KR20070111834A - A front filter of plasma display panel - Google Patents

Abstract

A front filter for a plasma display panel is provided to improve the reflectivity of external light and transmittance of visible rays emitted from an interior by forming a polarized portion on a transparent substrate. A front filter includes a polarized portion(110a) formed on a transparent substrate for polarizing an incident light. If an electric field is applied to the polarized portion, the polarized portion is transparent. If an electric field is not applied to the polarized portion, the polarized portion is opaque. The polarized portion has first and second electrodes(220) and a liquid crystal polymer. The first electrode is a transparent electrode, and the second electrode is a metal mesh.

Description

A front filter of plasma display panel

1 is a view showing the structure of an embodiment of a discharge cell of the plasma display panel according to the present invention,

FIG. 2 is a detailed view of portion A of FIG. 1,

3 is a schematic diagram showing a traveling path of incident light when no voltage is applied to the polarizing film,

4 is a schematic diagram showing a traveling path of incident light when a voltage is applied to the polarizing film.

<Explanation of symbols for the main parts of the drawings>

10 lower glass 20 address electrode

30: lower plate dielectric 40: partition wall

50a, 50b, 50c: phosphor 60: discharge gas

70: top glass 80a, 80b: transparent electrode

80a ', 80b': Bus electrode 90: Top dielectric

100: protective film 110: front filter

110a: polarizer 110b: NIR shielding film

110c: adhesive layer 200: polymer

210, 210 ': liquid crystal molecule 220: transparent electrode

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma display panel (PDP), which is one of new image display devices in the multimedia era, and more particularly, to a front filter of a plasma display panel.

With the advent of the multimedia era, display devices that can express more detailed, larger, and more natural colors are required. PDP is thin, light, self-luminous and enables real-time, realistic image, simple structure, and easy to produce large-screen flat panel display, and has been qualified for HDTV (High Definition Television) since early .

When discharge occurs in the discharge space, ultraviolet rays are generated and incident on the phosphor, and visible light is emitted from the phosphor by the ultraviolet rays to display an image. In general, the front surface of the PDP is provided with a front filter in order to achieve the purpose of shielding the electromagnetic waves emitted to the outside and to improve the optical characteristics. The front filter includes NIR (Near Infrared Rays), EMI (Electromagnetic Interference), and AR film (Anti-Reflection film).

However, the above-described plasma display panel has the following problems.

As a front filter of a conventional plasma display panel, an AR film or an AG (Anti-Glare) film is used to reduce reflectance of the panel. The AR film lowers the reflectance by using a film having a different refractive index, but does not completely remove the reflected light and has a problem of lowering the transmittance of light emitted from the inside of the panel. In addition, there is a problem that the body color of the PDP exhibits a gray tone even when the power is turned off due to some reflection of lighting or natural light.

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 plasma display panel which improves the reflectance of external light and improves the transmittance of visible light emitted therein.

In order to achieve the above object, the present invention is a front filter provided on the display surface of the plasma display panel, the polarizing light is formed on the transparent substrate and is incident from the outside, it is transparent when an electric field is applied and opaque without applying an electric field It provides a front filter of the plasma display panel comprising a polarizing unit characterized in that.

Preferably, the polarizer comprises a first electrode, a liquid crystal polymer, and a second electrode.

More preferably, the liquid crystal polymer portion is characterized in that the pigment is added to the near infrared blocking and / or color correction.

Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present invention that can specifically realize the above object will be described.

The same components as in the prior art are given the same names and the same reference numerals for convenience of description, and detailed description thereof will be omitted.

The basic configuration of the front filter of the plasma display panel according to the present invention is the same as in the related art, but differs in that the polarizer is provided. The polarizer may increase the reflectance of light incident from the outside and the transmittance of light emitted from the inside. The polarizer preferably shields electromagnetic waves emitted from the inside of the panel when the panel is driven, and further includes a color correction function.

1 is a view showing a discharge cell structure of a plasma display panel according to the present invention.

As shown in FIG. 1, a plasma display panel includes a lower plate having an address electrode 20, an upper plate having sustain electrode pairs 80a and 80b, and discharge cells Red, Green, Blue) and phosphors 50a, 50b, and 50c are provided in the discharge cell. Discharge is generated in the discharge space between the upper plate and the lower plate, and at this time, ultraviolet (VUV) generated from the discharge gas 60 is incident on the phosphors 50a, 50b, and 50c to generate red, green, and blue visible light. The screen is displayed by the visible light.

In addition, the front filter 110 is provided on the upper glass 70 to perform the above-described color correction, antireflection, and electromagnetic wave shielding. As shown in FIG. 2, the polarizer 110a is provided on the upper glass 70, and is bonded through the adhesive layer 110b. In the above-described embodiment, the polarizer is directly formed on the upper glass 70, but may be formed in the form of a film front filter or a glass front filter. That is, the glass-type front filter is formed by bonding each functional film on the glass and spaced apart from the upper glass at a predetermined interval. In the film type front filter, each functional film is formed on polyethylene terephtalate (PET) and bonded to the upper glass. In this case, when the front filter is manufactured in the form of glass, it is possible to prevent the top glass from being damaged from an external impact. However, when the front filter is manufactured in the form of a film, thickness and weight may be reduced and manufacturing costs may be reduced.

In addition, the NIR shielding film 110b may be further included in the front filter as illustrated in FIG. 2, but the NIR shielding film 110b is stacked on the polarizer 110a, but the stacking order may be changed. In addition, the NIR shielding film 110b may be included in the polarizer 110a. In this case, a pigment may be added to perform the above-mentioned near-infrared shielding function. In addition, the polarizer 110a may include a pigment for performing a color correction function. Hereinafter, the configuration of the polarizing film 110a will be described with reference to FIGS. 3 and 4.

3 is a schematic diagram showing a traveling path of incident light when no voltage is applied to the polarizing film, and FIG. 4 is a schematic diagram showing a traveling path of incident light when voltage is applied to the polarizing film. As shown in FIG. 3, the polarizer 110a includes a liquid crystal polymer between the first and second electrodes 220, and preferably, the liquid crystal polymer comprises a polymer 200 in which the liquid crystal molecules 210 are dissolved. Is made.

Among the normally white mode and normally black mode of the polarizer 110a, in the present invention, it is preferable to use the polarizer 110a of the normal black mode that is opaque when no electricity is applied. Do. The above-described characteristic is due to irregular arrangement of the liquid crystal molecules 210 in the polarizer 110a. That is, since the directivity of each molecule constituting the liquid crystal molecules 210 is not constant, light incident on the polarizer 110a is scattered. Therefore, the contrast of the PDP can be improved by increasing the reflectance of light incident from the outside of the panel.

As shown in FIG. 4, when electricity is applied to the polarizer 110a, the directivity of each molecule constituting the liquid crystal molecules 210 becomes constant, so that light incident from the outside is transmitted without being scattered. Therefore, most of the light emitted from the phosphor during the driving of the PDP passes through the front filter to display an image on the outside of the panel.

In addition, an electrode is formed on the side surface of the liquid crystal molecules 210 to perform a function of shielding electromagnetic waves. 3 and 4, the first and second electrodes 220 are provided at both sides of the liquid crystal molecules 210. The first and second electrodes 220 are preferably transparent and more preferably made of indium-tin-oxide (ITO). The first and second electrodes 220 perform a function of changing the orientation of the liquid crystal molecules 210 when a voltage is applied, and also shield a electromagnetic wave emitted from the inside when the panel is driven. In addition, the above-described transparent electrode may be formed on the entire surface of the display area of the panel, but may be formed by patterning. In this case, the transparent electrode may be patterned into a mesh type or a stripe type.

In addition, in order to prevent the image from being distorted due to the color temperature difference of the visible light emitted from the phosphor, an inorganic dye may be added to the polymer 200 to improve the color temperature.

Referring to the operation of the embodiment according to the present invention described above are as follows.

When no voltage is applied to the polarizer provided in the plasma display panel, the reflectance of external light is increased to improve contrast. When the voltage is applied, the transmittance of visible light emitted from the phosphor is increased to improve light efficiency and color temperature. In addition, the ITO or the like provided in the polarizer shields electromagnetic waves emitted from the inside of the panel, and the inorganic dye or the like provided in the polymer in the polarizer serves to sharpen the color.

The polarizer described above may be applied to not only a plasma display panel but also other displays, thereby improving contrast and lowering reflectance of external light. In addition, in the present invention, the red (R), green (G) and blue (B) light is all scattered or transmitted according to the voltage applied state of the liquid crystal molecules, but designed to transmit or scatter only the color of a specific wavelength range In this case, the luminance or light efficiency of a specific color may be increased.

The present invention is not limited to the above-described embodiments, and such modifications are included in the scope of the present invention even if modifications are possible by those skilled in the art to which the present invention pertains.

The effects of the front filter of the plasma display panel according to the present invention described above are as follows.

First, it is possible to increase the reflectance of the external light and improve the transmittance of the visible light emitted from the inside.

Second, the electromagnetic wave shielding film and the color correction film are provided in the polarizing film of the front filter, thereby simplifying the structure of the front filter.

Claims (9)

In the front filter provided on the display surface of the plasma display panel, And a polarizer formed on the transparent substrate to polarize the light incident from the outside, wherein the polarizer is transparent when an electric field is applied and opaque when no electric field is applied. The method of claim 1, wherein the polarizing portion, And a first electrode, a liquid crystal polymer part, and a second electrode. The method of claim 2, The first electrode is a transparent electrode, and the second electrode is made of a metal mesh (mesh) to block the electromagnetic waves, characterized in that the front filter of the plasma display panel. The method of claim 2, And the first electrode is formed of a metal mesh to block electromagnetic waves, and the second electrode is a transparent electrode. The method of claim 2, The first electrode and the second electrode is made of a metal mesh to block the electromagnetic wave, characterized in that the front filter of the plasma display panel. The method of claim 2, wherein the liquid crystal polymer portion, The front filter of the plasma display panel, characterized in that the pigment is added to the near infrared blocking and / or color correction. The method of claim 1, A front filter of a plasma display panel further comprising an anti-reflection film. The method of claim 1, wherein the transparent substrate, The front filter of the plasma display panel, characterized in that the film. The method of claim 1, wherein the transparent substrate, The front filter of the plasma display panel, characterized in that the glass.

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