JP2000228151A - Plasma display panel - Google Patents

Abstract

(57) [Summary] In a facing three-electrode surface discharge type AC plasma display panel, bright room contrast is degraded by external light incident on the panel. In a state where the panel does not emit light, the reflectance of external light as viewed from the front side substrate surface is kept low, and the reflectance as viewed from the phosphor side is extremely increased, so that light reflected on the phosphor surface is Do not transmit through the front substrate. Further, a mask layer whose optical constant is changed by at least one of short-wavelength light and heat generated by discharge is formed on the front-side substrate so that the transmittance of the front-side substrate only in the light-emitting portion of the panel becomes extremely high.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma display panel, and more particularly, to an opposed three-electrode surface discharge type AC plasma display panel. It is about technology.

[0002]

2. Description of the Related Art In manufacturing a PDP, a pair of glass substrates on which an electrode, a dielectric layer, a protective film and the like are sequentially formed are arranged to face each other, and the periphery is sealed with sealing glass. Next, the interior space is cleaned by exhaust processing, a discharge gas is introduced at a predetermined pressure, and the fabrication of the panel is completed.

FIG. 3 shows a structure of a conventional three-electrode surface discharge type AC plasma display panel. Front side substrate 1
The upper parallel display electrodes X and Y are formed, and an AC voltage is applied between the pair of parallel electrodes to perform surface discharge. Each display electrode is I
A transparent electrode 2 such as TO and an X1 bus electrode 3 made of Ag,
It is composed of a Y1 bus electrode 4 and an X2 bus electrode 5, and a dielectric layer 6 and a protective film 7 are provided on these display electrodes. The gap between the bus electrode X1 and the bus electrode Y1 is called a discharge gap 13, and the gap between the Y1 bus electrode and the X2 bus electrode is called an adjacent gap 14,
No discharge occurs in the adjacent gap. That is,
Since light emission occurs only between the display electrodes forming the discharge gap, this region is defined as a display region, whereas the region between the display electrodes forming the adjacent gap (Y1 bus electrode and X2
(Between the bus electrodes) is a non-display area.

On the other hand, an address electrode 9 is formed on a glass substrate 8 on the opposite back side in a direction perpendicular to the display electrodes. A dielectric layer 10 is provided on these address electrodes 9, and a partition 11 is formed thereon so as to be located between the address electrodes. The R, G, and B phosphors 12 are separately formed on the side and bottom of the partition wall 11. A penning gas such as Ne-Xe is sealed in the discharge space between the two glass substrates.

[0005] A high light transmittance is required for the glass substrate on the front side. For this reason, as the material formed on the front glass substrate, a material having an extinction coefficient of zero among the optical constants other than the bus electrode is used, and the refractive indexes are made as uniform as possible. This makes it possible to emit light emitted from the phosphor without loss. However, on the other hand, the display performance is reduced due to the influence of external light incident on the panel. That is, in the display area, the ratio of the brightness of the portion where light is emitted from the phosphor to the brightness of the portion where light is not emitted from the phosphor becomes a contrast, which affects display performance. The brightness of a portion where no light is emitted from the phosphor is determined mainly by the amount of external light reflected on the phosphor surface, and the contrast decreases as the external light becomes brighter.

Therefore, as shown in FIG. 4, a method of printing a black thick film in a non-display area of the front substrate, that is, in an adjacent gap, to suppress external light from entering the inside of the panel and to suppress a decrease in contrast. Is taken. That is, in FIG. 4, light from the phosphor is emitted only from the display region having the discharge gap. On the other hand, external light is originally a display area,
The light passes through the non-display area, is reflected on the phosphor surface, and is emitted to the outside. However, the black stripe almost eliminates external light reflection in the non-display area, and it is expected that the contrast is improved by almost twice. Regarding this,
There is 58727.

[0007]

However, this method is
It cannot be used in a panel structure without a non-display area (without an adjacent gap), and there is a problem that the above-described reduction in contrast due to external light occurs. FIG. 5 shows the electrode arrangement of the front substrate. In the discharge gap, discharge is performed between the pair of X and Y electrodes. That is, X1 and Y1, X2 and Y2, X
It is designed to generate a discharge between n and Yn. But,
In order to improve the display resolution about twice without doubling the number of electrodes, it is necessary to generate a discharge between two Y electrodes adjacent to one Y electrode. That is, two gaps formed by the three electrodes Y1, X1, and X2 are used as discharge gaps. According to this method, a discharge gap is formed between all the electrodes, and the conventional measures for improving the contrast cannot be taken.

[0008]

In order to solve the above-mentioned problems, a plasma display panel according to the present invention has an optical constant between at least one of light and heat between the dielectric layer and the protective film. It is characterized in that a changing mask layer is formed. That is, the front-side substrate including the mask layer has a low transmittance when the panel is not emitting light, and the transmittance of the front-side substrate including the mask layer is increased by causing the panel to emit light.

Thus, the amount of reflected external light in the portion that does not emit light is reduced, and the light emitted from the photophosphor is efficiently emitted. This operation can be realized by using a material whose optical constant is changed by at least one of light and heat emitted from the mask layer when the mask layer is a discharge space. Examples of this material include oxides of Na, Si, Ba, Al, Ti, and Co.

According to a second aspect of the present invention, there is provided a plasma display panel comprising, between the mask layer and the dielectric layer according to the first aspect, an asymmetric layer having a refractive index larger than that of the dielectric and having an extinction coefficient equal to that of the dielectric. It is characterized by having been provided. That is, the optical constants of the dielectric and the protective film are set to substantially equal values.

Therefore, even if only the mask layer is inserted during this time, when the optical constant of the mask layer changes, the reflectance as viewed from the front substrate and the reflectance as viewed from the protective film become substantially the same value, and No effect. In order for the mask layer to function so as to block external light, it is first necessary to reduce the reflectance of external light as viewed from the front-side substrate surface.

Furthermore, it is necessary to design the reflectance so as to be extremely high when viewed from the phosphor side so that external light reflected on the phosphor surface does not pass through the front substrate. As described above, in order to lower the reflectance as viewed from the front substrate surface and at the same time to extremely increase the reflectance as viewed from the phosphor side, it is necessary to asymmetrical the optical structure of the upper and lower layers centering on the mask layer. There is. It is inserted for this purpose.

According to a third aspect of the present invention, in the plasma display panel according to the first aspect, the protective film is made of Mg, O, F.
Characterized in that at least two or more of them are used as main components. The short-wavelength light amount applied to the mask layer changes depending on the absorption characteristics of the protective film. It is necessary to adjust the transmission characteristics of the protective film in consideration of the sensitivity of the optical constant change of the mask layer. Since MgF2 has a transmittance up to a shorter wavelength than MgO, the sensitivity of the mask layer is adjusted by the balance between the two.

In the plasma display according to the fourth aspect of the present invention, a mask layer is formed below the phosphor on the rear substrate instead of forming a mask layer on the front substrate. In the plasma display according to the present invention, in the front substrate, the surface reflectance is reduced, and the reflectance from the phosphor side is extremely increased, whereby the reflection of external light is reduced. In the display unit, the above condition is resolved by changing the optical constant of the mask layer in the display unit, and the visible light from the phosphor is transmitted by 90% or more, thereby improving the bright room contrast. According to the fourth aspect of the present invention, a mask layer is formed below the phosphor, and the optical constant of the underlying mask layer where the phosphor emits light is changed, so that the reflection as viewed from the phosphor is changed. The reflectance is increased, and the reflectance of the base is reduced in the base mask layer where the phosphor does not emit light. In this manner, by inserting a material whose optical constant changes by at least one of light and heat in the lower layer of the phosphor,
Bright room contrast can be improved.

The details of this will be described below. The reflection of external light alone causes a reduction in bright room contrast, but the reflection of external light mainly occurs at the phosphor surface and at the interface between the phosphor and the base. In order to suppress the reflection on the phosphor surface, it is conceivable to mix a substance that lowers the reflectance into the phosphor, but this reduces the luminance of the phosphor.

By forming a white material layer below the phosphor, the efficiency of taking out visible light from the phosphor is increased and the luminance is improved, but at the same time, the amount of reflected external light is increased and the contrast is increased. Does not improve. However, conversely, if a black material layer is formed below the phosphor, the efficiency of extracting visible light from the phosphor decreases, and the luminance decreases.

Therefore, in order to improve the luminance and the contrast at the same time, a mask layer whose optical constant changes at least one of heat and light is formed below the phosphor so that the phosphor emits light. Is to increase the luminance by improving the visible light extraction efficiency as a high reflection layer, and to function as a low reflection layer when no light is emitted, thereby suppressing the reflection of external light.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows the structure of a front substrate for carrying out the present invention. On a substrate 1, a transparent electrode 2, a bus electrode 3
Is formed, and a dielectric layer 6 is formed thereon by about 25 μm. Subsequently, a TiO film is formed as an asymmetric layer 16 by about 20 nm,
Na-Ba-Al-Ti-Co-O based thin film of 100 n as the mask layer 17
m, a MgO film 7 having a thickness of 700 nm was formed as a protective layer.

When manufacturing a panel having such a structure, first, a transparent electrode is formed on a front substrate, and then a Cr / Cu /
A metal thin film layer of Cr is formed by sputtering, and these are patterned to form electrodes. On this, a low-melting glass containing lead as a main component is formed about 25 μm, and after firing, a TiO film as an asymmetric layer, a Na-Ba-Al-Ti-Co-O-based thin film as a mask layer, and a MgO film as a protective film. Films are sequentially formed by sputtering to complete the front substrate.

The back side substrate is made of Cr / Cu on a glass substrate.
/ Cr metal thin film layer 9 is formed by sputtering and patterned to form a stripe-shaped address electrode.
A dielectric layer 12 is formed and fired. Next, a partition wall material is formed, which is patterned after heat treatment, and a partition wall (not shown) is formed by sandblasting. A phosphor film is formed on the partition walls thus manufactured by a screen printing method. After heat treatment again, the front side substrate and the back side substrate are bonded with frit glass, the sealing process to melt and harden the frit glass, the protective film is activated and Ne-Xe (Xe = 4%) gas is sealed as a discharge gas at 450 torr The panel fabrication is completed through an exhaust process.

As a result of evaluating the display performance of this panel, the dark room contrast was 300: 1, and the bright room contrast was 25:
It became 1. The peak luminance was 300 cd / m2.

In the conventional panel having the front-side substrate structure shown in FIG. 3 manufactured for comparison, the dark room contrast was 300: 1, but the bright room contrast was 16: 1.
And only about 60% of the bright room contrast of the embodiment can be obtained.
The peak luminance was 310 cd / m2.

In the above embodiment, the protective layer
When MgF2 was used, since the transmittance of MgF2 for short-wavelength light was high, the change in the optical constant of the mask layer was large, and the bright room contrast was improved to 30: 1. The peak brightness is 30
It was 5 cd / m2.

A second embodiment will be described.

In the first embodiment, a mask layer is inserted between the dielectric and the protective film exposed in the discharge space. In the present embodiment, the protective film also has the function of the mask layer. That is, the mask layer is exposed to the discharge space. As a result, the deterioration of the contrast due to external light can be suppressed, and the manufacturing cost can be reduced.

FIG. 2 shows the structure of the panel. This is a structure of the first embodiment without a protective film. A panel was manufactured under the same conditions as in the first embodiment, using the front-side substrate as the back-side substrate shown in the first embodiment. The bright room contrast of the panel is 30: 1, which is equivalent to the performance of the first embodiment.

A third embodiment will be described with reference to the drawings.

FIG. 6 shows the configuration of a panel for implementing the present invention. A transparent electrode 2 and bus electrodes 3, 4, and 5 are formed on a front substrate 1, and a dielectric layer 6 is formed thereon to a thickness of about 25 μm. Subsequently, the MgO film 7 was formed to a thickness of 700 nm as a protective layer.
Formed.

In manufacturing a panel having such a structure, first, a transparent electrode is formed on a front substrate, and then a Cr / Cu /
A metal thin film layer of Cr is formed by sputtering, and these are patterned to form electrodes. On this, a low-melting glass containing lead as a main component is formed to a thickness of about 25 μm, and after baking, an MgO film is sequentially formed as a protective film by sputtering to complete the fabrication of the front substrate.

The back side substrate is a glass substrate 8 on which Cr / C
A thin metal layer of u / Cr is formed by sputtering and patterned to form a stripe-shaped address electrode 9, and then a dielectric layer 10 is formed and fired. Next, a partition wall material is formed, which is patterned after heat treatment, and the partition wall 11 is formed by sandblasting. Next, an Al thin film 21 having a high reflectivity is formed to a thickness of about 80 nm on the substrate on which the partition walls 11 are formed, and then a Na-Ba-Al
-Ti-Co-O based thin films were formed by sputtering.

A phosphor film 12 is formed on the partition walls 11 thus manufactured by a screen printing method. After the heat treatment again, the front substrate and the rear substrate are bonded with frit glass, a sealing step of melting and hardening the frit glass, the protective film is activated, and Ne-Xe (Xe =
4%) Panel production is completed through an exhaust process in which gas is sealed at 450 torr.

As a result of evaluating the display performance of this panel, the dark room contrast was 331: 1, and the bright room contrast was 3
3: 1. The peak luminance was 350 cd / m2.

In this embodiment, A is formed below the mask layer.
l film was used, but other than that, a compound thin film of a metal element,
The effect of the present invention is not impaired even if the lower layer of the mask layer is made to be a high-reflectance layer, for example, by forming a partition wall using a dielectric mixed with metal particles. Further, an optically transparent layer may be formed on at least one interface of the mask layer in order to increase the reflectance by changing the optical constant of the mask layer. Further, even if a reflective layer and a mask layer are formed only on the surface of the dielectric formed on the address electrode, the effect is not changed.

[0035]

As described above, according to the present invention,
Since the external light reflectance of the front side substrate in the state where the panel does not emit light is low, and the phosphor side reflectance is high,
A decrease in contrast due to external light can be suppressed, and display performance can be improved. Also, by forming a mask layer below the phosphor on the rear substrate, the luminance of the phosphor can be improved and the amount of reflected external light can be reduced.
The display performance can be improved.

Further, when the optical constant of the mask layer is changed mainly by using short-wavelength light from the discharge gas, even if the afterglow time of the red, blue, and green three-color phosphors varies. In addition, there is an effect that the afterglow is masked irrespective of the phosphor color by the operation of the mask layer.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing a structure of a panel according to a first embodiment of the present invention.

FIG. 2 is a side sectional view showing a structure of a panel according to a second embodiment of the present invention.

FIG. 3 is a perspective view showing a structure of a conventional three-electrode surface discharge type AC plasma display panel.

FIG. 4 is a side sectional view showing the structure of a conventional three-electrode surface discharge type AC plasma display panel.

FIG. 5 is a view showing an arrangement of electrodes formed on a front substrate of a conventional three-electrode surface discharge type AC plasma display panel.

FIG. 6 is a perspective view showing the structure of a panel according to a third embodiment of the present invention.

[Explanation of symbols]

1, 8 front, rear substrate, 2 transparent electrode, 3 bus electrode, 6, 10 dielectric layer, 7 protective film, 11 partition, 9
... address electrodes, 12 ... phosphors

Continued on the front page (72) Inventor Akinori Yuhara 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Inside the Multimedia Systems Development Headquarters, Hitachi, Ltd. (72) Inventor Yasuhiro Ota 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Hitachi, Ltd. Multimedia Systems Development Division F-term (reference) 5C040 FA01 GB03 GB14 GD02 GD10 GE07 KA04 KB14 KB15 KB19 MA04

Claims (4)

[Claims] 1. A display device comprising a plurality of X electrodes and a plurality of Y electrodes covered with a dielectric layer, and a protective film covering the dielectric layer. And an address electrode, a partition, and a phosphor are formed on the other back plate in a direction orthogonal to the display electrodes. In the plasma display panel, at least one of light and heat is applied between the dielectric layer and the protective film. A plasma display panel comprising a mask layer having a variable optical constant. 2. A plasma display panel according to claim 1, further comprising an asymmetric layer between the mask layer and the dielectric layer, the refractive index being higher than that of the dielectric and the extinction coefficient being equal to that of the dielectric. . 3. The plasma display panel according to claim 1, wherein the protective film comprises at least two of Mg, O, and F as main components. 4. A substrate, which is disposed opposite to a gas space, has a display panel comprising a plurality of X electrodes and Y electrodes covered with a dielectric layer, and a protective film covering the dielectric layer. In the plasma display panel on which the address electrodes, partition walls, and phosphors are formed in the direction perpendicular to the display electrodes on the other back plate, heat and light are applied A plasma display panel comprising at least a mask layer whose optical constant is changed by at least one of them.