KR20040088695A - Front-filter - Google Patents

Abstract

PURPOSE: A front filter is provided to achieve improved contrast by transmitting light emitted from a PDP and absorbing an external light using an ultra contrast film and a circle polarizer. CONSTITUTION: A front filter(60) comprises two curvature layers(80a,80b) formed on the front filter and having a different refractive index each other. The curvature layers comprise a first curvature layer(80a) formed with a curvature shape toward a display panel, and a second curvature layer(80b) formed on the first curvature layer along the first curvature layer. A refractive index of the first curvature layer is lower than the second curvature layer and is higher than a refractive index of an adjacent layer to the first/a second curvature layer.

Description

Front filter {FRONT-FILTER}

The present invention relates to a front filter, and more particularly, to a front filter capable of improving contrast.

Plasma Display Panels (hereinafter referred to as "PDPs") are characterized by emitting phosphors by 147 nm ultraviolet rays generated during discharge of an inert mixed gas such as He + Xe, Ne + Xe or He + Ne + Xe. An image containing graphics is displayed. Such a PDP is not only thin and easy to enlarge, but also greatly improved in quality due to recent technology development. In particular, the three-electrode AC surface discharge type PDP has advantages of low voltage driving and long life because wall charges are accumulated on the surface during discharge and protect the electrodes from sputtering caused by the discharge.

1 is a perspective view illustrating a discharge cell structure of a conventional plasma display panel.

Referring to FIG. 1, a discharge cell of a three-electrode AC surface discharge type PDP includes a scan electrode Y and a sustain electrode Z formed on the upper substrate 10, and an address electrode formed on the lower substrate 18. X). Each of the scan electrode Y and the sustain electrode Z has a line width smaller than the line widths of the transparent electrodes 12Y and 12Z and the transparent electrodes 12Y and 12Z and is formed at one edge of the transparent electrode 13Y, 13Z).

The transparent electrodes 12Y and 12Y are usually formed on the upper substrate 10 by indium tin oxide (ITO). The metal bus electrodes 13Y and 13Z are usually formed of metals such as chromium (Cr) and formed on the transparent electrodes 12Y and 12Z to reduce voltage drop caused by the transparent electrodes 12Y and 12Z having high resistance. The upper dielectric layer 14 and the passivation layer 16 are stacked on the upper substrate 10 having the scan electrode Y and the sustain electrode Z side by side. In the upper dielectric layer 14, wall charges generated during plasma discharge are accumulated. The protective layer 16 prevents damage to the upper dielectric layer 14 due to sputtering generated during plasma discharge and increases emission efficiency of secondary electrons. As the protective film 16, magnesium oxide (MgO) is usually used.

The lower dielectric layer 22 and the partition wall 24 are formed on the lower substrate 18 on which the address electrode X is formed, and the phosphor layer 26 is coated on the surfaces of the lower dielectric layer 22 and the partition wall 24. The address electrode X is formed in the direction crossing the scan electrode Y and the sustain electrode Z. The partition wall 24 is formed in a stripe or lattice shape to prevent the ultraviolet rays and the visible light generated by the discharge from leaking to the adjacent discharge cells. The phosphor layer 26 is excited by ultraviolet rays generated during plasma discharge to generate visible light of any one of red, green, and blue. Inert mixed gas is injected into the discharge space provided between the upper and lower substrates 10 and 18 and the partition wall 24.

In such a PDP, a glass type front filter 30 is installed on the upper substrate 10 to shield electromagnetic waves and prevent reflection of external light.

The glass type front filter 30 has functions such as electromagnetic shielding, external light reflection prevention, near infrared shielding, and color correction generated from the PDP 42 to the front side. To this end, the glass type front filter 30 includes a first antireflection film 32 attached to the front surface of the glass substrate 34, an electromagnetic wave shielding film 36 and a near infrared shielding film sequentially attached to the rear surface of the glass substrate 34. 38 and a second antireflection film 40 are provided.

The glass substrate 34 supports the glass type front filter 30 by using tempered glass, and protects the front filter 30 and the PDP 42 from being damaged by an external impact. The first and second antireflection films 32 and 40 may improve contrast by preventing light incident from the outside from being reflected back to the outside. The electromagnetic shielding film 36 absorbs electromagnetic waves generated from the PDP 42 to shield the electromagnetic waves from being emitted to the outside. The near-infrared shielding film 38 absorbs near-infrared rays of about 800-1000 nm wavelength band generated by the PDP 42 to shield them from being radiated to the outside. It can be input normally to the infrared receiver provided in the PDP set. In addition, the near-infrared shielding film 38 includes a color control dye (Color Dye) to increase the color purity by adjusting the color tone. These multiple thin films 32, 36, 38, 40 are attached to the glass substrate 34 via adhesive or adhesive.

As such, the conventional PDP set uses a glass type front filter 30 for shielding electromagnetic waves and correcting optical characteristics. However, the glass type front filter 30 includes a relatively thick glass substrate 34, i.e., tempered glass, which is not only a major cause of increasing the thickness and weight of the PDP set, but also has a disadvantage of high manufacturing cost.

Accordingly, a film type front filter in which the glass substrate is removed as shown in FIG. 3 has been proposed. The film type front filter 44 illustrated in FIG. 3 includes a near-infrared shielding film 38, an electromagnetic wave shielding film 36, and an anti-reflection film 32 that are sequentially attached to the upper substrate 10 of the PDP 42.

The antireflection film 32 prevents light incident from the outside from being reflected back to the outside. The electromagnetic shielding film 36 absorbs and discharges electromagnetic waves generated from the PDP 42 to shield the electromagnetic waves from being emitted to the outside. The near infrared ray shielding film 38 absorbs the near infrared rays generated by the PDP 42 and shields them from being emitted to the outside. In addition, the near-infrared shielding film 38 includes a color control dye to increase color purity by adjusting the color tone. The plurality of thin films 32, 36, 38 are attached to the upper substrate 10 of the PDP 42 through an adhesive or an adhesive.

When external light is incident on the PDP in which the conventional glass type front filter 30 or the filter type front filter 44 is installed, the external light is reflected by the high reflectance of the PDP 42 as shown in FIG. Degrades. In particular, due to external light there is a problem that the black brightness in the bright room is increased and the contrast is lowered.

Accordingly, it is an object of the present invention to provide a front filter capable of improving contrast.

1 is a perspective view showing a discharge cell structure of a conventional three-electrode AC surface discharge type plasma display panel.

2 is a cross-sectional view illustrating a plasma display panel having a glass front filter.

3 is a cross-sectional view showing a plasma display panel having a film type front filter.

4 is a diagram illustrating an external light reflection phenomenon of the plasma display panel illustrated in FIG. 1.

5 is a cross-sectional view illustrating a front filter according to a first embodiment of the present invention.

FIG. 6 is a view illustrating the ultra contrast film shown in FIG. 5.

7 is a cross-sectional view illustrating a front filter according to a second embodiment of the present invention.

8A and 8B are detailed views illustrating an operation process of the circular polarizer shown in FIG. 7.

<Description of Symbols for Main Parts of Drawings>

10: upper substrate 12Y, 12Z: transparent electrode

13Y, 13Z: bus electrode 14, 22: dielectric layer

16: protective film 18: lower substrate

24: partition 26: phosphor layer

In order to achieve the above object, the front filter according to the present invention is formed in the front filter and is characterized by having at least two curvature layers having different refractive indices.

The at least two curvature layers may include a first curved layer formed in a curvature shape toward the display panel, and a second curved layer formed on the first curved layer along the first curved layer. do.

The refractive index of the first curved layer is lower than the refractive index of the second curved layer.

The refractive index of the first curved layer is higher than that of the layers adjacent to the first and second curved layers.

The thickness of the second curved layer is characterized in that it is relatively thinner than the thickness of the first curved layer.

The front filter may further include a first anti-reflection film that prevents reflection of the external light, a near-infrared shielding film for shielding near infrared rays, and an electromagnetic shielding film for shielding electromagnetic waves.

The front filter may further include a glass substrate formed to contact the electromagnetic wave shielding film, and a second anti-reflection film formed on the front surface of the glass substrate.

The at least two curvature layers are formed on any one of a glass substrate, first and second antireflection films, a near infrared shielding film, and an electromagnetic shielding film.

In order to achieve the above object, the front filter according to the present invention is characterized in that it comprises a circular polarizer formed in the front filter and for blocking the emission of external light reflected by the display panel.

The phases of the first external light polarized in the first direction through the circular polarizer and the second external light polarized in the second direction by the first external light reflected by the display panel are opposite to each other.

The circular polarizer is characterized in that the cholesteric liquid crystal.

The front filter may further include a first anti-reflection film that prevents reflection of the external light, a near-infrared shielding film for shielding near infrared rays, and an electromagnetic shielding film for shielding electromagnetic waves.

The front filter may further include a glass substrate formed to contact the electromagnetic wave shielding film, and a second anti-reflection film formed on the front surface of the glass substrate.

The circular polarizer is formed on any one of a glass substrate, first and second antireflection films, a near infrared shielding film, and an electromagnetic shielding film.

Other objects and features of the present invention in addition to the above objects will become apparent from the description of the embodiments with reference to the accompanying drawings.

Hereinafter, exemplary embodiments of the present invention will be described with reference to FIGS. 5 to 8B.

5 is a cross-sectional view illustrating a front filter according to a first embodiment of the present invention.

Referring to FIG. 5, the front filter 60 according to the first embodiment of the present invention includes an ultra contrast film 80 for absorbing external light and a glass substrate. A first anti-reflection film 62 attached to the front surface of the 64, an electromagnetic wave shielding film 66 sequentially attached to the rear surface of the glass substrate 64, a near-infrared shielding film 68, and a second anti-reflection film 70. do. The glass type front filter 60 has functions such as electromagnetic shielding, external light reflection prevention, near infrared shielding, and color correction generated from the PDP 104 to the front side.

The glass substrate 64 supports the glass type front filter 60 by using tempered glass, and protects the front filter 60 and the PDP (not shown) from being damaged by an external impact. The first and second antireflection films 62 and 70 may prevent the light incident from the outside from being reflected back to the outside, thereby improving contrast. The electromagnetic shielding film 66 absorbs electromagnetic waves generated from the PDP and shields the electromagnetic waves from being emitted to the outside. Near-infrared shielding film 68 absorbs near-infrared radiation in the 800-1000nm wavelength band generated by the PDP and shields it from being radiated to the outside. It can be normally input to the infrared receiver provided in the. In addition, the near-infrared shielding film 68 includes a color correction film for enhancing color purity by adjusting the color tone by including a color control dye (Color Dye).

The UCF 80 is formed on the rear surface of at least one of the glass substrate 64, the electromagnetic shielding film 66, the near-infrared shielding film 68, and the first and second anti-reflective films 62,70. The UCF 80 has a first curved layer 80a formed in a curvature shape toward the PDP, and a second curved layer formed bent along the first curved layer 80a on the first curved layer 80a ( 80b).

The first and second curved layers 80a and 80b are formed of a material that satisfies a relationship in which the refractive index n1 of the first curved layer 80a is lower than the refractive index n2 of the second curved layer 80b. The thickness of the second bend layer 80b is relatively thin.

The refractive indices n0 and n3 of the first and second adjacent layers 90 and 92 adjacent to each of the first curved layer 80a and the second curved layer 80b are lower than the refractive index of the first curved layer 80a. Is formed. For example, if the first and second adjacent layers 90 and 92 are air layers, their refractive index is 1.

Meanwhile, external light incident from the first curved layer 80a to the second curved layer 80b is totally reflected at the interface between the second curved layer 80b and the second adjacent layer 90 as shown in FIG. 6. do. This is because when the incident light is greater than the critical angle θ when the external light is incident on the second adjacent layer 92 having a relatively small refractive index, the second curved layer 80b having a large refractive index and Light is totally reflected at the interface with the second adjacent layer 92. At this time, the total reflection condition is shown in Equation (1). The refractive index n2 and the radius of the second curved layer 80b and the refractive index of the second adjacent layer 92 are adjusted to satisfy the condition as shown in Equation 1 below.

Under these conditions, the light totally reflected at the interface between the second curved layer 80b and the second adjacent layer 92 is totally reflected in the second curved layer 80b and exits to the front surface of the front filter 60. I can't. When some external light escapes, the intensity of the light reflected through the front filter front while passing through the plurality of reflective surfaces of the second curved layer 80b is relatively weak and does not significantly affect the contrast.

In addition, since the light emitted from the PDP is emitted from the second curved layer 80b having a relatively large refractive index to the outside through the first curved layer 80a having a relatively small refractive index, total reflection does not occur and thus is emitted to the front without loss of light. .

These multiple films 62, 80, 66, 68, 70 are attached to the glass substrate 64 via an adhesive or adhesive.

7 is a cross-sectional view illustrating a front filter according to a second embodiment of the present invention.

Referring to FIG. 7, the front filter according to the second exemplary embodiment of the present invention includes the same components except that the front filter shown in FIG. 5 includes a circular polarizer instead of the UCF. Detailed descriptions of the same components shown in FIGS. 7 and 5 will be omitted.

The circular polarizer 82 is formed on the rear surface of at least one of the glass substrate 64, the electromagnetic shielding film 66, the near-infrared shielding film 68, and the first and second anti-reflection films 62 and 70. While passing through the circular polarizer 82, external light is polarized to the left as shown in Figs. 8A and 8B and travels toward the PDP 72. The left circularly polarized external light is reflected by the PDP 72 and the phase shifts to the right circularly polarized light. External light whose phase is changed to right circularly polarized light cannot pass through the circularly polarized light 82. The circular polarizer 82 is formed of, for example, a cholesteric liquid crystal.

The front filter according to the first and second embodiments of the present invention is applicable to the filter type front filter as well as the glass type front filter. The glass type front filter and the filter type front filter are installed on the front surface of the plasma display panel 104. The plasma display panel 104 provided with the front filter includes an upper substrate 60 on which sustain electrode pairs are formed, and a lower substrate 66 on which address electrodes are formed. The plasma display panel 104 is formed by joining the upper substrate 60 and the lower substrate 66 with the partition 74 therebetween.

As described above, according to the front filter and the manufacturing method thereof according to the present invention, the front filter includes an ultra-contrast film or circular polarizer for preventing re-reflection of light incident from the outside. The ultra-contrast film or circular polarizer absorbs external light incident from the outside and transmits the light emitted from the PDP without loss, thereby improving the contrast ratio.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the technical spirit of the present invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification but should be defined by the claims.

Claims (14)

In the front filter attached to the front of the display panel, And at least two curvature layers formed in the front filter and having different refractive indices. The method of claim 1, The curvature layer of at least two layers A first curved layer formed in a curvature shape toward the display panel; And a second curved layer formed on the first curved layer along the first curved layer. The method of claim 2, The refractive index of the first curved layer is lower than the refractive index of the second curved layer, the front filter. The method of claim 2, And the refractive index of the first curved layer is higher than that of the layers adjacent to the first and second curved layers. The method of claim 2, The thickness of the second curved layer is a front filter, characterized in that relatively thinner than the thickness of the first curved layer. The method of claim 1, A first anti-reflection film for preventing reflection of the external light; A near infrared shielding film for shielding near infrared rays, A front filter further comprising an electromagnetic shielding film for shielding electromagnetic waves. The method of claim 6, A glass substrate formed in contact with the electromagnetic shielding film; And a second anti-reflection film formed on the entire surface of the glass substrate. The method of claim 7, wherein Wherein the at least two curvature layers are formed on any one of a glass substrate, first and second antireflection films, a near infrared shielding film, and an electromagnetic shielding film. In the front filter attached to the front of the display panel, And a circular polarizer formed in the front filter to block the emission of external light reflected by the display panel. The method of claim 9, A front surface of the first external light polarized in the first direction through the circular polarizer and the second external light polarized in the second direction by the first external light reflected by the display panel are opposite to each other. filter. The method of claim 9, The circular polarizer is a front filter, characterized in that the cholesteric liquid crystal. The method of claim 9, A first anti-reflection film for preventing reflection of the external light; A near infrared shielding film for shielding near infrared rays, A front filter further comprising an electromagnetic shielding film for shielding electromagnetic waves. The method of claim 12, A glass substrate formed in contact with the electromagnetic shielding film; And a second anti-reflection film formed on the entire surface of the glass substrate. The method of claim 13, The circular polarizer is formed on any one of a glass substrate, the first and second anti-reflection film, near-infrared shielding film and electromagnetic wave shielding film.