Polarization-Variable Element

Abstract

The present application relates to a polarization-variable element. The polarization-variable element of the present application has a fast response speed and excellent variable characteristics of polarization degree and transmittance. Such polarization-variable element may be applied to various applications including various architectural or vehicle materials requiring transmittance-variable characteristics, or eyewear such as goggles for augmented reality experience sports, sunglasses or helmets.

Claims

1. A polarization-variable element comprising a photochromic layer; and a guest host liquid crystal layer which comprises liquid crystals and an anisotropic dye, and the guest host liquid crystal layer is switchable between a horizontal orientation state and a vertical orientation state depending on a voltage application.

2. The polarization-variable element according to claim 1, wherein the photochromic layer comprises a photochromic material that is transmittance-variable depending on ultraviolet irradiation.

3. The polarization-variable element according to claim 1, wherein the photochromic layer satisfies Equation 1:
A−B≥50%   [Equation 1] wherein, A is a transmittance (%) of the photochromic layer before ultraviolet irradiation at ΔTmax wavelength, B is a transmittance (%) of the photochromic layer after ultraviolet irradiation at ΔTmax wavelength, and the ΔTmax wavelength means a wavelength having a largest difference in transmittance of the photochromic layer before and after ultraviolet irradiation.

4. The polarization-variable element according to claim 1, wherein the polarization-variable element is switchable between a polarized state having a polarization degree in a range of 45% to 95% and a non-polarized state having a polarization degree of 0% to 10%.

5. The polarization-variable element according to claim 4, wherein the polarization-variable element has a transmittance of 15% or less in the polarized state and a transmittance of 35% or more in the non-polarized state.

6. The polarization-variable element according to claim 4, wherein the polarization-variable element has haze of 10% or less in each of the polarized state and the non-polarized state.

7. The polarization-variable element according to claim 4, wherein the photochromic layer has a transmittance of 60% or less in the polarized state.

8. The polarization-variable element according to claim 4, wherein the photochromic layer has a transmittance of 80% or more in the non-polarized state.

9. The polarization-variable element according to claim 4, wherein the liquid crystals and the anisotropic dye are present in a horizontally oriented state in the polarized state.

10. The polarization-variable element according to claim 4, wherein the liquid crystals and the anisotropic dye are present in a vertically oriented state in the non-polarized state.

11. The polarization-variable element according to claim 1, wherein a first alignment film and a second alignment film are included on both sides of the guest host liquid crystal layer, and an angle formed between orientation axes of the first alignment film and the second alignment film is 10 degrees or less.

12. The polarization-variable element according to claim 1, further comprising a first electrode film and a second electrode film on both sides of the guest host liquid crystal layer.

13. The polarization-variable element according to claim 1, further comprising a substrate disposed on one side of the photochromic layer.

14. The polarization-variable element according to claim 13, further comprising a base layer disposed on the other side of the photochromic layer.

15. The polarization-variable element according to claim 1, further comprising an antireflection layer on one side of the guest host liquid crystal layer.

Description

DESCRIPTION OF DRAWINGS

[0067] FIG. 1 exemplarily shows a structure of a polarization-variable element in the present application.

[0068] FIG. 2 exemplarily shows a structure of a polarization-variable element in the present application.

[0069] FIG. 3 exemplarily shows a structure of a polarization-variable element in the present application.

[0070] FIG. 4 shows transmittance spectra of a photochromic layer.

MODE FOR INVENTION

[0071] Hereinafter, the present application will be described in detail through examples according to the present application and comparative examples not according to the present application, but the scope of the present application is not limited by the following examples.

MEASUREMENT EXAMPLE 1

Measurement of Transmittance and Haze

[0072] Haze and transmittance were measured according to ASTM D1003 standard using a haze meter (NDH-5000SP). Specifically, light is transmitted through the measurement object and incident into the integrating sphere, where in this process, the light is divided into diffusion light (DT, which means the sum of all diffused and emitted light) and parallel light (PT, which means exit light in the front direction excluding the diffusion light), and these lights are focused on the light receiving element in the integrating sphere, whereby the haze can be measured through the focused light. The total transmitted light (TT) by the above process is the sum (DT+PT) of the diffusion light (DT) and the parallel light (PT), where haze can be defined as a percentage (Haze (%)=100×DT/TT) of the diffusion light to the total transmitted light. In the following test examples, the total transmittance means the total transmitted light (TT).

[0073] MEASUREMENT EXAMPLE 2

Measurement of Polarization Degree

[0074] Polarization degree for a wavelength of 550 nm was measured using an ultraviolet-visible light spectrometer (V-7100, JASCO). The polarization degree (P) is a value calculated according to the following equation A.

Polarization degree (P) (%)={(Tp−Tc)/(Tp+Tc)}.sup.1/2×100   [Equation A]

[0075] In Equation A, Tp is the maximum transmittance of the polarizing element, and Tc is the minimum transmittance of the polarizing element. In Equation A, the maximum transmittance (Tp) is the transmittance at the time point showing the maximum value in a state where two polarizing elements are overlapped, when the transmittance has been measured while scanning the overlapped state for each angle so that the light absorption axis of each polarizing element forms an angle in the range of 0 to 360 degrees, and the minimum transmittance (Tc) is the transmittance at the time point showing the minimum value. The above-mentioned transmittance (Tc, Tp) is a value measured for light of about 550 nm.

EXAMPLE 1

Polarization-Variable Element (A)

[0076] VA mode GHLC cell (A)

[0077] A base film (product from Tejin) that an ITO (indium tin oxide) layer was formed on a PC (polycarbonate polymer) film was prepared. A vertical alignment film (SE-5661, product from Nissan) was coated on the ITO layer side of the base film by bar coating and then calcined at a temperature of 120° C. for 1 hour to obtain an alignment film having a thickness of 300 nm. The alignment film was subjected to rubbing in one direction using a rubbing cloth to prepare a first substrate.

[0078] On the ITO layer of the same film as the first substrate, column spacers having a height of 9 μm and a diameter of 15 μm were arranged at intervals of 250 μm. Next, a vertical alignment film was formed in the same manner as the first substrate, and then subjected to rubbing in one direction using a rubbing cloth to prepare a second substrate.

[0079] As a GHLC composition, a composition (MAT-16-568, Merck) comprising liquid crystals having refractive index anisotropy (An) of 0.13 and negative dielectric constant anisotropy, and an anisotropic dye was used.

[0080] A sealant was drawn at the edges on the alignment film surface of the second substrate with a seal dispenser. After applying the GHLC composition on the alignment film of the second substrate, the first substrate was laminated to produce a liquid crystal cell. At this time, the lamination was performed such that the rubbing direction of the alignment film of the first substrate and the rubbing direction of the alignment film of the second substrate were anti-parallel. The produced liquid crystal cell is a VA mode liquid crystal cell with a cell gap of 9 μm. An antireflection layer was attached to one side of the second substrate in the VA mode liquid crystal cell via OCA (LGC, V310).

[0081] Photochromic Layer

[0082] A product (ORDINA's spectacle lens part, product from OGK) that a photochromic material layer was coated on a PC plate having a thickness of 0.8T was prepared. FIG. 4 shows transmittance spectra of the photochromic layer. As shown in FIG. 4, the photochromic layer exhibits high transmittance in the visible light region when UV is not irradiated, and has lower transmittance in a predetermined wavelength region when UV is irradiated.

[0083] The VA mode GHLC cell (A) and the photochromic layer were attached via OCA (LGC, V310) adhesive. At this time, the photochromic layer and the first electrode film of the VA mode GHLC cell (A) were attached to contact each other.

EXAMPLE 2

Polarization-Variable Element (B)

[0084] A VA mode GHLC cell (B) was produced in the same manner as the VA mode GHLC cell (A) of Example 1, except that the cell gap was changed to 15 μm. The VA mode GHLC cell (B) and the photochromic layer used in Example 1 were attached via OCA (LGC, V310) adhesive. At this time, the photochromic layer and the first electrode film of the VA mode GHLC cell (B) were attached to contact each other.

Example 3

Polarization-Variable Element (C)

[0085] A VA mode GHLC cell (C) was produced in the same manner as the VA mode GHLC cell (A) of Example 1, except that the cell gap was changed to 15 μm, and a composition containing 1 wt % of anisotropic dye (X12, BASF) and liquid crystal (LC_ZGS8017, JNC) was used as the GHLC composition. The VA mode GHLC cell (C) and the photochromic layer used in Example 1 were attached via OCA (LGC, V310) adhesive. At this time, the photochromic layer and the first electrode film of the VA mode GHLC cell (C) were attached to contact each other.

EXAMPLE 4

Polarization-Variable Element (D)

[0086] ECB Mode GHLC Cell (D)

[0087] A base film (product from Tejin) that an ITO (indium tin oxide) layer was formed on a PC (polycarbonate polymer) film was prepared. A horizontal alignment film (SE-7492, product from Nissan) was coated on the ITO layer side of the base film by bar coating and then calcined at a temperature of 120° C. for 1 hour to obtain an alignment film having a thickness of 300 nm. The alignment film was subjected to rubbing in one direction using a rubbing cloth to prepare a first substrate.

[0088] On the ITO layer of the same film as the first substrate, column spacers having a height of 9 μm and a diameter of 15 μm were arranged at intervals of 250 μm. Next, a horizontal alignment film was formed in the same manner as the first substrate, and then subjected to rubbing in one direction using a rubbing cloth to prepare a second substrate.

[0089] As the GHLC composition, a composition containing 1 wt % of anisotropic dye (X12, BASF) and liquid crystal (HPC2180, HCCH) was used.

[0090] A sealant was drawn at the edges on the alignment film surface of the second substrate with a seal dispenser. After applying the GHLC composition on the alignment film of the second substrate, the first substrate was laminated to produce a liquid crystal cell. At this time, the lamination was performed such that the rubbing direction of the alignment film of the first substrate and the rubbing direction of the alignment film of the second substrate were anti-parallel. The produced liquid crystal cell is an ECB mode liquid crystal cell with a cell gap of 9 μm. An antireflection layer was attached to one side of the second substrate in the ECB mode liquid crystal cell via OCA (LGC, V310).

[0091] The ECB mode GHLC cell (D) and the photochromic layer used in Example 1 were attached via OCA (LGC, V310) adhesive. At this time, the photochromic layer and the first electrode film of the ECB mode GHLC cell (D) were attached to contact each other.

COMPARATIVE EXAMPLE 1

VA Mode GHLC Cell (A)

[0092] The VA mode GHLC cell (A) produced in Example 1 was prepared as Comparative Example 1.

COMPARATIVE EXAMPLE 2

VA Mode GHLC Cell (B)

[0093] The VA mode GHLC cell (B) produced in Example 2 was prepared as Comparative Example 2.

COMPARATIVE EXAMPLE 3

VA Mode GHLC Cell (C)

[0094] The VA mode GHLC cell (C) produced in Example 3 was prepared as Comparative Example 3.

COMPARATIVE EXAMPLE 4

ECB Mode GHLC Cell (D)

[0095] The ECB mode GHLC cell (D) produced in Example 4 was prepared as Comparative Example 4.

COMPARATIVE EXAMPLE 5 STN Mode GHLC Cell (E)

[0096] A base film (product from Tejin) that an ITO (indium tin oxide) layer was formed on a PC (polycarbonate polymer) film was prepared. A horizontal alignment film (SE-7492, product from Nissan) was coated on the ITO layer side of the base film by bar coating and then calcined at a temperature of 120° C. for 1 hour to obtain an alignment film having a thickness of 300 nm. The alignment film was subjected to rubbing in one direction using a rubbing cloth to prepare a first substrate.

[0097] On the ITO layer of the same film as the first substrate, column spacers having a height of 6 μm and a diameter of 15 μm were arranged at intervals of 250 μm. Next, a horizontal alignment film was formed in the same manner as the first substrate, and then subjected to rubbing in one direction using a rubbing cloth to prepare a second substrate.

[0098] As a GHLC composition, a liquid crystal composition that 0.519 wt % of a chiral dopant (S811, Merck) was added to a GHLC composition comprising liquid crystals (MDA-17-595, Merck) having refractive index anisotropy (An) of 0.1 and positive dielectric constant anisotropy, and an anisotropic dye (Merck) was used.

[0099] A sealant was drawn at the edges on the alignment film surface of the second substrate with a seal dispenser. After applying the GHLC composition on the alignment film of the second substrate, the first substrate was laminated to produce a liquid crystal cell. At this time, the lamination was performed such that the rubbing direction of the alignment film of the first substrate and the rubbing direction of the alignment film of the second substrate were anti-parallel. The produced liquid crystal cell is a 360degree STN mode liquid crystal cell with a cell gap of 6 μm. An antireflection layer was attached to one side of the second substrate in the STN mode liquid crystal cell via OCA (LGC, V310).

COMPARATIVE EXAMPLE 6

Photochromic Layer

[0100] The photochromic layer used in Example 1 was prepared as Comparative Example 6.

COMPARATIVE EXAMPLE 7

Polarization-Variable Element (E)

[0101] The STN mode GHLC cell (E) of Comparative Example 5 and the photochromic layer used in Example 1 were attached via OCA (LGC, V310) adhesive. At this time, the photochromic layer and the first electrode film of the STN mode GHLC cell (E) were attached to contact each other.

EVALUATION EXAMPLE 1

Evaluation of Electro-Optical Characteristics

[0102] Electro-optical characteristics of Comparative Examples 1 to 7 and Examples 1 to 4 were evaluated and the results were described in Tables 1 to 11 below.

[0103] For the GHLC cells of Comparative Examples 1 to 5, the transmittance, haze and polarization degree depending on voltage application were measured. Specifically, while an AC power source was connected to the first and second ITO layers and driven, the transmittance, haze and polarization degree depending on whether or not a voltage was applied were measured and the results were described in Tables 1 to 5 below.

[0104] For the photochromic element of Comparative Example 6, the transmittance and haze depending on the irradiated energy of UVA (wavelengths of 300 to 380 nm) were measured and the results were described in Table 6 below.

[0105] For the polarization-variable elements of Comparative Example 7 and Examples 1 to 4, the transmittance, haze and polarization degree depending on voltage application to the GHLC cell and irradiation of UVA of 150 mJ/cm.sup.2 to the photochromic layer were measured and the results were described in Tables 7 to 11 below.

[0106] The transmittance and haze were measured using a haze meter (NDH5000SP, manufactured by Secos). The transmittance and haze are the average transmittance for light having a wavelength of 380 nm to 780 nm.

[0107] In Tables 1 to 5 and 7 to 11 below, the response time is measured through a photodiode, normalized, and measured by converting the time of the transition section corresponding to the transmittance from 10% to 90%.

TABLE-US-00001 TABLE 1 Comparative Example 1 Transmittance Haze Polarization VA Mode GHLC Cell (A) (%) (%) Degree (%)  0 V 67.1% 1.0% <0.5% 15 V 36.8% 1.3% 88.2% Response Time On/Off <100 ms

TABLE-US-00002 TABLE 2 Comparative Example 2 Transmittance Haze Polarization VA Mode GHLC Cell (B) (%) (%) Degree (%)  0 V 61.5% <2% <4% 15 V .sup. 32% <2% 79% Response Time On/Off <100 ms

TABLE-US-00003 TABLE 3 Comparative Example 3 Transmittance Haze Polarization VA Mode GHLC Cell (C) (%) (%) Degree (%)  0 V 64.6% <2% .sup. <5% 15 V .sup. 37% <2% 76.6% Response Time On/Off <100 ms

TABLE-US-00004 TABLE 4 Comparative Example 4 Transmittance Haze Polarization ECB Mode GHLC Cell (D) (%) (%) Degree (%)  0 V 61.5% <2% <4% 15 V .sup. 32% <2% 79% Response Time On/Off <100 ms

TABLE-US-00005 TABLE 5 Comparative Example 5 Transmittance Haze Polarization STN Mode GHLC Cell (E) (%) (%) Degree (%)  0 V 27.0% 1.2% .sup. 38% 15 V 70.5 0.9% <0.5% Response Time On/Off <100 ms

TABLE-US-00006 TABLE 6 Comparative Example 6 Transmittance Haze (Photochromic Layer) (%) (%) UVA 0 90.2% 0.4% Irradiation 32.7 43.3% 0.4% Energy 89.0 20.1% 0.5% [mJ/cm.sup.2] 150.2 15.4% 0.5%

TABLE-US-00007 TABLE 7 Comparative Example 7 (STN Mode GHLC Cell (E) + Transmittance Haze Polarization Photochromic Layer) (%) (%) Degree (%) 0 V_w/o UV   5% 1.8% 38% 15 V_w/UV 67.8% 1.2% <2% Response Time On/Off <100 ms

TABLE-US-00008 TABLE 8 Example 1 (VA Mode GHLC Cell (A) + Transmittance Haze Polarization Photochromic Layer) (%) (%) Degree (%) 0 V_w/o UV  62% <2% <0.5% 15 V_w/UV 6.5% <2% 88.2% Response Time On/Off <100 ms

TABLE-US-00009 TABLE 9 Example 2 (VA Mode GHLC Cell (B) + Transmittance Haze Polarization Photochromic Layer) (%) (%) Degree (%) 0 V_w/o UV 55% <2% <4% 15 V_w/UV  5% <2% 79% Response Time On/Off <100 ms

TABLE-US-00010 TABLE 10 Example 3 (VA Mode GHLC Cell (C) + Transmittance Haze Polarization Photochromic Layer) (%) (%) Degree (%) 0 V_w/o UV 58% <2% .sup. <5% 15 V_w/UV  6% <2% 76.6% Response Time On/Off <100 ms

TABLE-US-00011 TABLE 11 Example 4 (ECB Mode GHLC Cell (D) + Transmittance Haze Polarization Photochromic Layer) (%) (%) Degree (%) 0 V_w/o UV  6% <2% 80.4% 15 V_w/UV 62% <2% .sup. <2% Response Time On/Off <100 ms

EXPLANATION OF REFERENCE NUMERALS

[0108] 101: substrate

[0109] 100: photochromic layer

[0110] 102: base layer

[0111] 300, 301, 302: adhesive layer

[0112] 200: GHLC layer

[0113] 201: first electrode film

[0114] 202: second electrode film