KR20220003721A - Viewing angle variable element and display assembly - Google Patents

Abstract

The present invention relates to a variable viewing angle element and a display assembly. The present application provides a viewing angle variable element capable of implementing a narrow viewing angle mode with low lateral transmittance and providing a wide viewing angle when driven, and a display assembly including the viewing angle variable element. The present invention comprises a liquid crystal cell and a polarizer on one surface of the liquid crystal cell, wherein the liquid crystal cell sequentially includes a first substrate, a first electrode layer, a first alignment layer, a liquid crystal layer, a second alignment layer, a second electrode layer and a second substrate.

Description

VIEWING ANGLE VARIABLE ELEMENT AND DISPLAY ASSEMBLY

The present application relates to a variable viewing angle element and a display assembly.

The use of security films is increasing according to the importance of information protection or personal privacy. For example, Patent Document 1 discloses a security film to which a micro louver technology is applied. The micro louver film has a structure in which a plurality of micro louvers are patterned at regular intervals. A plurality of micro louvers formed inside the micro louver film exerts an effect (direction control effect) of controlling the propagation direction of light passing through the louver film to a predetermined outflow angle range. When the micro louver film is applied, the screen can be seen clearly from the front, but it is difficult to see the screen from the side. As such, the micro louver film has excellent information protection power from the side, but the brightness is too low from the front side, so the brightness of the backlight must be increased.

Republic of Korea Patent Publication No. 10-2007-0090662

The present application provides a viewing angle variable element capable of implementing a narrow viewing angle mode with low transmittance from the side, and providing a wide viewing angle when driven, and a display assembly including the viewing angle variable element.

The present application relates to a viewing angle variable element. 1 exemplarily shows the structure of the variable viewing angle element of the present application. The variable viewing angle element may include a liquid crystal cell 100 and a polarizer 200 on one surface of the liquid crystal cell 100 . 2 exemplarily shows the structure of a liquid crystal cell. The liquid crystal cell 100 includes a first substrate 101A, a first electrode layer 102A, a first alignment layer 103A, a liquid crystal layer 104, a second alignment layer 103B, a second electrode layer 102B, and a second substrate ( 101B) may be included sequentially.

As the first substrate and/or the second substrate, a known substrate material may be used without any particular limitation. For example, as the substrate, an inorganic substrate such as a glass substrate, a crystalline or amorphous silicon substrate, or a quartz substrate, or a plastic substrate can be used. Examples of the plastic substrate include a triacetyl cellulose (TAC) substrate; COP (cyclo olefin copolymer) substrates such as norbornene derivative substrates; PMMA(poly(methyl methacrylate) substrate; PC(polycarbonate) substrate; PE(polyethylene) substrate; PP(polypropylene) substrate; PVA(polyvinyl alcohol) substrate; DAC(diacetyl cellulose) substrate; Pac(Polyacrylate) substrate; PES(polypropylene) substrate ether sulfone) substrate; PEEK (polyetheretherketon) substrate; PPS (polyphenylsulfone), PEI (polyetherimide) substrate; PEN (polyethylenemaphthatlate) substrate; PET (polyethyleneterephtalate) polyester substrate such as; PI (polyimide) substrate; PSF (polysulfone) substrate ; A PAR (polyarylate) substrate or a substrate including an amorphous fluororesin may be used, but is not limited thereto The thickness of the substrate is not particularly limited and may be selected within an appropriate range.

The first electrode layer and the second electrode layer may apply an appropriate electric field to the liquid crystal layer to change the alignment state of the liquid crystal layer. The direction of the electric field may be a vertical direction, for example, a thickness direction of the liquid crystal layer.

Each of the first electrode layer and the second electrode layer may include a continuous electrode. In the present specification, the continuous electrode may refer to an electrode having a continuous shape rather than a patterned shape of the electrode. That is, the continuous electrode has a single electrode area.

Each of the first electrode layer and the second electrode layer may be a transparent electrode layer. In the present specification, the transparent electrode layer may mean an electrode layer having an average transmittance of 80% or more, 85% or more, or 90% or more with respect to a wavelength of 380 nm to 780 nm. Each of the first electrode layer and the second electrode layer may include, but is not limited to, a conductive polymer, a conductive metal, a conductive nanowire, or a metal oxide such as indium tin oxide (ITO). Each of the first electrode layer and the second electrode layer may be formed by depositing, for example, a metal oxide such as the conductive polymer, conductive metal, conductive nanowire, or indium tin oxide (ITO).

The liquid crystal cell may change the alignment state of liquid crystal molecules and/or anisotropic dye included in the liquid crystal layer according to the application of voltage. Through this, when applied to a display device, a narrow viewing angle mode with low transmittance from the side can be implemented, and a wide viewing angle can be provided during operation.

The liquid crystal cell may switch between a horizontal alignment state and an inclined alignment state according to the application of a voltage. The liquid crystal molecules and/or the anisotropic dye may exist in a horizontal alignment state in a state in which no voltage is applied to the liquid crystal layer. The liquid crystal molecules and/or the anisotropic dye may exist in an inclined alignment state in a state in which a voltage is applied to the liquid crystal layer.

In the present specification, "horizontal alignment state" may mean a state in which the directors of liquid crystal molecules in the liquid crystal layer are arranged substantially horizontally with respect to the plane of the liquid crystal layer. In the horizontal alignment state, the angle formed by the director of the liquid crystal molecule with respect to the plane of the liquid crystal layer is, for example, in the range of about 0 degrees to 20 degrees, about 0 degrees to 10 degrees, about 0 degrees to 5 degrees, or about 0 degrees to 3 degrees. may be within or approximately zero degrees.

In the present specification, the "slanted alignment state" may mean a state in which the directors of liquid crystal molecules in the liquid crystal layer are arranged to be inclined with respect to the plane of the liquid crystal layer. In the inclined alignment state, the angle (inclination angle) formed by the director of the liquid crystal molecules with respect to the plane of the liquid crystal layer may be, for example, in the range of 0.5 degrees to 3 degrees. In this case, individual inclination angles of all liquid crystal molecules included in the liquid crystal layer may be within the above range, or an average inclination angle of all liquid crystal molecules included in the liquid crystal layer may be within the above range.

In the present specification, the liquid crystal molecule or the director of the liquid crystal compound may refer to an optical axis or a slow axis of the liquid crystal layer. The director of the liquid crystal molecules may mean a long axis direction when the liquid crystal molecules have a rod shape, and may mean an axis parallel to the normal direction of the plane of the disk when the liquid crystal molecules have a discotic shape. When a plurality of liquid crystal molecules having different directors exist in the liquid crystal layer, the director may be a vector sum.

The liquid crystal molecule may be a liquid crystal molecule exhibiting a nematic phase. The liquid crystal molecule may be, for example, a compound that does not have a polymerizable group or a crosslinkable group so that the alignment state can be changed by application of an external signal.

The liquid crystal molecules may have positive dielectric anisotropy. In the present specification, "dielectric anisotropy (Δε)" may mean a difference (ε// - ε⊥) between a horizontal dielectric constant (ε//) and a vertical dielectric constant (ε⊥) of liquid crystal molecules. As used herein, the term horizontal permittivity (ε//) refers to a dielectric constant value measured along the direction of the electric field in a state in which a voltage is applied so that the direction of the electric field by the applied voltage and the director of liquid crystal molecules is substantially horizontal, The perpendicular permittivity ε⊥ refers to a dielectric constant value measured along the direction of the electric field in a state in which a voltage is applied so that the direction of the electric field by the applied voltage is substantially perpendicular to the direction of the liquid crystal molecules. The dielectric anisotropy of the liquid crystal molecules may be in the range of 5 to 25.

The liquid crystal molecules may have refractive index anisotropy (Δn) in the range of 0.06 to 0.3. In the present specification, the refractive index anisotropy (Δn) is a difference (ne-no) between an extraordinary refractive index (ne, extraordinary refractive index) and an ordinary refractive index (no, ordinary refractive index), which can be confirmed using, for example, an Abbe refractometer. .

Each of the first alignment layer and the second alignment layer may be a horizontal alignment layer. In the present specification, “horizontal alignment layer” may refer to an alignment layer capable of inducing horizontal alignment with respect to adjacent liquid crystal molecules. The pretilt angle of the liquid crystal molecules with respect to the horizontal alignment layer may be in the range of about 0 degrees to 20 degrees, about 0 degrees to 10 degrees, about 0 degrees to 5 degrees, or about 0 degrees to 3 degrees, or about 0 degrees. By using the horizontal alignment layer as the first alignment layer and the second alignment layer, it may be advantageous to implement a narrow viewing angle mode with low transmittance from the side and to provide a wide viewing angle during driving.

In the present specification, the pretilt may have an angle and a direction. The pretilt angle may be referred to as a polar angle, and the pretilt direction may be referred to as an azimuthal angle. The pretilt angle may mean an angle formed by a director of liquid crystal molecules with respect to a plane horizontal to the alignment layer. The pretilt direction may refer to a direction in which a director of liquid crystal molecules is projected onto a horizontal surface of the alignment layer.

Each of the first alignment layer and the second alignment layer may be a rubbing alignment layer or a photo alignment layer. The pretilt direction can be controlled by the rubbing direction of the alignment layer. The alignment direction of the rubbing alignment layer is determined by the rubbing direction, and the alignment direction of the photo alignment layer is determined by the polarization direction of the irradiated light. The pre-tilt angle and pre-tilt direction of the alignment film may be determined by appropriately adjusting alignment conditions, for example, rubbing conditions or pressure conditions during rubbing alignment, or photo-alignment conditions, for example, polarization state of light, irradiation angle of light, light irradiation intensity, etc. It can be adjusted and implemented. For example, in the case of a rubbing alignment layer, the pretilt angle may be achieved by controlling the rubbing intensity of the rubbing alignment layer, etc., and the pretilt direction may be achieved by controlling the rubbing direction of the rubbing alignment layer. is a known method. In addition, in the case of a photo-alignment layer, it may be achieved by the alignment layer material, the direction, state or intensity of polarization applied to the alignment, and the like, and such an achievement method is a known method.

The liquid crystal layer including liquid crystal molecules and anisotropic dye may be referred to as a guest host liquid crystal (GHLC) layer. As used herein, the term "GHLC layer" refers to a functional layer in which anisotropic dyes are arranged together according to the arrangement of liquid crystals, and each exhibits anisotropic light absorption characteristics with respect to the alignment direction of the anisotropic dye and the direction perpendicular to the alignment direction. can

As used herein, the term "dye" may mean a material capable of intensively absorbing and/or transforming light within the visible light region, for example, at least a portion or the entire range within the wavelength range of 400 nm to 700 nm, The term “anisotropic dye” may refer to a material capable of anisotropic absorption of light in at least a part or the entire range of the visible light region. For example, an anisotropic dye is a material whose absorption rate varies depending on the polarization direction. If the absorption rate of light polarized in the long-axis direction is large, it is called a p-type dye, and if the absorption rate of light polarized in the short-axis direction is large, it is called an n-type dye. can do. In one example, when a p-type dye is used, polarized light vibrating in the long axis direction of the dye is absorbed, and polarized light vibrating in the short axis direction of the dye is absorbed and transmitted therethrough. Hereinafter, it is assumed that the anisotropic dye is a p-type dye, unless otherwise specified.

As the anisotropic dye, for example, a known dye known to have a property that can be aligned according to the alignment state of the liquid crystal may be selected and used. As the anisotropic dye, for example, black dye can be used. Such dyes are, for example, known as azo dyes or anthraquinone dyes, but are not limited thereto.

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

The content of the anisotropic dye in the liquid crystal layer may be less than 1.5 wt%. The content of the dye may be, for example, more than 0 wt%, 0.1 wt% or more, 0.2 wt% or more, 0.3 wt% or more, 0.4 wt% or more, or 0.5 wt% or more. When the content of the anisotropic dye is within the above range, it may be advantageous to implement a narrow viewing angle mode with low transmittance from the side and provide a wide viewing angle during driving.

The viewing angle variable element may further include a polarizer. In the present specification, the term polarizer may refer to a device that converts natural light or unpolarized light into polarized light. In one example, the polarizer may be a linear polarizer. In the present specification, linear polarizer refers to a case in which selectively transmitted light is linearly polarized light vibrating in one direction, and selectively absorbed or reflected light is linearly polarized light vibrating in a direction orthogonal to the vibration direction of the linearly polarized light. That is, the linear polarizer may have a transmission axis and an absorption axis orthogonal to each other in a plane direction.

The polarizer may be an absorption type polarizer polarizer. As the absorption type polarizer, for example, a polarizer in which iodine is dyed on a polymer stretched film, such as a PVA (poly(vinyl alcohol)) stretched film, or a liquid crystal polymerized in an aligned state is used as a host, and according to the orientation of the liquid crystal A guest-host type polarizer having an arrayed dichroic dye as a guest may be used, but is not limited thereto.

The transmittance of the polarizer for a wavelength of 550 nm may be in the range of 40% to 50%. The transmittance may mean a single transmittance of the polarizer with respect to a wavelength of 550 nm. The single transmittance of the polarizer can be measured using, for example, a spectrometer (V7100, manufactured by Jasco). For example, with the polarizer sample (not including the upper and lower protective films) mounted on the device, air is set as the base line, and the transmittance of each transmittance is measured with the axis of the polarizer sample aligned vertically and horizontally with the axis of the reference polarizer. After the measurement, the single transmittance can be calculated.

The polarizer may be attached to the outer surface of the first substrate or the second substrate of the liquid crystal cell. In this specification, "outer surface" may mean a side opposite to the side facing the liquid crystal layer, and "inner surface" may mean a side facing the liquid crystal layer.

The alignment direction of the anisotropic dye of the liquid crystal layer may be parallel to the absorption axis of the polarizer. The alignment direction of the anisotropic dye may mean an alignment direction in a state in which no voltage is applied to the liquid crystal layer. Through this, it may be advantageous to implement a narrow viewing angle mode with low transmittance from the side and provide a wide viewing angle during driving.

A spacer may be formed on an inner surface of any one of the first electrode layer and the second electrode layer. In this case, the polarizer may be attached to one surface of a substrate on which a spacer is formed or a substrate on which a spacer is not formed among the first substrate and the second substrate.

The spacer may serve to maintain a gap between the first substrate and the second substrate. As the spacer, as a commonly applied spacer, a ball spacer, a column spacer, or a barrier rib spacer may be applied. Considering the optical characteristics of the variable viewing angle element, the ball spacer may be more advantageous than the column spacer. As the barrier rib spacer, a honeycomb type, a rectangular barrier rib spacer, or a random spacer may be applied. In the above, the honeycomb or quadrangular barrier rib spacer is a case in which the shape formed by the barrier rib spacer is honeycomb or quadrangular when the shape of the barrier rib spacer formed on the substrate is observed in the normal direction of the substrate. it means. The honeycomb type is usually a combination of a regular hexagon, and in the case of a quadrangle, there may be a square, a rectangle, or a combination of a square and a rectangle. In addition, in the above, the random spacer refers to a case in which the partition walls are randomly arranged, and the partition walls do not form a figure or form a figure at random rather than a standardized figure even though the partition walls are formed. The dimension of the spacer may be appropriately selected in consideration of adhesion force or cell gap maintenance efficiency. The spacer may include at least one selected from the group consisting of a carbon-based material, a metal-based material, an oxide-based material, and a composite material thereof.

The thickness of the liquid crystal layer may be appropriately selected within a range that does not impair the purpose of the present application. The thickness of the liquid crystal layer may be, for example, 8 μm or more. The upper limit of the thickness of the liquid crystal layer may be, for example, 15 μm or less.

In the variable viewing angle device, the liquid crystal cell and the polarizer may be attached through an adhesive or an adhesive. As the pressure-sensitive adhesive or adhesive, a known transparent pressure-sensitive adhesive or transparent adhesive used for attaching an optical member may be appropriately selected and used. The pressure-sensitive adhesive or adhesive may include, for example, an acrylic, silicone-based, or epoxy-based pressure-sensitive adhesive or adhesive, but is not limited thereto.

The liquid crystal cell may change the alignment state of liquid crystal molecules and/or anisotropic dye included in the liquid crystal layer according to the application of voltage. Through this, the viewing angle variable element can switch between the narrow viewing angle mode and the wide viewing angle mode. In a state in which no voltage is applied to the liquid crystal layer, the liquid crystal molecules and/or the anisotropic dye may exist in a horizontally aligned state, and a wide viewing angle mode may be implemented. In the present specification, the wide viewing angle mode may refer to a state in which transmittance is 65% or more at the front of the variable viewing angle element, and transmittance is 60% or more at a viewing angle of 45 degrees or more with respect to the front surface. When the voltage in the liquid crystal layer is in the range of about 1.5V to 3V, the liquid crystal molecules and/or the anisotropic dye may exist in an obliquely aligned state, and a narrow viewing angle mode may be implemented. In the present specification, the narrow viewing angle mode may mean a state in which transmittance is 5% or less at a viewing angle of 45 degrees or more with respect to the front surface of the variable viewing angle element.

The present application relates to a display assembly including the variable viewing angle element. The viewing angle variable element may be applied to a display device to implement a narrow viewing angle mode with low transmittance from the side, and may be advantageous in providing a wide viewing angle during driving. Hereinafter, the above description of the variable viewing angle element may be applied unless there is a specific reference to the variable viewing angle element.

The display assembly may include a display device and the variable viewing angle element disposed on one surface of the display device. The viewing angle variable element may be disposed on the light output side of the display device. The viewing angle variable element may switch the alignment state of the liquid crystal layer according to the application of voltage, and thus the viewing angle of the display device may be switched.

For example, in a state in which no voltage is applied to the liquid crystal cell of the variable viewing angle element, the display assembly may implement a wide viewing angle mode. In this case, the liquid crystal molecules and/or the anisotropic dye included in the liquid crystal layer may exist in a horizontal alignment state.

For example, in a state in which a voltage within a range of about 1.5V to 3V is applied to the liquid crystal cell of the variable viewing angle element, the display assembly may implement a narrow viewing angle mode. In this case, the liquid crystal molecules and/or the anisotropic dye included in the liquid crystal layer may exist in an inclined alignment state.

The display device may include at least one polarizer or may not include a polarizer.

In one example, the display device may have at least an upper polarizer. The upper polarizer may mean a light emission side polarizer. The variable viewing angle element may be disposed on the upper polarizer of the display device, and the polarizer of the variable viewing angle element may be disposed further away from the display device than the liquid crystal cell. In this case, the absorption axis of the upper polarizer of the display device and the absorption axis of the polarizer of the variable viewing angle element may be parallel to each other.

The display device may include a liquid crystal display device or an organic light emitting display device.

The liquid crystal display device may include a liquid crystal display panel and two polarizers disposed on both surfaces of the liquid crystal display panel. Each of the two polarizers may be an absorption type linear polarizer. Among the two polarizers, a polarizer disposed on the light output side may be referred to as an upper polarizer, and a polarizer disposed on the opposite side of the light output side, that is, close to the light source, may be referred to as a lower polarizer. Absorption axes of the upper polarizer and the lower polarizer of the liquid crystal display may be orthogonal to each other. The liquid crystal display panel may include a liquid crystal layer between two opposing substrates, and an electrode layer and an alignment layer may be respectively formed on the liquid crystal layer side of the substrate. The driving mode of the liquid crystal display panel is not particularly limited and may be appropriately selected according to need. For example, as a driving mode of the liquid crystal cell, for example, an electrically controlled birefringence (ECB) mode, a twisted nematic (TN) mode, a super twisted nematic (STN) mode, a reverse twisted nematic (RTN) mode, a reverse super super Twisted Nematic) mode, HAN (Hybrid Aligned Nematic) mode, Twisted HAN (Twisted Hybrid Aligned Nematic) mode, Super twisted HAN (Super Twisted Hybrid Aligned Nematic) mode, IPS (In-Plane Switching) mode, VA (vertical alignment) mode etc. Depending on the desired driving mode of the liquid crystal cell, the type of liquid crystal, the type of the alignment layer, the type of the additive, etc. may be appropriately selected.

The organic light emitting display device may include an organic light emitting display panel and one polarizer disposed on one surface of the organic light emitting display panel. The single polarizer may be an absorption type linear polarizer. A quarter wave plate may be further included between the polarizer and the organic light emitting display panel. The quarter wave plate may have, for example, an in-plane retardation value for a wavelength of 550 nm in the range of 100 nm to 200 nm, and 100 nm to 170 nm to 110 nm to 150 nm. The quarter wave plate may be a liquid crystal polymerized film or a polymer stretched film. The polarizer and the quarter-wave plate may act as a circular polarizing plate or an elliptically polarizing plate to reflect external light of the organic light emitting display device and improve visibility.

The organic light emitting display panel may sequentially include a substrate, a lower electrode, an organic light emitting layer, and an upper electrode. The organic emission layer may include an organic material capable of emitting light when a voltage is applied to the lower electrode and the upper electrode. One of the lower electrode and the upper electrode may be an anode and the other may be a cathode. The anode is an electrode into which holes are injected and may be made of a conductive material having a high work function, and the cathode is an electrode into which electrons are injected and may be made of a conductive material having a low work function. In general, a transparent metal oxide layer such as ITO or IZO having a large work function may be used as the anode, and a metal electrode having a low work function may be used as the cathode. In general, since the organic light emitting layer is transparent, a transparent display can be realized when the upper and lower electrodes are made transparent. In one example, when the thickness of the metal electrode is very thin, a transparent display may be realized.

The organic light emitting display panel may further include an encapsulation substrate on the upper electrode to prevent moisture and/or oxygen from being introduced from the outside. An auxiliary layer may be further included between the lower electrode and the organic emission layer and between the upper electrode and the organic emission layer. The auxiliary layer may include a hole transporting layer, a hole injecting layer, an electron injecting layer, and an electron transporting layer for balancing electrons and holes. However, the present invention is not limited thereto.

The polarizer may be disposed on a side from which light is emitted from the organic light emitting display panel. For example, in the case of a bottom emission structure in which light is emitted toward the base substrate, it may be disposed on the outside of the base substrate, and in the case of a top emission structure in which light is emitted toward the encapsulation substrate, it may be disposed outside the encapsulation substrate. have. The circular polarizer may improve visibility and display performance by preventing external light from being reflected by a reflective layer made of metal such as electrodes and wires of the organic light emitting display panel and coming out of the organic light emitting display panel.

In another example, the display device may not have a polarizer. In this case, the variable viewing angle element may be disposed on the light output side of the display device, and the polarizer of the variable viewing angle element may be disposed further away from the display device than the liquid crystal cell. The display device having no polarizer may include, for example, a plasma display device, an electrophoretic display device, a field emission display device, and the like.

The present application also relates to a viewing angle switching method of a display device using the viewing angle variable element. The viewing angle switching method comprises the steps of implementing a wide viewing angle mode in a state in which no voltage is applied to the liquid crystal cell of the viewing angle variable element disposed on one side of the display device or the liquid crystal cell of the viewing angle variable element disposed on one side of the display device. It may include applying a voltage within the range of 1.5V to 3V to implement the narrow viewing angle mode. As for the specific details of the method, the contents mentioned in the variable viewing angle element or the display assembly may be equally applied.

The variable viewing angle element and the display device may be attached to each other through an adhesive or an adhesive. As the pressure-sensitive adhesive, a transparent pressure-sensitive adhesive or a transparent adhesive used for attaching an optical member may be appropriately selected and used.

The present application can implement a narrow viewing angle mode with low lateral transmittance, and provide a viewing angle variable element providing a wide viewing angle when driven, and a display assembly including the viewing angle variable element.

1 exemplarily shows a viewing angle variable element.
2 exemplarily shows a liquid crystal cell.
3 is a graph of transmittance according to a viewing angle.
4 is a graph showing the transmittance according to the concentration of the anisotropic dye.
FIG. 5 is a photographed image according to whether or not a voltage is applied to the viewing angle variable device of Example 1. FIG.
6 is a graph of transmittance at different viewing angles of Comparative Example 2.

Hereinafter, the present application will be specifically described 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 Examples presented below.

Example 1

After preparing an electrode film in which a first electrode layer (ITO layer) is deposited on a first base film (Super Retardation Film, manufactured by Toyobo), a horizontal alignment film (SE-7492, manufactured by Nissan) is bar-coated on the first electrode layer After coating with a furnace, it was baked at a temperature of 120° C. for 1 hour to form a first alignment layer having a thickness of 300 nm. The first alignment layer was rubbed in one direction using a rubbing cloth.

An electrode film in which a second electrode layer (ITO layer) was deposited on a second base film (Super Retardation Film, manufactured by Toyobo) was prepared. Column spacers having a height of 10 μm and a diameter of 15 μm were disposed on the second electrode layer at intervals of 250 μm. A horizontal alignment layer (SE-7492, manufactured by Nissan) was coated with a bar coating on the second electrode layer on which the column spacers were formed, and then fired at 120° C. for 1 hour to form a second alignment layer having a thickness of 300 nm. The second alignment layer was rubbed in one direction using a rubbing cloth.

As the GHLC composition, a composition including liquid crystal molecules having positive dielectric anisotropy (HPC2180, HCCH) and anisotropic dye (X12, BASF) was used. The content of the anisotropic dye in the GHLC composition is 0.5 wt%.

A sealant was drawn on the edge on the surface of the second alignment layer with a seal dispenser. After the GHLC composition was applied on the second alignment layer, the first base film was laminated to prepare a liquid crystal cell. At this time, the rubbing direction of the first alignment layer and the rubbing direction of the second alignment layer were laminated to be anti-parallel. The prepared liquid crystal cell is an ECB mode liquid crystal cell with a cell gap of 10 μm.

A polarizer was attached to the first base film through OCA (LGC, V310) to fabricate a variable viewing angle device. The polarizer is a PVA-based absorption type linear polarizer having a single transmittance of about 45%.

Example 2

A viewing angle variable device was manufactured in the same manner as in Example 1, except that the content of the anisotropic dye in the GHLC composition was changed to 0.7 wt%.

Example 3

A viewing angle variable device was manufactured in the same manner as in Example 1, except that the content of the anisotropic dye in the GHLC composition was changed to 1 wt%.

Example 4

A viewing angle variable device was manufactured in the same manner as in Example 1, except that the content of the anisotropic dye in the GHLC composition was changed to 1.3 wt%.

Comparative Example 1

A viewing angle variable device was fabricated in the same manner as in Example 1, except that the GHLC composition was not used, and a pharmaceutical composition containing liquid crystal molecules (HPC2180, HCCH) having positive dielectric anisotropy (HPC2180, HCCH) but not including an anisotropic dye was used. produced.

Comparative Example 2

A micro louver film (manufactured by 3M) was prepared as a viewing angle variable element of Comparative Example 2.

Evaluation Example 1. Evaluation of viewing angle characteristics

For Examples 1 to 4 and Comparative Examples 1 to 2, transmittance according to the viewing angle was measured. Transmittance was measured using LCMS-200 equipment (Seshim Optoelectronics). When measuring transmittance, a light source, a polarizer, a liquid crystal cell, and a detector are arranged in order. In Comparative Example 2, a micro louver film was placed on the light source and transmittance with respect to the viewing angle was measured.

Transmittance is the average transmittance for wavelengths from 380 nm to 780 nm. The intensity of the light of the light source before passing through the variable viewing angle element is regarded as 100%. The transmittance at the viewing angle is the transmittance measured in a direction inclined with respect to the front surface (viewing angle = 0°) of the variable viewing angle element. The angle formed by the normal direction and the inclined direction of the front surface of the variable viewing angle element is the viewing angle. When the viewing angle variable element is viewed with reference to the detector, the viewing angle in the left direction is indicated by (+) and the viewing angle in the right direction is indicated by (-). In this case, the positions of the light source and the detector are fixed, and the angle is adjusted by adjusting the position of the variable viewing angle element.

For Examples 1 to 4 and Comparative Example 1, AC power was connected to the first electrode layer and the second electrode layer, and the transmittance according to the viewing angle was measured while driving by applying a voltage of 2 V. 3 shows the characteristics of the viewing angle according to the concentration of the anisotropic dye. 4 shows the transmittance at a specific viewing angle according to the concentration of the anisotropic dye. In FIG. 4 , y=ax+b (a and b are constants, x is the concentration (wt%) of the anisotropic dye, and y is the transmittance (%)) is a trend line. R ² refers to the degree of fitting to the trend line, and it can be seen that the closer ^{R 2 to 1 is to the trend line, the more the same.}

Comparative Example 1 Example 1 Example 2 Example 3 Example 4 0 wt% 0.5 wt% 0.7 wt% 1.0 wt% 1.3 wt% viewing angle -45 degrees 3.0% 3.3% 2.1% 1.8% 2.0% -30 degrees 29.9% 27.9% 23.4% 23.1% 21.3% 0 degrees 86.4% 74.2% 72.3% 67.3% 62.2% +30 degrees 33.5% 29.7% 28.6% 25.5% 22.5% +45 degrees 3.7% 3.9% 3.2% 2.7% 2.1%

As shown in Table 1, it can be seen that as the concentration of the anisotropic dye increases, the transmittance from the side decreases and it is suitable for realizing the privacy function. FIG. 5 is an image taken at an inclination angle of +45 degrees showing the wide viewing angle mode and the narrow viewing angle mode when a voltage of 2V is applied in Example 1 in a state in which no voltage is applied.

On the other hand, in Example 2, compared with Comparative Example 2, the transmittance can be easily adjusted by adjusting the concentration of dye when implementing a narrow viewing angle, the decrease in front transmittance is small, and when a wide viewing angle mode is desired, the On/Off button is conveniently used. It is advantageous in that it can be converted.

10: variable viewing angle element, 100: liquid crystal cell, 200: polarizer, 101A: first substrate, 102A: first electrode layer, 103A: first alignment layer, 104: alignment layer, 101B: second substrate, 102B: second electrode layer, 103B : first alignment layer

Claims (14)

A liquid crystal cell and a polarizer on one surface of the liquid crystal cell, wherein the liquid crystal cell sequentially includes a first substrate, a first electrode layer, a first alignment layer, a liquid crystal layer, a second alignment layer, a second electrode layer, and a second substrate, The liquid crystal layer includes liquid crystal molecules having positive dielectric anisotropy and an anisotropic dye, the first alignment layer and the second alignment layer are each a horizontal alignment layer, and the liquid crystal cell moves between horizontal alignment and oblique alignment according to the application of voltage. A switching viewing angle variable element. The variable viewing angle element according to claim 1, wherein the alignment direction of the anisotropic dye in the liquid crystal layer and the absorption axis of the polarizer are parallel. The device of claim 1 , wherein the liquid crystal molecules and the anisotropic dye are in a horizontal alignment state in a state where no voltage is applied to the liquid crystal cell. The viewing angle variable device according to claim 1, wherein the wide viewing angle mode is implemented in a state where no voltage is applied to the liquid crystal cell. The viewing angle variable element according to claim 4, wherein the transmittance is 65% or more from the front in the wide viewing angle mode, and the transmittance is 60% or more at a viewing angle of 45 degrees from the front. The variable viewing angle device according to claim 1, wherein the liquid crystal molecules and the anisotropic dye exist in a tilted alignment state when a voltage within the range of 1.5V to 3V is applied to the liquid crystal cell. [Claim 7] The device of claim 6, wherein an average inclination angle of the liquid crystal molecules in an inclined alignment state is within a range of 0.5 degrees to 3 degrees. The viewing angle variable device according to claim 1, wherein the narrow viewing angle mode is implemented in a state in which a voltage within the range of 1.5V to 3V is applied to the liquid crystal cell. The viewing angle variable element according to claim 8, wherein the transmittance is 5% or less at a viewing angle of 45 degrees or more with respect to the front in the narrow viewing angle mode. The device of claim 1, wherein the content of the anisotropic dye in the liquid crystal layer is less than 1.5 wt%. A display assembly comprising a display device and the viewing angle variable element of claim 1 disposed on one surface of the display device. 12. The method of claim 11,
The display device has an upper polarizer,
The viewing angle variable element is disposed on the upper polarizer of the display device,
A display assembly in which the polarizer of the variable viewing angle element is disposed further away from the display device compared to the liquid crystal cell. 12. The method of claim 11,
A display assembly in which the light absorption axis of the upper polarizer of the display device and the light absorption axis of the polarizer of the variable viewing angle element are parallel to each other. 12. The method of claim 11,
The display device does not have a polarizer,
The viewing angle variable element is disposed on the light output side of the display device,
A display assembly in which the polarizer of the variable viewing angle element is disposed further away from the display device compared to the liquid crystal cell.

Images