JPH08287834A - Plasma display panel - Google Patents

Abstract

PURPOSE: To realize display whose image is not strained and which has high contrast while securing stable discharge characteristics. CONSTITUTION: A phosphor layer 28 to emit the light by discharge is provided in an opposing clearance of a pair of plates 11 and 21, and a neutral gray filter layer 17 composed of dielectric material in which, for example, a coloring agent mainly composed of metallic oxide is mixed, is provided between the front side plate 11 and the phosphor layer 28.

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 (PDP) having a phosphor layer for displaying a color different from a gas emission color.

In a PDP for color display, it is necessary to prevent a decrease in contrast due to reflection of external light on the surface of the phosphor layer.

[0003]

2. Description of the Related Art A PDP is a display panel having a structure in which a pair of substrates (usually glass plates) facing each other across a discharge space are used as a base. By providing the ultraviolet excitation phosphor in the discharge space, it is possible to display a color different from the emission color of the discharge gas. R (red), G for full color display
Phosphor layers of three colors (green) and B (blue) are provided.

In a PDP having a phosphor layer, the object color of the phosphor (color when not emitting light) is a whitish color such as white or light gray, and therefore external light is reflected on the surface of the phosphor layer. There is a problem that the display contrast is lowered.

Therefore, conventionally, as a method of increasing the contrast of a PDP for color display, a method of applying a semitransparent paint corresponding to the emission color of the phosphor on the outer surface of the front substrate to provide a color filter, There are proposed a method of disposing a separately manufactured filter on the front surface and a method of coloring an AC driving dielectric layer by dividing it into R, G, and B colors.

[0006]

However, it is extremely difficult to apply paint of each color corresponding to minute pixels.
There is a possibility that the paint may partially peel off during use. When the separate filter is arranged on the front surface, the display image is distorted due to the gap between the PDP and the filter. Further, when the dielectric layers are color-coded, since the colorant (pigment) is different for each color, the uniformity of the dielectric constant is impaired by the color-coding, and the discharge characteristics become unstable. in addition,
It is difficult to color-code the dielectric layers as in the case of coating different paints.

The present invention has been made in view of these problems, and it is an object of the present invention to realize a display of high contrast without distortion of an image while ensuring stable discharge characteristics.

[0008]

A PDP according to the invention of claim 1
Is a plasma display panel having a phosphor layer that emits light by discharge in a facing gap between a pair of substrates, and has a neutral gray filter layer between the substrate and the phosphor layer on the front side. Become.

According to a second aspect of the present invention, there is provided a plasma display panel in which a PDP has a phosphor layer which emits light by discharge in a facing gap of a pair of substrates, and electrodes are arranged on an inner surface of the substrate on the front side. The electrode is covered by the neutral gray filter layer with respect to the discharge space, and the phosphor layer is disposed on the back side of the neutral gray filter layer.

In the PDP of the third aspect of the present invention, the neutral gray filter layer is made of a dielectric material mixed with a colorant containing a metal oxide as a main component, and the neutral gray filter layer and the electrode are separated from each other. And a dielectric layer substantially free of the colorant.

[0011]

The neutral gray filter layer is a translucent layer that hardly changes the chromaticity of transmitted light. The light of a predetermined color emitted by the phosphor layer passes through the neutral gray filter layer and the substrate on the front side,
It is emitted as display light to the outside.

On the other hand, external light passes through the neutral gray filter layer, enters the phosphor layer, is reflected by the surface of the phosphor layer, and then passes through the neutral gray filter layer again and is emitted to the outside. That is, ambient light passes through the neutral gray filter layer twice.

Here, the amount of light emission (luminance) of the phosphor layer is A,
When the amount of external light is B, the contrast CONT in the case where the neutral gray filter layer is not provided is represented by the equation (1). CONT = (A−B) / B = A / B−1 (1) On the other hand, the contrast CONT ′ when the neutral gray filter layer of the transmittance τ is provided is represented by the formula (2). .

CONT ′ = [τ × A− (1−τ ² ) × B] / (1−τ ² ) × B = [τ / (1−τ ² )] × (A / B) −1 ( 2) For example, A = 200 [cd / m ² ] and B = 10 [cd /
m ² ], τ = 0.7, CONT = 19, CO
NT ′ = 26.4, and the neutral gray filter layer improves the contrast about 1.4 times.

[0015]

1 is an exploded perspective view of a main portion of a PDP 1 to which the present invention is applied, and FIG. 2 is a partial sectional view of the PDP 1.

The PDP 1 is a surface discharge type PDP having a three-electrode structure in which a pair of display electrodes X and Y and an address electrode A correspond to a unit light emitting area EU of matrix display, and is classified according to the arrangement form of phosphors. It is called a reflective type.

The display electrodes X and Y for surface discharge are provided on the inner surface of the glass substrate 11 on the front side, and are covered by the dielectric layer (neutral gray filter layer) 17 described later with respect to the discharge space 30. There is. On the surface of the dielectric layer 17, a protective film 18 made of MgO having a large secondary electron emission coefficient and having a thickness of about several thousand Å is provided. The display electrodes X and Y
Is disposed on the front side of the discharge space 30, so that the surface discharge is wide and the light shielding of the display light is minimized.
It is composed of a wide transparent conductive film 41 made of a Nesa film or the like and a narrow metal film (bus electrode) 42 that complements the conductivity thereof.

On the other hand, the address electrode A has a unit light emitting region E.
Electrodes for selectively emitting U, which are arranged on the rear glass substrate 21 at a constant pitch so as to be orthogonal to the display electrodes X and Y.

Between each address electrode A, 100 to 20
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.

Further, the glass substrate 21 is provided with a phosphor layer 28 of three primary colors of R, G and B 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. ing. The phosphor layer 28 of each color emits light when excited by the ultraviolet rays emitted by the discharge gas in the discharge space 30 during surface discharge. In PDP1, one pixel (pixel) EG
Are three unit light emitting areas (sub-pixels) E of R, G and B
It is composed of U and is capable of full-color display by combining R, G, and B. The address electrode A may be covered with a dielectric layer.

The dielectric layer 17 of the present embodiment is a fired body of a low-melting glass paste in which cobalt oxide (tricobalt tetraoxide: Co ₃ O ₄ ) is mixed as a coloring agent, and its transmittance for visible light varies with wavelength. It is almost constant regardless. That is,
The dielectric layer 17 has a function of accumulating wall charges for AC driving and a function of a neutral gray filter.
The thickness of the dielectric layer 17 is 20 to 30 μm, and a low melting point glass paste obtained by mixing a coloring agent composed of cobalt oxide and oxides of several kinds of metals (iron, manganese, nickel, etc.) at a ratio of about 1 wt% is used. By using the dielectric layer 1
The transmittance of No. 7 is set to 70%.

The low-melting glass paste is PbO ₂
A mixture of glass powder such as —SiO ₂ —B ₂ O ₂ and a binder such as ethyl cellulose, which is used for printing after being appropriately diluted with a solvent such as α-terpineol. When a black pigment consisting only of an oxide of a metal other than cobalt such as iron, manganese, or chromium is used as a colorant, if the amount of addition is relatively small so that the transmittance is 50% or more, it becomes pale. This results in a dark brown low melting point glass layer, impairing the color purity of the display.

In the PDP 1, since the neutral gray filter layer (dielectric layer) 17 is provided between the phosphor layer 28 and the glass substrate 11 on the front side, the chromaticity of light emission of the phosphor layer 28 is controlled. It is possible to realize high-contrast display by attenuating the external light reflected by the phosphor layer 28 without changing it. In addition, the number of manufacturing steps does not increase due to the provision of the neutral gray filter layer 17.

FIG. 3 is a partial sectional view of the PDP 2 according to the second embodiment. 3, constituent elements having the same functions as those in FIGS. 1 and 2 are designated by the same reference numerals. The following figures are also the same.

The PDP 2 is also a reflection type PDP in which the phosphor layer 28 is arranged on the glass substrate 21 on the back side, like the PDP 1 of the above example. However, in the PDP 2, the display electrodes X and Y arranged on the inner surface of the glass substrate 11 on the front side have three electrodes.
The discharge space 30 is covered with a dielectric layer 17b having a layered structure.

Of the three layers constituting the dielectric layer 17b,
The intermediate layer 172 is a neutral gray filter layer made of low melting point glass mixed with cobalt oxide. The other two layers 17
Reference numerals 1 172 are low-melting-point glass layers containing substantially no cobalt oxide.

The neutral gray filter layer 172 has a thickness of 5 μm.
m, and by using a low melting point glass paste in which cobalt oxide is mixed at a ratio of about 2 to 3 wt%,
The transmittance is set to 70%.

Neutral gray filter layer 1 containing cobalt oxide
Due to the presence of the low melting point glass layer 171 between the display electrode 72 and the display electrodes X and Y, even if a reduction reaction of cobalt oxide occurs due to discharge energy during use, the display electrodes X and Y are short-circuited by the cobalt. Can be avoided.
Further, since the low-melting-point glass layer 173 is present between the neutral gray filter layer 172 and the MgO film 18, the quality of the film is higher than that when the MgO film 18 is formed directly on the neutral gray filter layer 172. A good MgO film 18 can be obtained, and the MgO film 18 formed by precipitation of cobalt oxide
It is possible to prevent the discharge characteristics from changing with time due to the deterioration of.

FIG. 4 is a partial sectional view of the PDP 3 according to the third embodiment. The PDP 3 is a transmissive PDP in which a phosphor layer 28 is arranged on the front glass substrate 11. The light emitted from the surface layer portion of the phosphor layer 28 that is in contact with the discharge space 30 passes through the phosphor layer 28 and goes to the outer surface (display surface) of the glass substrate 11.

In the PDP 3, the neutral gray filter layer 172b made of low melting point glass in which cobalt oxide is mixed as a colorant between the phosphor layer 28 and the inner surface of the glass substrate 11.
Is arranged. That is, the neutral gray filter layer 172b is provided so as to uniformly cover the inner surface of the glass substrate 11 on which the address electrodes A are arranged, and the fluorescent substance 28 is provided after the partition wall 29 is provided by multiple printing of low melting point glass, for example. ing.

According to the above-described embodiment, even if the plurality of phosphor layers 28 having different emission colors are provided, the uniform neutral gray filter layers 17, 172 and 172b can be used to increase the contrast over the entire display surface. Since it is possible to increase the contrast, it is possible to extremely easily improve the contrast, as compared with the case where a filter having different spectral characteristics for each emission color is provided.

In the above-described embodiment, the amount of the colorant added for forming the neutral gray filter layers 17, 172, 172b may be set according to the selection of the layer thickness and the transmittance. The upper limit is preferably about 0.3 to 5 wt%.

In the above-described embodiment, P having a three-electrode structure is used.
Although DP1 to DP3 are exemplified, the present invention can be applied to PDPs of other configurations such as a segment display type PDP without the address electrode A. The address electrode A may be arranged on the same substrate as the display electrodes X and Y.

[0034]

According to the inventions of claims 1 to 3,
It is possible to realize a display with high image contrast without distortion of the image while ensuring stable discharge characteristics.

According to the third aspect of the invention, it is possible to prevent a short circuit between the electrodes and improve the reliability.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of a main part of a PDP to which the present invention is applied.

FIG. 2 is a partial cross-sectional view of a PDP.

FIG. 3 is a partial cross-sectional view of a PDP according to a second embodiment.

FIG. 4 is a partial sectional view of a PDP according to a third embodiment.

[Explanation of symbols]

 1,2,3 PDP (plasma display panel) 11,21 Glass substrate (substrate) 17 Dielectric layer (neutral gray filter layer) 28 Phosphor layer 30 Discharge space 171 layer (dielectric substance substantially containing no colorant) Layer) 172, 172b neutral gray filter layer A address electrode (electrode) X, Y display electrode (electrode)

Claims (3)

[Claims] 1. A plasma display panel having a phosphor layer that emits light by discharge in a facing gap between a pair of substrates, wherein a neutral gray filter layer is provided between the substrate on the front side and the phosphor layer. A plasma display panel characterized by having. 2. A plasma display panel having a phosphor layer which emits light by discharge in a gap between a pair of substrates facing each other, wherein electrodes are arranged on an inner surface of the substrate on the front side, wherein the electrodes are neutral gray. A plasma display panel, characterized in that the discharge space is covered with a filter layer, and the phosphor layer is disposed on the back side of the neutral gray filter layer. 3. The neutral gray filter layer is made of a dielectric material mixed with a colorant containing a metal oxide as a main component, and the colorant is provided between the neutral gray filter layer and the electrode. The plasma display panel according to claim 2, wherein a dielectric layer which is substantially free from the dielectric layer is arranged.