KR20140039399A - Touch screen with improved transmittance by forming anti-reflection and low-reflection coating layer - Google Patents

Touch screen with improved transmittance by forming anti-reflection and low-reflection coating layer Download PDF

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Publication number
KR20140039399A
KR20140039399A KR1020120104937A KR20120104937A KR20140039399A KR 20140039399 A KR20140039399 A KR 20140039399A KR 1020120104937 A KR1020120104937 A KR 1020120104937A KR 20120104937 A KR20120104937 A KR 20120104937A KR 20140039399 A KR20140039399 A KR 20140039399A
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KR
South Korea
Prior art keywords
refractive index
index layer
transparent electrode
zinc oxide
oxide transparent
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KR1020120104937A
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Korean (ko)
Inventor
박병창
윤영선
김희영
서범식
김석
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(주)플라웍스
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Priority to KR1020120104937A priority Critical patent/KR20140039399A/en
Publication of KR20140039399A publication Critical patent/KR20140039399A/en

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    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F3/00—Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
    • G06F3/01—Input arrangements or combined input and output arrangements for interaction between user and computer
    • G06F3/03—Arrangements for converting the position or the displacement of a member into a coded form
    • G06F3/041—Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B5/00—Non-insulated conductors or conductive bodies characterised by their form
    • H01B5/14—Non-insulated conductors or conductive bodies characterised by their form comprising conductive layers or films on insulating-supports

Abstract

The present invention is a substrate made of plastic; A high refractive index layer formed on the substrate; A low refractive index layer formed on the high refractive index layer; A zinc oxide transparent electrode layer formed on the low refractive index layer; And it provides a zinc oxide transparent electrode laminated film comprising a low refractive index layer formed under the substrate.

Description

TOUCH SCREEN WITH IMPROVED TRANSMITTANCE BY FORMING ANTI-REFLECTION AND LOW-REFLECTION COATING LAYER}

The present invention relates to a method of increasing the transmittance of a touch screen on which a zinc oxide (ZnO) transparent electrode is deposited, and to a method of increasing the transmittance upon deposition of a ZnO transparent electrode.

Transparent electrodes are widely used in various applications such as flat panel displays such as LCD, PDP, OLED or amorphous silicon thin film solar cells, dye-sensitized solar cells, transparent electrodes in solar cells, functional glass such as IR shielding, and EMI shielding. As the number of touch screen panels increases, the use of indium tin oxide (ITO) is increasing.

Indium (In), the main constituent element of the ITO transparent electrode, which is used most at present, is present in only 0.00001% in the surface and seawater, and since it is obtained as a by-product of zinc (Zn) or lead (Pb) production, supply is limited. . Therefore, indium (In) is so expensive that it is comparable to silver (Ag). In addition, since about 45% of the world's indium (In) production is already consumed as a material for FPD transparent electrodes, the price increase due to supply problems of indium (In) should be avoided if the transparent electrode is continuously used. Can't.

In addition, ITO transparent electrodes are deposited and used on substrates such as glass and polymer films, but in the situation where next-generation displays are pursuing low cost, large area, and light weight, they are lighter than glass to realize this. It is required to use plastic as a substrate material, and development of a transparent electrode capable of exhibiting optimal physical properties on a plastic substrate is required.

In order to commercialize the transparent electrode on the plastic substrate, it is necessary to satisfy mechanical stability when bending or folding the device, matching thermal expansion coefficient with the plastic substrate, excellent adhesion to the substrate, chemical resistance for subsequent process stability, and reliability of the device. Durability, etc. to consider.

In consideration of flexibility, adhesiveness, thermal expansion characteristics, and printability, flexible electrode materials for flexible displays have been studied for transparent electrodes using conductive polymers and carbon nanotubes, which are organic materials that best balance physical properties with plastic substrates. Despite the advantages of adhesion to the plastic substrate, coefficient of thermal expansion, flexibility, etc., most conductive polymers have low solubility, are difficult to process, and exhibit semiconducting properties with energy band gap of less than 3 eV. Since it absorbs light in the wavelength range, it is essentially colored, and when it is coated with a thin film to increase its transmittance, surface resistance is increased and thus it is not developed as a transparent electrode.

ZnO, which is most studied as a transparent electrode material to replace ITO, has high electrical conductivity with excellent crystallinity even at low temperature deposition, and thus is considered as the most likely candidate to replace ITO.

However, since ZnO has a specific resistivity higher than that of ITO, it is common to increase the thickness of the ZnO transparent electrode deposited to have a resistivity similar to that of ITO. By depositing using a ZnO target doped with a Ga element or an Al element, the specific resistance of the ZnO transparent electrode can be lowered. Therefore, there is a need to explore various ways to increase the transmittance as the thickness of the ZnO transparent electrode increases.

In order to solve the problems of the prior art as described above, the present invention aims to provide a touch screen having a high transmittance even when applying ZnO which can be utilized as a transparent electrode in place of ITO.

An object of the present invention as described above, the substrate made of plastic; A high refractive index layer formed on the substrate; A low refractive index layer formed on the high refractive index layer; A zinc oxide transparent electrode layer formed on the low refractive index layer; And it is achieved by a zinc oxide transparent electrode laminated film comprising a low refractive index layer formed under the substrate.

Here, preferably the plastic of the substrate is PET, PEN or PES.

Preferably, the hard coating layer further comprises an upper layer and a lower layer of the plastic of the substrate.

Preferably, the material of the high refractive index layer is Nb 2 O 5 .

Preferably, the refractive index of the high refractive index layer is 1.95 to 2.55.

Preferably, the high refractive index layer has a thickness of 50 to 100 ohms.

Preferably, the material of the low refractive index layer is SiO 2 .

Preferably, the refractive index of the low refractive index layer is 0.95 to 1.55.

Preferably, the low refractive index layer is 400 to 900 ohms thick.

Preferably, the high and low refractive index layers are wet coated as an antireflective coating layer.

Preferably, the low refractive index layer formed below the substrate is wet coated as a low reflection coating layer.

Still another object of the present invention is to achieve a touch screen panel having improved transmittance by applying an antireflection and total reflection coating layer including the zinc oxide transparent electrode laminated film.

According to the present invention, the antireflective coating and the low reflection coating can be appropriately applied, thereby making it possible to have a high transmittance even when the ITO transparent electrode is replaced with a ZnO transparent electrode.

1 is a view showing a structure in which the AR layer is formed by a deposition method on the back surface is implemented in the present invention and when using the conventional AR coating fabric.
2 is a view of the structure of the conventional AR coating fabric and the structure added LR coating on the back.
3 is a graph showing changes in sheet resistance and transmittance.

The present invention provides a structure that can have a high transmittance even by replacing the ITO transparent electrode with a ZnO transparent electrode by appropriately applying an antireflective coating and a low reflection coating.

In more detail, the structure of the present invention, a plastic substrate; A high refractive index layer formed on the substrate; A low refractive index layer formed on the high refractive index layer; A zinc oxide transparent electrode layer formed on the low refractive index layer; And a low refractive index layer formed under the substrate.

Here, preferably the plastic of the substrate is PET, PEN or PES.

Preferably, the hard coating layer further comprises an upper layer and a lower layer of the plastic of the substrate.

Preferably, the material of the high refractive index layer is Nb 2 O 5 .

Preferably, the refractive index of the high refractive index layer is 1.95 to 2.55.

Preferably, the high refractive index layer has a thickness of 50 to 100 ohms.

Preferably, the material of the low refractive index layer is SiO 2 .

Preferably, the refractive index of the low refractive index layer is 0.95 to 1.55.

Preferably, the low refractive index layer is 400 to 900 ohms thick.

Preferably, the high and low refractive index layers are wet coated as an antireflective coating layer.

Preferably, the low refractive index layer formed below the substrate is wet coated as a low reflection coating layer.

Hereinafter, the present invention will be described in detail with reference to examples, but these examples are only directed to more clearly understand the present invention, and are not intended to limit the scope of the present invention. It will be determined within the scope of the technical spirit of the claims.

In the present invention, a ZnO transparent electrode was formed by a physical vapor deposition method using a ZnO target, and sputtering was also applied among physical vapor deposition methods.

Sputtering is the most widely used thin film deposition method and has advantages such as relatively high deposition rate, large area deposition, and relatively low temperature deposition. In particular, the biggest feature of the sputtering method is the deposition of metal atoms having a relatively high electron concentration, which is due to the release of oxygen atoms by the collision of neutral atoms.

In the present invention, when the transparent electrode is deposited using a pure ZnO (purity: 99.99%) target, there is a problem that the light transmittance is lowered due to a very high specific resistance and a tendency to increase the film thickness near the target resistance. As an alternative, the ZnO target is doped with an Al element, and preferably, a ZnO target with 1.5% doping of the Al element is used.

By using the ZnO target doped with Al element to generate oxygen vacancies by the substitution action of Zn and Al, the specific resistance could be reduced by increasing the density of electrons, and 1.5% e doping of Al element to ZnO By using the target, the specific resistivity can be further improved, and thus the film thickness can be obtained, resulting in light transmittance.

However, since the thickness of the transparent electrode is limited due to the Al-doped ZnO target, anti-reflection (AR) and low-reflection (LR) to improve the transmittance of AZO (ZnO doped with Al element) are limited. The experiment was performed to increase the transmittance by applying a coating layer.

An AZO (Al-doped ZnO) thin film was deposited on the AR-coated fabric, and a new AR layer was deposited on the back of the AR coating by deposition to improve the transmittance. The AR coating fabric was fabricated in a wet coating method using a solvent and dried or cured. AR deposition of bowel movements was carried out by dry vacuum deposition by a sputtering method, a PVD method. The high refractive index layer was deposited on the backside and then the low refractive index layer was deposited. NbO was used as the material of the high refractive index layer, and the refractive index corresponds to 2.35 level. SiO was used as the material of the low refractive index layer and the refractive index corresponds to 1.45 level.

The NbO thin film may be deposited using pulsed DC power using an NbO target, and the O may be injected by a predetermined amount during deposition to inject only an amount of O vaporized during deposition to form a thin film. The SiO thin film was applied with RF power in the same manner as in the previous experiment and was deposited using the SiO target immediately.

1 illustrates a structure in which an AR layer is formed by a deposition method on the back surface of the present invention when using an AR coating fabric and the present invention. The structure shown on the right is a back AR coating structure that is newly tested.

The thickness of the NbO thin film was 50, 100, and 200, respectively, and the thickness of the NbO thin film was increased with 200 intervals from 200 to 1,000. The results of the resistance value and the transmittance change of the AZO film thus deposited are shown in Table 1 below.

Nb 2 O 5
(Om Strong) SiO
(Om Strong) division Resistance (ohm / sq) Transmittance (%) RO R1 Honey. CTR T1 Honey. 50 200 419 437 (Arc) 18 87.7 81.6 (Arc) -6.1 400 468 449 -19 87.7 85.9 -1.8 600 444 425 -19 87.8 84.5 -3.3 800 419 419 (Arc) 0 87.7 83.9 (Arc) -3.8 1,000 468 430 -38 87.7 85.3 -2.4 100 200 454 Arc - 86.6 Arc - 400 452 422 -30 86.6 84.7 -1.9 600 454 439 -15 86.6 84.7 -1.9 800 407 466 (Arc) 59 88.0 81.4 (Arc) -6.6 1,000 407 391 -16 88.0 84.7 -3.3 200 200 416 427 11 86.0 81.0 -5.0 400 444 425 -19 86.5 80.7 -5.8 600 416 412 -4 86.0 80.6 -5.4 800 444 452 8 86.5 82.3 -4.2 1,000 468 448 -20 87.7 83.5 -4.2

As a result, when the AR coating on the back, the transmittance was lowered as the transmittance lower than the conventional transmittance under all conditions. Although there was a difference in the degree of the drop depending on the coating film thickness condition, the transmittance decreased from the minimum 2% to the maximum 6%, and the sheet resistance increased relatively high in the arced area, but slightly decreased in the case of the normal sample. Is the result.

The reason for the decrease in transmittance is that the optical matching of the conventional AR coating layer and the AZO coating layer is caused by mismatching while AR deposition is applied to the rear surface, and it is necessary to review the optical design part before applying AR coating on the rear surface. It seems to be.

In the above experiments, AR deposition was performed on the back surface, so that the mismatching of the optical design resulted in a decrease in the transmittance. Therefore, the next experiment is to apply a low reflection (LR) layer having a relatively simple process and easy optical matching The experiment was conducted.

2 is a view of the structure of the conventional AR coating fabric and the structure added LR coating on the back. In FIG. 1, the two-layer structure of the high refractive index layer and the low refractive index layer corresponds to AR deposition. However, the LR coating of FIG. 2 is a one-layer structure in which only the low refractive layer is coated to improve transmittance. The refractive index of the low refractive index layer was controlled to 1.5, and the experiment was conducted in such a way that the light transmittance was improved while adjusting the film thickness. Existing LR coatings are applied to films used to prevent light loss of light sources that require light sources, such as LCDs, to reduce reflectance and improve transmittance. LR films have a single-sided coating and a double-sided coating, and double-sided coating is more advantageous in terms of transmittance than single-sided coating.

PET fabric Single side LR coating Double sided LR coating Transmittance (%) 90.5 93.5 95.0

Table 2 shows the change in light transmittance when the LR coating is applied to the existing base PET fabric on each side and both sides. It can be seen that LR single-sided coated products rather than PET fabrics, and LR double-sided coated products have higher light transmittance than LR single-sided coated products. In this experiment, however, a single-sided structure was applied to the back side, and the opposite side was AZO deposited, so both sides were not applied. LR coating is a solvent-based wet coating, which is coated in the same way as the conventional AR wet coating method, so it is very advantageous in terms of mass production and is a single layer structure, which is very advantageous in terms of yield and manufacturing cost. It is advantageous. However, due to the constraints of the sample in this experiment, the experiment was conducted by a method of confirming the tendency by applying a bar coating to a sheet state rather than a roll coating.

AZO was deposited using AR coated fabrics prior to applying the LR coating. As a result of AZO deposition by applying the optimum deposition conditions of AZO, the sheet resistance was 432 ohm / sq and the light transmittance was 86.6%. LR coating was performed on the back by curing under exposure to UV light of 3,000 mJ.

AZO LR coating thickness 3 탆 6 μm 9㎛ Resistance (ohm / sq) 432 434 428 437 Transmittance (%) 86.6 88.5 89.2 87.5 Turbidity (%) 0.8 0.8 0.9 0.9

Table 3 is a result of the LR coating by thickness, Figure 3 is a graph showing the change in sheet resistance and transmittance. When the LR coating was applied to the back, the transmittance tended to increase. In particular, the 6-thick back LR coating showed 89.2% transmittance, which is 89.0% or more, which is the final target of the third year. It was found that the sheet resistance of AZO was initially maintained unchanged with respect to resistance, and the haze value of the back LR coating was also unchanged at less than 1.0%.

Claims (12)

A substrate made of plastic;
A high refractive index layer formed on the substrate;
A low refractive index layer formed on the high refractive index layer;
A zinc oxide transparent electrode layer formed on the low refractive index layer; And
Zinc oxide transparent electrode laminated film comprising a low refractive index layer formed under the substrate. The zinc oxide transparent electrode laminate film of claim 1, wherein the plastic of the substrate is PET, PEN or PES. The zinc oxide transparent electrode laminate film according to claim 1, further comprising a hard coating layer on upper and lower layers of the plastic of the substrate. The zinc oxide transparent electrode laminate film according to claim 1, wherein the high refractive index layer is made of Nb 2 O 5 . The zinc oxide transparent electrode laminate film according to claim 4, wherein the refractive index of the high refractive index layer is 1.95 to 2.55. The zinc oxide transparent electrode laminate film according to claim 4, wherein the high refractive index layer has a thickness of 50 to 100 ohms. The zinc oxide transparent electrode laminate film according to claim 1, wherein the low refractive index layer is made of SiO 2 . The zinc oxide transparent electrode laminate film according to claim 7, wherein the low refractive index layer has a refractive index of 0.95 to 1.55. The zinc oxide transparent electrode laminate film according to claim 7, wherein the low refractive index layer has a thickness of 400 to 900 ohms. The zinc oxide transparent electrode laminate film according to claim 1, wherein the high refractive index layer and the low refractive index layer are wet coated as an antireflective coating layer. The zinc oxide transparent electrode laminate film according to claim 1, wherein the low refractive index layer formed under the substrate is wet coated as a low reflection coating layer. 12. A touch screen having improved transmissivity by applying an antireflection and total reflection coating layer comprising a zinc oxide transparent electrode laminated film according to any one of claims 1 to 11.
KR1020120104937A 2012-09-21 2012-09-21 Touch screen with improved transmittance by forming anti-reflection and low-reflection coating layer KR20140039399A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20160071652A (en) 2014-12-12 2016-06-22 현대자동차주식회사 Touch screen structure and manufacturing method thereof

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20160071652A (en) 2014-12-12 2016-06-22 현대자동차주식회사 Touch screen structure and manufacturing method thereof

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