Optical device

Abstract

This application relates to an optical device. The optical device of this application can maintain an appropriate cell gap of the liquid crystal element, has excellent adhesion between the upper substrate and the lower substrate, and can solve the light leakage caused by the phenomenon of liquid crystal alignment disorder occurring during an external impact.

Description

Technical Field

[0001] This application relates to an optical device.

[0002] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0070893, filed on June 10, 2022, and all the contents disclosed in the corresponding Korean patent application are incorporated herein by reference.

Background Art

[0003] For the long-term stability and large-area expandability of a liquid crystal film cell using a flexible substrate, it is important to maintain the cell gap between the upper substrate and the lower substrate and to provide an adhesive force between the upper substrate and the lower substrate.

[0004] Non-Patent Document 1 (「Tight Bonding of Two Plastic Substrates for Flexible LCDs」 SID Symposium Digest, 38, pp.653-656 (2007)) discloses a technique of forming an organic film pattern in the form of columns or walls with a cell gap height on one side substrate and fixing it to the opposite side substrate using an adhesive. However, in such a technique, the adhesive must be located only on the column surface or the wall surface. However, the technique of micro-stamping the adhesive on the column surface or the wall surface has a high process difficulty, it is difficult to control the thickness and area of the adhesive, and there is a high possibility that the adhesive will be extruded out when the upper and lower substrates are joined, and there is a risk that the adhesive will contaminate the alignment film or the liquid crystal.

Summary of the Invention

Problems to be Solved by the Invention

[0005] In order to maintain the cell gap of the liquid crystal cell and ensure the adhesion between the upper substrate and the lower substrate, it can be considered to form a spacer and an alignment film on the lower substrate, and after forming an adhesive layer having both a liquid crystal alignment force and an adhesion force on the upper substrate, the substrates are joined together. However, when assuming the case where the liquid crystal cell is mounted on a mobile vehicle, when passing through a road surface with severe bumps and unevenness, there is a problem of light leakage due to a temporary phenomenon of liquid crystal alignment disorder occurring during an external impact.

[0006] An object of the present application is to provide an optical device in which the cell gap of a liquid crystal cell is appropriately maintained, the upper substrate and the lower substrate have excellent adhesion, and light leakage due to a liquid crystal alignment disorder phenomenon occurring during an external impact can be solved.

Means for Solving the Problem

[0007] Among the physical properties referred to in this specification, when the measurement temperature affects the result, unless otherwise specified separately, the relevant physical property is the physical property measured at room temperature. The term room temperature is the natural temperature without being heated or warmed, and is usually a temperature within the range of about 10°C to 30°C or about 23°C or about 25°C. Also, unless otherwise specifically mentioned in this specification, the unit of temperature is °C. Among the physical properties referred to in this specification, when the measurement pressure affects the result, unless otherwise specified separately, the relevant physical property is the physical property measured at normal pressure. The term normal pressure is the natural pressure without being pressurized or depressurized, and usually about 1 atmosphere is referred to as normal pressure.

[0008] The present application relates to an optical device. The optical device of the present application can sequentially include a first outer substrate; a liquid crystal cell and a second outer substrate. The liquid crystal cell can include an upper substrate, a lower substrate, and a liquid crystal layer containing a liquid crystal compound between the upper substrate and the lower substrate. The upper substrate can include a first base material layer and an adhesive layer. The lower substrate can include a second base material layer and a spacer. The first base material layer can be disposed closer to the first outer substrate than the second base material layer, and the second base material layer can be disposed closer to the second outer substrate than the first base material layer.

[0009] The optical device of the present application can include a first buffer layer located between a first base material layer and a first outer substrate. The liquid crystal cell can have a structure in which an adhesive layer capable of alignment and a spacer are adjacent to each other. In the case of such a structure, due to the low elastic modulus of the adhesive layer, it is vulnerable to external pressure, deformation occurs due to instantaneous pressure, and the alignment of the liquid crystal vertically aligned by the corresponding deformation may be disturbed, resulting in light leakage. According to the present application, by introducing a buffer layer between the outer substrate and the liquid crystal cell, external impact can be absorbed, and the defect of the occurrence of the light leakage can be suppressed. In particular, by applying a buffer layer having a loss elastic modulus even lower than that of the adhesive layer inside the liquid crystal cell as the buffer layer, the defect of the occurrence of the light leakage can be effectively suppressed.

[0010] In one example, the loss modulus of the adhesive layer at a temperature of 25°C and a frequency of 1 Hz can be in the range of 50,000 Pa to 2 MPa. Specifically, the loss modulus can be 100,000 Pa or more, 300,000 Pa or more, 500,000 Pa or more, 700,000 Pa or more, or 900,000 Pa or more, and can be 1.8 MPa or less, 1.6 MPa or less, 1.4 MPa or less, 1.2 MPa or less, or 1.0 MPa or less. In one example, the storage modulus of the adhesive layer at a temperature of 25°C and a frequency of 1 Hz can be in the range of 0.2 MPa to 10 MPa. Specifically, the storage modulus of the adhesive layer can be 0.3 MPa or more, 0.4 MPa or more, 0.5 MPa or more, 0.6 MPa or more, or 0.7 MPa or more, and can be 8 MPa or less, 6 MPa or less, 4 MPa or less, 2 MPa or less, or 1 MPa or less. The storage modulus and loss modulus of the adhesive layer are in the range of 0.6 rad / sec to 100 rad / sec, and the values can increase as the frequency increases. For example, the storage modulus and loss modulus of the adhesive layer at a temperature of 25°C and a frequency of 10 Hz may be higher than the storage modulus and loss modulus of the adhesive layer at a temperature of 25°C and a frequency of 1 Hz, respectively. The loss modulus and storage modulus of the adhesive layer at a temperature of 25°C and a frequency of 10 Hz can each independently be in the range of 1 MPa to 10 MPa. The loss modulus and storage modulus of the adhesive layer can each independently be 1.5 MPa or more, and can be 10 MPa or less, 8 MPa or less, 6 MPa or less, 4 MPa or less, or 2 MPa or less. If the loss and / or storage modulus of the adhesive layer inside the liquid crystal cell is excessively low, it may be difficult to maintain the cell gap of the liquid crystal cell. If the loss and / or storage modulus of the adhesive layer inside the liquid crystal cell is excessively high, it may be difficult to impart an adhesive effect. Therefore, it may be advantageous for the loss and / or storage modulus to be within the above range. In one example, under the same frequency condition, the storage modulus of the adhesive layer can have a higher value than the loss modulus.

[0011] In one example, the loss elastic modulus of the first buffer layer at a temperature of 25°C and a frequency of 1 Hz can be in the range of 1,000 Pa to 500,000 Pa. Specifically, the loss elastic modulus can be 3,000 Pa or more, 5,000 Pa or more, 7,000 Pa or more, 9,000 Pa or more, 10,000 Pa or more, 15,000 Pa or more, 20,000 Pa or more, 30,000 Pa or more, 40,000 Pa or more, or 50,000 Pa or more, and can be 400,000 Pa or less, 300,000 Pa or less, 200,000 Pa or less, 100,000 Pa or less, 80,000 Pa or less, 60,000 Pa or less, 40,000 Pa or less, 20,000 Pa or less, or 10,000 Pa or less. In one example, the storage elastic modulus of the first buffer layer at a temperature of 25°C and a frequency of 1 Hz can be in the range of 100 Pa to 500,000 Pa. Specifically, the storage elastic modulus of the first buffer layer can be 1,000 Pa or more, 10,000 Pa or more, 30,000 Pa or more, 50,000 Pa or more, 70,000 Pa or more, 90,000 Pa or more, or 11,000 Pa or more, and can be 400,000 Pa or less, 300,000 Pa or less, 200,000 Pa or less, 150,000 Pa or less, 100,000 Pa or less, 80,000 Pa or less, 60,000 Pa or less, or 50,000 Pa or less. The loss elastic modulus and the storage elastic modulus of the first buffer layer are in the range of 0.6 rad / sec to 100 rad / sec, and the values can increase as the frequency increases. For example, the loss elastic modulus and the storage elastic modulus of the first buffer layer at a temperature of 25°C and a frequency of 10 Hz may be higher than the loss elastic modulus and the storage elastic modulus at a temperature of 25°C and a frequency of 1 Hz, respectively. The loss elastic modulus and the storage elastic modulus of the first buffer layer at a temperature of 25°C and a frequency of 10 Hz can each independently be in the range of 10,000 Pa to 500,000 MPa. Specifically, the loss elastic modulus of the first buffer layer at a frequency of 10 Hz can be 15,000 Pa or more, and can be 400,000 Pa or less, 300,000 Pa or less, 200,000 Pa or less, 100,000 Pa or less, 80,000 Pa or less, 60,000 Pa or less, 40,000 Pa or less, or 20,000 Pa or less.Specifically, the storage elastic modulus of the first buffer layer at a frequency of 10 Hz can be 30,000 Pa or more, 50,000 Pa or more, and can be 400,000 Pa or less, 300,000 Pa or less, 200,000 Pa or less, 150,000 Pa or less, 100,000 Pa or less, 80,000 Pa or less, or 70,000 Pa or less. When the loss and / or storage elastic modulus of the first buffer layer is excessively low, it may be difficult to fabricate it to an appropriate thickness, and problems may occur in subsequent processes such as glue leakage. When the loss and / or storage elastic modulus of the first buffer layer is excessively high, it may be insufficient to absorb external shocks applied to the liquid crystal cell. Therefore, it may be appropriate for the loss and / or storage elastic modulus of the first buffer layer to be within the above range. In one exemplary case, the storage elastic modulus of the first buffer layer can have a higher value compared to the loss elastic modulus under the same frequency conditions.

[0012] The first outer substrate and the second outer substrate can each independently be an inorganic substrate or a plastic substrate. The inorganic substrate is not particularly limited, and a known inorganic substrate can be used. As an example, a glass substrate with excellent light transmissibility can be used as the inorganic substrate. As the glass substrate, for example, a soda-lime glass substrate, a general toughened glass substrate, a borosilicate glass substrate, or a non-alkali glass substrate, etc. can be used, but it is not limited thereto. As the polymer substrate, a cellulose film such as TAC (triacetyl cellulose) or DAC (diacetyl cellulose); a COP (cyclo olefin copolymer) film such as a norbornene derivative; an acrylic film such as PAR (Polyacrylate) or PMMA (poly(methyl methacrylate)); a PC (polycarbonate) film; a polyolefin film such as PE (polyethylene) or PP (polypropylene); a PVA (polyvinyl alcohol) film; a PI (polyimide) film; a sulfone-based film such as a PSF (polysulfone) film, a PPS (polyphenylsulfone) film, or a PES (polyethersulfone) film; a PEEK (polyetheretherketon) film; a PEI (polyetherimide) film; a polyester-based film such as a PEN (polyethylenenaphthalate) film or a PET (polyethyleneterephtalate) film; or a fluororesin film, etc. can be used, but it is not limited thereto. The first outer substrate and the second outer substrate may each have a functional layer such as a coating layer of silicon compounds such as gold, silver, or silicon dioxide or silicon monoxide, or an antireflection layer, as required.

[0013] In one example, the first outer substrate and / or the second outer substrate can be a glass substrate.

[0014] The thickness of the first outer substrate and the second outer substrate can each be about 0.3 mm or more. In other examples, the thickness can be about 0.5 mm or more, 1 mm or more, 1.5 mm or more, or about 2 mm or more, and may be 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.

[0015] The first outer substrate and the second outer substrate can be flat substrates or substrates having a curved surface. For example, the first outer substrate and the second outer substrate can be flat substrates simultaneously, have a curved surface simultaneously, or one of them can be a flat substrate and the other can be a curved substrate. Also, when they have a curved surface simultaneously, the curvature or radius of curvature of each can be the same or different. In this specification, the curvature or radius of curvature can be measured by a method known in the industry. For example, it can be measured using non-contact equipment such as a 2D Profile Laser Sensor (laser sensor), a Chromatic confocal line sensor (confocal sensor), or 3D Measuring Confocal Microscopy. The method of measuring the curvature or radius of curvature using such equipment is known.

[0016] Regarding the first outer substrate and the second outer substrate, for example, when the curvature or radius of curvature is different between the front and back surfaces, the curvature or radius of curvature of the opposing surfaces, that is, in the case of the first outer substrate, the curvature or radius of curvature of the surface opposing the second outer substrate, and in the case of the second outer substrate, the curvature or radius of curvature of the surface opposing the first outer substrate can be used as a reference. Also, when there are portions where the curvature or radius of curvature on the corresponding surface is not constant and different, the largest curvature or radius of curvature can be used as a reference, the smallest curvature or radius of curvature can be used as a reference, or the average curvature or average radius of curvature can be used as a reference.

[0017] The difference in curvature or radius of curvature between the first outer substrate and the second outer substrate can be within about 10%, within 9%, within 8%, within 7%, within 6%, within 5%, within 4%, within 3%, within 2%, or within about 1%. The difference in curvature or radius of curvature is a numerical value calculated as 100×(CL - CS) / CS, where CL is the larger curvature or radius of curvature and CS is the smaller curvature or radius of curvature. Also, 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 between the first and second outer substrates can be the same, the difference in curvature or radius of curvature can be about 0% or more, or can exceed about 0%. Control of the curvature or radius of curvature as described above is useful in a structure where a liquid crystal cell and an adhesive layer are in contact, such as the optical device of the present application. That is, when the difference in curvature or radius of curvature exceeds 10%, when the outer substrate and the liquid crystal cell are in contact with the adhesive layer described later, a problem may occur in that the combined outer substrate spreads due to a decrease in the bonding force. However, when it is controlled within 10%, the problem that the combined outer substrate spreads due to a decrease in the bonding force can be efficiently prevented.

[0018] The first outer substrate and the second outer substrate can have the same sign of curvature. In other words, the first and second outer substrates may both be bent in the same direction. That is, in the above case, the centers of curvature of the first outer substrate and the second outer substrate both exist in the same part among the upper and lower parts of the first and second outer substrates. When the first outer substrate and the second outer substrate are bent in the same direction, the first and second outer substrates can be adhered more efficiently with an adhesive layer, and a decrease in the bonding force between the first and second outer substrates and the liquid crystal cell and / or polarizer after adhesion can be more efficiently prevented.

[0019] The specific ranges of the curvature or radius of curvature of the first outer substrate and the second outer substrate are 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, 1,500R or less, 1,400R or less, 1,300R or less, 1,200R or less, 1,100R or less, or about 1,050R or less. Here, R means the degree of curvature of a circle with a radius of 1 mm. Therefore, for example, 100R is the degree of curvature of a circle with a radius of 100 mm or the radius of curvature with respect to such a circle. The first and second outer substrates can 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 with the larger curvature can be within the above range. In one example, when the curvatures of the first and second outer substrates are different from each other, the substrate with the larger curvature can be the substrate arranged in the direction of gravity during the use of the optical device. When the curvature or radius of curvature of the first and second outer substrates is controlled as described above, even if the adhesive force by the adhesive layer described later decreases, the net force, which is the sum of the restoring force and gravity, acts to prevent spreading.

[0020] The optical device can further include at least one or more adhesive layers located between the first outer substrate and the liquid crystal cell and between the second outer substrate and the liquid crystal cell.

[0021] In one example, the optical device can further include a first adhesive layer in contact with the inner surface of the first outer substrate and a second adhesive layer in contact with the inner surface of the second outer substrate. As used herein, the inner surface of the first outer substrate may mean the surface facing the liquid crystal cell of the first outer substrate, and the inner surface of the second outer substrate may mean the surface facing the liquid crystal cell of the second outer substrate. As used herein, when A is in contact with B, it may mean a state where A and B are in direct contact without an intermediate between them. The surface of the first adhesive layer that is not in contact with the first outer substrate may be in contact with a first polarizer or a first buffer layer described later. The surface of the second adhesive layer that is not in contact with the second outer substrate may be in contact with a second polarizer or a second buffer layer described later.

[0022] In one example, the loss elastic modulus of the first adhesive layer and the second adhesive layer may be higher than the loss elastic modulus of the adhesive layer inside the liquid crystal cell, respectively. Also, the storage elastic modulus of the first adhesive layer and the second adhesive layer may be higher than the storage elastic modulus of the adhesive layer, respectively. When the storage elastic modulus or loss elastic modulus of the first adhesive layer and the second adhesive layer is excessively low, it may not be possible to control the thermal behavior of the film during the durability process, and appearance defects may occur. In one example, the loss elastic modulus of the first adhesive layer and the second adhesive layer at a temperature of 25°C and a frequency of 1 Hz may be within the range of 1 MPa to 100 MPa, respectively. Specifically, the loss elastic modulus may be 80 MPa or less, 60 MPa or less, 40 MPa or less, 20 MPa or less, 10 MPa or less, 8 MPa or less, 6 MPa or less, 4 MPa or less, or 2 MPa or less. In one example, the storage elastic modulus of the first adhesive layer and the second adhesive layer at a temperature of 25°C and a frequency of 1 Hz may be within the range of 1 MPa to 100 MPa, respectively. Specifically, the storage elastic modulus may be 2 MPa or more or 3 MPa or more, and may be 80 MPa or less, 60 MPa or less, 40 MPa or less, 20 MPa or less, 10 MPa or less, 8 MPa or less, 6 MPa or less, or 4 MPa or less. The storage elastic modulus and loss elastic modulus of the adhesive layer are within the range of 0.6 rad / sec to 100 rad / sec, and the value may increase as the frequency increases. For example, the storage elastic modulus and loss elastic modulus of the first adhesive layer and the second adhesive layer at a temperature of 25°C and a frequency of 10 Hz may be higher than the storage elastic modulus and loss elastic modulus at a temperature of 25°C and a frequency of 1 Hz, respectively. The loss elastic modulus and storage elastic modulus of the first adhesive layer and the second adhesive layer at a temperature of 25°C and a frequency of 10 Hz may be independently within the range of 1 MPa to 100 MPa, respectively. The storage elastic modulus of the first adhesive layer and the second adhesive layer may be specifically 2 MPa or more, 4 MPa or more, or 6 MPa or more, and may be 80 MPa or less, 60 MPa or less, 40 MPa or less, 20 MPa or less, 10 MPa or less, or 8 MPa or less. The loss elastic modulus of the first adhesive layer and the second adhesive layer may be specifically 2 MPa or more or 3 MPa or more, and may be 80 MPa or less, 60 MPa or less, 40 MPa or less, 20 MPa or less, 10 MPa or less, 8 MPa, 6 MPa or less, or 4 MPa or less.In one example, the storage elastic modulus of the first adhesive layer and the second adhesive layer under the same frequency condition can have values higher than the loss elastic modulus of the first adhesive layer and the second adhesive layer, respectively.

[0023] In one example, the first buffer layer can be in contact with the outer surface of the first base layer. As used herein, the outer surface of the first base layer can mean the surface facing the first outer contour substrate of the first base layer.

[0024] In another example, the first buffer layer can be in contact with the inner surface of the first adhesive layer. As used herein, the inner surface of the first adhesive layer can mean the surface facing the liquid crystal cell of the first adhesive layer.

[0025] In one example, the optical device can further include a third adhesive layer in contact with the outer surface of the first base layer and a fourth adhesive layer in contact with the outer surface of the second base layer. As used herein, the outer surface of the second base layer can mean the surface facing the second outer contour substrate of the second base layer. The surface of the third adhesive layer that does not contact the first base layer may be in contact with a first polarizer described below. The surface of the fourth adhesive layer that does not contact the second base layer may be in contact with a second polarizer described below.

[0026] The third adhesive layer can be located between the first polarizer and the liquid crystal cell, and the fourth adhesive layer can be located between the second polarizer and the liquid crystal cell. At this time, the thickness of the third adhesive layer and / or the fourth adhesive layer can be 380 μm or less, respectively. Through this, the separation distance between the first polarizer and the second polarizer can be minimized to reduce light leakage, and the structural safety of the optical device can be ensured. The lower limit of the thickness of the third adhesive layer and / or the fourth adhesive layer can be 10 μm or more, respectively.

[0027] The loss elastic modulus of the third adhesive layer and the fourth adhesive layer may each be higher than that of the adhesive layer. Also, the storage elastic modulus of the third adhesive layer and the fourth adhesive layer may each be higher than that of the adhesive layer. If the storage elastic modulus or loss elastic modulus of the third adhesive layer and the fourth adhesive layer is excessively low, the thermal behavior of the film cannot be controlled during the durability process, and there may be an appearance defect. In one example, the storage elastic modulus of the third adhesive layer and the fourth adhesive layer may each be in the range of 1 MPa to 100 MPa. In one example, the loss elastic modulus of the third adhesive layer and the fourth adhesive layer may each be in the range of 1 MPa to 100 MPa. The specific content regarding the loss elastic modulus or storage elastic modulus of the third and fourth adhesive layers may be equally applicable to the content described for the first and second adhesive layers.

[0028] The optical device may further include a first polarizer located between the first outer substrate and the liquid crystal cell and a second polarizer located between the second outer substrate and the liquid crystal cell. As used herein, the term "polarizer" means a film, sheet, or element having a polarization function. A polarizer is a functional element capable of extracting light vibrating in one side direction from incident light vibrating in various directions.

[0029] The first polarizer and the second polarizer may each be an absorption-type polarizer or a reflection-type polarizer. As used herein, an absorption-type polarizer means an element that exhibits selective transmission and absorption characteristics with respect to incident light. A polarizer can, for example, transmit light vibrating in any one direction from incident light vibrating in various directions and absorb light vibrating in the remaining directions. As used herein, a reflection-type polarizer means an element that exhibits selective transmission and reflection characteristics with respect to incident light. A polarizer can, for example, transmit light vibrating in any one direction from incident light vibrating in various directions and reflect light vibrating in the remaining directions. According to one embodiment of the present application, the polarizer may be an absorption-type polarizer.

[0030] The first polarizer and the second polarizer can each be a linear polarizer. As used herein, a linear polarizer means a linearly polarized light in which the light that is selectively transmitted vibrates in one direction, and a linearly polarized light in which the light that is selectively absorbed or reflected vibrates in a direction perpendicular to the vibration direction of the linearly polarized light. In the case of an absorption-type linear polarizer, the optical transmission axis and the optical absorption axis can be perpendicular to each other. In the case of a reflection-type linear polarizer, the optical transmission axis and the optical reflection axis can be perpendicular to each other.

[0031] In one example, the first polarizer and the second polarizer can each be a polymer stretched film dyed with iodine or an anisotropic dye. Examples of the polymer stretched film include a PVA (poly(vinyl alcohol)) stretched film. In another example, the first polarizer and the second polarizer can each be a guest-host type polarizer in which a liquid crystal polymerized in an oriented state serves as a host and an anisotropic dye arranged by the orientation of the liquid crystal serves as a guest. In another example, the first polarizer and the second polarizer can each be a thermotropic liquid crystal film or a lyotropic liquid crystal film.

[0032] A protective film, an antireflection film, a retardation film, an adhesive layer, an adhesive layer, a surface treatment layer, etc. may be additionally formed on one or both surfaces of the first polarizer and the second polarizer. The retardation film can be, for example, a quarter-wave plate or a half-wave plate. The quarter-wave plate can have an in-plane retardation value for light with a wavelength of 550 nm in the range of about 100 nm to 180 nm, 100 nm, or 150 nm. The half-wave plate can have an in-plane retardation value for light with a wavelength of 550 nm in the range of about 200 nm to 300 nm or 250 nm to 300 nm. The retardation film can be, for example, a polymer stretched film or a liquid crystal polymerized film.

[0033] The transmittances of the first polarizer and the second polarizer for light with a wavelength of 550 nm can each be in the range of 40% to 50%. The transmittance can mean the single transmittance of the polarizer for light with a wavelength of 550 nm. The single transmittance of the polarizer can be measured, for example, using a spectrometer (V7100, manufactured by Jasco). For example, with the polarizer sample (excluding the upper and lower protective films) placed in the instrument, air is set as the baseline, and after measuring the respective transmittances with the axis of the polarizer sample aligned perpendicular and horizontal to the axis of the reference polarizer, the single transmittance can be calculated.

[0034] The optical transmission axes of the first polarizer and the second polarizer can be perpendicular to each other. Specifically, the angle formed by the optical transmission axis of the first polarizer and the optical transmission axis of the second polarizer can be in the range of 80 degrees to 100 degrees or 85 degrees to 95 degrees. When the optical transmission axes of the first polarizer and the second polarizer are perpendicular, there is a possibility of light leakage and the like due to the separation distance between the first polarizer and the second polarizer.

[0035] In one example, the optical device can further include a fifth adhesive layer in contact with the outer surface of the first polarizer and a sixth adhesive layer in contact with the outer surface of the second polarizer. The outer surface of the first polarizer may mean the surface facing the first outer substrate of the first polarizer. The outer surface of the second polarizer may mean the surface facing the second outer substrate of the second polarizer. The surface of the fifth adhesive layer that does not contact the first polarizer can contact the first buffer layer, and the surface of the sixth adhesive layer that does not contact the second polarizer can contact the second buffer layer described below. The storage elastic modulus of the fifth adhesive layer and the sixth adhesive layer may each be higher than that of the adhesive layer. Also, the loss elastic modulus of the fifth adhesive layer and the sixth adhesive layer may each be higher than that of the adhesive layer. If the storage elastic modulus or the loss elastic modulus of the fifth adhesive layer and the sixth adhesive layer is excessively low, it may not be possible to control the thermal behavior of the film during the durability process, and appearance defects may occur. In one example, the storage elastic modulus of the fifth adhesive layer and the sixth adhesive layer may each be in the range of 1 MPa to 100 MPa. In one example, the loss elastic modulus of the fifth adhesive layer and the sixth adhesive layer may each be in the range of 1 MPa to 100 MPa. The specific content regarding the loss elastic modulus or the storage elastic modulus of the fifth and sixth adhesive layers may be equally applicable to the content described for the first and second adhesive layers.

[0036] In one example, the optical device can further include a second buffer layer. The second buffer layer can be located between the second base layer of the liquid crystal cell and the second outer substrate. The loss elastic modulus of the second buffer layer may be lower than that of the adhesive layer. The storage elastic modulus of the second buffer layer may be lower than that of the adhesive layer. When the optical device further includes a second buffer layer, it may be more advantageous for absorbing external shocks and suppressing light leakage. Unless otherwise specifically mentioned for the second buffer layer, the same configuration as the first buffer layer can be applied.

[0037] In one example, the second buffer layer can contact the outer surface of the second base layer. Or the second buffer layer can contact the inner surface of the second adhesive layer.

[0038] In one example, the optical device may include a first buffer layer and may not include a second buffer layer. In another example, the optical device can include both the first buffer layer and the second buffer layer. At this time, when the optical device includes both the first buffer layer and the second buffer layer, it may be advantageous in terms of suppressing light leakage.

[0039] The total thickness of the buffer layer included in the optical device can be, for example, in the range of 50 μm to 2000 μm. Specifically, the total thickness of the buffer layer can be 100 μm or more, 200 μm or more, 300 μm or more, 400 μm or more, 500 μm or more, 600 μm or more, 700 μm or more, 800 μm or more, 900 μm or more, or 1000 μm or more, and can be 1800 μm or less, 1600 μm or less, or 1400 μm or less. When the optical device includes the first buffer layer and does not include the second buffer layer, the total thickness of the buffer layer can mean the thickness of the first buffer layer. When the optical device includes both the first buffer layer and the second buffer layer, the total thickness of the buffer layer can mean the sum of the thickness of the first buffer layer and the thickness of the second buffer layer. The first buffer layer and / or the second buffer layer can each be a single-layer structure or a multi-layer structure. When the first buffer layer and / or the second buffer layer is a multi-layer structure in which a plurality of sub-buffer layers are stacked, the thickness of the sub-buffer layer can be, for example, in the range of 100 μm to 500 μm, 200 μm to 400 μm, or 200 μm to 300 μm.

[0040] As the first buffer layer and the second buffer layer, an adhesive layer that satisfies the storage elastic modulus or the loss elastic modulus can be used. The adhesive layer can be optically transparent. The adhesive layer can have an average transmittance of about 80% or more, 85% or more, 90% or more, or 95% or more for the visible light region, for example, wavelengths of 380 nm to 780 nm.

[0041] As the adhesive layer, various types of adhesives known as so-called OCA (Optically Clear Adhesive) in the industry can be appropriately used. The adhesive can be different from OCR (Optically Clear Resin) type adhesives that cure after the adherend is joined in that it cures before the adherend is joined. As the adhesive, for example, acrylic-based, silicone-based, epoxy-based or urethane-based adhesives can be applied.

[0042] In one example, the storage modulus of the first buffer layer and / or the second buffer layer can be 500,000 Pa or less, 400,000 Pa or less, 300,000 Pa or less, 200,000 Pa or less, 150,000 Pa or less, 100,000 Pa or less, 80,000 Pa or less, or 60,000 Pa or less over the entire range of frequencies in the range of 0.6 rad / sec to 100 rad / sec at a temperature of 25°C. The storage modulus of the first buffer layer and / or the second buffer layer can be 100 Pa or more, 1,000 Pa or more, 5,000 Pa or more, 10,000 Pa or more, 20,000 Pa or more, 30,000 Pa or more, or 40,000 Pa or more over the entire range of frequencies in the range of 0.6 rad / sec to 100 rad / sec at a temperature of 25°C.

[0043] In one example, the loss modulus of the first buffer layer and / or the second buffer layer can be 500,000 Pa or less, 400,000 Pa or less, 300,000 Pa or less, 200,000 Pa or less, 150,000 Pa or less, 100,000 Pa or less, 80,000 Pa or less, 60,000 Pa or less, 40,000 Pa or less, or 20,000 Pa or less over the entire range of frequencies in the range of 0.6 rad / sec to 100 rad / sec at a temperature of 25°C. The loss modulus of the first buffer layer and / or the second buffer layer can be 1,000 Pa or more, 3,000 Pa or more, 5,000 Pa or more, 7,000 Pa or more, or 9,000 Pa or more over the entire range of frequencies in the range of 0.6 rad / sec to 100 rad / sec at a temperature of 25°C.

[0044] In one example, the adhesive layer may have a loss modulus of 6,000,000 Pa or less, 5,000,000 Pa or less, 4,000,000 Pa or less, 3,000,000 Pa or less, or 2,500,000 Pa or less, and 1,000 Pa or more, 3,000 Pa or more, 5,000 Pa or more, 7,000 Pa or more, or 9,000 Pa or more over the entire range of frequencies from 0.6 rad / sec to 100 rad / sec at a temperature of 25°C. In one example, the adhesive layer may have a storage modulus of 6,000,000 Pa or less, 5,000,000 Pa or less, 4,000,000 Pa or less, 3,000,000 Pa or less, or 2,500,000 Pa or less, and 1,000 Pa or more, 3,000 Pa or more, 5,000 Pa or more, or 7,000 Pa or more over the entire range of frequencies from 0.6 rad / sec to 100 rad / sec at a temperature of 25°C.

[0045] In one example, each of the first to sixth adhesive layers may independently have a loss modulus of 100 MPa or less, 80 MPa or less, 60 MPa or less, 40 MPa or less, 20 MPa or less, or 10 MPa or less, and 0.1 MPa or more, 0.5 MPa or more, or 1.0 MPa or more over the entire range of frequencies from 0.6 rad / sec to 100 rad / sec at a temperature of 25°C. In one example, each of the first to sixth adhesive layers may independently have a storage modulus of 100 MPa or less, 80 MPa or less, 60 MPa or less, 40 MPa or less, 20 MPa or less, or 10 MPa or less, and 0.1 MPa or more, 0.5 MPa or more, or 1.0 MPa or more over the entire range of frequencies from 0.6 rad / sec to 100 rad / sec at a temperature of 25°C.

[0046] FIGS. 1 to 4 exemplarily show the structures of the optical devices of the first to fourth embodiments of the present application, respectively.

[0047] FIG. 1 exemplarily shows the structure of an optical device sequentially including a first outer substrate 101, a first adhesive layer 401, a first polarizer 501, a first buffer layer 301, a liquid crystal cell 200, a second buffer layer 302, a second polarizer 502, a second adhesive layer 402, and a second outer substrate 102.

[0048] FIG. 2 exemplarily shows the structure of an optical device sequentially including a first outer substrate 101, a first adhesive layer 401, a first buffer layer 301, a first polarizer 501, a third adhesive layer 403, a liquid crystal cell 200, a fourth adhesive layer 404, a second polarizer 502, a second buffer layer 302, a second adhesive layer 402, and a second outer substrate 102.

[0049] FIG. 3 exemplarily shows the structure of an optical device sequentially including a first outer substrate 101, a first adhesive layer 401, a first buffer layer 301, a fifth adhesive layer 405, a first polarizer 501, a third adhesive layer 403, a liquid crystal cell 200, a fourth adhesive layer 404, a second polarizer 502, a sixth adhesive layer 406, a second buffer layer 302, a second adhesive layer 402, and a second outer substrate 102.

[0050] FIG. 4 exemplarily shows the structure of an optical device sequentially including a first outer substrate 101, a first adhesive layer 401, a first buffer layer 301, a first polarizer 501, a third adhesive layer 403, a liquid crystal cell 200, a fourth adhesive layer 404, a second polarizer 502, a second adhesive layer 402, and a second outer substrate 102.

[0051] FIG. 5 exemplarily shows a liquid crystal cell. As shown in FIG. 5, the liquid crystal cell can include a first base material layer 10a, an adhesive layer 10c formed inside the first base material layer, a second base material layer 20a disposed opposite to the first base material layer 10a, a spacer 20c formed inside the second base material layer 20a, and a liquid crystal layer 30 positioned between the first base material layer 10a and the second base material layer 20b.

[0052] As the first base material layer and the second base material layer, for example, inorganic films such as glass films, crystalline or amorphous silicone films, quartz or ITO (Indium Tin Oxide) films, and polymer films can be used, and polymer films can be used in terms of realizing flexible elements.

[0053] In one example, the first substrate layer and the second substrate layer can each be a polymer film. Examples of the polymer film include, but are not limited to, TAC (triacetyl cellulose); COP (cyclo olefin copolymer) such as norbornene derivatives; PMMA (poly(methyl methacrylate)); PC (polycarbonate); PE (polyethylene); PP (polypropylene); PVA (polyvinyl alcohol); DAC (diacetyl cellulose); PAC (Polyacrylate); PES (poly ether sulfone); PEEK (polyetheretherketon); PPS (polyphenylsulfone), PEI (polyetherimide); PEN (polyethylenemaphthatlate); PET (polyethyleneterephtalate); PI (polyimide); PSF (polysulfone); PAR (polyarylate); or amorphous fluororesin. The first substrate layer and the second substrate layer may optionally have 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.

[0054] The first substrate layer and the second substrate layer can each have a thickness of about 10 μm to about 1,000 μm. In other examples, the substrate layers can each have a thickness of about 20 μm or more, 40 μm or more, 60 μm or more, 80 μm or more, 100 μm or more, 120 μm or more, 140 μm or more, 160 μm or more, or about 180 μm or more, and can be 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 thicknesses of the first substrate layer and the second substrate layer satisfy the above ranges, when manufacturing an optical device by attaching a liquid crystal cell to an outer substrate, appearance defects such as wrinkles can be reduced.

[0055] The adhesive layer can be present on the inner surface of the first substrate layer. As used herein, the "inner surface" of a component included in the liquid crystal cell can mean the surface facing the liquid crystal layer.

[0056] The adhesive layer can be optically transparent. The average transmittance of the adhesive layer in the visible light region, for example, at wavelengths from 380 nm to 780 nm, can be about 80% or more, 85% or more, 90% or more, or 95% or more.

[0057] The adhesive layer can be a liquid crystal aligning adhesive layer. The adhesive layer can be, for example, a vertical alignment adhesive layer or a horizontal alignment adhesive layer. As used herein, the "vertical alignment adhesive" can mean an adhesive that imparts a vertical alignment force to an adjacent liquid crystal compound and has an adhesive force capable of adhering an upper substrate and a lower substrate. As used herein, the "horizontal alignment adhesive" can mean an adhesive that imparts a horizontal alignment force to an adjacent liquid crystal compound and has an adhesive force capable of adhering an upper substrate and a lower substrate. The pretilt angle of the adjacent liquid crystal compound with respect to the vertical alignment adhesive can be in the range of 80 degrees to 90 degrees, 85 degrees to 90 degrees, or about 87 degrees to 90 degrees, and the pretilt angle of the adjacent liquid crystal compound with respect to the horizontal alignment adhesive can be in the range of 0 degrees to 10 degrees, 0 degrees to 5 degrees, or 0 degrees to 3 degrees.

[0058] As used herein, the pretilt angle can mean the angle formed by the director of the liquid crystal compound with respect to a plane horizontal to the liquid crystal aligning adhesive or the alignment film in a state where no voltage is applied. As used herein, the director of the liquid crystal compound can mean the optical axis or the slow axis of the liquid crystal layer. Alternatively, the director of the liquid crystal compound can mean the long axis direction when the liquid crystal compound has a rod shape, and can mean an axis parallel to the normal direction of the disc plane when the liquid crystal compound has a discotic shape.

[0059] The thickness of the adhesive layer can be, for example, in the range of 3 μm to 15 μm. When the thickness of the adhesive layer is within the above range, it can be advantageous for minimizing defects such as pushing or gathering of the adhesive during the manufacture of the liquid crystal cell while ensuring the adhesive force between the upper substrate and the lower substrate.

[0060] As the adhesive layer, various types of adhesives known in the industry as so-called OCA (Optically Clear Adhesive) can be appropriately used. The adhesive can be different from OCR (Optically Clear Resin) type adhesives that cure after the adherend is joined, in that it cures before the adherend is joined. As the adhesive, for example, acrylic, silicone, epoxy, or urethane adhesives can be applied.

[0061] The adhesive layer can include a cured product of an adhesive resin. In one example, the adhesive layer can include a silicone-based adhesive. The silicone-based adhesive can include a cured product of a curable silicone compound as the adhesive resin.

[0062] The type of the curable silicone compound is not particularly limited, and for example, a heat-curable silicone compound or an ultraviolet-curable silicone compound can be used. The curable silicone compound can be referred to as an adhesive resin.

[0063] In one example, the curable silicone compound can be an addition-curable silicone compound.

[0064] Specifically, examples of the addition-curable silicone compound can include (1) organopolysiloxane containing two or more alkenyl groups in the molecule and (2) organopolysiloxane containing two or more silicon-bonded hydrogen atoms in the molecule, but are not limited thereto. Such silicone compounds can form a cured product by an addition reaction in the presence of a catalyst such as platinum, for example.

[0065] More specific examples of the (1) organopolysiloxane that can be used in the present application include branched-chain dimethylsiloxane-methylvinylsiloxane copolymer blocked at both ends with trimethylsiloxane groups, branched-chain methylvinylpolysiloxane blocked at both ends with trimethylsiloxane groups, branched-chain dimethylsiloxane-methylvinylsiloxane-methylphenylsiloxane copolymer blocked at both ends with trimethylsiloxane groups, branched-chain dimethylpolysiloxane blocked at both ends with dimethylvinylsiloxane groups, branched-chain methylvinylpolysiloxane blocked at both ends with dimethylvinylsiloxane groups, branched-chain dimethylsiloxane-methylvinylsiloxane copolymer blocked at both ends with dimethylvinylsiloxane groups, branched-chain dimethylsiloxane-methylvinylsiloxane-methylphenylsiloxane copolymer blocked at both ends with dimethylvinylsiloxane groups, R1 2 SiO 1 / 2 The siloxane unit represented by and R1 2 R 2 SiO 1 / 2 The siloxane unit represented by and SiO 4 / 2 Organopolysiloxane copolymers containing the siloxane unit represented by, R 1 2 R 2 SiO 1 / 2 The siloxane unit represented by and SiO 4 / 2 Organopolysiloxane copolymers containing the siloxane unit represented by, R 1 R 2 SiO 2 / 2 The siloxane unit represented by and R 1 SiO 3 / 2 The siloxane unit represented by or R 2 SiO 3 / 2 Organopolysiloxane copolymers containing the siloxane unit represented by and mixtures of two or more of the above are included, but not limited thereto. In the above, R 1is a hydrocarbon group other than an alkenyl group, specifically, an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group or a heptyl group; an aryl group such as a phenyl group, a tolyl group, a xylyl group or a naphthyl group; an aralkyl group such as a benzyl group or a phenethyl group; a halogen-substituted alkyl group such as a chloromethyl group, a 3-chloropropyl group or a 3,3,3-trifluoropropyl group, etc. Further, R in the above 2 is an alkenyl group, specifically, it may be a vinyl group, an allyl group, a butenyl group, a pentenyl group, a hexenyl group or a heptenyl group, etc.

[0066] More specific examples of the organopolysiloxane (2) that can be used in the present application include methylhydrogenpolysiloxane blocked at both ends of the branched chain with trimethylsiloxane groups, dimethylsiloxane-methylhydrogen copolymer blocked at both ends of the branched chain with trimethylsiloxane groups, dimethylsiloxane-methylhydrogensiloxane-methylphenylsiloxane copolymer blocked at both ends of the branched chain with trimethylsiloxane groups, dimethylpolysiloxane blocked at both ends of the branched chain with dimethylhydrogensiloxane groups, dimethylsiloxane-methylphenylsiloxane copolymer blocked at both ends of the branched chain with dimethylhydrogensiloxane groups, methylphenylpolysiloxane blocked at both ends of the branched chain with dimethylhydrogensiloxane groups, R 1 3 SiO 1 / 2 and the siloxane units represented by R 1 2 HSiO 1 / 2 and the siloxane units represented by R 4 / 2 and the siloxane units represented by SiO 1 2 HSiO 1 / 2 and the siloxane units represented by SiO 4 / 2 and the siloxane units represented by SiO 1 HSiO 2 / 2 and the siloxane units represented by R 1 SiO 3 / 2 or the siloxane units represented by HSiO 3 / 2Examples include, but are not limited to, organopolysiloxane copolymers containing siloxane units represented therein, and mixtures of two or more of the foregoing. In the foregoing, R 1 is a hydrocarbon group other than an alkenyl group, specifically, an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, or a heptyl group; an aryl group such as a phenyl group, a tolyl group, a xylyl group, or a naphthyl group; an aralkyl group such as a benzyl group or a phenethyl group; a halogen-substituted alkyl group such as a chloromethyl group, a 3-chloropropyl group, or a 3,3,3-trifluoropropyl group, and the like.

[0067] When the adhesive layer is a vertically oriented adhesive layer, the surface energy can be 16 mN / m or less. The lower limit of the surface energy can be, for example, 5 mN / m or more. When the adhesive layer is a horizontally oriented adhesive layer, the surface energy can exceed 16 mN / m. The upper limit of the surface energy can be, for example, 50 mN / m or less. The surface energy can be measured using a drop shape analyzer (product DSA100 of KRUSS). Specifically, the process of dropping deionized water with a known surface tension onto the surface of the adhesive and obtaining its contact angle is repeated 5 times, the average value of the 5 obtained contact angle values is determined, and in the same way, the process of dropping diiodomethane with a known surface tension and obtaining its contact angle is repeated 5 times, and the average value of the 5 obtained contact angle values is determined. Then, using the average values of the contact angles for the obtained deionized water and diiodomethane, a numerical value (Strom value) regarding the surface tension of the solvent is substituted by the Owens-Wendt-Rabel-Kaelble method to obtain the surface energy. The surface energy (γ surface ) can be calculated considering the dispersion force between non-polar molecules and the interaction force between polar molecules (γ surface =γ dispersion +γ polar ), but for the surface energy γ surface , the polar term (γ polar) The ratio can be defined as the polarity of its surface.

[0068] The upper substrate and the lower substrate of the liquid crystal cell may be adhered by an adhesive layer. Specifically, the adhesive layer of the upper substrate and the spacers of the lower substrate may be adhered. When an alignment film is formed on the spacers of the lower substrate, the region corresponding to the spacers of the alignment film may be adhered to the adhesive layer of the upper substrate.

[0069] The liquid crystal layer can contain a liquid crystal compound. As the liquid crystal compound, a liquid crystal compound whose alignment direction can be changed by the application of an external action can be used. In this specification, the term "external action" can mean all external factors that can affect the behavior of substances contained in the liquid crystal layer, such as an external voltage. Therefore, the state without an external action can mean a state without the application of an external voltage or the like.

[0070] The type and physical properties of the liquid crystal compound can be appropriately selected in consideration of the purpose of this application. In one example, the liquid crystal compound can be a nematic liquid crystal or a smectic liquid crystal. A nematic liquid crystal can mean a liquid crystal in which rod-shaped liquid crystal molecules are arranged parallel to the long axis direction of the liquid crystal molecules without regularity in position, and a smectic liquid crystal can mean a liquid crystal in which rod-shaped liquid crystal molecules are regularly arranged to form a layered structure and are arranged parallel to each other with regularity in the long axis direction. According to one embodiment of this application, the liquid crystal compound can be a nematic liquid crystal compound.

[0071] The nematic liquid crystal compound can be selected, for example, to have a clearing point of about 40 °C or higher, 50 °C or higher, 60 °C or higher, 70 °C or higher, 80 °C or higher, 90 °C or higher, 100 °C or higher, or about 110 °C or higher, or 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 can be about 160 °C or lower, 150 °C or lower, or about 140 °C or lower.

[0072] The liquid crystal compound can be a non-reactive liquid crystal compound. The non-reactive liquid crystal compound can mean a liquid crystal compound having no polymerizable group. Examples of the polymerizable group can include, but are not limited to, an acryloyl group, an acryloyloxy group, a methacryloyl group, a methacryloyloxy group, a carboxy group, a hydroxy group, a vinyl group, or an epoxy group, and can include known functional groups known as polymerizable groups.

[0073] The liquid crystal compound can have a positive or negative dielectric anisotropy. The absolute value of the dielectric anisotropy of the liquid crystal compound can be appropriately selected in consideration of the purpose of the present application. The term "dielectric anisotropy (Δε)" can mean the difference (ε / / - ε⊥) between the parallel dielectric constant (ε / / ) and the perpendicular dielectric constant (ε⊥) of the liquid crystal. In this specification, the term parallel dielectric constant (ε / / ) means the dielectric constant value measured along the direction of the electric field in a state where a voltage is applied so that the director of the liquid crystal compound and the direction of the electric field due to the applied voltage are substantially horizontal, and the perpendicular dielectric constant (ε⊥) means the dielectric constant value measured along the direction of the electric field in a state where a voltage is applied so that the director of the liquid crystal compound and the direction of the electric field due to the applied voltage are substantially perpendicular. The dielectric anisotropy of the liquid crystal molecules can be in the range of 5 to 25.

[0074] The refractive index anisotropy of the liquid crystal compound can be appropriately selected in consideration of the purpose of the present application. In this specification, the term "refractive index anisotropy" can mean the difference between the extraordinary refractive index and the ordinary refractive index of the liquid crystal compound. The refractive index anisotropy of the liquid crystal compound can be, for example, from 0.01 to 0.3. The refractive index anisotropy can be 0.01 or more, 0.05 or more, or 0.07 or more, and can be 0.3 or less, 0.2 or less, 0.15 or less, or 0.13 or less.

[0075] The liquid crystal layer can further contain a dichroic dye. When the liquid crystal layer contains a dichroic dye, since the liquid crystal cell is less affected by fluctuations in the cell gap during the step of attaching the outer substrate even if it includes an adhesive layer, there is an advantage that the thickness of the adhesive layer for ensuring the structural stability and quality uniformity of the liquid crystal cell can be made relatively thin.

[0076] The dichroic dye can control the light transmittance variable characteristics of the liquid crystal layer. As used herein, the term "dye" may mean a substance that can intensively absorb and / or deform at least part or the entire range of light within the visible light region, for example, within the wavelength range of 400 nm to 700 nm. The term "dichroic dye" may mean a substance capable of anisotropic absorption of light in at least part or the entire range of the visible light region.

[0077] The liquid crystal layer containing a liquid crystal compound and a dichroic dye can be a GHLC layer (Guest host liquid crystal layer). As used herein, the term "GHLC layer (Guest host liquid crystal layer)" may mean a functional layer in which the dichroic dyes are arranged together due to the arrangement of the liquid crystal compound, and exhibit anisotropic light absorption characteristics with respect to the alignment direction of the dichroic dye and the direction perpendicular to the alignment direction. For example, a dichroic dye is a substance whose light absorption rate varies depending on the polarization direction. If the absorption rate of light polarized in the major axis direction is large, it is called a p-type dye, and if the absorption rate of light polarized in the minor axis direction is large, it can be called an n-type dye. In one exemplary case, when a p-type dye is used, the polarization oscillating in the major axis direction of the dye is absorbed, and the polarization oscillating in the minor axis direction of the dye is less absorbed and thus can be transmitted. Hereinafter, unless otherwise specified, it is assumed that the dichroic dye is a p-type dye.

[0078] As the dichroic dye, for example, a known dye known to have the property of being aligned by the alignment state of the liquid crystal compound by the so-called guest-host effect can be selected and used. Examples of such dichroic dyes include azo dyes, anthraquinone dyes, methine dyes, azomethine dyes, merocyanine dyes, naphthoquinone dyes, tetrazine dyes, phenylene dyes, quaterrylene dyes, benzothiadiazole dyes, diketopyrrolopyrrole dyes, squalirine dyes, or pyromethene dyes, etc. However, the dyes applicable in this application are not limited to the above.

[0079] As the dichroic dye, a dye can be used in which the dichroic ratio, that is, the value obtained by dividing the absorption of polarized light parallel to the major axis direction of the dichroic dye by the absorption of polarized light parallel to the direction perpendicular to the major axis direction, is 5 or more, 6 or more, or 7 or more. The dye can satisfy the dichroic ratio at at least some wavelengths or any one wavelength within the wavelength range of the visible light region, for example, within the wavelength range of about 380 nm to 700 nm or about 400 nm to 700 nm. The upper limit of the dichroic ratio can be, for example, about 20 or less, 18 or less, 16 or less, or 14 or less.

[0080] The content of the dichroic dye in the liquid crystal layer can be appropriately selected in consideration of the object of the present application. For example, the content of the dichroic dye in the liquid crystal layer can be 0.2% by weight or more. Specifically, the content of the dichroic dye can be 0.5% by weight or more, 1% by weight or more, 2% by weight or more, or 3% by weight or more. The upper limit of the content of the dichroic dye can be, for example, 10% by weight or less, 9% by weight or less, 8% by weight or less, 6% by weight or less, or 5% by weight or less. When the content of the dichroic dye in the liquid crystal layer is excessively small, it may be difficult to exhibit the target transmittance variable characteristics, and it may be insufficient to reduce the thickness of the adhesive layer for reducing the variation of the cell gap that may occur during the bonding process of the outer substrates. On the other hand, when the content of the dichroic dye in the liquid crystal layer is excessively large, there is a risk of precipitation. Therefore, it may be advantageous that the content of the dichroic dye is within the above range.

[0081] The thickness of the liquid crystal layer is not particularly limited. For example, the thickness of the liquid crystal layer can be 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, 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. The upper limit of the thickness of the liquid crystal layer is not particularly limited and can generally be about 30 μm or less, 25 μm or less, 20 μm or less, or 15 μm or less.

[0082] The liquid crystal layer can switch between a first alignment state and a second alignment state different from the first alignment state. The switching can be adjusted through the application of external energy such as, for example, a voltage. For example, the liquid crystal layer can maintain one of the first and second alignment states in a state without voltage applied, and then be switched to the other alignment state by the application of a voltage.

[0083] In one example, the first alignment state can be a twisted alignment state. That is, the liquid crystal layer can switch between a twisted alignment and another alignment state through the application of external energy.

[0084] In one example, the liquid crystal layer can switch between a twisted alignment and a vertical alignment state. In one example, the liquid crystal layer can be in a vertical alignment state when no voltage is applied, and can be in a twisted alignment state when a voltage is applied.

[0085] As used herein, the "vertical alignment state" means a state in which the directors of the liquid crystal compounds in the liquid crystal layer are arranged substantially perpendicular to the plane of the liquid crystal layer. For example, the angle formed by the directors of the liquid crystal compounds with respect to the plane of the liquid crystal layer can be, for example, within the range of about 80 degrees to 100 degrees or 85 degrees to 95 degrees, or can form an angle of approximately 90 degrees.

[0086] As used herein, the "twisted alignment state" can mean a helical structure in which the directors of the liquid crystal compounds in the liquid crystal layer are wound along a virtual helical axis to form a layer. The twisted alignment state can be embodied in a vertical, horizontal or inclined alignment state. That is, the vertical twisted alignment mode is a state in which individual liquid crystal compounds are vertically aligned and wound along the helical axis to form a layer, the horizontal twisted alignment mode is a state in which individual liquid crystal compounds are horizontally aligned and wound along the helical axis to form a layer, and the inclined twisted alignment mode is a state in which individual liquid crystal compounds are inclined and wound along the helical axis to form a layer. According to the present application, the twisted alignment state can be a twisted alignment state in a horizontal alignment state.

[0087] In the twisted alignment state, the ratio (d / p) of the thickness d to the pitch p of the liquid crystal layer can be 20 or less, and the lower limit can be 0.5 or more. When the ratio (d / p) of the thickness d to the pitch p is within the above range in the twisted alignment state, the optical device can exhibit excellent light transmittance variable characteristics even in a state without a polarizer. Usually, when the ratio d / p is 0.7 or more and less than 2.5, it can be called the STN (Super Twisted Nematic) mode, and when the ratio d / p is 2.5 or more, it can be called the HTN (Highly Twisted Nematic) driving mode.

[0088] The pitch p of the liquid crystal layer can be measured by a measurement method using a Wedge cell. Specifically, it can be measured by the method described in D. Podolskyy et al., "Simple method for accurate measurements of the cholesteric pitch using a'stripe-wedge Grandjean-Cano cell'" (Liquid Crystals, Vol. 35, No. 7, July 2008, 789-791). The ratio (d / p) can be achieved by introducing an appropriate amount of chiral dopant into the liquid crystal layer.

[0089] The liquid crystal layer can further contain a chiral dopant. When the liquid crystal layer contains a chiral agent, a twisted alignment state can be realized. The chiral agent (chiral agent or chiral dopant) that can be contained in the liquid crystal layer can be used without particular limitation as long as it can induce the desired twisting without damaging the liquid crystallinity, for example, nematic regularity. The chiral agent for inducing rotation in a liquid crystal compound needs to contain at least chirality in its molecular structure. Examples of the chiral agent include a compound having one or more asymmetric carbons, a compound having an asymmetric point on a heteroatom such as a chiral amine or a chiral sulfoxide, or a compound having an axially asymmetric and optically active site such as cumulene or binaphthol. The chiral agent can be, for example, a low molecular weight compound having a molecular weight of 1,500 or less. As the chiral agent, commercially available chiral nematic liquid crystals such as chiral dopant liquid crystal S-811 commercially available from Merck or LC756 from BASF may be used.

[0090] The application ratio of the chiral dopant is selected so as to achieve the above-mentioned target ratio (d / p). Generally, the content (% by weight) of the chiral dopant can be calculated by the formula of 100 / HTP (Helixcal Twisting power) × pitch p (nm). The HTP represents the strength of the twist of the chiral dopant, and the content of the chiral dopant can be determined in consideration of the target pitch with reference to the above formula.

[0091] The upper substrate of the liquid crystal cell can further include a first electrode layer 10b between the first base material layer 10a and the adhesive layer 10c. The first electrode layer 10b can be in contact with the inner surface of the first base material layer 10a. The adhesive layer 10c can be in contact with the inner surface of the first electrode layer 10b. The lower substrate of the liquid crystal cell can further include a second electrode layer 20b between the second base material layer 20a and the spacer 20c. The second electrode layer 20b can be in contact with the inner surface of the second base material layer 20a. The spacer 20c can be in contact with the inner surface of the second electrode layer 20b.

[0092] The first electrode layer and the second electrode layer can perform the role of applying an external action, for example, applying an electric field, so as to transmit or block the light incident on the substances contained in the liquid crystal layer. In one exemplary embodiment, the first electrode layer and / or the second electrode layer can include, but are not limited to, a conductive polymer, a conductive metal, a conductive nanowire, or a metal oxide such as ITO (Indium Tin Oxide). The first electrode layer and / or the second electrode layer can be formed by depositing, for example, the conductive polymer, the conductive metal, the conductive nanowire, or a metal oxide such as ITO (Indium Tin Oxide).

[0093] The lower substrate of the liquid crystal cell can further include an alignment film 20d. The alignment film 20d can be present on the spacer 20c. That is, the upper surface portion and / or the side surface portion of the spacer 20c can be in contact with the alignment film. The lower surface of the spacer 20c can be in contact with the second electrode layer 20b. Since the adhesive layer included in the upper substrate can have liquid crystal alignment properties, the upper substrate may not include a separate alignment film. That is, the inner surface of the first electrode layer 10b may not include an alignment film.

[0094] In this specification, the combination of the first base material layer, the first electrode layer, and the adhesive layer can be referred to as the upper substrate, and the combination of the second base material layer, the second electrode layer, the spacer, and the alignment film can be referred to as the lower substrate. In the liquid crystal cell, the upper substrate does not include a separate alignment film other than the adhesive layer, and the lower substrate can include an alignment film.

[0095] The alignment film and the liquid crystal layer may be in contact. The alignment film can be a vertical alignment film or a horizontal alignment film. As used herein, the term "horizontal alignment film" may mean a layer containing an alignment substance that imparts a horizontal alignment force to the liquid crystal compound present in the adjacent liquid crystal layer. As used herein, the term "vertical alignment film" may mean a layer containing an alignment substance that imparts a vertical alignment force to the liquid crystal compound present in the adjacent liquid crystal layer. The pretilt angle of the adjacent liquid crystal compound with respect to the vertical alignment film can be in the range of 80 degrees to 90 degrees, 85 degrees to 90 degrees, or about 87 degrees to 90 degrees, and the pretilt angle of the adjacent liquid crystal compound with respect to the horizontal alignment film can be in the range of 0 degrees to 10 degrees, 0 degrees to 5 degrees, or 0 degrees to 3 degrees. Different from the adhesive layer, the alignment film may not have an adhesive force for bonding the upper substrate and the lower substrate. In one exemplary case, the peeling force of the alignment film with respect to the upper substrate in the state of the liquid crystal cell of FIG. 2 may be close to 0.

[0096] The alignment film can be a rubbed alignment film or a photo-alignment film. The alignment direction of the alignment film can be the rubbing direction in the case of a rubbed alignment film or the direction of the polarized light irradiated in the case of a photo-alignment film. Such an alignment direction can be confirmed by a detection method using an absorption-type linear polarizer. Specifically, with the liquid crystal compound contained in the liquid crystal layer being horizontally aligned, an absorption-type linear polarizer is disposed on one surface of the liquid crystal layer, and the alignment direction can be confirmed by rotating the polarizer 360 degrees and measuring the transmittance. When measuring the luminance (transmittance) on the other side while irradiating light on the liquid crystal layer or the absorption-type linear polarizer side in the above state, the transmittance tends to be low when the absorption axis or the transmission axis coincides with the alignment direction of the liquid crystal alignment film. However, the alignment direction can be confirmed through a simulation that reflects the refractive index anisotropy of the applied liquid crystal compound, etc. The method for confirming the alignment direction according to the mode of the liquid crystal layer is known, and in the present application, the alignment direction of the alignment film can be confirmed by such a known method.

[0097] Examples of the alignment film include substances known to exhibit alignment ability by rubbing alignment, such as polyimide compounds, poly(vinyl alcohol) compounds, poly(amic acid) compounds, polystyrene compounds, polyamide compounds, and polyoxyethylene compounds, and substances known to be able to exhibit alignment ability by light irradiation, such as polyimide compounds, poly(amic acid) compounds, polynorbornene compounds, phenylmaleimide copolymer compounds, polyvinylcinamate compounds, polyazobenzene compounds, polyethyleneimide compounds, polyvinylalcohol compounds, polyimide compounds, polyethylene compounds, polystyrene compounds, polyphenylenephthalamide compounds, polyester compounds, CMPI (chloromethylated polyimide) compounds, PVCI (polyvinylcinnamate) compounds, and polymethyl methacrylate compounds. However, the alignment film is not limited thereto and may include one or more selected from the group consisting of these substances.

[0098] The spacer 20c can maintain the interval between the upper substrate and the lower substrate. A liquid crystal layer can exist in a region where no spacer exists between the upper substrate and the lower substrate.

[0099] The spacer can be a patterned spacer. The spacer can have a columnar or partition wall shape. In one exemplary case, the spacer can have a partition wall shape. When the spacer has a partition wall shape, it can be advantageous in terms of maintaining the height of the liquid crystal cell and improving the physical rigidity of the liquid crystal cell. The partition wall can partition the space between the lower substrate and the upper substrate into two or more spaces. In the region where the spacer is absent, other films or other layers present below may be exposed. For example, the second electrode layer may be exposed in the region where the spacer is absent. The alignment film may cover the spacer and the second electrode layer exposed in the region where the spacer is absent. In a liquid crystal cell in which the upper substrate and the lower substrate are joined together, the alignment film present on top of the spacer of the lower substrate and the adhesive layer of the upper substrate may be in contact with each other.

[0100] In the region where there is no spacer between the upper substrate and the lower substrate, a liquid crystal compound and the aforementioned additives, such as a dichroic dye, a chiral agent, etc., can be present. The shape of the spacer is not particularly limited, and can be applied without limitation, for example, to have polyhedral shapes such as circles, ellipses, or other polygons.

[0101] The spacer can contain a curable resin. The type of curable resin is not particularly limited, and for example, a thermosetting resin or a photocurable resin, such as an ultraviolet curable resin, can be used. As the thermosetting resin, for example, silicone resin, silicon resin, furan resin, polyurethane resin, epoxy resin, amino resin, phenol resin, urea resin, polyester resin, or melamine resin, etc. can be used, but it is not limited thereto. As the ultraviolet curable resin, typically acrylic polymers, such as polyester acrylate polymer, polystyrene acrylate polymer, epoxy acrylate polymer, polyurethane acrylate polymer, polybutadiene acrylate polymer, silicone acrylate polymer, or alkyl acrylate polymer, etc. can be used, but it is not limited thereto.

[0102] The spacer can be formed by a patterning process. For example, the spacer can be formed by a photolithography process. The photolithography process can include a step of applying a curable resin composition onto a base layer or an electrode layer and then irradiating ultraviolet light through a pattern mask. The pattern mask may be patterned with an ultraviolet-transmitting region and an ultraviolet-blocking region. The photolithography process can further include a step of washing the curable resin composition irradiated with ultraviolet light. Since the region irradiated with ultraviolet light is cured and the region not irradiated with ultraviolet light remains in a liquid phase, it can be patterned into a partition shape by removing it through the washing process. In the photolithography process, after ultraviolet irradiation, a release treatment may be performed on the pattern mask or a release paper may be positioned between the layer of the resin composition and the pattern mask in order to easily separate the resin composition and the pattern mask.

[0103] The width (line width), interval (pitch), thickness, and area of the spacer can be appropriately selected within a range that does not damage the purpose of the present application. For example, the width (line width) of the spacer can be in the range of 10 μm to 500 μm or in the range of 10 μm to 50 μm. The interval (pitch) of the spacer can be in the range of 10 μm to 1000 μm or in the range of 100 μm to 1000 μm. The area of the spacer can be about 5% or more and 50% or less with respect to the total area of 100% of the second base layer. When the area of the spacer is within the above range, it can be advantageous for ensuring excellent electro-optical characteristics while appropriately securing the adhesion force between the upper substrate and the lower substrate. The thickness of the spacer can be, for example, in the range of 1 μm to 30 μm or in the range of 3 μm to 20 μm.

[0104] In order to overcome the physical limitations of the liquid crystal cell, an outer substrate can be attached to both sides of the liquid crystal cell through an adhesive layer. However, due to the low modulus of the adhesive layer, it is vulnerable to external pressure, so defects such as the collapse of the cell gap, the flow and aggregation of the liquid crystal may occur during the attachment process. By controlling the thickness of the adhesive layer included in the optical device, the above defects can be minimized, and the structural stability and uniform appearance characteristics of the optical device can be ensured.

[0105] As an example, the sum of the total thicknesses of the adhesive layers included in the optical device may be 200 μm or more. The sum of the total thicknesses of the adhesive layers means the sum of the thicknesses of all the adhesive layers included in the optical device. For example, in the case of the structure of FIG. 1, it means the sum of the thicknesses of the first and second adhesive layers; in the case of the structures of FIGS. 2 and 4, it means the sum of the thicknesses of the first, second, third, and fourth adhesive layers; or in the case of the structure of FIG. 3, it means the sum of the thicknesses of the first, second, third, fourth, fifth, and sixth adhesive layers. When the total thickness of the adhesive layers is within the above range, by minimizing defects during the process of attaching the outer substrate, the structural stability and uniform appearance characteristics of the optical device can be ensured. Specifically, the sum of the total thicknesses of the adhesive layers may be 500 μm or more, 1,000 μm or more, 1,500 μm or more, or 2,000 μm or more. The sum of the total thicknesses of the adhesive layers may be, for example, about 6,000 μm or less, 5,000 μm or less, 4,000 μm or less, or 3,000 μm or less. When the total thickness of the adhesive layers is excessively thick, it may reduce electro-optical characteristics such as the transmittance characteristics of the optical device, so it may be advantageous to be within the above range.

[0106] The first to sixth adhesive layers may each have a single-layer structure of one adhesive layer or may be a laminate of two or more sub-adhesive layers. The thickness and number of the sub-adhesive layers can be controlled in consideration of the target thickness of the adhesive layer. In one exemplary case, the thickness of one single-layer structure adhesive layer or sub-adhesive layer may be in the range of 100 μm to 500 μm or in the range of 300 μm to 400 μm.

[0107] As an example, the Young's modulus (E) of the first to sixth adhesive layers can each be in the range of 0.1 MPa to 100 MPa. In other examples, the Young's modulus (E) of the first to sixth adhesive layers can be 0.2 MPa or more, 0.4 MPa or more, 0.6 MPa or more, 0.8 MPa or more, 1 MPa or more, 5 MPa or more, or about 10 MPa or more, and can be about 95 MPa or less, 80 MPa or less, 75 MPa or less, 70 MPa or less, 65 MPa or less, 60 MPa or less, 55 MPa or less, or about 50 MPa or less. The Young's modulus (E) can be measured, for example, in the manner specified in ASTM D882. The film can be cut into the form provided by the corresponding standard, and equipment capable of measuring the Stress-Strain curve (capable of simultaneously measuring force and length), for example, a UTM (Universal testing machine), can be used for measurement. When the Young's modulus of the adhesive layer included in the optical device is within the above range, it may be more advantageous to ensure excellent durability of the optical device. When the adhesive layer is a laminate of at least two or more sub-adhesive layers, each of the sub-adhesive layers can satisfy the range of the Young's modulus.

[0108] As an example, the first to sixth adhesive layers may each have a coefficient of thermal expansion of 2,000 ppm / K or less. The coefficient of thermal expansion may be, in other examples, about 1,900 ppm / K or less, 1,700 ppm / K or less, 1,600 ppm / K or less, or about 1,500 ppm / K or less, or about 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, 60 ppm / K or more, 70 ppm / K or more, 80 ppm / K or more, 90 ppm / K or more, 100 ppm / K or more, 200 ppm / K or more, 300 ppm / K or more, 400 ppm / K or more, 500 ppm / K or more, 600 ppm / K or more, 700 ppm / K or more, or about 800 ppm / K or more. The coefficient of thermal expansion of the adhesive layer can be measured, for example, according to the provisions of ASTM D696. Cut it into the form provided by the corresponding standard, measure the change in length per unit temperature, and calculate the coefficient of thermal expansion, which can be measured by a known method such as TMA (ThermoMechanic Analysis). When the coefficient of thermal expansion of the adhesive layer included in the optical device is within the above range, it may be more advantageous to ensure excellent durability of the optical device. When the adhesive layer is a laminate of at least two or more sub-adhesive layers, each of the sub-adhesive layers can satisfy the range of the coefficient of thermal expansion.

[0109] The first to sixth adhesive layers may each be a thermoplastic polyurethane (TPU; Thermoplastic Polyurethane) adhesive layer, a polyamide adhesive layer, a polyester adhesive layer, an EVA (Ethylene Vinyl Acetate) adhesive layer, an acrylic adhesive layer, a silicone adhesive layer, or a polyolefin adhesive layer. According to an embodiment of the present application, each of the at least one or more adhesive layers may be a thermoplastic polyurethane.

[0110] The optical device can further include an outer layer surrounding the side surface of the liquid crystal cell. FIG. 1 exemplarily shows an optical device including the outer layer 600. In the optical device, the upper area of the liquid crystal cell may be smaller than the upper area of the first outer substrate or the second outer substrate. Also, the upper area of the liquid crystal cell may be smaller than the upper areas of the first to sixth adhesive layers included in the optical device. In one exemplary case, the liquid crystal cell may be encapsulated by a first adhesive layer positioned between the first outer substrate and the first polarizer, a second adhesive layer positioned between the second outer substrate and the second polarizer, and the outer layer. In the present application, the term "encapsulation" may mean covering the entire surface of the liquid crystal cell with an adhesive layer and an outer layer. In one exemplary case, when no other layer exists between the first adhesive layer and the second adhesive layer, the first adhesive layer and the second adhesive layer can be in direct contact with the liquid crystal cell. In another exemplary case, when another layer exists between the first adhesive layer and the second adhesive layer, the liquid crystal cell can be in direct contact with the other layer. According to the structure of FIG. 1, the upper surface of the liquid crystal cell can be in contact with the first buffer layer 301, the lower surface can be in contact with the second buffer layer 302, and the side surface can be in contact with the outer layer 600. Depending on the intended structure, for example, a laminate including a first outer substrate, a first adhesive layer, a first polarizer, a liquid crystal cell, a second polarizer, a second adhesive layer, and a second outer substrate in sequence and including an outer layer surrounding the side surface of the liquid crystal cell can be pressure-bonded in a vacuum state to implement the encapsulation structure. Such an encapsulation structure greatly improves the durability and weather resistance of the optical device, and as a result, it can be stably applied to outdoor uses such as sunroofs.

[0111] The outer layer can include, for example, a thermoplastic polyurethane (TPU) adhesive, a polyamide adhesive, a polyester adhesive, an EVA (Ethylene Vinyl Acetate) adhesive, an acrylic adhesive, a silicone adhesive, or a polyolefin adhesive. In one exemplary case, the outer layer can be formed of the same material as the adhesive layer.

[0112] This application also relates to a method for manufacturing an optical device. The method for manufacturing the optical device sequentially includes a first outer substrate, a first adhesive layer, a first polarizer, a liquid crystal cell, a second polarizer, a second adhesive layer, and a second outer substrate, and may further include a step of preparing a laminate including a first buffer layer located between a first base layer and the first outer substrate, and a step of performing an autoclave treatment on the laminate. Unless otherwise specifically mentioned in the method for manufacturing an optical device, the content described for the optical device can be equally applied.

[0113] The laminate may further include an outer layer surrounding the side surface of the liquid crystal cell.

[0114] When the optical device further includes other elements other than the liquid crystal cell and the polarizer, the laminate may further include other elements other than the liquid crystal cell and the polarizer at a targeted position.

[0115] The autoclave process can be performed by heating and / or pressurizing the laminate formed after the laminating step.

[0116] The conditions of the autoclave process are not particularly limited. For example, it can be performed under appropriate temperature and pressure depending on the type of the applied adhesive layer. The temperature of a normal 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 it is not limited thereto. The upper limit of the process temperature can be about 200 °C or lower, 190 °C or lower, 180 °C or lower, or about 170 °C or lower, and the upper limit of the process pressure can be about 10 atmospheres or lower, 9 atmospheres or lower, 8 atmospheres or lower, 7 atmospheres or lower, or 6 atmospheres or lower.

[0117] The optical device as described above can be used in various applications. For example, it can be used in eyewear such as sunglasses, AR (Augmented Reality) or VR (Virtual Reality) eyewear, and can also be used on the outer walls of buildings or sunroofs of vehicles. In one exemplary case, the optical device can itself be a sunroof for a vehicle. For example, in an automobile including a vehicle body with at least one or more openings, the optical device or the vehicle sunroof mounted on the opening can be used.

Advantages of the Invention

[0118] The optical device of the present application can properly maintain the cell gap of the liquid crystal cell, has excellent adhesion between the upper substrate and the lower substrate, and can solve the light leakage caused by the phenomenon of liquid crystal orientation disorder occurring during an external impact.

Brief Description of the Drawings

[0119]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7a

Figure 7b

Figure 7c

Figure 7d

Figure 7e

Figure 8a

Figure 8b

Figure 8c

Figure 8d

Figure 8e

Mode for Carrying Out the Invention

[0120] Hereinafter, the present application will be specifically described through examples, but the scope of the present application is not limited by the following examples.

[0121] Measurement Example 1. Measurement of Storage Elastic Modulus and Loss Elastic Modulus The storage elastic modulus and loss elastic modulus were measured using a TA Instruments ARES G2 rheometer. Specifically, the adhesive layer, adhesive layer, and buffer layer used in the examples and comparative examples were each fabricated into circular samples (diameter: 8 mm, thickness: 600 μm). For the circular samples, using the parallel plates (Al Plate) of the ARES G2, after setting the axial force to 50 gf (vertical force) at a temperature of 25°C, the loss elastic modulus and storage elastic modulus were measured while changing the frequency from 0.6 rad / s to 100 rad / s under a strain condition of 5% (Frequency Sweep), and the results are shown in FIGS. 7a - 7e and FIGS. 8a - 8e, respectively. Also, Table 1 lists the loss elastic modulus values and storage elastic modulus values at 1 Hz and 10 Hz. All the elastic modulus values for the rad / sec frequency and Hz frequency can be obtained with the measuring equipment. Numerically on the measuring equipment, 1 Hz is approximately 6.30957 rad / sec, and 10 Hz is approximately 63.0957 rad / sec.

[0122] Example 1. Manufacture of Liquid Crystal Cell A polycarbonate film (Keiwa Co., Ltd.) with a thickness of about 100 μm and a horizontal × vertical area of 300 mm × 300 mm was prepared as the first substrate layer. ITO (indium - tin - oxide) was deposited on the first substrate layer with a thickness of 50 nm to form the first electrode layer. After bar - coating an adhesive composition (KR - 3700, Shin - Etsu Chemical Co., Ltd.) on the first electrode layer, it was dried at about 150°C for about 5 minutes to form an adhesive layer with a thickness of about 10 μm. The loss elastic modulus of the adhesive layer at a frequency of 1 Hz was 906,687 Pa. The combination of the first substrate layer, the first electrode layer, and the adhesive layer is referred to as the upper substrate.

[0123] A polycarbonate film (Keiwa) with a thickness of about 100 μm and a horizontal × vertical area of 300 mm × 300 mm was prepared as the second substrate layer. ITO (indium-tin-oxide) was deposited on the second substrate layer with a thickness of 50 nm to form the second electrode layer. After coating an acrylic resin composition (KAD-03, Minutatec) on the second electrode layer, a honeycomb-shaped spacer was formed by a photolithography method. The pitch of the regular hexagon (closed figure) constituting the honeycomb is about 350 μm, the height is about 6 μm, and the line width is about 30 μm. After coating a vertically aligned film (Nissan, 5661) with a thickness of about 300 nm on the spacer, it was rubbed in one direction. The combination of the second substrate layer, the second electrode layer, the spacer, and the vertically aligned film is referred to as the lower substrate.

[0124] After coating a liquid crystal composition on the vertically aligned film of the lower substrate to form a liquid crystal layer, an adhesive layer of the upper substrate was laminated so as to face the surface coated with the liquid crystal composition to manufacture a liquid crystal cell. The liquid crystal composition contains a liquid crystal compound (JNC, SHN-5011XX) and a chiral dopant (HCCH, S811), and the pitch p of the liquid crystal layer was about 20 μm. The liquid crystal cell is an RTN mode liquid crystal cell in an initial vertically aligned state.

[0125] Optical device manufacturing A laminate including a first outer substrate, a first adhesive layer, a first polarizer, a first buffer layer, the manufactured liquid crystal cell, a second buffer layer, a second polarizer, a second adhesive layer, and a second outer substrate, and including an outer layer surrounding the side surface of the liquid crystal cell was prepared. The second outer substrate was arranged in the gravitational direction compared to the first outer substrate.

[0126] As the first outer substrate and the second outer substrate, flat glass with a thickness of about 3 mm and an area of horizontal × vertical = 350 mm × 350 mm was used. For the first adhesive layer, the second adhesive layer, and the outer layer, one layer of a TPU layer (Argotec) with a thickness of 380 μm was used. The loss modulus of the TPU layer (Argotec) at a frequency of 1 Hz was 1,485,510 Pa. As the first buffer layer and the second buffer layer, an OCA (Optical Clear Adhesive) layer M1 with a thickness of 500 μm and a loss modulus at a frequency of 1 Hz of 9,696 Pa was used.

[0127] An autoclave process was performed on the laminate at a temperature of about 110 °C and a pressure of about 2 atmospheres to fabricate an optical device having the structure of FIG. 1.

[0128] Example 2 An optical device was fabricated in the same manner as in Example 1, except that in Example 1, an OCA layer M2 with a thickness of 500 μm and a loss modulus at a frequency of 1 Hz of 17,340 Pa was used as the first buffer layer and the second buffer layer, respectively.

[0129] Example 3 An optical device was fabricated in the same manner as in Example 1, except that in Example 1, an OCA layer M3 with a thickness of 500 μm and a loss modulus at a frequency of 1 Hz of 23,434 Pa was used as the first buffer layer and the second buffer layer, respectively.

[0130] Example 4 An optical device was fabricated in the same manner as in Example 1, except that in Example 1, an OCA layer M4 with a thickness of 500 μm and a loss modulus at a frequency of 1 Hz of 46,158 Pa was used as the first buffer layer and the second buffer layer, respectively.

[0131] Example 5 In Example 1, an optical device was fabricated in the same manner as in Example 1, except that an OCA layer M5 with a thickness of 500 μm and a loss elastic modulus of 56,571 Pa at a frequency of 1 Hz was used as the first buffer layer and the second buffer layer, respectively.

[0132] Example 6 A liquid crystal cell was manufactured in the same manner as in Example 1.

[0133] A laminate including a first outer substrate, a first adhesive layer, a first buffer layer, a first polarizer, a third adhesive layer, the manufactured liquid crystal cell, a fourth adhesive layer, a second polarizer, a second buffer layer, a second adhesive layer, and a second outer substrate was prepared. The second outer substrate was disposed in the direction of gravity relative to the first outer substrate.

[0134] The same first outer substrate and second outer substrate as those in Example 1 were used.

[0135] The same first, second, third, and fourth adhesive layers as the first and second adhesive layers in Example 1 were used.

[0136] As the first buffer layer and the second buffer layer, the same OCA layer M2 as in Example 2 was used with a thickness of 500 μm. The first buffer layer and the second buffer layer were formed by laminating the adhesive layer on the outside of the first polarizer and the outside of the second polarizer, respectively.

[0137] An autoclave process was performed on the laminate at a temperature of about 110°C and a pressure of about 2 atmospheres to fabricate an optical device having the structure of FIG. 2.

[0138] Example 7 In Example 6, an optical device was fabricated in the same manner as in Example 6, except that an OCA layer M2 with a thickness of 400 μm was used as the first buffer layer and the second buffer layer, respectively.

[0139] Example 8 In Example 6, an optical device was fabricated in the same manner as in Example 6, except that an OCA layer M2 with a thickness of 300 μm was used as each of the first buffer layer and the second buffer layer.

[0140] Example 9 In Example 6, an optical device was fabricated in the same manner as in Example 6, except that an OCA layer M2 with a thickness of 200 μm was used as each of the first buffer layer and the second buffer layer.

[0141] Example 10 In Example 6, an optical device was fabricated in the same manner as in Example 6, except that an OCA layer M2 with a thickness of 100 μm was used as each of the first buffer layer and the second buffer layer.

[0142] Example 11 A liquid crystal cell was manufactured in the same manner as in Example 1.

[0143] A laminate including a first outer substrate, a first adhesive layer, a first buffer layer, a fifth adhesive layer, a first polarizer, a third adhesive layer, the manufactured liquid crystal cell, a fourth adhesive layer, a second polarizer, a sixth adhesive layer, a second buffer layer, a second adhesive layer, and a second outer substrate was prepared. The second outer substrate was disposed in the gravitational direction relative to the first outer substrate.

[0144] The same ones as those in Example 1 were used as the first outer substrate and the second outer substrate.

[0145] The same ones as the first and second adhesive layers in Example 1 were used as the first, second, third, fourth, fifth, and sixth adhesive layers, respectively.

[0146] The same OCA layer M3 as in Example 3 was used with a thickness of 500 μm as each of the first and second buffer layers. The first buffer layer and the second buffer layer were formed by laminating the adhesive layer inside the first adhesive layer and inside the second adhesive layer, respectively.

[0147] An autoclave process was performed on the laminate at a temperature of about 110 °C and a pressure of about 2 atmospheres to fabricate an optical device having the structure of FIG. 3.

[0148] Example 12 A liquid crystal cell was fabricated in the same manner as in Example 1.

[0149] A laminate including a first outer substrate, a first adhesive layer, a first buffer layer, a first polarizer, a third adhesive layer, the fabricated liquid crystal cell, a fourth adhesive layer, a second polarizer, a second adhesive layer, and a second outer substrate was prepared. The second outer substrate was disposed in the direction of gravity relative to the first outer substrate.

[0150] The same first outer substrate and second outer substrate as those in Example 1 were used.

[0151] The same first, second, third, and fourth adhesive layers as those in Example 1 were used respectively. As the first buffer layer, the same OCA layer M3 as in Example 3 was used with a thickness of 500 μm. The first buffer layer was formed by laminating the adhesive layer outside the first polarizer.

[0152] An autoclave process was performed on the laminate at a temperature of about 110 °C and a pressure of about 2 atmospheres to fabricate an optical device having the structure of FIG. 4.

[0153] Comparative Example 1 A liquid crystal cell was fabricated in the same manner as in Example 1.

[0154] A laminate including a first outer substrate, a first adhesive layer, a first polarizer, a third adhesive layer, the fabricated liquid crystal cell, a fourth adhesive layer, a second polarizer, a second adhesive layer, and a second outer substrate, and including an outer layer surrounding the side surface of the liquid crystal cell was prepared. The second outer substrate was disposed in the direction of gravity relative to the first outer substrate. Comparative Example 1 does not include the first and second buffer layers.

[0155] The same first outer substrate and second outer substrate as those in Example 1 were used.

[0156] As the first and second adhesive layers, three TPU layers (manufactured by Argotec) with a loss modulus of 1,485,510 Pa at a frequency of 1 Hz and a thickness of 380 μm were laminated respectively. As the third and fourth adhesive layers, one TPU layer (manufactured by Argotec) with a loss modulus of 1,485,510 Pa at a frequency of 1 Hz and a thickness of 380 μm was used respectively. The above-mentioned TPU layer was also used as the outer layer.

[0157] An autoclave process was performed on the laminate at a temperature of about 110 °C and a pressure of about 2 atmospheres to fabricate an optical device having the structure shown in FIG. 6.

[0158] Evaluation Example 1. Measurement of Flicker amount The Flicker amount was measured for the optical devices of Examples 1 to 12 and Comparative Example 1 to evaluate light leakage, and the results are shown in Table 1 below. After positioning the optical device on a back light, the Flicker amount was measured using a CA-310 (luminance meter manufactured by KONICA MINOLTA). The Flicker amount was measured by reading the maximum value of the transmittance change while applying pressure at a cycle of 300 g and 2 Hz by utilizing the K-9205 equipment of MIK21. The smaller the Flicker amount, the less the change in luminance. Table 1 below shows the storage modulus and loss modulus values of the adhesive layer (G1), adhesive layer (G2), and buffer layer (G3) of Examples 1 to 12 and Comparative Example 1. It can be confirmed that Examples 1 to 12 show a lower Flicker amount compared to Comparative Example 1.

[0159] [Table 1] [Explanation of Signs]

[0160] 101: First outer substrate 102: Second outer substrate 200: Liquid crystal cell 301: First buffer layer 302: Second buffer layer 401: First adhesive layer 402: Second adhesive layer 403: Third adhesive layer 404: Fourth adhesive layer 405: Fifth adhesive layer 406: Sixth adhesive layer 501: First polarizer 502: Second polarizer 600: Outer layer 10a: First base layer 10b: First electrode layer 10c: Adhesive layer 20a: Second base layer 20b: Second electrode layer 20c: Spacer 20d: Alignment film 30: Liquid crystal layer

Claims

1. An optical device sequentially including a first outer substrate, a first adhesive layer in contact with an inner surface of the first outer substrate, a liquid crystal cell, a second adhesive layer in contact with an inner surface of a second outer substrate, and the second outer substrate, wherein the liquid crystal cell includes an upper substrate including a first base material layer and an adhesive layer; a lower substrate including a second base material layer and spacers; and a liquid crystal layer including a liquid crystal compound between the upper substrate and the lower substrate, the first base material layer is disposed closer to the first outer substrate than the second base material layer, and further includes a first buffer layer positioned between the first base material layer and the first outer substrate.

2. The optical device according to claim 1, wherein the first outer substrate and the second outer substrate are each a glass substrate.

3. The optical device according to claim 1, wherein a loss elastic modulus of the adhesive layer at a temperature of 25° C. and a frequency of 1 Hz is in a range of 50,000 Pa to 2 MPa.

4. The optical device according to claim 1, wherein a loss elastic modulus of the first buffer layer at a temperature of 25° C. and a frequency of 1 Hz is in a range of 1,000 Pa to 500,000 Pa.

5. The optical device according to claim 1, wherein a loss elastic modulus of the first adhesive layer and a loss elastic modulus of the second adhesive layer are each higher than the loss elastic modulus of the adhesive layer.

6. The optical device according to claim 1, wherein a loss elastic modulus of the first adhesive layer and the second adhesive layer at a temperature of 25° C. and a frequency of 1 Hz are each in a range of 1 MPa to 100 MPa.

7. The optical device according to claim 1, wherein the first buffer layer is in contact with an outer surface of the first base material layer or in contact with an inner surface of the first adhesive layer.

8. The optical device according to claim 1, further including a third adhesive layer in contact with an outer surface of the first base material layer and a fourth adhesive layer in contact with an outer surface of the second base material layer.

9. The optical device according to claim 1, further including a first polarizer positioned between the first outer substrate and the liquid crystal cell and a second polarizer positioned between the second outer substrate and the liquid crystal cell.

10. The optical device according to claim 9, further including a fifth adhesive layer in contact with an outer surface of the first polarizer and a sixth adhesive layer in contact with an outer surface of the second polarizer.

11. The optical device according to claim 1, further including a second buffer layer positioned between the second base material layer and the second outer substrate.

12. The optical device according to claim 1, wherein the liquid crystal layer exists in a vertically aligned state when no voltage is applied and exists in a twisted alignment state when a voltage is applied.

13. The optical device according to claim 1, wherein the upper substrate further includes a first electrode layer between the first base material layer and the adhesive layer, and the lower substrate further includes a second electrode layer between the second base material layer and the spacer.

14. The optical device according to claim 13, wherein the upper substrate does not include an alignment film, and the lower substrate further includes an alignment film.

15. An automobile including a vehicle body in which one or more openings are formed; and the optical device according to any one of claims 1 to 14 mounted in the opening.

Images