KR100730150B1 - Optical filter and plasma display apparatus employing the same - Google Patents

Abstract

The present invention relates to an optical filter comprising a transparent substrate, an antireflection layer, an electromagnetic wave shielding layer, and an optional light absorbing layer, wherein the antireflection layer has a lattice structure, and a plasma display panel having the optical filter. The optical filter has an excellent antireflection effect against external light and has a low haze, so that the optical filter may be provided in various flat panel display devices, particularly plasma display panels, to provide high quality images.

Description

Optical filter and plasma display apparatus employing the same

1 is a view schematically showing a structure of a plasma display device having a conventional optical filter,

2a and 2b schematically show an embodiment of the optical filter according to the present invention;

3A to 3D schematically illustrate a process of forming an anti-reflection layer in one embodiment of the optical filter according to the present invention;

4 is a partial perspective view showing an embodiment of a plasma display device having an optical filter according to the present invention;

5 is an optical micrograph of an antireflective layer in one embodiment of an optical filter according to the present invention;

6 is a front photograph of a plasma display device having a conventional optical filter,

7 is a front photograph of a plasma display device having an embodiment of an optical filter according to the present invention.

<Brief description of the major symbols in the drawings>

13, 23, 33, 403: antireflection layer 12, 22, 32, 402: transparent substrate

14, 24, 404: electromagnetic shielding layer 15, 25, 405: selective light absorption layer

11, 400: optical filter

The present invention relates to an optical filter and a plasma display apparatus using the same, and more particularly, to an optical filter including an antireflective layer formed of a plurality of patterns forming a lattice structure and having reduced external light reflection and haze, and employing the same. The present invention relates to a plasma display device.

The plasma display device is a thin, light-emitting display device that is easy to be enlarged as compared with other image display devices, and is considered to have the most suitable characteristics for high-quality digital television. The plasma display panel is deteriorated in color purity characteristics and contrast characteristics due to unnecessary light emission of near-infrared radiation caused by plasma generated by plasma light emission and circuits, and plasma of an inert gas used for screen emission. Therefore, in addition to preventing harmful effects of human body and malfunction of precision instruments caused by electromagnetic waves and near-infrared rays generated from the plasma display panel, filters are installed in front of the plasma display panel to reduce surface reflection and improve color purity and contrast. .

Optical filters used in the plasma display apparatus of the prior art generally consist of an antireflection layer, a transparent substrate, an electromagnetic shielding layer and an optional light absorbing layer.

1 is a view schematically showing the structure of a plasma display device employing a general optical filter. Referring to this, the optical filter 11 is installed in front of the plasma display panel and the driving circuit 10. At this time, the anti-reflection layer 13 is formed on the transparent substrate 12 such as a glass or plastic substrate, and the optical filter 11 has an electromagnetic wave shielding layer 14 and a near infrared ray under the transparent substrate 12. Has a structure in which a selective light absorbing layer 15 for blocking the light and selectively absorbing light having a specific wavelength is sequentially stacked. The stacking order of the transparent substrate 12, the antireflection layer 13, the electromagnetic wave shielding layer 14, and the selective light absorbing layer 15 may be variously modified according to the structure of the desired plasma display device. The plasma display panel and drive circuit 10 and the optical filter 11 are housed in a case 16. For more detailed structure of the optical filter, see, for example, Korean Patent No. 0424254 and the like.

In this case, the anti-reflection layer 13 is provided to prevent the visual field of the person viewing the plasma display device from being disturbed due to external light reflection. However, the antireflection layer of the conventional structure cannot obtain a satisfactory level of external light reflection reduction effect and needs to be improved.

Accordingly, an object of the present invention is to solve the above problems, to reduce the reflection effect and haze caused by external light to realize a high quality image, an optical having an antireflection layer consisting of a plurality of patterns forming a lattice structure An object of the present invention is to provide a filter and a plasma display device having the same.

In order to achieve the above object of the present invention, a first aspect of the present invention includes a transparent substrate, an antireflection layer, an electromagnetic wave shielding layer, and an optional light absorbing layer, wherein the antireflection layer comprises an optical filter having a plurality of patterns forming a lattice structure. to provide.

In order to achieve the another object of the present invention, the second aspect of the present invention provides a plasma display device having the optical filter as described above.

Since the optical filter can reduce reflection effects and haze caused by external light, the plasma display device employing the optical filter can realize high quality images.

Hereinafter, the present invention will be described in more detail with reference to the drawings.

The optical filter according to the present invention includes a transparent substrate, an antireflection layer, an electromagnetic wave shielding layer, and an optional light absorbing layer, wherein the antireflection layer is formed of a plurality of patterns forming a lattice structure.

Referring to FIG. 2A, an optical filter having a structure in which the selective light absorbing layer 25, the electromagnetic wave shielding layer 24, the transparent substrate 22, and the antireflection layer 23 are sequentially stacked is illustrated. Meanwhile, FIG. 2B illustrates a structure of the optical filter illustrated in FIG. 2A as viewed from the side of the antireflection layer 23, and illustrates a plurality of patterns of the antireflection layer 23 in more detail.

In FIG. 2A, the anti-reflection layer 23 serves to prevent reflection of external light and to reduce diffuse reflection affecting contrast, and is provided on the transparent substrate 22. The anti-reflection layer 23 is composed of a plurality of patterns forming a lattice structure. Although not intended to be limited to a specific theory, since the anti-reflection layer 23 is composed of a plurality of patterns forming a lattice structure, compared to the conventional anti-reflection layer having a flat film type, the reflected light is prevented by the extinction interference of the light by the transparent lattice, while being transparent. Transmittance due to the transparency of the grating can be improved, so that the external light reflection effect and haze can be reduced.

The shape of the individual patterns constituting the antireflection layer 23 is not particularly limited as long as a plurality of patterns can form a lattice structure. For example, the pattern may have various shapes such as a square pillar and a cylinder.

As shown in FIGS. 2A and 2B, an inter-pattern pitch d ₁ of the plurality of patterns forming the anti-reflection layer 23 may be 1 μm to 100 μm, preferably 1 μm to 10 μm. When the inter-pattern pitch d ₁ of the plurality of patterns constituting the anti-reflection layer 23 is less than ₁ μm, the defective rate may increase in production productivity, and the inter-pattern among the plurality of patterns constituting the anti-reflection layer 23 may be increased. This is because the specification may be too large when the pitch d ₁ exceeds 100 µm.

As shown in FIGS. 2A and 2B, the pattern width d ₂ of the plurality of patterns forming the anti-reflection layer 23 may be 1 μm to 100 μm, preferably 1 μm to 10 μm. When the pattern width d ₂ of the plurality of patterns constituting the anti-reflection layer 23 is less than 1 μm, the defective rate may increase during mass production, and the pattern width d ₂ of the plurality of patterns constituting the anti-reflection layer 23 may be increased. It is because a specification may increase too much when is more than 100 micrometers.

As shown in FIGS. 2A and 2B, the pattern height d ₃ of the plurality of patterns forming the anti-reflection layer 23 may be 1 μm to 50 μm, preferably 1 μm to 10 μm. When the pattern height d ₃ of the plurality of patterns constituting the anti-reflection layer 23 is less than 1 μm, a defective rate may increase during mass production, and the pattern height d ₃ of the plurality of patterns constituting the anti-reflection layer 23 may be increased. It is because the improvement of characteristics, such as a haze, may be saturated when exceeds 50 micrometers.

The antireflection layer 23 may include a cured product of the photosensitive resin.

The cured product of the photosensitive resin is not particularly limited as long as it is a transparent material and can form a pattern constituting the antireflection layer as described above. The photosensitive resin includes acrylic resins, and the like, but is not limited thereto. In some cases, the photosensitive resin may be used together with a photoinitiator. Meanwhile, the photosensitive resin (used with a photoinitiator, if necessary) may be a commercially available material such as, for example, an acrylic resin of SU series manufactured by Microchem.

Meanwhile, the antireflection layer 23 may further include an antireflection material. The anti-reflection material is not particularly limited as long as it has a high light transmittance (for example, 95% or more light transmittance), a material capable of preventing external light reflection and reducing diffuse reflection affecting contrast. The antireflective material includes, but is not limited to, TiO ₂ , SiO ₂ , Y ₂ O ₃ , MgF ₂ , Na ₃ AlF _6, and the like. One or more antireflection materials may be used, and when two or more antireflection materials are used, the antireflection layer 23 may have a single layer or a multilayer structure, and various modifications are possible.

The light transmittance of the anti-reflection layer 23 may be 80% or more. This is because when the light transmittance is less than 80%, there is too little light extracted to the outside, which may impair the sense of vision.

On the other hand, the transparent base material 22, as well as glass, polyethylene terephthalate film (PET), TAC (Tri-acetyl-cellulose), It may be a substrate made of a transparent material such as polyvinyl alcohol (PVA), polyethylene (PE) and the like. The thickness of the transparent substrate 22 may typically be 10 to 1000 μm.

The electromagnetic wave shielding layer 24 is provided in one surface of the transparent base material 22 not provided with the antireflection layer 23. The electromagnetic shielding layer is for shielding electromagnetic waves generated from a display, but is not limited thereto, and a metal mesh made of Ag, Cu, Ni, Al, Au, Fe, In, Zn, Pt, Cr, Pd, or the like. The material may be produced in the form of a multilayer thin film. Typically, the thin film is formed to a thickness of 10nm to 500nm, in the case of a metal mesh may be formed to a thickness of 1㎛ to 100㎛. This is because if the thickness is out of the range, the problem of not meeting the class B of the electromagnetic shielding standards may occur .

The lower surface of the electromagnetic wave shielding layer 24 is provided with an optional light absorption layer 25. The selective light absorbing layer 25 is a layer for improving color reproducibility, and includes, but is not limited to, a selective light absorbing material such as a tetraazaporphyrin compound. The thickness of the selective absorbing layer is usually 1 μm to 100 μm. When the thickness of the selective light absorbing layer is less than 1 μm, it may be difficult to coat with a uniform thickness, and the light absorption rate itself is low, so that it may be difficult to realize an appropriate level of color reproduction range, and the thickness of the selective light absorbing layer is 100 μm. If it exceeds, there is a possibility that a bubble problem may occur in the post-treatment process, because the coating layer may be cracked.

Looking at one embodiment of the manufacturing method of the optical filter according to Figures 2a and 2b, first forming an anti-reflection layer consisting of a plurality of patterns forming a lattice structure as described above on one surface of the transparent substrate as described above and the transparent Forming an electron shielding layer and an optional light absorbing layer on the other side of the substrate may be made.

More specifically, the process of forming the antireflection layer according to the present invention on the transparent substrate is referred to FIGS. 3A to 3D. First, referring to FIG. 3A, the antireflective layer forming composition 33 ′ containing the photosensitive resin and the solvent as described above is coated on the transparent substrate 32, and then a predetermined amount of solvent is evaporated to dryness. In this case, the composition for forming an antireflection layer may further include an antireflection material as described above. The solvent may be, for example, PGMEA or the like as a material that provides a constant viscosity and flowability for smooth application of the antireflective layer forming composition.

Next, as shown in FIG. 3B, in consideration of the desired antireflection layer pattern, the antireflection layer forming composition 33 ′ is selectively exposed to the exposure light beam 37 to cure the photosensitive resin according to the antireflection layer pattern. Let's do it. Thus, as shown in Fig. 3c, a layer 33 " in which the hardened portion and the non-cured portion exist is formed according to the antireflective layer pattern. As the exposure light, UV or the like can be used. For example, a mask 39 or the like may be used for the exposure, but is not limited thereto.

After drying, the non-cured portion of the antireflective layer-forming composition is removed using a conventional developer such as TMAH 2.38%. Thus, as shown in FIG. 3D, the antireflection layer 33 made of a cured product of the photosensitive resin (optionally including an antireflective material) on the transparent substrate 32 and formed of a plurality of patterns forming a lattice structure. Can be formed.

Thereafter, the electromagnetic shielding layer and the selective light absorbing layer as described above are formed on the other side of the transparent substrate. The electromagnetic wave shielding layer and the selective light absorbing layer forming method are not particularly limited. For example, an adhesive layer which may be made of an acrylic resin, a polyester resin, an epoxy resin, a urethane resin, or the like may be used.

In the above, the optical filter of the present invention has been described by taking an optical filter having a structure as shown in FIGS. 2A and 2B and a manufacturing method thereof as an example. However, the stacking order of the anti-reflection layer, the transparent substrate, the electromagnetic shielding layer, and the selective light absorbing layer and the method of forming the optical filter according to the present invention may be variously modified according to the structure of the optical filter desired.

The optical filter according to the present invention can be provided in various flat panel devices, particularly plasma display devices. One embodiment of the plasma display device according to the present invention, for example, a front substrate; A rear substrate disposed in parallel with the front substrate; The optical filter disposed at a predetermined distance from the front substrate; A partition wall disposed between the front substrate and the rear substrate to partition the light emitting cells; Address electrodes extending over the light emitting cells arranged in one direction and embedded by a rear dielectric layer; A phosphor layer disposed in the light emitting cell; Sustain electrode pairs extending in a direction crossing the extending direction of the address electrode and buried by a front dielectric layer; And a discharge gas in the light emitting cell.

4 is a partial perspective view showing the structure of a plasma display device employing an optical filter (particularly, the optical filter of FIGS. 2A and 2B) according to the present invention.

Referring to FIG. 4, the optical filter 400 according to the present invention is disposed at a predetermined distance in front of the front panel 470 of the plasma display device including the front panel 470 and the rear panel 460.

The optical filter 400 of the present invention has a structure in which an optional light absorption layer 405, an electromagnetic wave shielding layer 404, a transparent substrate 402, and an antireflection layer 403 are sequentially stacked from the direction toward the front panel 470. However, the stacking order of these can be variously modified. As shown in FIG. 4, the anti-reflection layer 403 has a plurality of patterns, and the plurality of patterns have a lattice structure to reduce external light reflection and haze.

The front panel 470 includes a front substrate 451, a storage electrode pair having a Y electrode and an X electrode formed on a rear surface of the front substrate, a front dielectric layer 455a covering the storage electrode pairs, and a protective layer covering the front dielectric layer. 456 is provided. Each of the Y electrode and the X electrode includes transparent electrodes 453a and 453b formed of ITO and the like, and a bus electrode 454 made of metal having excellent conductivity.

The rear panel 460 is formed on the rear substrate 452, address electrodes 453c formed on the front surface of the rear substrate to intersect the pair of sustain electrodes, a rear dielectric layer 456b covering the address electrodes, and a rear dielectric layer. And a partition wall 457 for partitioning the light emitting cells, and a phosphor layer 458 disposed in the light emitting cell.

As the plasma display apparatus according to the present invention, the plasma display apparatus as illustrated in FIG. 4 is described as an example. However, the present invention is not limited thereto, and various modifications are possible.

Hereinafter, the present invention will be described in more detail with reference to the following examples, but the present invention is not limited to the following examples.

Example

Example  One

A PET film having a thickness of about 125 μm was prepared as a transparent substrate. Meanwhile, a composition for forming an antireflection layer comprising 10 g of acrylic resin (produced by SU-2005) as a photosensitive resin and 6 g of PGMEA as a solvent was applied on the PET film, and then dried at 65 ° C. and 95 ° C. for 0.1 hour, respectively. . Then, after exposure to UV of 360nm wavelength using an exposure mask, and then dried for 65 hours at 65 ℃ and 95 ℃ respectively, and then developed using a developer (manufactured by Microchem). As a result, an antireflection layer formed of a plurality of patterns forming a lattice structure was formed on the PET film. The pitch between the patterns was 10 mu m, the pattern width was 4 mu m, and the pattern height was 4 mu m.

On the other hand, a copper mesh (line width 10 μm, pitch 300 μm) using an acrylic resin (trade name is # 1170, manufactured by Korean Geomyung Co., Ltd.) as an adhesive on the other side of the transparent base material not provided with the antireflection layer. After the electromagnetic wave shielding layer was formed by adhering, the selective light absorbing layer including the tetraaza porphyrin compound was adhered to the lower part of the electromagnetic wave shielding layer using the same adhesive as described above to prepare an optical filter. This is called optical filter 1.

Example 2

An optical filter was manufactured in the same manner as in Example 1, except that the pitch between the patterns was 20 μm when the antireflection layer was formed. This is called optical filter 2.

Example 3

An optical filter was manufactured in the same manner as in Example 1, except that the pitch between the patterns of the antireflective layer was 30 μm when the antireflective layer was formed. This is called optical filter 3.

Example 4

An optical filter was manufactured in the same manner as in Example 1, except that the pitch between the patterns of the antireflective layer was 40 μm when the antireflective layer was formed. This is called optical filter 4.

Comparative example

An optical filter was manufactured in the same manner as in the method of Example 1, except that an antireflection layer in the form of a flat film was used instead of the antireflection layer consisting of a plurality of patterns forming a lattice structure as the antireflection layer. This is called optical filter A.

Evaluation example 1

The anti-reflection layer of the optical filter prepared in Example 1 was observed using an optical microscope, and is shown in FIG. 5. Referring to FIG. 5, it can be seen that an antireflection layer formed of a plurality of patterns forming a lattice structure is formed.

Evaluation example 2

Reflectance, haze and transmittance were evaluated for the optical filters 1 to 4 and A, and the results are shown in Table 1. Reflectance was measured using a domestic PSIT reflectometry device under vertical conditions, and haze and transmittance were measured using a domestic PSIT reflectometry device under normal light conditions.

Optical filter number Inter-pattern pitch of the antireflection layer (μm) Pattern width of the antireflective layer (μm) Pattern height of the antireflection layer (㎛) reflectivity(%) Haze (%) Transmittance (%) One 10 4 4 0.68 4.9 96.5 2 20 4 4 0.86 4.2 96.4 3 30 4 4 1.14 4.1 95.6 4 40 4 4 1.38 3.5 95.2

As can be seen from Table 1, it can be seen that the reflectance, haze and transmittance of the optical filters 1 to 4 according to the present invention are superior to those of the conventional optical filter A. In particular, optical filter 1 exhibited a reflectance of only 0.68%, and optical filter 4 exhibited a haze of only 3.5%. Also, in the transmittance, the optical filters 1 to 4 exhibited excellent values of 95% or more, and therefore, it is understood that they are suitable for various display devices, especially plasma display devices.

Evaluation Example 3

6 and 7 show the optical filter A and the optical filter 1 mounted on the plasma display panel to observe the external light reflection effect.

FIG. 6 is a front view of the plasma display device equipped with the optical filter A, and FIG. 7 is a front view of the plasma display device equipped with the optical filter 1, and reflects external light of the plasma display device with the optical filter 1 mounted thereon. It can be seen that is significantly reduced compared to the plasma display device equipped with the optical filter A.

Since the optical filter of the present invention has an antireflection layer composed of a plurality of patterns forming a lattice structure, the reflection and haze of external light is significantly reduced. By using the optical filter, a plasma display device capable of providing a high quality image can be obtained.

Claims (8)

An optical filter comprising a transparent substrate, an antireflection layer, an electromagnetic wave shielding layer, and an optional light absorbing layer, wherein the antireflection layer is formed of a plurality of patterns forming a lattice structure, and an empty space exists between the plurality of patterns. The optical filter according to claim 1, wherein the pattern is a square pillar or a cylinder. The optical filter according to claim 1, wherein the pitch between patterns of the anti-reflection layer is in the range of 1 µm to 100 µm. The optical filter according to claim 1, wherein the antireflection layer has a pattern width of 1 µm to 100 µm. The optical filter according to claim 1, wherein the antireflection layer has a pattern height of 1 µm to 50 µm. The optical filter according to claim 1, wherein the light transmittance of the antireflection layer is 80% or more. The optical filter of claim 1, wherein the anti-reflection layer further comprises a material selected from the group consisting of TiO ₂ , SiO ₂ , Y ₂ O ₃ , MgF _2, and Na ₃ AlF ₆ . Front substrate; A rear substrate disposed in parallel with the front substrate; An optical filter according to any one of claims 1 to 7 disposed at a predetermined distance from the front substrate; A partition wall disposed between the front substrate and the rear substrate to partition the light emitting cells; Address electrodes extending over the light emitting cells arranged in one direction and embedded by a rear dielectric layer; A phosphor layer disposed in the light emitting cell; Sustain electrode pairs extending in a direction crossing the extending direction of the address electrode and buried by a front dielectric layer; And And a discharge gas in the light emitting cell.

Images