WO2002054440A1

WO2002054440A1 - Plasma display panel for preventing field spreading

Info

Publication number: WO2002054440A1
Application number: PCT/KR2000/001471
Authority: WO
Inventors: Gil Young Kang; Yang Ho Kwon
Original assignee: Orion Electric Co., Ltd.
Priority date: 2000-12-15
Filing date: 2000-12-15
Publication date: 2002-07-11

Abstract

The present invention provides a plasma display panel for preventing field spreading in which each electric field can be concentrated on each discharge space and field spreading to exert an influence on adjoining cells can be prevented. The plasma display panel is characterized by comprising dielectric layers 12 of a low dielectric constant with the relative dielectric constant of 6 to 10 formed on at least upper surfaces of black stripes 10 and dielectric layers 11 of a high dielectric constant with the relative dielectric constant of 13 to 17 formed on portions except the dielectric layers 12 of a lower dielectric constant.

Description

Title of the Invention

PLASMA DISPLAY PANEL FOR PREVENTING FIELD SPREADING

Technical Field

The present invention relates to a plasma display panel for

preventing field spreading, and more particularly, to a plasma

display panel in which each electric field can be concentrated on

each discharge space and field spreading to exert an influence on

adjoining cells can be prevented.

Background Art

Fig. 1 illustrates a schematic partial sectional view for

explaining a structure of a conventional plasma display panel of a

alternative-current, surface-discharge type. As shown in Fig. 1,

the plasma display panel comprises a front substrate 1 wherein the

front substrate is provided with a front electrode group

consisting of an X electrode 3 and an Y electrode 4 as transparent

electrodes such as ITO in common, bus electrodes 3a and 4a as

metal electrodes such as Ag formed on the X electrodes 3 and the Y

electrodes 4, black stripes 10 formed between each pair of the X

electrodes 3 and the Y electrodes 4, and a dielectric layer 6 and

a protective layer 6a formed thereon. And a rear substrate 2 faced parallel to the front substrate 1 is provided with address

electrodes 5 as data electrodes, a dielectric layer 7 and a

phosphor pattern 9 of three different color phosphors formed

between barrier ribs 8.

In an illustrative method of driving the plasma display

panel, one frame is divided into a plurality of subframes and each

subframe is divided into a reset period, an address period and a

sustain period, with different sustain periods set in each

subframe, thus, a gray scale display of an image screen is

obtained by combining each subframe.

During the reset period, a write pulse is applied to the X

electrodes 3 connected commonly to each other in order to equalize

or initialize discharge conditions in all cells of the panel,

thereby totally discharging all cells. A sustain pulse is applied

to the Y electrodes 4 in order to sustain the discharge and then

an erasure pulse is applied to the commonly connected X electrodes

3 in order to erase wall charges accumulated on the dielectric

layers 6 and 7.

During the address period, wall charges are accumulated on

the front dielectric layer 6 of cells to be displayed by applying data pulses to the address electrodes 5 in order to selectively

address cells to be displayed depending on inputted image data and

sequentially applying scan pulses to the Y electrodes 4. Then, by

applying alternately the sustain pulses to the X electrodes 3 and

the Y electrodes 4, sustain discharge is produced in only the

cells which were addressed during the address period, that is,

which had a wall charge accumulated thereon.

In the reset period and the address period in the course of

displaying one subframe as discussed above, the address electrodes

5 are maintained at the reference level, that is, a ground level,

equal to that of the X electrodes 3 and the Y electrodes 4 of the

front electrode group, as the result of which space charges and

wall charges are generated, thereby to facilitate writing and

erasing operations necessary for electric discharge.

Alternatively, in the sustain period, the address electrodes 5 may

be maintained at a high impedance, not at the ground level and, at

this time, a voltage is induced to the address electrodes 5 by the

space charges formed on the front electrode group. As a matter of

convenience, a floated address voltage is referred to as an

induced voltage. During the sustain discharge, the induced address voltage to be maintained at the ground level may cause the

instability of the sustain discharge. Therefore, in a surface

discharge structure of a plasma display panel, the induced sustain

voltage is typically maintained at the high impedance.

SUMMARY OF THE INVENTION

In such structure of the conventional plasma display panel,

since the thickness of the dielectric layer 6 on the metal

electrodes 3a and 4a and the black stripes 10 is thinner than that

of the dielectric layer 6 on the X electrodes 3 and the Y

electrodes 4, electrostatic capacitances on the metal electrodes

3a and 4a and the black stripes 10 becomes higher. Thus, due to a

field spreading effect that each electric field does not become

concentrated on each discharge space and becomes spreaded to

adjoining cells, there are problems that discharging efficiency

decreases and probability of cross-talk becomes higher. In order

to solve such problems, a stepped dielectric structure, in where

one more layer of the dielectric layer is formed on the metal

electrodes 3a and 4a, is proposed by Pioneer Co. , Ltd. However,

such a structure still has a danger such as cross-talk by

intersection with barrier ribs in a vertical direction. Accordingly, in order to solve the above discussed

problems, an object of the present invention is to provide a

plasma display panel in which each electric field can be

concentrated on each discharge space and field spreading to exert

an influence on adjoining cells can be prevented.

In order to accomplish the object, in accordance with a

first embodiment of the present invention, a plasma display panel

for preventing field spreading is presented, in which comprises a

plurality of front electrode groups consisting of an X electrode

and an Y electrode formed on the rear surface of a front

substrate, black stripes formed at the exterior of the X

electrodes and the Y electrodes, metal electrodes formed on each

of the X electrodes and the Y electrodes, address electrodes

formed on the interior surface of a rear substrate faced parallel

to the front substrate so as to form a plurality of cells for

discharge-by-display in each region crossing with each of the

front electrode groups, dielectric layers formed on the front

electrode groups and the address electrodes, respectively, and a

phosphor pattern formed on the rear dielectric layer between

barrier ribs, said plasma display panel being characterized in that said dielectric layer comprises dielectric layers of a low

dielectric constant with the relative dielectric constant of 6 to

10 formed on at least the upper surfaces of the black stripes and

dielectric layers of a high dielectric constant with the relative

dielectric constant of 13 to 17 formed on portions except the

dielectric layers of a low dielectric constant.

The dielectric layers of a high dielectric constant may be

formed only on upper surfaces of the X electrodes and the Y

electrodes except those of the metal electrodes, and said

dielectric layers of a low dielectric constant may be formed on

each upper surface between the metal electrodes on the X

electrodes and the metal electrodes on the Y electrodes over each

upper surface of the black stripes. That is, it is to print on the

metal electrodes and the black stripes with a material of a lower

dielectric constant than that of dielectric layers on the X

electrodes, and the Y electrodes, of ITO in order to prevent field

spreading.

BRIEF DESCRIPTION OF DRAWINGS

Fig. 1 illustrates a schematic partial sectional view for

explaining a structure of a conventional plasma display panel. Fig. 2 illustrates a schematic partial sectional view of a

front substrate of a plasma display panel for preventing field

spreading in accordance with one embodiment of the present

invention.

Fig. 3 illustrates a schematic partial sectional view of a

front substrate of a plasma display panel for preventing field

spreading in accordance with another embodiment of the present

invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Now, preferred embodiments of the present invention will be

described in detail with reference to the accompanying drawings.

A structure of the plasma display panel according to one

embodiment of the present invention is shown in Fig. 2 as a

schematic partial sectional view similar to Fig. 1.

Even in Fig. 2 as shown in Fig. 1, a plasma display panel

of the present invention for preventing field spreading comprises

a plurality of front electrode groups consisting of an X electrode

3 and an Y electrode 4 formed on the rear surface of a front

substrate 1, black stripes 10 formed at the exterior of the X

electrodes 3 and the Y electrodes 4, metal electrodes 3a and 4a formed on each of the X electrodes 3 and the Y electrodes 4, and

dielectric layers 11 and 12 formed thereon by printing.

A rear substrate is not shown in Figs. 2 and 3, but a rear

substrate 2, as shown in Fig. 1, may be employed in the present

invention which comprises address electrodes 5 formed on the

interior surface of the rear substrate 2 faced parallel to the

front substrate 1 so as to form a plurality of cells for display

by discharge in each region crossing with the front electrode

groups, dielectric layer 7 formed on the address electrodes 5,

respectively, barrier ribs 8 formed at a constant distance and a

phosphor pattern 9 formed on the rear dielectric layer 7 between

the barrier ribs 8.

In accordance with one embodiment of the present invention

in the plasma display panel of such a structure, the dielectric

layers 12 of a low dielectric constant, which has the relative

dielectric constant of 6 to 10, are formed on the upper surfaces

of the black stripes 10, as shown in Fig. 2, and the dielectric

layers 11 of a high dielectric constant, which has the relative

dielectric constant of 13 to 17, are formed on portions except the

dielectric layers 12 of a low dielectric constant. In general, where an electric field or flux density passes

through a boundary surface of two dielectrics(each dielectric

constant: εl, ε₂) in contact with each other at an incidence

angle θ i from one dielectric and flows into the other dielectric

at an angle #₂, the following relationships are established. That

is:

CD each vertical component of each electric flux density Di and D₂

before and after the boundary surface is identical at both side of

the boundary surface, i.e.,

(D each component of each electric field Ei and E₂ parallel with

the boundary surface is identical at opposite sides of the

boundary surface, i.e.,

(3) From the relation of Dι= ε ιEι and D₂= ε ₂E₂,

@ an electric field or flux density is refracted at the boundary

surface largely toward the dielectric with the higher dielectric

constant(since, if ε₂>ει, θ 2> θ x) .~

dielectric constant, and the strength of an electric field is low

in a dielectric with a high dielectric constant, i. e. , D₂>Dι and Eι>E₂(since, if ε₂>ει, θ-2> θ .

Meanwhile, tubes, which consist of electric fluxes

diverging from the circumference of minute area ^S of a surface

of the charged conductor within a dielectric, are called electric

power tubes. Particularly among the electric power tubes, a tube

which charge within ^S is a unit value(1[C]) is called a Faraday

tube. The characteristics of the Faraday tube are as follows:

CD the number of electric fluxes within a Faraday tube is

constant;

(D there are positive and negative unit charges at the

opposite ends of a Faraday tube;

(D a Faraday tube is continuous at points of no true

charge;

the electric flux.

In addition, an energy of an electric field per a unit

volume in a dielectric of a dielectric constant ε is as the

following equation, i.e., W = E ^• D/2 = ε E²/2 = D/2 ε .

From the above-described relations, each electric flux

density becomes higher, and each electric field weaker, in the dielectric layers 11 of a high dielectric constant, and

contrariwise in the dielectric layers 12 of a low dielectric

constant.

Thus, each electric flux density and each electric field

are changed according to the present invention, and therefore each

electric field is concentrated on each discharge space, thereby

preventing decrease in discharging efficiency and danger such as

cross-talk.

In an embodiment as shown in Fig. 3, the dielectric layers

11 of a high dielectric constant having the relative dielectric

constant of 13 to 17 are formed only on upper surfaces of ITO

electrodes of the X electrodes 3 and the Y electrodes 4 except

those of the metal electrodes 3a and 4a and between the X

electrodes 3 and the Y electrodes 4. And, said dielectric layers

12 of a low dielectric constant having the relative dielectric

constant of 6 to 10 are formed on each upper surface of the metal

electrodes 3a and 4a on the X electrodes 3 and the Y electrodes 4

and on each upper surface of the black stripes 10, and between the

black stripes 10 and the metal electrodes 3a and 4a.

Even in case of such a structure, as in Fig. 2, each electric flux density becomes higher, and each electric field

weaker, in the dielectric layers 11 of a high dielectric constant,

and contrariwise in the dielectric layers 12 of a low dielectric

constant, so that each electric flux density and each electric

field are changed and therefore each electric field is

concentrated on each discharge space, thereby preventing decrease

in discharging efficiency and excluding danger such as cross-talk.

Here, the upper surfaces mean exposed surfaces during

manufacturing, and will be lower surfaces on the drawings.

In the above-description, two types of embodiments are

illustrated and explained, but the dielectric layers 12 of a low

dielectric constant are formed on at least the upper surfaces of

the black stripes 10 separating cells and the dielectric layers 11

of a high dielectric constant are formed on portions on at least

upper surfaces of ITO electrodes of the X electrodes 3 and the Y

electrodes 4 except those of the metal electrodes 3a and 4a,

thereby creating the above-describing effect of the present

invention. The dielectric layers 12 of a low dielectric constant

can be expanded onto the upper surfaces of the metal electrodes 3a

and 4a, and the present invention can be also applied to other types of plasma display panels.

By forming dielectric layers 12 of a low dielectric

constant on at least the upper surfaces of the black stripes 10

separating cells and dielectric layers 11 of a high dielectric

constant on at least upper surfaces of ITO electrodes of the X

electrodes 3 and the Y electrodes 4 except those of the metal

electrodes 3a and 4a, there are effects such that each electric

field can be concentrated on each discharge space and field

spreading to exert an influence on adjoining cells can be

prevented, according to the constructions and their acting effects

of the plasma display panel for preventing field spreading in the

above preferred embodiments of the present invention.

Claims

1. A plasma display panel for preventing field spreading, which

comprises a plurality of front electrode groups consisting of an X

electrode 3 and an Y electrode 4 formed on the rear surface of a

front substrate 1, black stripes 10 formed at the exterior of the

X electrodes 3 and the Y electrodes 4, metal electrodes 3a and 4a

formed on each of the X electrodes 3 and the Y electrodes 4,

address electrodes 5 formed on the interior surface of a rear

substrate 2 faced parallel to the front substrate 1 so as to form

a plurality of cells for display by discharge in each region

crossing with the front electrode groups, dielectric layers 6 and

7 formed on the front electrode group and the address electrodes

5, respectively, and a phosphor pattern 9 formed on the rear

dielectric layer 7 between barrier ribs 8, said plasma display

panel being characterized in that said dielectric layer 6

comprises dielectric layers 12 of a low dielectric constant with

the. relative dielectric constant of 6 to 10 formed on at least the

upper surfaces of the black stripes 10 and dielectric layers 11 of

a high dielectric constant with the relative dielectric constant

of 13 to 17 formed on portions except the dielectric layers 12 of a low dielectric constant.

2. A plasma display panel for preventing field spreading according

to claim 1, wherein the dielectric layers 11 of a high dielectric

constant are formed only on upper surfaces of the X electrodes 3

and the Y electrodes 4 except those of the metal electrodes 3a and

4a, and said dielectric layers 12 of a low dielectric constant are

formed between each upper surface of the metal electrodes 3a on

the X electrodes 3 and each upper surface of the metal electrodes

4a on the Y electrodes 4 covering each upper surface of the black

stripes 10.