KR100964100B1 - Protection filter for display - Google Patents

Abstract

A protective filter for a display device is disclosed. The protective filter for a display device is a transparent base material; A first functional film formed on one surface of the transparent substrate and having a hydrophilic surface through a surface modification treatment; And a second functional film formed on the other side of the transparent substrate.

Description

Protective filter for display unit {PROTECTION FILTER FOR DISPLAY}

The present invention relates to a display device, and more particularly, to a protective filter for a display device provided in the display device.

With the development of information technology, the market for a display device, which is a connection medium between a user and information, is growing. In response to this, the use of flat panel displays (FPDs) such as liquid crystal displays (LCDs), organic light emitting displays (OLEDs), and plasma display devices is increasing. Among them, liquid crystal displays capable of realizing high resolution and being capable of miniaturization as well as large scale are widely used. Hereinafter, the liquid crystal display will be described as an example.

A liquid crystal display device according to the background art includes a liquid crystal display module provided in a housing to display an image. The liquid crystal display is used not only for desktop monitors used for personal or office use, but also for televisions, and its application field is gradually expanded, and recently, it is used as a public display (PD).

The liquid crystal display device used as the public display is generally stored outdoors and may be directly affected by the external environment. For example, a risk that the liquid crystal display module provided in the liquid crystal display device is exposed to an external shock may increase. For this reason, according to the background art, a protective filter for protecting the liquid crystal display module may be mounted in front of the liquid crystal display module.

However, when the temperature difference between the internal and external environment of the liquid crystal display is generated by the temperature change of the external environment, the above-described structure may cause a fog on the protective filter, which may lower display quality of the display device. .

Accordingly, an object of the present invention is to provide a protective filter for a display device that can cope with a temperature change in an external environment.

Other problems to be solved by the present invention are not limited to the above-mentioned problems, and other problems not mentioned above will be clearly understood by those skilled in the art from the following transparent substrate. Could be.

According to an aspect of the present invention, there is provided a protective filter for a display device comprising: a transparent substrate; A first functional film formed on one surface of the transparent substrate and having a hydrophilic surface through surface modification; And a second functional film formed on the other surface of the transparent substrate.

Specific details of other embodiments are included in the detailed description and the drawings. Advantages and features of the present invention and methods for achieving them will be apparent with reference to the embodiments described below in detail with the accompanying drawings.

According to the present invention, by forming a functional film having a hydrophilic surface on one surface of the protective filter for a display device, it is possible to prevent the fog from being frosted on the protective filter, thereby preventing display quality degradation of the display device. . Such a protective filter for a display device may be very useful when mounted on a public display that is provided outdoors.

Hereinafter, a protective filter for a display device according to an exemplary embodiment of the present invention will be described in detail with reference to the accompanying drawings. Like reference numerals refer to like elements throughout.

1 is a view schematically illustrating a protection filter for a display device according to an exemplary embodiment of the present invention.

Referring to FIG. 1, a protective filter 120 for a display device according to an exemplary embodiment may include a transparent substrate 130, a first functional film 140 formed on one surface of the transparent substrate 130, and the transparent substrate. The second functional film 150 formed on the other surface of the substrate 130 is included. Here, each of the first and second functional films 140 and 150 may be attached to each of one side and the other side of the transparent substrate 130 by an adhesive (or an adhesive), but is not limited thereto.

The transparent substrate 130 may include glass, which is less scratchable and has good strength, thereby ensuring stability against fracture, but is not limited thereto. For example, the transparent substrate 130 may be a transparent polymer instead of the glass, for example, polyethylene terephthalate, polysulfone, polyether sulfone, polystyrene, polyethylene naphthalate, polyarylate, polyether ether ketone, It may contain one or more selected from the group consisting of polycarbonate, polypropylene, polyimide, triacetyl cellulose, polymethyl methacrylate.

When the protective filter 120 is mounted on the display device, the first function film 140 may be formed to face the display module of the display device, but is not limited thereto.

The first functional film 140 may have a hydrophilic surface 140a to perform an anti-fog function. Here, hydrophilic means that the surface energy of the first functional film 140 is high so that the contact angle of the droplets dropped on the first functional film 140 is 30 degrees or less. On the other hand, the contact angle can be converted to surface energy, which will be described later.

The first functional film 140 is one or more selected from a polymer resin having good transparency and excellent processability, for example, polyethylene, polypropylene, polyethylene terephthalate, polyvinyl chloride, polycarbonate, triacetyl cellulose, or acrylic resin It may include.

However, the polymer resin of the first functional film 140, as shown in Table 1, has a low wettability (wettability) due to the low surface energy (γ1). Here, Table 1 shows the surface energy (γ1) per unit area of each material.

γ1 (mN / m) Polyethylene 31-33 Polypropylene 29-30 Polyethylene terephthalate 41-42 Polyvinylchloride 33-35 Polycarbonate 34-37

In order to increase the surface energy of the first functional film 140, any one of various known surface modification treatment methods may be used. For example, the surface 140a of the first functional film 140 may be corona discharge treatment, sputtering discharge treatment using RF power or DC power, plasma discharge treatment overlapping RF power and DC power, and ion beam treatment. By doing so, the surface 140a of the first functional film 140 may be modified.

For example, in the plasma discharge treatment in which the RF power source and the DC power source are superimposed, in detail, two electrodes are formed and the first functional film 140 is introduced into a plasma discharge device filled with a gas such as oxygen. Accelerating the electron or inert gas formed by applying the RF power and the DC power between the two electrodes to the first functional film 140, the electron or inert gas surface 140a of the first functional film 140 Inelastic collisions. At this time, carbon-hydrogen and carbon-carbon bonds of the polymer resin of the first functional film 140 are cut off, and carbonyl (-C = O) on the surface 140a of the first functional film 140, Functional groups such as carboxyl (-COOH) and hydroxyl (-OH) are generated to increase the surface free energy of the first functional film 140, thereby improving wettability.

The first functional film 140 subjected to the plasma discharge treatment may have a more rough surface than the discharge treatment described above, and may have a hydrophilic surface 140a having a contact angle of 30 degrees or less. On the other hand, the contact angle may be converted into surface energy through the following equation (1).

γ 2 = γ 1 (1 + cosθ)

Here, γ1 represents the surface energy per unit area for each material described in Table 1, θ represents the contact angle, and γ2 represents the surface energy per unit area for each material changed by the surface modification treatment.

Using Table 1 and Equation 1, the case where the contact angle is 30 degrees is converted to surface energy as shown in Table 2 below.

γ2 (mN / m) Polyethylene 57.8-61.6 Polypropylene 54.1-56.0 Polyethylene terephthalate 76.5 ~ 78.4 Polyvinylchloride 61.6 to 65.3 Polycarbonate 63.4 ~ 69.0

As shown in Table 2, in the embodiment of the present invention, the first functional film 140 has a hydrophilic surface 140a to improve the surface energy of the first functional film 140. Therefore, as described above, the corona discharge treatment which can increase the surface roughness of the first functional film 140, the sputtering discharge treatment using the RF power supply or the DC power supply, the plasma discharge treatment superimposing the RF power supply and the DC power supply, and The surface energy of the first functional film 140 is improved by selecting an appropriate one from the ion beam treatment.

As described above, since the first functional film 140 having the hydrophilic surface 140a is formed in the protective filter 120 for the display device according to the exemplary embodiment of the present invention, the protective filter 120 may be formed on the protective filter 120. This frost can be prevented. In addition, it is possible to prevent display quality deterioration of the display device including the protective filter 120.

The second functional film 150 is an anti-reflection (AR) film, an anti-glare (AG) film, and a color correction film having a neon-cut function, and a near infrared shielding film. And a composite functional film having a neon-cut and a near infrared shielding function. In addition, the functional films may be used alone or in combination of two or more. Hereinafter, the case where the second functional film 150 is an antireflection film will be described as an example for convenience of explanation.

The second functional film 150 may reduce reflection of external environmental light incident from the outside and may include a base film 152 and an anti-reflection film 154.

The base film 152 is a polymer resin having good transparency, for example, polyethylene terephthalate, polysulfone, polyether sulfone, polystyrene, polyethylene naphthalate, polyarylate, polyether ether ketone, polycarbonate, polypropylene, polyimide It may include one or more selected from triacetyl cellulose, polymethyl methacrylate.

As the anti-reflection film 154, for example, a thin film of an inorganic compound such as metal oxides, fluorides, silicides, borides, carbides, nitrides, sulfides having different refractive indices or organic compounds such as silicone resins, acrylic resins, and fluorine resins may be used. Two or more laminated ones can be used. For example, the antireflection film 154 may be formed by alternately stacking a low refractive index oxide film such as silicon oxide and a high refractive index oxide film such as titanium oxide.

However, the anti-reflection film 154 may be formed in the form of a single film. For example, the anti-reflection film 154 may include a fluorine-based transparent polymer resin, a magnesium fluoride, a silicon-based resin, or a silicon oxide thin film having a refractive index of 1.5 or less, preferably 1.4 or less, in a visible region. What is formed in the form of a single film by the optical film thickness can be used.

2 is a diagram schematically illustrating a protection filter for a display device according to an exemplary embodiment of the present invention. The protective filter illustrated in FIG. 2 is the same as the protective filter illustrated in FIG. 1 except that a coating layer is further formed on the first functional film, and thus, redundant descriptions thereof will be omitted and only the features thereof will be described.

Referring to FIG. 2, a protective filter 220 for a display device according to an exemplary embodiment may include a transparent substrate 230, a first functional film 240 formed on one surface of the transparent substrate 230, and the transparent substrate. The second functional film 250 formed on the other surface of the substrate 230 is included. In addition, the protective filter 220 for a display device according to an exemplary embodiment may further include a coating layer 260 formed on the first functional film 240. Here, each of the first and second functional films 240 and 250 may be attached to each of one side and the other side of the transparent substrate 230 by an adhesive (or an adhesive), but is not limited thereto.

The first functional film 240 may have a hydrophilic surface 240a through surface modification.

The second functional film 250 may be an anti-reflection (AR) film including the base film 252 and the anti-reflection film 254, but is not limited thereto, and may be an anti-glare (AG). Film, color correction film with neon-cut function, near infrared shielding film. And a composite functional film having a neon-cut and a near infrared shielding function. In addition, the functional films may be used alone or in combination of two or more. The coating layer 260 may include a surfactant such that the surface 260a of the coating layer 260 together with the surface 240a of the first functional film 240 is hydrophilic. Specifically, the surfactant may include at least one of cationic surfactants, anionic surfactants, amphoteric surfactants, and nonionic surfactants.

The coating layer 260 may be formed by coating a known coating solution including the surfactant on the transparent substrate 230 and curing the coating. Here, a method of coating the coating liquid on the transparent substrate 230 may include dip coating, flow coating, spin coating, roller coating, screen printing, and flexo. It can select suitably from methods, such as printing.

As described above, the protective filter 220 for a display device according to an embodiment of the present invention has a coating layer 260 having a hydrophilic surface 260a on the first functional film 240 having a hydrophilic surface 240a. Since it is further formed, it is possible to further prevent the frost on the protective filter 220. In addition, the display quality of the display device including the protection filter 220 may be further prevented.

3 is a diagram schematically illustrating a display device including a protection filter for a display device according to an exemplary embodiment of the present invention. 3 shows the protective filter shown in FIG. 1 as a protective filter. However, the display device of the present invention is not limited thereto, and may include the protective filter shown in FIG. 2 instead of the protective filter shown in FIG. 1 as the protective filter. On the other hand, since the protection filter shown in FIG. 3 is the same as the protection filter shown in FIG. 1, the same reference numerals will be used to describe the same.

Referring to FIG. 3, the display device 300 according to an exemplary embodiment may be used as a public display, but is not limited thereto. The display device 300 includes a display module 310 and a protective filter 120 that are stored in the housing 302.

The display module 310 may be, for example, a liquid crystal display module displaying an image by using the electro-optical characteristics of the liquid crystal, but is not limited thereto, and may be an organic light emitting display module or a plasma display module.

The protection filter 120 may be disposed in front of the display module 310 and may protect the display module 310 from an external environment. In particular, the protective filter 120 may be hydrophilic even when the temperature difference between the internal and external environments of the display device 300 occurs due to a change in temperature of the external environment. As a result, it is possible to prevent the fog from being frosted on the protection filter 120, thereby preventing the display quality of the display device 300 from being lowered.

Hereinafter, the surface characteristics of the protective filter for a display device according to an exemplary embodiment of the present invention will be described in more detail with reference to the following embodiments. However, the following examples are intended to illustrate the protective filter for display device of the present invention in more detail, and therefore the contents of the present invention are not limited to the following examples.

EXAMPLE

Example 1

After putting the first functional film containing polyethylene terephthalate into the RF sputtering equipment, RF sputtering plasma discharge treatment was performed for 3 minutes. At this time, the power applied to the two electrodes of the equipment is 500W, the temperature in the equipment was 230 ℃. In addition, oxygen gas was used as the filling gas, and the flow rate thereof was 1900 sccm. Subsequently, the surface of the RF sputtered plasma discharge-treated first functional film was photographed with an atomic force microscope (AFM), and this is illustrated in FIG. 4A, and the surface roughness and contact angle were measured. Table 3 shows.

Example 2

After putting the first functional film containing polyethylene terephthalate into the RF sputtering equipment, RF sputtering plasma discharge treatment was performed for 10 minutes. At this time, the power applied to the two electrodes of the equipment is 500W, the temperature in the equipment was 230 ℃. In addition, oxygen gas was used as the filling gas, and the flow rate thereof was 1900 sccm. Then, the surface roughness and contact angle of the RF sputtered plasma discharge treated first functional film are measured and shown in Table 3.

Comparative Example 1

After photographing the surface of the first functional film containing polyethylene terephthalate without RF sputtering plasma discharge treatment with an atomic force microscope, this is shown in FIG. 4 (b), and the surface roughness and contact angle were measured. It is shown in Table 3.

Surface roughness Contact angle (°) Surface roughness (Rpv) Surface Average Roughness (Rrms) Example 1 154 17.9 30 Example 2 221 23.2 24 Comparative Example 1 90.6 12.1 77.1

4 is an atomic force microscope photograph for comparing surface roughness before and after surface modification of a first functional film of a protective filter for a display device according to an embodiment of the present invention, and FIG. It is a nuclear nuclear microscope picture of Figure 4, Figure 4 (b) is a nuclear nuclear microscope picture of Comparative Example 1.

4 and Table 3, it can be seen that the surface roughness had a relatively small value before the RF sputtering plasma discharge treatment of the first functional film, but the surface roughness had a relatively large value after the RF sputtering plasma discharge treatment. there was. In addition, the contact angle exceeded 30 degrees before the RF sputtering plasma discharge treatment of the first functional film, but after the RF sputtering plasma discharge treatment it was confirmed that the 30 degrees or less. In particular, it can be seen that when the RF sputtering plasma discharge treatment time of the first functional film is long, it has a larger surface roughness and a smaller contact angle.

Although the embodiments of the present invention have been described above with reference to the accompanying drawings, those skilled in the art to which the present invention pertains can realize that the present invention can be implemented in other specific forms without changing the technical spirit or essential features. I can understand that.

Therefore, it should be understood that the above-described embodiments are provided so that those skilled in the art can fully understand the scope of the present invention. Therefore, it should be understood that the embodiments are to be considered in all respects as illustrative and not restrictive, The invention is only defined by the scope of the claims.

1 is a view schematically illustrating a protection filter for a display device according to an exemplary embodiment of the present invention.

2 is a view schematically illustrating a protection filter for a display device according to an exemplary embodiment of the present invention.

3 is a view schematically illustrating a display device including a protection filter for a display device according to an exemplary embodiment of the present invention.

4 is an atomic force microscope photograph for comparing the surface roughness before and after the surface modification treatment of the first functional film of the protective filter for a display device according to an embodiment of the present invention.

{Description of symbols for main parts of the drawing}

120, 220: Protective filter 130, 230: Transparent base material

140, 240: first functional film 150, 250: second functional film

Claims (5)

Transparent substrates; A first functional film formed on one surface of the transparent substrate and having a hydrophilic surface having a contact angle of 30 degrees or less through surface modification; And Second functional film formed on the other side of the transparent substrate Protective filter for display device comprising a. The method of claim 1, A coating layer formed on the first functional film and including a surfactant Protective filter for display device further comprising. delete The method of claim 1, The second functional film is an anti-reflection (AR) film, an anti-glare (AG) film, a color correction film having a neon-cut function, a near infrared shielding film. And a composite function film having a neon-cut and a near infrared shielding function. The method of claim 1, The protective filter for display device is a protective filter for display device, characterized in that for a liquid crystal display device.

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