be used.

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

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

The present application can provide an optical device capable of varying transmittance and reducing bubble generation even when internal negative pressure is generated in an environment varying between a high temperature and a low temperature, thereby improving appearance defects. Such an optical device may be used for various applications such as sunglasses or eyewear such as AR (Argumented Reality) or VR (Virtual Reality) eyewear, an exterior wall of a building, or a sunroof for a vehicle.

1 to 2 are exemplary cross-sectional views of liquid crystal elements that can be used in the optical device of the present application.
3-5 are exemplary cross-sectional views illustrating exemplary optical devices of the present application.
6 is an image photographed using a digital camera after the optical device manufactured according to the Examples and Comparative Examples is subjected 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 transmittance

Oxygen transmittance was measured at 23 degreeC and the relative humidity of 0% by the ASTM D 3985 system using OX-TRAN by MOCON about the base material layer used for liquid crystal element manufacture of an Example and a comparative example.

Visual defects Occurrence

The appearance defect was measured in the 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. The liquid crystal element encapsulated between the first and second outer substrates is subjected to a high temperature long-term durability test (maintaining about 168 hours at a temperature of 100 ° C.), and bubbles are formed on the appearance of the optical device when left at room temperature for 24 hours or more. The appearance defect of the optical device was measured.

<Evaluation Criteria>

○: bubble generation

X: Bubble not generated

Example

Liquid crystal elements

Polyethylene terephthalate (PET) films 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 were used as the first and second base layers, respectively. And indium-tin-oxide (ITO) on the second base layer, respectively, was deposited to a thickness of 200 nm to form a conductive layer. A horizontal alignment layer (SE-7492, Nissan Chemical Co., Ltd.) was coated and cured to a thickness of 100 nm to 300 nm on the conductive layer to form first and second alignment layers.

The sealant was apply | coated to the outer periphery of a 1st alignment film, the liquid crystal (MDA14-4145, Merck company make) was apply | coated to the inner region of the said sealant, and the 2nd alignment film was laminated | stacked, and the liquid crystal element was manufactured. The area of the prepared liquid crystal device is 600 mm Х 300 mm, and the cell gap is 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 this order, and the adhesive film was also disposed on all sides of the liquid crystal element to prepare a laminate. Compared to the second outer substrate 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) ) Was used. Meanwhile, a thermoplastic polyurethane adhesive film (thickness: about 0.38 mm, manufacturer: Argotec, product name: ArgoFlex) was used as the adhesive film.

The laminate was subjected to an autoclave process at a temperature of about 100 ° C. and a pressure of about 2 atmospheres to prepare an optical device.

Comparative example

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

Table 1 below shows oxygen transmittance and appearance defect measurement results of optical devices manufactured in Examples and Comparative Examples with respect to the substrate layer used in manufacturing the liquid crystal elements of Examples and Comparative Examples.

Oxygen transmittance of the base layer
(cm ³ / m ² * day * atm) Of optical device
Poor appearance Example About 14.6 X Comparative example 1,048 approx. ○

6 is a photograph of the optical device after the durability test, the left side of which is a device photograph of an example, and the right side of a device photograph of a comparative example. In the optical device of the embodiment, even if internal negative pressure occurs due to temperature change, bubbles are not generated in the external appearance of the device, so that the optical device can be stably manufactured without appearance defects. It can be seen that bubbles are generated in the appearance defects.

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

Claims (14)

A liquid crystal element having a structure in which a first base material layer, a liquid crystal layer, and a second base material layer are sequentially stacked;
At least one of the first substrate layer and the second substrate layer has an oxygen transmission rate of less than 100 cm ³ / m ² * day * atm. The optical device of claim 1, wherein the first and second substrate layers each have an oxygen transmission rate of less than 100 cm ³ / m ² * day * atm. The optical device of claim 1, wherein the first substrate layer and the second substrate layer each have a thickness of 10 μm to 1,000 μm. The optical device of claim 1, wherein the first substrate layer and the second substrate layer each have a crystallinity of 40% or more. The method of claim 1, wherein the first substrate layer and the second substrate layer are each independently a polyethylene-naphthalate (PEN) film, a polyimide (PI) film, a cyclo-olefin polymer (COP) film, tri-acetyl-cellulose (TAC) Optical device that is a film or polyethyleneterephtalate (PET) film. The optical device of claim 1, wherein the liquid crystal layer comprises a dichroic dye guest. The optical device according to claim 1, wherein the liquid crystal element comprises a conductive layer formed on the first base layer and the second base layer, respectively. The optical device according to claim 7, wherein the liquid crystal element comprises 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. The optical device of claim 1, comprising a first and second outer substrate, wherein the liquid crystal element is located between the first and second outer substrate. The optical device of claim 10, further comprising a polarizer positioned between the first and second outer substrates. The optical device according to claim 10, further comprising an adhesive film positioned between the first outer substrate and the liquid crystal element and between the second outer substrate and the liquid crystal source. 12. 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 having one or more openings formed therein; And the optical device of claims 1 to 13 mounted to the opening.

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