KR100797409B1 - Contrast ratio film and plasma display panel including the same - Google Patents

Abstract

A film having an improved contrast ratio and a plasma display panel having the same are provided to increase the shielding effect of the external light regardless of defects of black stripes. A film having an improved contrast ratio(420) includes transparent resin(424) capable of transmitting the light and plural black stripes(426) formed in the transparent resin and shaped like a wedge, a trapezoid, or a square, wherein the refractive index of the black stripe is higher than the refractive index of the transparent resin. A plasma display panel comprises lower and upper substrates disposed with facing each other; address electrodes installed at the lower substrate and discharge maintaining electrodes installed at the upper substrate; a barrier disposed in a space between the lower and upper substrates to divide plural discharge cells; RGB(Red, Green, Blue) fluorescent layers formed in the discharge cells divided by the barrier; and a filter arranged on the upper part of the upper substrate and provided with the film having an improved contrast ratio.

Description

CONTRAST RATIO FILM AND PLASMA DISPLAY PANEL INCLUDING THE SAME}

1 is a cross-sectional view showing a portion of a conventional contrast ratio improving film.

2A is an exploded perspective view illustrating a plasma display panel according to an exemplary embodiment of the present invention.

FIG. 2B is a cross-sectional view of the plasma display panel of FIG. 2A taken along line A-A.

3A is a perspective view illustrating a contrast ratio improving film according to an embodiment of the present invention.

FIG. 3B is a cross-sectional view illustrating a portion of the contrast ratio improving film of FIG. 3A.

The present invention relates to a plasma display panel. More specifically, it relates to the contrast ratio improvement film used for 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. To prevent this, a contrast ratio enhancing film is used as the PDP filter.

1 is a cross-sectional view showing a portion of a conventional contrast ratio improving film.

Referring to FIG. 1, the contrast ratio enhancement film 100 includes a transparent resin 110 that transmits light and a plurality of black stripes 120 formed of a material capable of absorbing light in the transparent resin 110.

In addition, in order to totally reflect incident light incident on the contrast ratio enhancement film 100 in the discharge cells in the PDP panel, the refractive index of the transparent resin 110 is greater than that of the black stripe 120.

The external light 131 incident on the contrast ratio improvement film 100 configured as described above is mostly absorbed by the black stripe 120.

However, when bubbles (122) are formed in the black stripe 120 due to defects in manufacturing process or other causes of the contrast ratio enhancement film 100, the external light 132 is refracted by the bubbles and then exits again to the outside. It happens.

In this case, superposition of light generated in the discharge cells in the panel and external light occurs.

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 contrast ratio improving film which can improve the brightness and contrast ratio of a plasma display panel.

In addition, an object of the present invention is to provide a contrast ratio improving film and a plasma display panel which can increase the external light shielding effect irrespective of the defect of the black stripe.

Contrast ratio improvement film according to an embodiment of the present invention is a transparent resin for transmitting light; And a plurality of black stripes formed in the transparent resin, wherein the refractive index of the black stripe is higher than the refractive index of the transparent resin.

In addition, the plasma display panel of the present invention includes a lower substrate and an upper substrate disposed to face each other; Address electrodes provided on the lower substrate and discharge sustain electrodes provided on the upper substrate; A partition wall disposed in a space between the lower substrate and the upper substrate, for partitioning a plurality of discharge cells; Red, green, and blue phosphor layers formed in discharge cells partitioned by the barrier ribs; And a filter disposed on the upper substrate and including a contrast ratio enhancement film.

The filter may include a filter base including an antireflection layer and an electromagnetic shielding layer formed on a transparent substrate; And contrast ratio enhancement films.

The contrast ratio improving film and the plasma display panel including the same may increase the external light shielding effect regardless of the defect of the black stripe.

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

2A is an exploded perspective view illustrating a plasma display panel according to an exemplary embodiment of the present invention, and FIG. 2B is a cross-sectional view of the plasma display panel shown in FIG. 2A taken along line A-A.

2A and 2B, 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 shown in FIG. 2A, 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 the 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. 2B.

The PDP filter 400 includes a filter base 410 and a contrast ratio enhancement film 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 a contrast ratio enhancing film 420 to block external light from entering the panel assembly, thereby essentially reducing the amount of orange light.

Hereinafter, the contrast ratio improvement film 420 will be described in detail.

3A is a perspective view illustrating a contrast ratio improvement film according to an embodiment of the present invention, and FIG. 3B is a cross-sectional view illustrating a portion of the contrast ratio enhancement film of FIG. 3A.

2A, 2B, 3A, and 3B, 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.

On the other hand, the shape of the black stripe 426, in addition to the trapezoidal shape shown, there is no limitation that can be configured in a wedge shape or a square shape.

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 shielding functions can be efficiently implemented, a photosensitive black resin including carbon black may be used as the 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. 3B, 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 absorb external light 520.

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, the progress of the incident light 510 incident from the panel assembly to the contrast ratio enhancement film 420 and the external light 520 incident from the exterior to the contrast ratio enhancement film 420 will be described using a solid line and a dotted line. do.

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, is incident on the second inclined surface 426d of the black stripe 426, and is absorbed by the black stripe 426. .

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 third external light 523 is incident on the first inclined plane at a predetermined angle w through the transparent resin 424 through which the light can pass, between the second surface 426b. In this case, it is assumed that bubbles 428 are formed in the black stripes 426. Bubbles 428 may be formed in the black stripe 426 during formation or storage of the contrast ratio enhancement film 420.

Here, the refractive index of the transparent resin 424 is preferably smaller than the refractive index of the black stripe 426.

Accordingly, the third external light 523 incident on the first inclined surface 426c is refracted by the bubble 428 to enter the second inclined surface 426d, and the refractive index of the transparent resin 424 is black stripe 426. Is totally reflected at the second inclined surface 426d because it is smaller than the index of refraction. Subsequently, the process of total reflection in the black stripe 426 is repeated and absorbed by the black stripe 426.

As such, even when the bubble 428 is formed in the black stripe 426, the third external light 523 may be absorbed by the black stripe 426 without being emitted to the outside again.

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.

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. 3B, the first surface 426a of the black stripe 426 absorbs a part 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.

On the other hand, 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 is transmitted through the transparent resin 424 as it is to 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. Especially, ultraviolet rays having wavelengths of 147 nm and 173 nm, which Xe emits in a metastable state, are applied to the fluorescent layer 350 and visible in red, green, or blue color. 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.

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.

Contrast ratio improvement film according to the present invention has the advantage that can improve the brightness and contrast ratio of the plasma display panel.

In addition, the contrast ratio improving film and the plasma display panel including the same according to the present invention has an advantage of increasing the external light shielding effect regardless of the defect of the black stripe.

Claims (8)

Transparent resin which transmits light; And It includes a plurality of black stripes formed in the transparent resin, The refractive index of the black stripe is higher than the refractive index of the transparent resin, contrast ratio enhancement film. The method of claim 1, The black stripe is contrast ratio enhancement film, characterized in that forming a wedge shape, trapezoidal shape or a square shape. (a) a lower substrate and an upper substrate disposed to face each other; (b) address electrodes provided on the lower substrate and discharge sustain electrodes provided on the upper substrate; (c) a partition wall disposed in a space between the lower substrate and the upper substrate, for partitioning a plurality of discharge cells; (d) red, green, and blue phosphor layers formed in discharge cells partitioned by the barrier ribs; And (e) a filter disposed on the upper substrate and including a contrast enhancing film, The contrast ratio improvement film, Transparent resin which transmits light; And And a plurality of black stripes formed in the transparent resin, wherein the refractive index of the black stripes is higher than that of the transparent resin. The method of claim 3, wherein And the black stripe has a wedge shape, a trapezoid shape, or a square shape. A filter base including an anti-reflection layer and an electromagnetic shielding layer formed on the transparent substrate; And Including contrast enhancement films, The contrast ratio improvement film, Transparent resin which transmits light; And And a plurality of black stripes formed in the transparent resin, wherein the refractive index of the black stripe is higher than the refractive index of the transparent resin. The method of claim 5, The black stripe filter has a wedge shape, a trapezoidal shape or a quadrangle shape. The method of claim 5, The anti-reflection layer is formed on one surface of the transparent substrate and reduces reflection of external light, and the vehicle shielding layer is formed on the other surface of the transparent substrate and reflects or absorbs electromagnetic waves. Filter in the panel. The filter of claim 5, wherein the filter of the plasma display panel comprises: And a color compensating layer for changing or correcting color balance.

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