JPH0831325A - Surface discharge type plasma display panel - Google Patents

Abstract

PURPOSE:To suppress chromatic change in display by forming a phosphor layer from a number of fluorescent substance particles covered individually with a photo-transmissive oxide film, and thereby suppressing degradation of the fluorescent substance caused by reactions with silver contained in the electrode. CONSTITUTION:A plasma display panel of surface discharge type has a silver electrode located right under a phosphor layer 28B to emit a displaying light in the blue range, wherein the layer 28B is formed from a number of fluorescent substance particles 80 whose surfaces are all covered with a photo-transmissive oxide film consisting of a MgO film 81. The MgO film 81 has a thickness of 1000-2000Angstrom and transmits the light in the ultraviolet and visible regions. The film 81 can be formed by any method, for example evaporation, dipping, sputtering, spraying, etc. Covering the fluorescent substance 80 with MgO film 81 enables suppression of degradation of the substance 80 at the time of baking.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface discharge type plasma display panel (PDP) having a phosphor layer.

[0002] PDPs are self-luminous display devices that are advantageous in terms of visibility, and because they are capable of large screens and high-speed display, they have attracted attention as thin display devices that replace CRTs. In particular, the surface discharge PDP that performs full-color display by using a phosphor is expanding its application to the field of television images including high definition.

[0003]

2. Description of the Related Art As a PDP suitable for full-color display using three-color phosphors, an AC drive type surface discharge PDP having a three-electrode structure is known.

As shown in FIG. 1 showing an embodiment of the present invention, this type of PDP includes a glass substrate 11 on the display surface H side, a pair of display electrodes X and Y extending in parallel and adjacent to each other. A
Dielectric layer 17 for driving C, magnesium oxide (Mg
O) protective film 18, glass substrate 21 on the back side, address electrodes A orthogonal to the display electrodes X and Y, stripe-shaped partition walls 29 parallel to the address electrodes A, and phosphor layers of three colors for full-color display. 28R, 28G, 28B and the like. A surface discharge cell (main discharge cell for display) is defined by the display electrodes X and Y, and an address for selecting lighting or non-lighting of the unit light emitting area EU of matrix display by one display electrode Y and the address electrode A. A discharge cell is defined.

The phosphor layers 28R, 28G and 28B are provided so as to cover the address electrodes A on the glass substrate 21 on the side opposite to the display electrodes X and Y in order to avoid ion bombardment during discharge, and the main discharge is performed. It emits light by being excited by ultraviolet rays generated by the surface discharge of the cell. The phosphor layers 28R, 28
G and 28B are fired bodies of a phosphor paste containing a granular phosphor material as a main component.

The address electrode A immediately below the phosphor layers 28R, 28G and 28B is formed by a thick film method, and is usually a silver electrode having good conductivity and good affinity with other members. On the other hand, when the address electrode A is a thin film electrode, since the phosphor layers 28R, 28G, and 28B are porous, the glass substrate 11 during and after firing the phosphor layers 28R, 28G, and 28B. , 21 oxidize the electrodes during the heat treatment at the time of sealing, thereby impairing the conductivity.

[0007]

However, in the prior art, the fluorescent substance reacts with the silver of the address electrode A to deteriorate, and the chromaticity of emitted color (coordinates on the chromaticity diagram) changes significantly with time. It was Further, chromaticity change also occurred at the stage of firing the phosphor layers 28R, 28G, 28B. In particular, a barium oxide-based fluorescent substance such as blue (B) 3 (Ba, Mg) O.
With 8Al ₂ O ₃ : Eu, deterioration (blackening) proceeded rapidly.

The present invention has been made in view of such problems, and an object thereof is to suppress a change in chromaticity of display.

[0009]

A PDP according to the invention of claim 1
In order to solve the above problems, as shown in FIG. 1, a silver electrode is provided directly below a phosphor layer that emits light when excited by ultraviolet rays, and the phosphor layers are individually covered with a transparent oxide film. It is a surface discharge type PDP having a structure composed of a large number of particulate fluorescent substances.

The PDP of the second aspect of the present invention is a surface discharge type PDP in which the phosphor layer is composed of a large number of particulate fluorescent substances individually coated with a magnesium oxide film.

[0011]

The translucent oxide film separates the particulate fluorescent substance from the silver electrode and suppresses the alteration of the particulate fluorescent substance due to the reaction with silver. In addition, the particulate fluorescent material is protected from ion bombardment during discharge.

Unlike the case where an isolation layer is provided on the silver electrode, the silver electrode is covered with a transparent oxide film so as to cover the particulate fluorescent substance individually, and the silver electrode is discharged through the porous phosphor layer. Since it is exposed to the surface, it does not hinder the function of the silver electrode. In addition, since the number of manufacturing steps that should be performed in sequence (which cannot be performed in parallel) does not increase, mass productivity is not impaired.

If the light-transmissive oxide film is a magnesium oxide (MgO) film, in the particulate fluorescent material, secondary electron emission enhances discharge, and excitation energy increases, so that emission brightness increases.

[0014]

1 is an exploded perspective view showing the structure of a portion corresponding to one pixel EG of a PDP 1 according to the present invention, and FIG. 2 is an enlarged sectional view schematically showing the structure of a blue phosphor layer 28B.

As shown in FIG. 1, the PDP 1 has a three-electrode structure in which a pair of display electrodes X, Y and an address electrode A correspond to each other in a unit light emitting region EU of matrix display. Surface discharge type PD, which is called reflection type above
P.

The display electrodes X and Y for surface discharge are provided on the glass substrate 11 on the display surface H side, and a discharge space is provided by a dielectric layer 17 for AC driving that uses wall charges to maintain discharge. Coated for 30. On the surface of the dielectric layer 17, a protective film of MgO having a thickness of about several thousand liters is used.
A membrane 18 is provided.

Since the display electrodes X and Y are arranged on the display surface H side with respect to the discharge space 30, the surface discharge is made wide and the shielding of the display light is minimized. The transparent conductive film 41 has a wide width and the bus metal film 42 has a narrow width to compensate for the conductivity.

On the other hand, on the rear glass substrate 21, address electrodes A are arranged at a constant pitch so as to be orthogonal to the display electrodes X and Y in order to selectively emit light in the unit light emitting region EU. The address electrode A is composed of silver (A
g), lead borosilicate glass (glass frit), bismuth oxide (filler), ethyl cellulose resin (binder), and silver paste consisting of an organic solvent, 600
It is a thick film electrode having a thickness of about 5 to 15 μm, which is fired at a temperature of about ° C.

Between each address electrode A, 100 to 15
Stripe-shaped barrier ribs 29 having a height of about 0 μm are provided, whereby the discharge spaces 30 are divided into unit light emitting regions EU in the line direction (extension direction of the display electrodes X and Y), and the discharge spaces 30 are formed. The gap size is specified.

The glass substrate 21 includes R (red), G (green), and B (blue) so as to cover the inner surface of the rear surface including the upper surface of the address electrode A and the side surface of the partition wall 29. The primary color phosphor layers 28R, 28G, 28B are provided by applying a paste by a screen printing method or the like and then firing it. The firing temperature of the phosphor layer is about 500 ° C. lower than the firing temperature of the address electrode A. The address electrode A in each phosphor layer 28R, 28G, 28B
The thickness of the portion covering the upper surface of is about 20 μm.

Such phosphor layers 28R, 28G, 28
B is excited by the ultraviolet rays (wavelength λ = 147 nm) emitted from the discharge gas in the discharge space 30 during surface discharge and emits light. The discharge gas is Penning gas in which neon is mixed with xenon (about 1 to 15% mol).

In the display surface H, each pixel EG is composed of three unit light emitting regions EU having the same area and arranged in the line direction, and one phosphor layer 28R, 28G, 28B is provided in each of these three unit light emitting regions EU. It is associated with each color. Note that the phosphor layers 28R, 28G, and 28B of the respective colors are continuous in the extension direction of the address electrode A, but the discharge is local, so that the phosphor layers 28R, 28G, and 28B are local.
It is possible to selectively emit light in a portion corresponding to each unit light emitting region EU in.

At the time of display, by using the write address method or the erase address method, wall charges are accumulated in the unit light emitting region EU selected according to the display content, and then a sustaining voltage pulse is alternately applied to the display electrodes X and Y. To do. As a result, only in the unit light-emission region EU having wall charges, surface discharge occurs each time a pulse is applied, and the phosphor layer 28R of a predetermined color,
28G and 28B emit light. At this time, multi-color display can be performed by appropriately selecting the combination of the phosphor layers 28R, 28G, 28B that emit light, and gradation control of the brightness of each phosphor layer 28R, 28G, 28B can be performed. This enables full-color display.

Now, as shown in FIG. 2, the phosphor layer 28B which emits the display light in the blue region is composed of a large number of granular phosphor substances 80 whose entire surface is individually covered with the MgO film 81. The MgO film 81 has a thickness of 1000 to 2000.
It is a thin film of about Å and has translucency in the ultraviolet and visible regions. As a method for forming the MgO film 81, a microencapsulation method such as a vapor deposition method, a dipping method, a sputtering method, or a spray method can be used.

The fluorescent substance 80 is 3 (Ba, Mg) O.8Al ₂ having an average particle size of 5.5 μm measured by the corta counting method.
O ₃ : Eu, and the chromaticity of the emission color when excited by an ultraviolet lamp (wavelength 254 nm) in a powder state is x =
0.145 and y = 0.065.

In the PDP 1 of the present embodiment, the chromaticity of blue in the initial state at the time of completion by forming the phosphor layer 28B by firing was x = 0.198 and y = 0.131. On the other hand, in the conventional example using the fluorescent substance 80 not covered with the MgO film 81, the chromaticity of blue in the initial state was x = 0.202, y = 0.133. That is, by covering with the MgO film 81, the deterioration of the fluorescent material 80 during firing could be suppressed.

Further, as shown in Table 1, the change in chromaticity due to continuous use for 1000 hours could be reduced as compared with the conventional example.

[0028]

[Table 1]

Further, the blue unit light emitting region E of the PDP 1
The brightness of U was 1.3 times that of the conventional example. This is Mg
Since O is a substance having a large secondary electron emission coefficient, it is considered that the discharge was strengthened in the vicinity of the fluorescent substance 80 and the excitation efficiency was increased.

In the above-mentioned embodiment, the blue phosphor layer 28B is made of the phosphor 80 covered with the MgO film 81, but the red and green phosphor layers 28R, 28 are formed.
With respect to G as well, the MgO film 81 may prevent chromaticity change. Especially as green fluorescent material, BaO.6A
The effect is great when a barium oxide-based substance such as l ₂ O ₃ : Mn is used. That is, B coated with MgO film
aO.6Al ₂ O ₃ : Mn has chromaticity in the powder state of x = 0.186, y = 0.721, and chromaticity in the initial state of the panel is x = 0.192, y = 0.713. Is. On the other hand, when not coated, the chromaticity in the powder state is x = 0.185, y = 0.726, and the chromaticity in the initial state is x = 0.191, y = 0.718. .

Further, if MgO is used as the coating oxide, the discharge characteristics are improved as described above, so R, G, B
By changing the film thickness of the MgO film 81 for each color, the lower limit value of the drive voltage can be lowered and the drive voltage margin of full color display can be expanded.

In the above-mentioned embodiment, the composition and particle size of the fluorescent substance 80 may be variously selected according to the application. It is also possible to change the composition of the silver paste. Instead of the MgO film 81, another oxide film such as SiO ₂ may be provided.

The present invention can be applied to PDPs having various other structures for displaying a single color or multi-colors, as long as the PDP has a structure in which the silver electrode and the phosphor layer are in direct contact with each other.

[0034]

According to the inventions of claim 1 and claim 2,
The change in chromaticity of display can be suppressed. In particular, according to the second aspect of the invention, the brightness can be increased, the voltage margin can be expanded, and the driving can be facilitated.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of a PDP according to the present invention.

FIG. 2 is an enlarged sectional view schematically showing the structure of a phosphor layer.

[Explanation of symbols]

 1 PDP (Surface Discharge Plasma Display Panel) 28B Phosphor Layer 80 Phosphor Substance 81 MgO Film (Translucent Oxide Film) A Address Electrode (Silver Electrode)

Claims (2)

[Claims] 1. A surface discharge type plasma display panel having a silver electrode immediately below a phosphor layer which emits light when excited by ultraviolet rays, wherein the phosphor layer is individually coated with a transparent oxide film. A surface discharge type plasma display panel comprising a particulate fluorescent material. 2. A surface discharge type plasma display panel having a silver electrode directly below a phosphor layer which emits light when excited by ultraviolet rays, wherein the phosphor layer is formed of a large number of particles individually coated with a magnesium oxide film. A surface discharge type plasma display panel comprising a fluorescent substance.