KR20090019580A - Electromagnetic wave blocking member for display apparatus - Google Patents

Abstract

The present invention provides an electromagnetic wave shielding member including a glass substrate and an electromagnetic wave shielding pattern formed by printing a conductive paste on one surface of the glass substrate, and having a line width of 15 to 25 µm and a mesh pattern having a thickness of 1.5 to 4.0 µm. The present invention provides an electromagnetic shielding member for a display device, wherein the electromagnetic shielding member has a visible light reflectance of 11% or less and a sheet resistance of 0.4 Ω / □ or less. The electromagnetic shielding member for a display device according to the present invention can achieve a high electromagnetic shielding efficiency even when using the electromagnetic shielding layer of the transparent conductive film type, it can be efficiently manufactured without additional process.

Description

Electromagnetic wave blocking member for display apparatus

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic wave shielding member for a display device, and more particularly, to an electromagnetic wave shielding member for a display device that is simple in a manufacturing process and can improve electromagnetic wave shielding ability.

As the modern society is highly informationized, image display-related parts and devices have been remarkably advanced and disseminated. Among them, display apparatuses for displaying images are widely used for television apparatuses, monitor apparatuses of personal computers, and the like, and thinning is progressing at the same time as these displays are enlarged.

In general, a plasma display panel (PDP) device is in the spotlight as a next-generation display device because it can satisfy both an enlargement and a thinning at the same time as a cathode ray tube (CRT) representing a conventional display device. The PDP apparatus displays an image using a gas discharge phenomenon, and is excellent in various display capabilities such as display capacity, brightness, contrast, afterimage, viewing angle, and the like. In addition, PDP devices are easier to be enlarged than other display devices, and are considered to be thin display devices having the most suitable characteristics as high quality digital televisions in the future.

The PDP device generates a discharge in the gas between the electrodes by a direct current or an alternating current voltage applied to the electrode, and excites the phosphor by the radiation of ultraviolet rays, which emits light.

However, due to its driving characteristics, the PDP device has a high emission amount of electromagnetic waves and near infrared rays, high surface reflection of the phosphor, and color purity of the PDP device due to the orange light emitted from the encapsulated helium (He) or xenon (Xe), which does not reach the cathode ray tube. There is this. Electromagnetic waves and near-infrared rays generated by PDP devices may have a harmful effect on the human body and may cause malfunctions of precision devices such as cordless phones or remote controls. In order to use such a PDP apparatus, it is required to suppress the emission of electromagnetic waves and near-infrared rays emitted from the PDP apparatus below a predetermined value.

To this end, there is a method of mounting the electromagnetic shielding plate on the front of the display portion of the display, and the electromagnetic shielding plate used as the front plate is required not to degrade the transparency of the display display screen in addition to the function of shielding the electromagnetic waves.

However, in the PDP, various functions such as shielding of near infrared rays, reducing reflected light, improving color purity, and improving contrast ratio, as well as electromagnetic shielding, are required. The PDP filter is a structure in which functional layers such as an electromagnetic shielding layer, a near infrared shielding layer, a color correction layer, an external light shielding layer, or a composite layer that simultaneously performs two or more of these functions are stacked. At the same time, a lot of efforts are being made to simplify and economicize the manufacturing process.

Conventionally commercialized electromagnetic shielding layer is a method using a metal mesh (mesh) and a method of coating a transparent conductive thin film is used. Among these methods, there are two methods of using a metal mesh, a method of weaving a large metal coated fiber and a method of etching a thin copper foil, and a mesh film by an etching method is most commonly used. Way.

The method for etching the copper foil proceeds to the following process. After forming a copper film by the plating method, surface treatment, such as blackening treatment for image quality improvement, surface unevenness | corrugation treatment, and antioxidant treatment, for improving adhesive force is performed. Next, this copper foil is adhere | attached with PET film using an adhesive agent. The bonded film is patterned using a lithography method and partially etched to form a mesh.

The biggest problem of the mesh by the etching method is that the cost of the etching process and the lithography process is expensive, and the material cost is high because more than 90% of the copper must be removed by etching. A method of removing one of the etching process and the lithography process has been developed, but the method of removing both processes has not been realized yet.

In addition, a method of forming an electromagnetic wave shielding layer by coating a transparent electroconductive thin film has a problem that the electromagnetic wave shielding ability is inferior to the method using a metal mesh to date.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide an electromagnetic wave shielding member for a display device having high electromagnetic wave shielding efficiency even when an electromagnetic wave shielding layer of a conductive film type is used.

Technical problems to be achieved by the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art from the following description.

Electromagnetic shielding member for a display device according to an aspect of the present invention is a glass substrate and a conductive paste is printed on one surface of the glass substrate is formed, the line width is 15 to 25㎛, the thickness of the mesh pattern of 1.5 to 4.5㎛ The electromagnetic wave shielding pattern is formed, and the visible light reflectance is 11% or less and the sheet resistance is 0.4 Ω / □ or less.

The electromagnetic shielding member for a display device according to another aspect of the present invention is characterized in that the printing is made by a gravure offset method. In the case of the conventional screen printing printing method, the line width is about 40 μm and the printing thickness is not so large that the shielding ability of the electromagnetic shielding member is poor, while in the gravure offset method used in the present invention, the line width can be reduced while increasing the printing thickness. It is possible to manufacture an electromagnetic shielding member having an improved electromagnetic shielding ability compared to the conventional screen printing method.

In the electromagnetic shielding member for a display device according to another aspect of the present invention, a plurality of wedge-shaped grooves are formed on one surface of the glass substrate, and the wedge-shaped grooves are filled with a conductive material.

The electromagnetic shielding member for a display device according to another aspect of the present invention is characterized in that the conductive paste is a sintered silver paste. When using a sintered silver paste, a thin line width and a large print thickness can be printed.

The electromagnetic shielding member for a display device according to another aspect of the present invention may further include a ground electrode formed by printing a conductive paste on at least one region of the edge region of the glass substrate.

The conductive paste may be a silver paste. The silver paste may be blackened by including at least one material selected from the group consisting of carbon, cobalt, and copper.

The electromagnetic wave shielding member for display devices according to the present invention can be manufactured by directly printing a electromagnetic wave shielding pattern having a thin line width and a thick mesh on a glass substrate, whereby lower sheet resistance can be obtained. In addition, by printing the ground electrode together on the substrate, it is possible to form the electrode efficiently in a single process without additional processing. In addition, the present invention determines the reflectance of the electromagnetic shielding member that can optimize the visibility of the display screen and the electrical conductivity of the electromagnetic shielding member by adjusting the degree of blackening treatment of the conductive paste used for printing.

The electromagnetic wave shielding member for a display device according to the present invention can lower the manufacturing cost of the filter for the display device by increasing the shielding ability of the electromagnetic wave shielding layer of the conductive film type, and the manufacturing process is simple and can efficiently manufacture the filter for the display device. Can be.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Although not shown, a PDP device according to an embodiment of the present invention includes a case, a cover covering the top of the case, a driving circuit board accommodated in the case, a panel assembly including a light emitting cell and a phosphor layer in which gas discharge occurs, and a PDP. It consists of a filter. Discharge gas is enclosed in the light emitting cell. As the discharge gas, for example, a Ne-Xe-based gas, a He-Xe-based gas, or the like can be used. The panel assembly basically has a light emitting principle such as a fluorescent lamp, and the ultraviolet rays emitted from the discharge gas are converted into visible light by exciting the phosphor layer in the panel assembly with the discharge in the light emitting cell.

The PDP filter is disposed above the front substrate of the panel assembly. The PDP filter may be spaced apart from or contacted with the front substrate of the panel assembly, and may also be used to prevent side effects such as foreign matter entering between the panel assembly and the PDP filter or to reinforce the strength of the PDP filter itself. The front substrate may be combined with an adhesive or an adhesive.

The PDP filter is provided with a conductive layer formed of a material having excellent conductivity on the transparent substrate, which is grounded to the case through the cover. That is, before the electromagnetic wave generated from the panel assembly reaches the viewer, it is grounded to the cover and the case through the conductive layer of the PDP filter.

1 is a cross-sectional view showing a PDP filter according to an embodiment of the present invention.

Referring to FIG. 1, the PDP filter 100 includes an antireflection film 130, an electromagnetic wave shielding member 150, a color correction film 170, and a near infrared shielding film 180 as functional layers having various shielding functions. . The present invention is not limited thereto, and the functional layers may perform a complex function in one layer, and other functional layers such as a protective film or an external light shielding film may be included in addition to the functional layer.

The electromagnetic shielding member 150 includes a glass substrate 152 and an electromagnetic shielding pattern 154.

The anti-reflection film 130 prevents external light incident from the viewer direction to be reflected back to the outside, thereby improving the contrast ratio of the display. In the present embodiment, the anti-reflection film 130 is formed on the other surface of the glass substrate 152, but the present invention is not limited to this stacking order. However, preferably, as shown in FIG. 1, the antireflection film 130 is formed on the side facing the viewer when the PDP filter 100 is mounted on the PDP apparatus, that is, on the side opposite to the panel assembly side. Efficient

Specifically, the antireflection film 130 includes 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 the visible region. What was formed in a single layer by the optical film thickness of 4 wavelength can be used. Then, as the antireflection film 130, two layers of thin films of inorganic compounds such as metal oxides, fluorides, silicides, borides, carbides, nitrides, sulfides or organic compounds such as silicone resins, acrylic resins, and fluorine resins are used. Multilayered or multilayered ones can be used.

Here, the antireflection film 130 formed of a single layer is easy to manufacture, but the antireflection performance is lower than that of the multilayer layer. The multilayer stack has antireflection performance over a wide wavelength range. For example, the antireflection film 130 according to an embodiment of the present invention may use a structure in which a low refractive index oxide film such as SiO ₂ and a high refractive index oxide film such as TiO ₂ or Nb ₂ O ₅ are alternately stacked. Such oxide films may be formed using physical vacuum deposition or wet coating.

Although the electromagnetic shielding member 150 is formed on one surface of the glass substrate 152, that is, the surface of the panel assembly side, the present invention is not limited to this arrangement. As the base substrate of the electromagnetic shielding member in the filter for a display device, a polymer molded product such as acrylic, polycarbonate (PC), or polyethylene terephthalate (PET) having high transparency, heat resistance, etc. can be used in addition to glass. The glass substrate 152 is used. The glass substrate 152 serves as a support for the PDP filter, and is essential for obtaining a low sheet resistance. Conventional electromagnetic wave shielding member is a form in which a metal mesh is adhered to the PET with an adhesive, in the present invention, a conductive material is fused to one surface of the glass substrate 152. The electromagnetic shielding member 150 and its manufacturing method will be described in detail below.

The PDP filter 100 includes a color correction film 170 that selectively absorbs light of a specific wavelength band. Although the color correction film 170 is located on one surface of the electromagnetic shielding member 150, the color correction film 170 is not limited thereto.

The color correction film 170 reduces or adjusts the amount of red (R), green (G), and blue (B) to change or correct the color balance to increase the color reproduction range of the display and improve the sharpness. .

The color correction film 170 includes various pigments, and as the pigments, dyes or pigments may be used. Kinds of pigments include organic pigments having a neon light shielding function such as anthraquinone, cyanine, azo, stryl, phthalocyanine and methine, but the present invention is not limited thereto. Since the type and concentration of the dye are determined by the absorption wavelength, absorption coefficient, and transmission characteristics required in the display, the dye is not limited to a specific value and is not used.

The PDP filter 100 includes a near infrared shielding film 180. The near-infrared shielding film 180 serves to shield strong near-infrared rays generated from the panel assembly and causing malfunction of electronic devices such as a wireless telephone or a remote controller.

In order to shield the near infrared rays, a polymer resin containing a near infrared absorbing dye that absorbs the wavelength of the near infrared region can be used. For example, organic dyes of various components, such as cyanine, anthraquinone, naphthoquinone, phthalocyanine, naphthalocyanine, dimonium, and nickel dithiol, can be used as the near infrared absorbing dye. Since PDP devices emit strong near infrared rays over a wide wavelength range, it is necessary to use a near infrared shielding film that can absorb near infrared rays over a wide wavelength range.

The near-infrared shielding film 180, the color correction film 170, and the anti-reflection film 130 may be composed of respective films as in the present embodiment. Alternatively, one film may perform a plurality of functions. You may. For example, the single film which performs an anti-reflective-color correction function, the single film which performs an anti-reflective-color correction- near-infrared shielding function, etc. are mentioned. In this case, the position where the film is disposed may be appropriately selected depending on the configuration of the film.

In addition, although not shown, the PDP filter may include an external light shielding film. The external light shielding film absorbs external light to prevent external light from entering the panel assembly, and serves to totally reflect incident light emitted from the panel assembly toward the viewer. Thus, a high transmittance to visible light and a high contrast ratio can be obtained.

When sticking each layer or film of this invention, a transparent adhesive or an adhesive agent can be used. Specific materials include acrylic adhesives, silicone adhesives, urethane adhesives, polyvinyl butyral adhesives (PMB), ethylene-vinyl acetate adhesives (EVA), polyvinyl ethers, saturated amorphous polyesters, melamine resins, and the like.

Hereinafter, the electromagnetic shielding member will be described in detail.

2 is a perspective view showing an electromagnetic shielding member according to an embodiment of the present invention. 3 is a cross-sectional view taken along the line II ′ of FIG. 2.

2 and 3, the electromagnetic shielding member 200 includes a glass substrate 260 and an electromagnetic shielding pattern 220 and a ground electrode 240 formed on one surface of the glass substrate 260. The electromagnetic wave shielding pattern 220 is formed by printing a conductive paste on the glass substrate 260, and preferably in the form of a continuous geometric pattern. In the present invention, the electromagnetic shielding pattern 220 is not limited thereto.

For clear image quality of the display when emitting incident light from the panel assembly to the outside, the aperture ratio should be improved and the moiré phenomenon should be suppressed. For this purpose, it is necessary to limit the line width H ₁ of the mesh. If the line width H ₁ is too large, the aperture ratio decreases, so that the amount of incident light emitted from the panel assembly is emitted to the screen, thereby reducing the transparency. When the screen printing method is used, the line width cannot be printed smaller than 40 μm, but the line width of 25 μm or less can be realized in the present invention. When the line width H ₁ is 25 μm or less, the degree of freedom in designing the other functional layers in the filter for the display device may be increased.

In addition, the thicker the thickness (H ₃ ) of the printed electromagnetic shielding pattern 220, the better the electromagnetic shielding ability. In the present invention, the thickness (H3) of the mesh type electromagnetic shielding pattern is characterized in that 1.5 to 4.0 ㎛. Since the line width H ₁ of the mesh type electromagnetic shielding pattern 220 is smaller than 25 μm, when the thickness H ₃ is larger than 4.0 μm, it may be difficult to uniformly form the electromagnetic shielding pattern 220. However, the present invention is not limited thereto, and if the problem can be solved, the thickness H _{3 of the} pattern may be 4.0 μm or more. In addition, when the thickness H ₃ of the pattern is smaller than 1.5 μm, it is difficult to exhibit a sufficient shielding effect.

On the other hand, the interval (H ₂ ), that is, the pitch (H ₂ ) between the adjacent electromagnetic wave shielding pattern 220 is usually a problem in showing the electromagnetic shielding ability in the range of 150 to 500 ㎛.

In the present invention, the line width H ₁ of the electromagnetic shielding pattern 220 may be as thin as 15 to 25 μm and the thickness H ₃ may be as thick as 1.5 to 4.0 μm because the gravure offset printing method is used. Hereinafter, a description will be given of the reasons for using the gravure offset printing method in the present invention after examining the different printing methods.

First, the screen printing method is as follows. Fill with an emulsion resin, leaving only the portion to be printed on a mesh woven from polyester fiber or stainless steel yarn, and then place the fiber horizontally on the glass plate to be printed and apply ink. Once rubbed on the fiber with rubber, the ink falls down and prints on the glass only at the portion not filled with the emulsion resin.

The reason why it is difficult to reduce the line width in the screen printing method is that the line width is determined by the thickness of the fiber used, because at present, it is impossible to use a fiber having a sufficiently small line width. Usually, the line width of the printed pattern is three times the line width of the fiber used. The polyester fiber currently used has the thinnest 30 μm, and the stainless steel fiber also has a line width of about 14 μm, and thus, the line width of the pattern printed by the screen printing method cannot be represented by 40 μm or less.

On the other hand, the offset printing method is as follows. Applying a lipophilic substance and a hydrophilic substance on the metal surface, and then using water-based ink, the ink is only in the hydrophilic part. The ink is transferred to a rubber roll or the like, and the ink transferred to the rubber roll is transferred to paper or a glass substrate for printing. Since the offset printing method does not have irregularities for filling ink on the metal surface, the ink may be deposited only on the surface of the roll, and thus the line width may be thinned, but the thickness of the printing pattern may not be thickened.

The gravure printing method is as follows. After the groove is formed in the same shape as the metal roller to be printed, ink is deposited on the roller and the surface is scraped off with rubber or the like to collect ink only in the groove. When the metal roller is rolled on an adherend such as paper, PET film or glass substrate, a portion of the ink inside the groove is buried in the adherend to be printed. The gravure printing method enables a thin line printing of 10 μm or less. However, since most of the glass substrates are slightly bent, the roller and the glass substrate may not be in contact with each other depending on the degree of warpage of the glass substrate, and thus a portion of the glass substrate may not be printed. Direct gravure printing is not suitable.

The gravure offset printing method is to transfer the ink by first transferring the ink of the metal roller to a rubber roll, and then contacting the rubber roll with a glass substrate to compensate for the disadvantage of the gravure printing method. The gravure offset method uses a roller filled with ink inside the groove, so that the printed pattern can be thickened and the line width can be printed thinly.

Hereinafter, the ground electrode 240 will be described. The electromagnetic shielding member 200 may use the conductive paste to print not only the mesh pattern but also the ground electrode 240 together on the glass substrate 260. The ground electrode 240 may be formed by printing a conductive paste on at least one region of the edge region of the glass substrate 260. The edge region refers to a portion positioned at the edge side of the glass substrate and having a width of a predetermined size. The ground electrode 240 is formed to be connected to the electromagnetic shielding pattern 220. The ground electrode 240 may be formed only at both ends of the glass substrate 260, that is, at two opposite regions of the edge region of the glass substrate 260. In addition, as shown in FIG. 2, it may be formed in all edge regions of the glass substrate 260. It is preferable that the ground electrode 240 is formed in all the edge regions than the case where the ground electrode 240 is formed only at both ends of the glass substrate because the electromagnetic shielding ability is better. The width of the ground electrode 240 is approximately 10 to 15 mm, which is equal to the width of the edge region mentioned above. The present invention has the advantage that can be manufactured in a single process by printing the electromagnetic shielding pattern 220 and the ground electrode 240 together.

The conductive paste, which is a component of the electromagnetic shielding pattern 220 and the ground electrode 240, includes metal particles and a black material. The metal particles are at least one material selected from the group consisting of gold, silver, nickel, and copper, and the black material is at least one selected from the group consisting of carbon, molybdenum, cobalt, copper, ruthenium, and oxides thereof. Compound.

In order to raise the blackening level of an electrode part, black ink may be first printed on a glass substrate, and the blackening process conductive paste may be printed on this.

In an embodiment of the present invention, the silver paste is used as the conductive paste, and in order to obtain more excellent electrical conductivity and printing characteristics, a paste using silver nanoparticle powder is preferable. Color after printing is advantageous to obtain a color closer to black than silver to improve the image quality characteristics. For this purpose, a silver paste treated with blackening by adding a small amount of black material such as carbon to the silver nano paste is used. If the blackening process is not performed, the color of silver or copper used as the conductive metal particles is displayed as it is, so that a small amount of black material is added to correct the color and reduce the reflectance of the screen to improve visibility.

In the case of the electromagnetic shielding member produced by printing an electromagnetic shielding pattern with a pitch of 300 µm and a line width of 20 µm on a glass substrate using a silver paste not blackened, the reflectance was about 12.8%. When the filter for the display device was manufactured by attaching, the reflectance of the filter was 6.1%, which was outside the reflectance standard of 4% of the filter for the display device. As a result of controlling the degree of blackening, when the reflectance of the printed glass substrate was about 10.7%, the value of the product standard was about 4.0%. Therefore, in the present invention, the reflectance of the electromagnetic shielding member for the display device is preferably 11% or less. As the degree of blackening increases, the electrical conductivity tends to deteriorate. Therefore, it is necessary to optimize the electrical conductivity and the degree of blackening.

In addition, a sintered silver paste is used as the conductive paste. Silver paste can be divided into hardened silver paste and sintered silver paste. Curable silver pastes generally include silver powders, acrylic solutions and other additives. In the case of using a curable silver paste, the printed silver powder is fixed in a predetermined pattern while the acrylic solution is cured.

On the other hand, the sintered silver paste contains a volatile oil instead of an acrylic solution, and when the drying and firing process is carried out, the volatile oil flies and the silver powder is cured to form a predetermined pattern. When the sintered silver paste is used, the size of the printed pattern is reduced as the volatile components fly off, thereby forming a thinner line width pattern having better electrical conductivity. In addition, by using the gravure offset printing method, the thickness of the printing pattern can be increased.

The sheet resistance value of the said electromagnetic wave shield member 200 is 0.4 ohms / square or less, Preferably it is 0.3 ohms / square or less. In order to obtain such a sheet resistance value, the glass substrate 260 must be used essentially. The smaller the sheet resistance value, the better the electromagnetic shielding performance.

Although not shown, in the electromagnetic shielding member for a display device according to another embodiment of the present invention, a plurality of wedge-shaped grooves are formed on one surface of a glass substrate, and the inside of the wedge-shaped grooves includes a conductive material and carbon black. It can be prepared by filling with a light absorbing material of. In this case, the electromagnetic wave shielding efficiency can be further increased, and the electromagnetic shielding member for the display device can be combined to perform the role of external light shielding.

As described above, the present invention has been described by way of limited embodiments and drawings, but the present invention is not limited to the above embodiments, and those skilled in the art to which the present invention pertains various modifications and variations from such descriptions. This is possible. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined not only by the claims below but also by the equivalents of the claims.

1 is a cross-sectional view showing a PDP filter according to an embodiment of the present invention.

FIG. 2 is a perspective view illustrating the electromagnetic shielding member of FIG. 1.

3 is a cross-sectional view taken along the line II ′ of FIG. 2.

[Description of Major Symbols in Drawing]

100: PDP filter 130: antireflection film

150: electromagnetic wave shielding member 152: glass substrate

154: electromagnetic shielding pattern 170: color correction film

180: near infrared shielding film 200: electromagnetic shielding member

220: electromagnetic shielding pattern 240: grounding electrode

260: glass substrate

Claims (5)

Glass substrates; And An electromagnetic shielding pattern formed by printing a conductive paste on one surface of the glass substrate, having a line width of 15 to 25 μm, and a thickness of 1.5 to 4.0 μm; As an electromagnetic wave shield member comprising: The electromagnetic wave shielding member for display apparatuses, wherein the electromagnetic shielding member has a visible light reflectance of 11% or less and a sheet resistance of 0.4 Ω / □ or less. The method of claim 1, The printing is an electromagnetic shielding member for a display device, characterized in that the gravure offset method. The method of claim 1, A plurality of wedge-shaped grooves are formed on one surface of the glass substrate, and the inside of the wedge-shaped grooves is filled with a conductive material. The method of claim 1, The conductive paste is a sintered silver paste, electromagnetic shielding member for a display device. The method of claim 1, The electromagnetic shielding member for a display apparatus further includes a ground electrode formed by printing a conductive paste on at least one region of the edge region of the glass substrate.

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