KR100793084B1 - Manufacturing method of contrast ratio film, plasma display panel including contrast ration film and manufacturing method thereof - Google Patents

Abstract

A method of manufacturing a contrast ratio enhancement film, a plasma display panel having the contrast ratio enhancement film, and a method of manufacturing the PDP(Plasma Display Panel) are provided to decrease a manufacturing cost by using a photo-sensitive black resin for forming the contrast ratio enhancement film. A photo-sensitive black resin(726') is applied to a base film(722). A photomask(730) is arranged to the photo-sensitive black resin. Exposure and developing processes are performed on the photo-sensitive black resin, so that a black stripe is formed. A transparent resin is coated on the base film, on which the black stripe is formed. The transparent resin is cured. An adhesive layer is formed on the transparent resin. A protective film is attached on a lower surface of the base film and an upper surface of the adhesive layer.

Description

Manufacturing method of contrast ratio improvement film, plasma display panel containing contrast ratio improvement film, and manufacturing method thereof

1A is an exploded perspective view illustrating a plasma display panel according to an exemplary embodiment of the present invention.

FIG. 1B is a cross-sectional view taken along the line A-A of FIG. 1A.

2A and 2B are a perspective view and a cross-sectional view showing a contrast ratio improvement film according to an embodiment of the present invention.

3A and 3B are a perspective view and a cross-sectional view showing a contrast ratio improving film according to another embodiment of the present invention.

4 is a cross-sectional view showing a portion of a contrast ratio improving film according to another embodiment of the present invention.

5A to 5I are cross-sectional views illustrating a manufacturing process of a contrast ratio improving film according to an exemplary embodiment of the present invention.

The present invention relates to a plasma display panel and a method of manufacturing the same. More specifically, the present invention relates to a method for producing a contrast ratio improving film used in a plasma display panel.

In general, a plasma display panel (hereinafter referred to as a "PDP") is a flat panel display that displays an image or information using light emission caused by plasma discharge. Divided into

PDP generates plasma discharge inside the discharge cells separated by the partition wall, and at this time, the energy difference when the ultraviolet rays generated by the discharge of gas such as He and Xe injected into each discharge cell excite the phosphor to return to the ground state. A display device using the light emission phenomenon of visible light generated by the.

The PDP has a merit of realizing a large screen of 40 inches or more as well as having ease of fabrication due to a simple structure, excellent brightness and high luminous efficiency, a memory function, and a wide viewing angle of 160 degrees or more.

However, PDP has a high emission rate of electromagnetic waves and near-infrared rays due to its driving characteristics, high surface reflection of phosphors, and color purity that does not reach the cathode ray tube (CRT) due to orange light emitted from He and Xe injected into each discharge cell. There is this.

Therefore, in order to shield electromagnetic waves and near infrared rays, while reducing reflected light and improving color purity, PDP filters having functions such as electromagnetic shielding, near infrared shielding, light surface reflection prevention and color purity improvement are employed. Since the PDP filter is mounted on the front of the panel, transparency must be satisfied.

On the other hand, in the PDP, in an external bright condition, external light may pass through the PDP filter and flow into the panel. In this case, an overlapping phenomenon occurs between light generated in the discharge cells in the panel and external light introduced through the PDP filter from the outside. As a result, the contrast ratio is lowered, resulting in poor display capability of the PDP.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a method for manufacturing a contrast ratio improving film which can improve the brightness and contrast ratio of a plasma display panel.

It is also an object of the present invention to provide a method for manufacturing a contrast ratio enhancement film, a plasma display panel including a contrast ratio enhancement film, and a method of manufacturing the same, which can achieve a simplified process, a reduction in manufacturing cost, and an improvement in productivity.

In accordance with another aspect of the present invention, there is provided a method of manufacturing a contrast ratio improving film, applying a photosensitive black resin to a base film, placing a photo mask on the photosensitive black resin, and performing exposure and development to form a black stripe. And coating and curing the transparent resin on the base film on which the black stripe is formed. The method may further include forming an adhesive layer on the transparent resin and attaching a protective film to the bottom surface of the base film and the top surface of the adhesive layer.

A method of manufacturing a plasma display panel according to the present invention includes removing the protective film from the contrast ratio enhancing film and bonding the surface on which the adhesive layer is formed to an upper substrate of the plasma display panel.

The method of manufacturing the contrast ratio improvement film and the plasma display panel including the same may form a contrast ratio enhancement film using photosensitive black resin, thereby simplifying a process, reducing manufacturing cost, and improving productivity.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred method of manufacturing a contrast ratio enhancement film according to the present invention, a plasma display panel including a contrast ratio enhancement film and a method of manufacturing the same.

1A is an exploded perspective view illustrating a plasma display panel according to an exemplary embodiment of the present invention, and FIG. 1B is a cross-sectional view taken along the line A-A of FIG. 1A.

1A and 1B, a plasma display panel (hereinafter referred to as "PDP") includes a panel assembly and a PDP filter 400.

First, the panel assembly is divided into an upper plate structure 200 and a lower plate structure 300.

On the upper plate 200 of the PDP, a transparent electrode 220, a bus electrode 230, an upper dielectric layer 240, and a protective layer 250 are formed under the glass substrate 210 (hereinafter, referred to as an upper substrate). It is.

The transparent electrode 220 is formed of transparent indium tin oxide (hereinafter referred to as “ITO”) to transmit light supplied from the discharge cell.

The bus electrode 230 is formed under the transparent electrode 220 and reduces the line resistance of the transparent electrode 220.

The bus electrode 230 is formed of silver (Ag) paste having high conductivity. As described above, since the bus electrode 230 is formed of a material having high conductivity, the bus electrode 230 reduces the driving voltage of the transparent electrode 220 having low conductivity.

The upper dielectric layer 240 is a layer in direct contact with the bus electrode 230 made of a metal material, and glass is used to avoid chemical reaction with the bus electrode 230.

The upper dielectric layer 240 maintains a glow discharge by limiting the discharge current, and the charge generated during the plasma discharge is accumulated.

The passivation layer 250 prevents damage to the upper dielectric layer 240 due to sputtering during plasma discharge and increases discharge efficiency of secondary electrons. The passivation layer 250 is formed of magnesium oxide (MgO).

In the lower plate 300 of the PDP, an address electrode 320, a lower dielectric layer 330, a partition wall 340, and a fluorescent layer 350 are formed on the glass substrate 310 (hereinafter referred to as a lower substrate). .

The address electrode 320 is located at the center of each discharge cell. The address electrode 320 has a line width of about 70 to 80 μm.

The lower dielectric layer 330 is positioned in front of the address electrode 320 and the lower substrate 310 and protects the address electrode 320.

The partition wall 340 is formed above the lower dielectric layer 330 and is spaced apart from the address electrode 320 by a predetermined distance, and has a longer shape in the vertical direction.

The partition wall 340 is necessary to maintain the discharge distance and to prevent electrical and optical interference between adjacent discharge cells.

The fluorescent layer 350 is positioned on both sides of the barrier rib 340 and the upper portion of the lower dielectric layer 330.

The fluorescent layer 350 is excited by ultraviolet rays generated during plasma discharge to generate visible light of any one of red (R), green (G), and blue (B).

Next, the PDP filter 400 is disposed on the upper substrate 210 of the panel assembly. As illustrated in FIG. 1A, the PDP filter 400 may be disposed to be spaced apart from or in contact with the upper substrate 210. The PDP filter 400 may prevent foreign substances from flowing between the panel assembly and the PDP filter 400 and may prevent PDP from being introduced. In order to reinforce the strength of the filter 400 itself, it may be combined with the adhesive 500 as shown in FIG. 1B.

The PDP filter 400 includes a filter base 410 and a contrast ratio enhancement layer 420. Preferably, the color correction layer 430 is further included.

The filter base 410 includes an antireflection layer 416 and an electromagnetic shielding layer 414 formed on the transparent substrate 412.

The electromagnetic wave shielding layer 414 may be a layer that reflects or absorbs electromagnetic waves, and may use a conductive mesh film or a multilayer transparent conductive film in which a metal thin film and a high refractive index transparent film are laminated. In one embodiment of the present invention, the electromagnetic shielding layer 414 is formed on one surface of the transparent substrate 412, that is, the surface adjacent to the panel assembly, but is not limited thereto.

The conductive mesh film may be a metal coating on a mesh of grounded metal mesh, synthetic resin or metal fiber.

The multilayer transparent conductive film may be a high refractive transparent thin film represented by ITO.

In order for the electromagnetic shielding layer 414 to effectively absorb the electromagnetic waves generated from the panel assembly, the conductive metal thin film should be formed to have a predetermined thickness or more, but the thicker the conductive metal thin film is, the lower the visible light transmittance. However, the multilayer transparent conductive film laminated alternately with the conductive metal thin film using the high refractive index transparent thin film can increase the reflection interface and increase the reflection of electromagnetic waves.

The anti-reflection layer 416 may be formed on one surface of the transparent substrate 412, that is, on the opposite surface of the panel assembly. The antireflection layer 416 improves visibility by reducing reflection of external light.

The antireflection layer 416 may be formed using a fluorine-based transparent polymer resin having a refractive index of 1.5 or less with respect to visible light, a thin film of magnesium fluoride, a silicon resin, or silicon oxide.

Meanwhile, the filter base 410 may further include a near infrared shielding layer (not shown) that shields the near infrared rays generated from the panel assembly.

The PDP filter 400 may further include a color correction layer 430 having a transmittance of 60% or more in the wavelength range of 580 to 600 nm. The color correction layer 430 changes or corrects the color balance by reducing or adjusting the amounts of red, green, and blue.

Generally, red visible light generated from plasma in the panel assembly tends to appear orange. Therefore, the orange color is represented as red using the color correction layer 430.

On the other hand, the orange is strongly emitted from the panel assembly, because the light emitted from the plasma itself and the external light is reflected back from the panel assembly tends to have an orange color. The PDP filter 400 of the present invention forms the contrast ratio enhancement layer 420 to block external light from entering the panel assembly, thereby essentially reducing the amount of orange light.

Hereinafter, the contrast ratio enhancement layer 420 will be described in detail.

2A and 2B are a perspective view and a cross-sectional view showing a contrast ratio improvement film according to an embodiment of the present invention, Figures 3A and 3B are a perspective view and a cross-sectional view showing a contrast ratio improvement film according to another embodiment of the present invention, 4 is a cross-sectional view showing a portion of a contrast ratio improving film according to another embodiment of the present invention.

1A, 1B, 2A, and 2B, the contrast ratio enhancing film 420 according to an embodiment of the present invention has a substantially trapezoidal shape formed in the transparent resin 424 and the transparent resin 424 that transmit light. A plurality of black stripes 426 having a.

In one embodiment of the present invention, the contrast ratio enhancement film 420 supports the transparent resin 424 and the black stripe 426, and further includes a base film 422, for stability of manufacture. It is preferable that the base film 422 uses a transparent resin film. For example, polyethylene terephthalate (PET), polycarbonate (PC), polyvinyl chloride (PVC) and the like can be used.

The direction in which the black stripe 426 is disposed on the transparent resin 424 is preferably formed in the transverse direction in consideration of securing the viewing angle in the left and right directions from the viewpoint of the observer.

The transparent resin 424 is formed of an ultraviolet curable resin or the like.

The black stripe 426 may be made of a black inorganic material, a black organic material, or a metal that can absorb light.

Since the metal has a large electrical conductivity, when the black stripe 426 is formed by adding the metal powder, the metal resistance may be adjusted to adjust the electrical resistance. In addition, when the surface is black, since external light shielding and electromagnetic wave shielding functions can be efficiently implemented, a photosensitive black resin including carbon black may be used as a material of the black stripe 426.

The photosensitive black resin is formed by including a material in which carbon black is mixed with a thermosetting resin, a photocurable resin, or an ultraviolet curable resin.

The said ultraviolet curable resin is a substance containing the oligomer or monomer which has polyester, urethane, epoxy, a silicone, and an acryl functional group.

More specifically, referring to FIG. 2B, the contrast ratio enhancing film 420 of the present invention includes a transparent resin 424 and a black stripe 426.

The black stripe 426 may include a first surface 426a penetrating one surface of the transparent resin 424, a second surface 426b positioned in the transparent resin 424 at a position opposite to the first surface 426a, And a first inclined surface 426c and a second inclined surface 426d inclined at predetermined angles a and b with respect to the first surface 426a.

The first surface 426a absorbs the incident light 510 emitted from the panel assembly, and the second surface 426b serves to absorb the external light 520.

The first inclined surface 426c and the second inclined surface 426d serve to absorb external light 520 or totally reflect incident light 510 from the panel assembly to the outside.

The first inclined surface 426c and the second inclined surface 426d are inclined at predetermined angles a and b with respect to the generally flat first surface 426a, and the predetermined angle is an angle of less than 90 degrees. Preferably the angles a and b are in the range of 80 ° or more and less than 90 °.

The inclination angle a of the first inclined surface 426c of the black stripe 426 and the inclination angle b of the second inclined surface 426d may be the same or different.

Hereinafter, a process of the incident light incident from the panel assembly to the contrast ratio enhancement film 420 and the external light incident from the outside to the contrast ratio enhancement film 420 will be described using a solid line and a dotted line.

The first incident light 512 is substantially perpendicular to one surface of the transparent resin 424, proceeds inside the transparent resin 424, and is emitted to the other surface.

The second incident light 514 is incident on a generally flat surface of the transparent resin 424 at a predetermined angle α and is incident on the second inclined surface 426d of the black stripe 426 to cause total reflection or to generate a black stripe ( 426).

Here, as a condition for causing total reflection, it is preferable that the refractive index of the transparent resin 424 is larger than that of the black stripe 426. Incident light incident on the second inclined plane 426d at an angle smaller than the critical angle β determined by the refractive index of the transparent resin 424 and the refractive index of the black stripe 426 is absorbed by the black stripe 426. On the other hand, incident light incident on the second inclined surface 426d at an angle larger than the critical angle β causes total reflection and is emitted through the other surface of the transparent resin 424.

The third incident light 516 is incident on the first surface 426a of the black stripe 426 and is absorbed by the black stripe 426.

The first external light 521 is incident on the first inclined surface 426c at a predetermined angle w through the transparent resin 424 between the second surface 426b and through which light can pass, mostly black stripes. 426 is absorbed.

The second external light 522 is incident on the second surface 426b of the black stripe 426 and is absorbed by the black stripe 426.

The progress of the light is for convenience of explanation, and light may be incident on the contrast ratio enhancement film 420 at various angles, and the light proceeds by the same process as described above.

Meanwhile, referring to FIGS. 3A and 3B, the contrast ratio enhancing film 520 according to another embodiment of the present invention includes a plurality of transparent trapezoidal shapes formed in the transparent resin 524 and the transparent resin 524 that transmit light. Black stripe 526.

The black stripe 526 is different from the above-described black stripe 426 in that the black stripe 526 is formed by penetrating not only one surface of the transparent resin 524 but also a shaving facing the black stripe 524.

Other configurations are the same as the contrast ratio enhancement film 420 shown in FIGS. 2A and 2B, and thus descriptions thereof will be omitted.

In addition, referring to FIG. 4, in the contrast ratio improvement film 620 according to another embodiment of the present invention, the black stripe 626 may have a first pass with respect to the first through surface 626a and the second through surface 626b. The inclined surface 626c and the second inclined surface 626d are characterized in that they are formed to be vertical.

When the incident light 614 is incident on the black stripe 626, if the incident light 614 enters the second inclined surface 626d at an angle greater than the predetermined angle θ, total reflection occurs and is emitted to the other surface of the transparent resin 624.

In general, the PDP preferably has a high transmittance to visible light and a high contrast ratio. Contrast ratio can be expressed as Equation 1.

[Equation 1]

When the light emitted from the panel assembly is passed through the PDP filter 400 without filtration in order to increase the transmittance of the PDP, not only the luminance of white light but also the luminance of black light is increased. Therefore, when the brightness of the PDP is increased, the overall contrast ratio is relatively low.

In the present invention, in the contrast ratio enhancement film 420 as shown in FIG. 2B, the first side 426a of the black stripe 426 absorbs a portion of the incident light 510 to the visible light of the panel assembly. By adjusting the amount of permeation, it serves to increase the contrast ratio of the PDP.

Meanwhile, a part of the incident light 510 from the panel assembly is absorbed by the first surface 426a, and the part of the incident light 512 passes through the transparent resin 424 as it is. In addition, some incident light 514 is totally reflected from the first inclined surface 426c or the second inclined surface 426d of the black stripe 426 to face the outside to increase the transmittance of the PDP.

Hereinafter, the light emission operation of the PDP will be described in detail.

When a constant voltage (in a voltage margin range) is applied between the transparent electrode 220 and the bus electrode 230, when an additional voltage that generates plasma is applied to the address electrode 320, the bus electrode 230 is applied. Plasma is formed between the adjacent bus electrode 230. There is a certain amount of free electrons in the gas. When the electric field is applied, the free electrons receive a force (F = qE).

When these energized electrons get enough energy to dissociate the outermost electrons of the inert gases (first ionization energy), they ionize the gas, where the ions and electrons are moved to both electrodes under the force of the electromagnetic field. . In particular, when ions collide with the protective layer 250, secondary electrons are generated in the protective layer 250, which helps the formation of plasma.

Therefore, a high voltage is required to start the initial discharge, but once discharged, the electron density increases and a low voltage is required.

Gases injected into the PDP are mainly inert gases such as Ne, Xe, and He. In particular, ultraviolet rays having wavelengths of 147 nm and 173 nm, which Xe emits in a metastable state, are applied to the fluorescent layer 350 so that red, green, or blue visible rays are visible. Allow light rays to be generated.

The visible light generated at this time is determined according to the type of the fluorescent layer 350. Accordingly, each discharge cell becomes a pixel displaying red, green, and blue, respectively.

The color is controlled by a combination of RGB values of each discharge cell. In the case of the PDP, the plasma generation time is controlled.

The generated visible light is emitted to the outside through the upper substrate 210 and the PDP filter 400.

Hereinafter, the manufacturing process of the contrast ratio improvement film in the PDP filter 400 is explained in full detail.

5A to 5I are cross-sectional views illustrating a manufacturing process of a contrast ratio improving film according to an exemplary embodiment of the present invention.

As shown in FIG. 5A, a photosensitive black resin 726 ′ is coated on the base film 722 to a predetermined thickness. At this time, the photosensitive black resin 726 ′ should be applied to a thickness corresponding to the height of the black stripe 726 to be actually formed.

Subsequently, as illustrated in FIG. 5B, the mask 730 is positioned on the photosensitive black resin 726 ′ and then exposed to light for a predetermined time, and then developed.

At this time, when the photosensitive black resin 726 ′ is a positive type, only the photosensitive black resin 726 ′ at a position corresponding to the opening formed in the mask 730 is cured, and the photosensitive black resin 726 of the uncured portion is hardened. ') Is removed.

As described above, the photosensitive black resin 726 ′ may use a material in which carbon black is added to the ultraviolet curable resin.

Accordingly, as shown in FIG. 5C, a shape corresponding to the black stripe 726 is formed. Meanwhile, in the present embodiment, the black stripe having a trapezoidal shape is described as an example. However, as illustrated in FIG. 4, the black stripe having a rectangular shape may be formed in the same manner.

Subsequently, as shown in FIG. 5D, the transparent resin 724 is applied to the base film 722 on which the black stripes 726 are formed at a height corresponding to the height of the black stripes 726.

Meanwhile, as illustrated in FIG. 5E, the transparent resin 724 may be applied to cover the black stripe 726.

Subsequently, the transparent resin 724 is irradiated with a lamp or the like for a predetermined time to cure the transparent resin 724.

In this way, the contrast ratio enhancement film 720a or 720b can be manufactured in large quantities.

Meanwhile, as illustrated in FIG. 5F or 5G, an adhesive layer 740 may be further formed on the contrast ratio enhancement film 720a or 720b as illustrated in FIG. 5D or 5E. This is effective when the contrast ratio enhancement film 720a or 720b needs to be attached directly to the PDP.

In addition, when the contrast ratio enhancement film 720a or 720b is stored separately, in order to prevent damage of the contrast ratio enhancement film 720a or 720b, as shown in FIG. 5H or 5I, the contrast ratio enhancement film 720a or 720b may be formed. The upper and lower protective films 752 and 754 may be further coated.

When manufacturing the PDP filter 400 using the contrast ratio film 720a or 720b manufactured as described above, after removing the protective films 752 and 754, the adhesive layer 740 is the upper plate 200 of the PDP. Can be attached to

Preferred embodiments of the present invention described above are disclosed for purposes of illustration, and those skilled in the art having various ordinary knowledge of the present invention may make various modifications, changes, and additions within the spirit and scope of the present invention. Additions should be considered to be within the scope of the following claims.

The manufacturing method of the contrast ratio improvement film according to the present invention has an advantage of improving the brightness and contrast ratio of the plasma display panel.

In addition, the manufacturing method of the contrast ratio improving film and the plasma display panel using the same according to the present invention has an advantage of achieving a process simplification, manufacturing cost reduction, and productivity improvement.

Claims (9)

(a) applying a photosensitive black resin to the base film; (b) forming a black stripe by placing a photo mask on the photosensitive black resin and performing exposure and development; And (c) coating and curing the transparent resin on the base film on which the black stripe is formed. The method of claim 1, wherein the method for producing the contrast ratio film (d) forming an adhesive layer on the transparent resin; And (e) attaching a protective film to a lower surface of the base film and an upper surface of the adhesive layer.  The method of claim 1, The photosensitive black resin is a manufacturing method of the contrast ratio improvement film, characterized in that the carbon black (carbon black) is mixed with a thermosetting resin, a photocurable resin or an ultraviolet curable resin.  The method of claim 3, wherein The said ultraviolet curable resin contains the oligomer or monomer which has polyester, urethane, epoxy, a silicone, and an acryl functional group, The manufacturing method of the contrast ratio improvement film characterized by the above-mentioned. The method of claim 1, In the step (c), the coating method of the contrast ratio improvement film, characterized in that the coating so that the height of the transparent resin is greater than the height of the black stripe. The method of claim 1, In the step (c), the method of manufacturing a contrast ratio improvement film, characterized in that the coating so that the height of the transparent resin is the same as the height of the black stripe.  The method of claim 1, The black stripe is a manufacturing method of the contrast ratio film, characterized in that forming a wedge shape or a rectangular shape. A plasma display panel comprising a filter formed of a contrast ratio enhancing film manufactured by the method of claim 1. Removing the protective film from the contrast ratio film produced by the method of claim 2; And And bonding the surface on which the adhesive layer is formed to an upper substrate of the plasma display panel.

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