KR101892563B1 - Polymer dispersed liquid crystal lenz using flexible board - Google Patents

Abstract

The present invention relates to a polymer dispersed liquid crystal lens having a high-speed switching function and an auto-shading function, and more particularly, to a polymer dispersed liquid crystal lens which is dissolved in a polymer matrix and is formed in accordance with a phase separation phenomenon at the time of polymerizing a prepolymer of a polymer matrix. Disclosed is a polymer dispersed liquid crystal lens using a plastic polymer film substrate including a liquid crystal.
According to the polymer dispersed liquid crystal lens using the plastic polymer film substrate according to the present invention, since the switching characteristic is excellent at the time of application of the AC voltage, it can be used for high performance lenses such as three-dimensional goggles.
Further, the polymer dispersed liquid crystal lens using the plastic polymer film substrate according to the present invention has an auto shading function because it has excellent light transmittance unlike the conventional liquid crystal, and can be used for sunglasses and the like.

Description

TECHNICAL FIELD [0001] The present invention relates to a polymer dispersed liquid crystal lens using a polymeric polymer film substrate,

The present invention relates to a polymer dispersed liquid crystal lens, and more particularly, to a polymer dispersed liquid crystal lens using a plastic polymer film substrate having a high-speed switching function and an auto shading function when an AC voltage is applied.

Polymer dispersed liquid crystal (PDLC) is a device capable of actively controlling transparency and opacity by using an electric field without using a polarizer because a droplet of a liquid crystal having a micro size is dispersed in a polymer matrix.

Problems such as cross talk and motion blur when using an active shutter type goggle such as a three-dimensional display are caused by vomiting and physiological And the like.

Particularly, the goggles which can be applied to the three-dimensional display can be applied to the three-dimensional goggles by using a lens mounted on the goggles at a frequency of 120 Hz in order to request a quick response characteristic. When using a lens having a slow response characteristic, There has been a problem that it is difficult to apply it because it causes the above-described problems.

1 is a schematic diagram showing a configuration and operation principle of a conventional LCD.

1, in order to induce a twisted nematic structure, the rubbing directions of the upper and lower substrates 10 and 20 are arranged to be 90 degrees with respect to each other. When the voltage is not applied, since the arrangement of the molecules of the liquid crystal 30 is determined only by the orientation film of the upper and lower substrates, the structure is tilted 90 degrees continuously from the lower substrate 20 to the upper substrate 10. At this time, the upper and lower polarizing plates 40 and 50 are attached to the outside of the substrate such that their polarization axes are parallel to the alignment direction of the substrate. The light polarized by the linearly polarized light from the upper polarizer 10 is polarized stepwise along the twisted structure of the liquid crystal and polarized parallel to the zero transmission axis of the lower polarizer 20.

At this time, when 3 to 5 V is applied across the upper and lower electrodes, the optical axis of the central portion of the liquid crystal layer 30 becomes parallel to the electric field, and the twisted structure disappears.

Therefore, the direction of polarization of the light does not rotate any more, and the light passing through the liquid crystal molecules is absorbed by the second polarizer 20.

However, in the case of using the nematic liquid crystal without using the polymer dispersed liquid crystal as described above, the use efficiency of the light is low due to the use of the polarizer, the surface orientation is required and the pixel density increases, And the viewing angle is narrowed to about 20 DEG or less.

Further, in the case of using an LCD, there is a problem that it is difficult to apply it to a lens requiring a light transmittance because the light transmission amount is too small.

In order to solve these drawbacks, it is a polymer dispersed liquid crystal lens of a light scattering mode in which a liquid crystal is dispersed in a polymer as described above recently.

However, a liquid crystal lens which can be used for the three-dimensional goggles or a sunglass which can control the light transmission efficiency has not been developed yet even though the polymer dispersed liquid crystal lens is used.

Patent Document 10-257894 (polymer liquid crystal complex)

Disclosure of the Invention The present invention has been made in order to solve the above problems, and it is an object of the present invention to provide a polymer dispersed liquid crystal lens having a high-speed switching function in a relatively simple process, It is possible to provide a polymer dispersed liquid crystal lens using a plastic polymer film substrate having design-free characteristics.

The present invention relates to a transparent plastic film substrate on which an ITO disposed on an upper and a lower side is vacuum-deposited, and a polymer matrix and a transparent glass or plastic film between the plastic film substrate and the transparent substrate, The present invention provides a polymer dispersed liquid crystal lens using a plastic polymer film substrate comprising a liquid crystal having

The polymer matrix is prepared by using EHA (2-ethylhexyl acrylate) or BDVE (butanediol vinyl ether) as a monomer, TMPT (trimethylolpropane trimethacrylate) as a cross linker, 2- 2-methylpropiophenone is used as the liquid crystal, and the liquid crystal is selected from the group consisting of n-pentylcyanobiphenyl, n-heptylcyanobiphenyl, n-heptylcyanobiphenyl, an eutectic mixture of n-octyloxycyanobiphenyl and n-pentylcyanoterphenyl, and may be a mixture of the polymer and the liquid crystal, followed by UV curing.

The polymer matrix is prepared by using EHA (2-ethylhexyl acrylate) or BDVE (butanediol vinyl ether) as a monomer, TMPT (trimethylolpropane trimethacrylate) as a cross linker, 2- (2-hydroxy-2-methylprophenone) is used as the liquid crystal, and the liquid crystal is selected from the group consisting of n-pentylcyanobiphenyl, n-heptylcyanobiphenyl Eutectic mixture, and may be a mixture of the polymer and liquid crystal and UV-cured.

The plastic film substrate may be any one selected from the group consisting of PC (Polycarbonate), PES (Polyether Sulphone), PET (PolyEthylene Terephthalate) and PEN (Polyethylene (2,6-Naphthalate)

According to the polymer dispersed liquid crystal lens using the plastic polymer film substrate according to the present invention, it is possible to realize a lens having excellent light-transmittance characteristics with little light loss due to the passage of an LCD (Liquid Crystal Display).

In addition, since it is possible to realize a lens having excellent response characteristics according to the driving of voltage, even when applied to a three-dimensional stereoscopic TV, the phenomenon of cross talk, motion blur, Problems do not occur.

Further, since the polymer dispersed liquid crystal lens according to the present invention is excellent in light transmittance unlike the conventional liquid crystal, it can be used for sunglasses and the like by having an auto shading function.

1 is a schematic view showing transmission characteristics of a twisted nematic lens in an LCD lens.
2 is a schematic diagram showing the structure of a polymer dispersed liquid crystal lens using a plastic polymer film substrate according to the present invention.
FIG. 3 is a schematic view showing an application of an electric field to a polymer dispersed liquid crystal lens using a plastic polymer film substrate according to the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, it should be understood that the following embodiments are provided so that those skilled in the art will be able to fully understand the present invention, and that various modifications may be made without departing from the scope of the present invention. It is not. Wherein like reference numerals refer to like elements throughout.

The polymer dispersed liquid crystal lens according to the present invention comprises a transparent plastic film substrate on which ITO is vacuum deposited on top and bottom and a polymer matrix between the glass or plastic film substrate and a transparent substrate made of glass, And a polymer dispersed liquid crystal having transparency when a driving voltage of 10 V is applied.

The transparent plastic film substrate is mainly a polymer plastic substrate such as PC (Polycarbonate), PES (Polyether Sulphone), and PET (PolyEthylene Terephthate).

The polymer dispersed liquid crystal lens according to the present invention is a transparent plastic film liquid crystal in which ITO is vacuum deposited on the upper and lower sides, and has a medium property between solid and liquid. That is, it has the property of flowing like a liquid, and the arrangement is like a solid. Unlike other phases, liquid crystal has optical anisotropy such as birefringence and permittivity, and has a property of aligning in the direction of an electric field when an electric field is applied. This statue was discovered in 1888 by an Austrian biologist, Freidrich Reinizer, who found that there were two melting points. It was a cloudy liquid after the first melting point, but turned into a transparent liquid after passing through the second melting point. This cloudy liquid state is liquid crystal. Subsequently, a material with a nematic phase was synthesized and a more chemical, low melting point material was synthesized, which is a step for commercialization.

Liquid crystals are largely divided into thermotropic and lyotropic liquid crystals. The lyotropic liquid crystal has an image such as lamella and hexagonal phase in which not only the temperature but also the solvent varies depending on the concentration. Inferior liquid crystal is divided into polymer liquid crystal and low molecular liquid crystal which are used in LCD as phase changing liquid crystal. The low-molecular liquid crystal of this liquid crystal is divided into a rod-shaped liquid crystal and a disc-shaped liquid crystal according to the shape.

 The low-molecular liquid crystal of this liquid crystal is divided into a rod-shaped liquid crystal and a disc-shaped liquid crystal according to the shape. The diversity of the liquid crystal phase is determined according to the arrangement type. The rod type liquid crystal is divided into the smectic, nematic and cholesteric phases depending on the degree of arrangement of the molecules.

A low-molecular-weight rod-shaped liquid crystal with a nematic phase has anisotropy in material properties in a direction perpendicular to the molecular axis and has anisotropic properties such as refractive index and permittivity when it is aligned in a certain direction by an external electric field, . Arrangement by external electric field occurs reversibly, and the light from the backlight can be controlled when the arrangement is changed. The LCD is a display device that controls the amount of light transmitted through the effect of polarized incident light and anisotropy of liquid crystal.

In this driving mode of LCD, there are TN (Twisted nematic) and STN (super twisted nematic). STN has twisted angle larger than that of TN, which shows a large transmittance change even with a small voltage change.

However, these LCDs have problems such as slow response speed, difficulty in displaying perfect black and white. The difficulty of perfect black and white display is due to the optical anisotropy of the liquid crystal and the rusk is caused by the phase difference at various wavelengths, and the use of retarder film is required to solve this problem. The initial retarder film was used as a stretched polymer film and attached between the cell and the polarizer. At least one of the refractive indices (nx, ny, nz) has a different value in the film drawn in one direction. Refractive index values on the stretching plane are nx and ny values, and nz is a value in the thickness direction. The refractive index value nx in one direction and the refractive index value ny in the direction perpendicular to the stretched direction have different values and the phase difference can be compensated by using this optical anisotropy.

As described above, since the film is produced by the stretching method, the thickness of the film is inevitably increased. Since the film is produced by the stretching method, not only the thickness of the film is not uniform but also the thickness control is difficult and the optical efficiency may be restricted. One of the ways to improve these disadvantages and to support new technology development is the development of high performance liquid crystal films using low molecular weight liquid crystals.

On the other hand, liquid crystal polymer film is a liquid crystal molecule that can keep film form on its own or on a support, unlike a liquid crystalline low molecular liquid crystal used in an LCD. When the liquid crystal polymer film is used as a retarder film rather than the stretched polymer film described above, the thickness of the film can be remarkably reduced due to a large birefringence value of the liquid crystal molecule itself.

The liquid crystal forming the liquid crystal polymer film is structurally different from the low-molecular fluid liquid crystal in the cell. In order to form a liquid crystalline polymer film, it may be thermally polymerized or photopolymerized. In order to perform polymerization, an acrylate structure, which is a photoreactive group, should be present at the end of the liquid crystal. When irradiated with UV light, the acrylate structure is polymerized in the excited state and fixes the arrangement of the liquid crystal.

Efforts are being made to improve the design characteristics of the polymer plastic film substrate due to external impact and damage to the goggles. Replacing the glass substrate with a polymer plastic film substrate also contributes to the reduction in weight, thickness and power consumption of the goggles.

In the case of the conventional active shutter goggles for commercial 3D TVs, a nematic liquid crystal has been applied to a glass substrate. However, since the active shutter goggles use a quadratic liquid crystal, the response speed is slow and the image quality is bad due to the crosstalk phenomenon, the motion blur, and the residual image.

In addition, since the polarizing film is used in two sheets, the light transmission characteristic is very bad, and when applied to the 3D TV screen, the brightness of the 3D TV is reduced to 35% .

There was also a problem in the manufacturing process. That is, since a lens using a quadratic liquid crystal requires a high temperature of at least 200 ° C. at a maximum temperature of the process, when the polymer film substrate such as PC, PET, or PES described above is used, It is necessary to develop a manufacturing process of a four-material liquid crystal lens, and it is necessary to replace or modify the existing glass nematic liquid crystal manufacturing process equipment.

However, in the case of using a polymer dispersed liquid crystal lens, a simple process which does not require an aligning process, a spacer spreading process, a sealant and an end sealant manufacturing process, and a polarizing film attaching process, which are essential processes for manufacturing a nematic liquid crystal lens Process.

The polymer dispersed liquid crystal lens is basically manufactured at room temperature, so even if a glass substrate is replaced with a polymer plastic film substrate, it is unnecessary to develop and add a new low temperature lens manufacturing process as in a nematic liquid crystal process. You can use the production process and equipment you were using.

The manufacturing process of the polymer dispersed liquid crystal lens is very simple compared to the manufacturing process of the nematic liquid crystal lens using fundamentally expensive equipment. Therefore, the cost of the manufacturing process is very low as less than one tenth of that of the nematic liquid crystal lens manufacturing process in the case of the polymer dispersed liquid crystal lens, so that the cost of the process equipment used for manufacturing is very different.

When a plastic film substrate is used as a substrate for liquid crystals as in the present invention, a slight improvement in process such as the use of a chiller in a UV curing process is required because a good property can be obtained as the film proceeds from a low temperature.

Polymer Dispersed Liquid Crystal Lens Using Plastic Polymer Film Substrate Inexpensive, rich light quantity, fast response speed and new functions are given. Designed with a new type of active shutter goggles, auto shading function sunglasses, visual concentration training High-performance goggles such as professional goggles can be developed.

In addition, due to the nature of polymer materials such as polymer dispersed liquid crystals, the price is very low in the case of mass production, and the polymer dispersed liquid crystal device and the lens are manufactured at low temperature and simple, so that the mass production is easy and the customized lens Production is possible.

The basic structure of the polymer dispersed liquid crystal lens using the plastic polymer film substrate is as shown in Fig. 2 and Fig.

2 is a schematic view showing a structure of a polymer dispersed liquid crystal lens using a flexible substrate according to the present invention. FIG. 3 is a schematic view showing a state in which an electric field is applied to a polymer dispersed liquid crystal lens using a flexible substrate according to the present invention.

The basic driving principle of the polymer dispersed liquid crystal lens using the flexible substrate will be described in detail with reference to FIGS. 2 and 3. FIG. As shown in FIG. 2, when the electric field is not applied, the alignment of the liquid crystal 30 is randomly arranged in the droplet, resulting in light scattering. When the electric field is applied, the liquid crystal 30 is arranged in the direction of the electric field to transmit the light.

When the electric field is applied, the behavior of the liquid crystal in the liquid droplet is oriented along the interface due to the anchoring energy, and the liquid crystal 30 in the liquid droplet is oriented in the direction of the electric field so that the direction of the electric field is aligned with the director of the liquid crystal 30 Light is transmitted.

 The transmittance is determined by the difference between the ordinary refractive index (n0) of the liquid crystal and the refractive index (np) of the polymer. When the electric field is removed again, it returns to its original state and light scattering occurs.

The polymer dispersed liquid crystal has a structure in which droplets of a generally elliptical liquid crystal 30 having a diameter of 1 to 5 μm are uniformly dispersed in a polymer film having a thickness of 5 to 50 μm.

In the case of the polymer dispersed liquid crystal, since the polymer matrix fixes the liquid crystal, the orientation process like the conventional LCD using the nematic liquid crystal is not necessary. Also, since the transmittance is changed through self-scattering and electric field application, a polarizing film for use above and below the polymer dispersed liquid crystal lens is not required.

In addition, as described above, there is no alignment process, and a polarizing film is not required, so that the manufacturing process is simplified and the production temperature is low, so that it is easy to apply to a plastic polymer film.

The composition of the polymer dispersed liquid crystal material is composed of a prepolymer and a liquid crystal, and the following prepolymer is used.

The polymer matrix is prepared by using EHA (2-ethylhexyl acrylate) or BDVE (butanediol vinyl ether) as a monomer, TMPT (trimethylolpropane trimethacrylate) as a cross linker, 2- 2-methylpropiophenone is used as the liquid crystal, and the liquid crystal is selected from the group consisting of n-pentylcyanobiphenyl, n-heptylcyanobiphenyl, n-heptylcyanobiphenyl, an eutectic mixture of n-octyloxycyanobiphenyl and n-pentylcyanoterphenyl, which is obtained by mixing the polymer with the liquid crystal and UV-curing the mixture.

Alternatively, the polymer matrix may be prepared by using a mixture of tetrafunctional allylether and trifunctional monomer as a prepolymer, benzo-phenone as a photoinitiator, The process of n-pentylcyanobiphenyl, n-heptylcyanobiphenyl, n-octyloxycyanobiphenyl and n-pentylcyanoterphenyl, (eutectic) mixture, and the liquid crystal and the prepolymer are mixed and UV-cured.

Polymerization Induced Phase Separation (PIPS) is used to prepare a polymer dispersed liquid crystal using the polymer dispersed liquid crystal as described above.

After mixing the photoinitiator with the prepolymer, the liquid crystal is stirred with a magnetic stirrer at room temperature for 24 hours or more at a room temperature to be uniformly mixed.

Then, spacers having a height of 5 to 50 탆 are formed on the plastic film substrate by photolithography using negative photoresist (PR). Then, a plastic film substrate is installed so that ITO (Indium Tin Oxide) deposited portions of the prepared polymer dispersed liquid crystal lens mixed with the prepared prepolymer and liquid crystal are opposed to each other.

Uniformly dispersed polymer dispersed liquid crystal is poured uniformly between the plastic film substrates thus installed. When the polymer dispersed liquid crystal device fabricated as described above is UV-cured, a device having a microstructure composed of a liquid crystal having a relatively small size uniformly dispersed in a polymer matrix can be manufactured.

UV intensity at UV irradiation was in the range of 100 ~ 1000mW / ㎠, irradiation amount was 0.5mW / ㎠, irradiation time was more than 30min.

Since the polymer dispersed liquid crystal lens using the flexible substrate thus manufactured can be manufactured at a low temperature because a plastic substrate is used, the production process is simplified, the production cost is reduced, and mass production is facilitated.

In addition, the polymer dispersed liquid crystal using the flexible substrate during the ON time given as the control signal at the driving frequency of 120 Hz becomes the state where power is applied for 160 μs, and the light transmission amount approaches 100% A voltage can not be applied to the polymer dispersed liquid crystal lens using the flexible substrate.

In addition, since the polymer dispersed liquid crystal lens using the flexible substrate according to the present invention is excellent in light transmission efficiency as compared with the conventional LCD, it has an advantage that it can be used for sunglasses having an auto shading function.

In addition, since it is manufactured by using a flexible substrate, it is possible to manufacture a polymer dispersed liquid crystal lens which is free from shape limitation.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, This is possible.

10: upper substrate 20: lower substrate
25: polymer matrix 30: liquid crystal

Claims (4)

A flexible plastic film substrate on which ITOs arranged on and under are vacuum deposited;
A polymer matrix between the upper and lower plastic film substrates; And
A liquid crystal having transparency when a driving voltage of 1 to 10 V is applied to both ends of the plastic film substrate, the liquid crystal being located inside the polymer matrix; ≪ / RTI >
The polymer matrix may be prepared by using a mixture of tetrafunctional allylether and trifunctional monomer as a prepolymer,
Using benzo-phenon as a photoinitiator,
The liquid crystal is preferably selected from the group consisting of n-pentylcyanobiphenyl, n-heptylcyanobiphenyl, n-octyloxycyanobiphenyl and n-pentylcyanophenyl (n < / RTI > pentylcyanoterphenyl,
Wherein the liquid crystal and the prepolymer are mixed and UV-cured. The polymer dispersed liquid crystal lens using the polymeric polymer film substrate. delete delete The method according to claim 1,
Wherein the plastic film substrate is any one selected from the group consisting of PC (Polycarbonate), PES (Polyether Sulfone), PET (PolyEthylene Terephthalate) and PEN (Polyethylene (Ethylene 2,6-Naphthalate) Dispersive liquid crystal lens.

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