JPH04342926A - Gas discharge type display panel - Google Patents

Abstract

PURPOSE:To provide a gas discharge type display panel consuming a low electric power and presenting good displaying quality by improving the cathode material for plasma display which displays letters and figures through utilization of gas electrodisharge. CONSTITUTION:As the material for cathode 3, an oxide type conductor is used which has such a characteristic that its electric resistance increases with rising temp. in the temp. range from 20 deg.C to 500 deg.C.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas discharge type display panel that displays characters, figures, etc. using gas discharge.

0002

[Prior Art] The cathode of a conventional gas discharge display panel is
It is created by screen-printing Ni paste on a glass substrate and firing it in air.The cathode made with such Ni paste has a relatively high discharge starting voltage and minimum discharge sustaining voltage, and has a sufficient It cannot be said that it is a cathode material.

[0003] In recent years, in order to solve this problem, a work function of 2.66 eV, which is smaller than Ni's work function of 5.24 eV, has been developed.
A cathode using LaB6 has been developed. This type of technology is described in, for example, the Television Society Technical Report IDP59-10 (1981).

However, LaB6, which is originally a good conductor in bulk, has the characteristic that it tends to form an oxidized layer on its surface, and when it is made into small particles of several μm in size for use in screen printing paste, its surface area decreases. As a result, the area of the oxide layer increases, and the electrical conductivity in a macroscopic sense decreases significantly after firing, resulting in the problem that the original properties of LaB6 cannot be utilized.

In order to solve this problem, oxide conductors having a perovskite structure, such as La1-X Sr
The applicant has proposed a cathode using materials such as X CoO3 and La1-X SrX MnO3 (referred to as cobaltate). By using such an oxide conductor, deterioration of conductive properties due to oxidation can be prevented, and since the oxide conductor has a high secondary electron emission rate,
This has the effect that the discharge starting voltage and the minimum discharge sustaining voltage can be lowered.

[0006]

[Problems to be Solved by the Invention] However, such oxide conductors, La1-X SrX MnO3,
Or LaB6 has a similar problem. That is, the electrical resistance of the material decreases as the temperature rises.

[0007] Although the resistance/temperature characteristics of LaB6 are metallic in that the resistance increases as the temperature rises in the bulk, the resistance/temperature characteristics of the LaB6 cathode made by the screen printing process are as follows: The resistance decreases as the resistance decreases, which is the opposite of the bulk characteristic. Moreover, La1-X SrX MnO3 is
Originally, it has semiconductor-like resistance/temperature characteristics, and such temperature change characteristics cause a big problem in gas discharge type display panels.

[0008] The cathode portion of the display panel has some variation even within one cell. Naturally, electrons flowing through the cathode toward the cathode portion exposed to the gas space pass through areas with low resistance in a microscopic sense. On the other hand, in the light emitting state of a gas discharge type display panel, gas ions collide with the cathode, electrons are emitted from the cathode, and the electrons ionize the gas again, a process repeated. At this time, the temperature of the minute portion of the cathode that the ions collide with rises instantaneously. Therefore, when using a cathode material such as Ni whose resistance increases as the temperature rises, the temperature of the area where ions collide at a certain moment increases, and the electrons that flow next move to other areas where the temperature is relatively lower. It becomes easier to concentrate. For this reason, in the Ni cathode, electrons flow on average to all the cathode parts in one cell, and light is emitted uniformly over the entire surface of one cell.

However, in the case of a cathode material with resistance/temperature characteristics such as LaB6, the resistance decreases as the temperature rises, so the cathode part that is bombarded with ions at a certain moment has a relatively low resistance compared to other parts. resistance decreases. This makes it easier for the next inflow of electrons to concentrate in that area again. Concentration of the electron flow also causes a rise in temperature in that area, causing further concentration of electrons. When this process is repeated, the electron emitting portion of the cathode is concentrated at one point. As a result, light emission within one cell occurs only in a certain part.

The present invention solves such conventional problems, and the discharge starting voltage and the minimum discharge sustaining voltage are
It is an object of the present invention to provide a gas discharge type display panel equipped with a cathode that maintains good conductivity even when fired in an air atmosphere and does not cause concentration of light emitting parts in one cell. shall be.

[0011]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a cathode of a gas discharge type display panel that is
It is made of an oxide conductor whose electrical resistance increases as the temperature rises in a temperature range of 500° C. or higher and 500° C. or higher.

0012

[Function] Therefore, according to the present invention, since the cathode is formed of an oxide conductor, there is no increase in electrical resistance due to oxidation, and the secondary electron emission efficiency is high.
The minimum discharge sustaining voltage can be lowered. Furthermore, since the electrical resistance has a characteristic of increasing as the temperature rises, it is possible to prevent the light emitting parts from being partially concentrated in one cell.

[0013] The numerical limitations on temperature in the present invention are based on the lower limit being room temperature and the upper limit being the firing temperature at which the oxide conductor is obtained.

[0014]

[Example] Hereinafter, an example of the present invention will be described in which La0.5 Sr0.5 having a perovskite structure is used as the cathode material.
The case where 5 CoO3 is used will be explained.

As starting materials, nitric acid solutions of La, Sr, and Co are mixed in an elemental ratio of La=0.5, Sr=0.5, and Co=1, and each solution is mixed with oxalic acid and ethanol. Drop into the mixture to form each oxalate precipitate. Dry this precipitate at 70°C, mix the dried solids,
Heat at 500°C for 3 hours in an air atmosphere using an electric furnace. In this way, unnecessary oxalate is thermally decomposed, and La,
Create oxides of Sr and Co. And this oxide is 500
By firing at 1300°C for 5 hours in an oxygen stream introduced at 300cc/min at a temperature higher than °C,
Obtain cobaltite crystals. Since the powder after firing has particles bonded together, it is ground to a size of several micrometers or less using a mortar, a ball mill, or the like.

Next, a procedure for producing a gas discharge type display panel using the above cobaltite powder will be explained. First, by the generally known three-roller method, the cobaltite powder prepared by the above procedure, the alkali glass powder, and the organic solvent are adjusted to an appropriate viscosity, and the bonded particles are sufficiently loosened to form a paste. create. Next, as shown in FIG.
Screen print the paste and bake it to form the Ni base electrode 2.
form. The cathode 3 of this embodiment is placed on this Ni base electrode 2.
Cobaltite paste is laminated by screen printing. After that, it is dried at 100°C and then baked at 550 to 660°C for 30 minutes in an air atmosphere. The back glass substrate 1 on which the cathode 3 was formed in this way and the front glass substrate 6 on which the anode, which is a transparent electrode, and the partition wall 5 were provided were stacked together with the partition wall 5 interposed therebetween, and the surrounding area was fired using a glass frit. and seal it. After that, the inside of the discharge space 7 is evacuated to a high vacuum, and gases such as Ne-Ar, Ne-Xe, etc.
A gas discharge type display panel is created by introducing 0 to 500 torr.

As described above, regarding the discharge characteristics of the gas discharge type display panel obtained using La0.5 Sr0.5 CoO3 of this example formed on the Ni base electrode 2, LaB6 was formed on the Ni base electrode 2. Compare with the formed conventional example.

FIG. 2 schematically shows one discharge cell in a discharge panel, with the total area within the cell being taken as 100%, and is a diagram obtained by observing the area in which discharge is actually occurring using a microscope. As is clear from this figure, in the case of the conventional example, discharge does not occur in the corner areas, and the area ratio of the discharge area is 70%, whereas
It can be seen that in this example, discharge occurs over the entire area within the cell.

FIG. 3 shows the temperature characteristics of the resistance of each of the above electrode materials. As is clear from this figure, the conventional example exhibits a semiconductor-like tendency in which the resistance decreases as the temperature rises, whereas the present example exhibits metallic characteristics in which the resistance increases with temperature. .

On the other hand, the cathode formed of La0.8 Sr0.2 CoO3 having the same perovskite structure has different resistance/temperature characteristics from this example, and has the characteristic that the electrical resistance decreases as the temperature rises. In FIG. 2, the area ratio of the discharge portion was 70%, similar to the conventional example.

[0021]

As described above, according to the present invention, the cathode is made of an oxide conductor having a property that the electrical resistance increases as the temperature rises in the temperature range of 20°C or higher and 500°C or lower, compared to the conventional method. Compared to the above, it is possible to obtain a gas discharge type display panel having a lower minimum discharge sustaining voltage and a lower discharge starting voltage, and in addition, a good display quality in which the discharge area in the cell is not biased.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a gas discharge display panel according to an embodiment of the present invention.

FIG. 2 is a schematic diagram illustrating the bias of the discharge area within one discharge cell for comparing the present example and the conventional example.

[Figure 3] Characteristic diagram showing the resistance/temperature characteristics of the electrode material for comparison between this example and the conventional example

[Explanation of symbols]

1　Back glass substrate 2 Ni base electrode 3 Cathode 4 Anode 5 Partition wall 6 Front glass substrate 7 Discharge space

Claims (2)

[Claims] 1. A gas discharge type display panel comprising a cathode formed of an oxide conductor having a characteristic that electrical resistance increases as temperature rises in a temperature range of 20° C. or higher and 500° C. or lower. 2. The gas discharge display panel according to claim 1, wherein the oxide conductor has a perovskite structure.