Gas filling method and device, and method for filling...

Fluent material handling – with receiver or receiver coacting mea – Processes – Gas or variation of gaseous condition in receiver

Reexamination Certificate

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C141S011000, C141S066000, C141S082000, C141S085000, C445S040000

Reexamination Certificate

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06189579

ABSTRACT:

This application is based on Japanese Patent Application No. 10-139320 filed May 21, 1998, which is incorporated herein by reference in its entirety.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for manufacturing a plasma display panel and particularly to a method for exhausting gas in a panel to fill discharge gas thereinto.
2. Description of the Related Art
A plasma display panel (hereinafter referred to as a PDP) is filled with discharge gas. To stabilize a discharge characteristic of the PDP, to reduce a driving voltage, and lessen a change in the discharge characteristic with time, the degree of purity of the discharge gas filled into the PDP must be enhanced.
To enhance the degree of purity of the discharge gas, the discharge gas is filled into the PDP by the following way.
First, a vent pipe is connected to a panel (cell) of the PDP. Next, the panel is heated and the interior of the panel is evacuated through the vent pipe so as to remove impurity gases such as water, nitrogen gas, carbon dioxide gas, etc. After removing impurity gases, the discharge gas is filled into the panel through the vent pipe, and finally the vent pipe is sealed.
However, in the aforementioned method, discharge gas is charged to the panel through the vent pipe where the impurity gases have been exhausted. For this reason, impurity gases adhered and absorbed on an inner wall of the vent pipe at an exhausting time are mixed into the discharge gas at the time of filling discharge gas into the panel with the result that impurity gases enter the interior of the panel again. Therefore, the mixing of impurity gases into the discharge gas cannot be prevented.
In order to reduce the amount of impurity gases in the discharge gas, there is proposed a gettering method in which impurity gases of the cell are absorbed by a getter formed of a ZrAl (zirconium aluminum) alloy, etc.
For example, Published Unexamined Japanese Patent Application (Kokai) No. Hei 4-269425 discloses a PDP manufacturing method having the following processes.
(1) A vent pipe having a getter in its interior is attached to a panel;
(2) The interior of the panel is exhausted to a vacuum state through the vent pipe;
(3) Discharge gas is introduced into PDP through the vent pipe;
(4) The vent pipe is chipped off (sealing due to heat-melting, cutting); and
(5) The panel is heated to diffuse mercury into the panel. During the use of the PDP, the getter absorbs impurity gases existing in the PDP as well as at an internal gas exhausting time, and a discharge gas introducing (filling) time.
Also, Published Unexamined Japanese Patent Application (Kokai) No. Sho 61-264654 discloses a gas filling method having the following processes though this relates to a technique of a plate-like fluorescent lamp.
(1) A vent pipe having a getter in its interior is connected to the fluorescent lamp;
(2) The interior of the fluorescent lamp is exhausted through the vent pipe;
(3) Discharge gas is introduced into the interior of the fluorescent lamp;
(4) The vent pipe is chipped off; and
(5) The getter is heated to diffuse mercury therefrom. The getter absorbs impurity gases existing in a fluorescent lamp during the use of the lamp as well.
However, if the method disclosed in Published Unexamined Japanese Patent Application No. Hei 4-269425 and the technique disclosed in Published Unexamined Japanese Patent Application No. Sho 61-264654 are applied to the PDP manufacture, the following problems will occur:
(1) The getter is left in the completed the PDP.
(2) In the PDP, the inner space of the panel is divided by walls into a plurality of discharge spaces each of which forms a picture element. For this reason, the gas flow worsens, and complete exhaust of impurity gases is difficult to be carried out. As a result, there is a high possibility that impurity gases will be left in the PDP.
(3) In addition to the point that the interior of the PDP is divided by the wall, discharge gas pressure in the PDP is high. For this reason, the gas circulation in the PDP worsens. Although the impurity gases are removed by absorption in the portion close to the getter, no absorption of impurity gases occurs in the portion away from the getter, and impurity gases are left as they are. For this reason, there is a case in which the driving voltage and luminance and brightness become unequal due to influence of impurity gases when an image is displayed using the PDP.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide method and device for filling gas containing less impurity gases to cells or panels.
It is further object of the present to provide a method for filling a plasma display panel with discharge gas without distribution of gas components.
In order to achieve the above object, according to a first aspect of this invention, there is provided a method for filling gas into a cell, comprising:
heating a cell to which at least one pipe where getters are arranged in a line is connected, and at least a portion of the pipe located between the cell and getters;
exhausting the interior (or evacuating the inner space) of the heated cell through the pipe;
activating the getters arranged in the pipe;
introducing gas into the cell through the pipe while removing impurities by the activated getters; and
cutting the pipe in the vicinity of the cell and sealing the cell after introducing gas.
According to the above-mentioned method, since the activated getters absorb impurities mixed into gas to be introduced into the interior of the cell, gas containing almost no impurity can be introduced into the cell.
The cell may comprise a plate-like panel having a space in its interior.
The cell may form a part of a plasma display panel, having electrodes for discharging arranged on its inner surfaces and a space into which gas is to be filled, and the gas to be filled into the cell may be a the discharge gas;
The getters may be of low-temperature activation type. In this case, the heating heats the cell, the getters and the portion of the pipe which is located between the cell and the getters.
The exhausting may exhaust gas from the cell through the heated and activated getters.
The getters may be of high-temperature activation type and non-vaporization type. In this case, the heating heats the cell and the portion of the pipe which is located between the cell and the getters, and the getter activating activates the getters by heating the getters.
In this case, the getter activating heats the getters by getter heating devices provided in the vicinity of the getters, to activate the getters.
The exhausting exhausts the cell until pressure of the cell reaches a predetermined value, and the gas introducing may introduce gas until pressure of the cell reaches the predetermined value.
The at least one pipe may include an exhaust pipe connected to the cell and an introduction pipe connected to the cell, the getters are arranged in the exhaust pipe, the exhausting exhausts gas from the cell through the exhaust pipe, and the gas introducing may introduce gas into the cell through the introduction pipe.
In this case, the exhausting may heat the cell and the portion of the exhaust pipe which is located between the cell and the getters so as to exhaust the cell, and heat a vicinity of the cell of the introduction pipe. Also, the introduction pipe has getters arranged in a line, and the heating may heat at least the cell and the portion of the exhaust pipe which is located between the cell and the getters, and a portion of the introduction pipe which is located between the cell and the getters.
In order to achieve the above object, according to a second aspect of this invention, there is provided a gas filling device, which exhausts an interior of a cell and fills gas into the cell after the end of exhaust, the gas filling device comprising:
a heating furnace in which the cell is to be provided;
an exhaust pipe to be connected to the cell provided in the heating furnace;
an exhausting device connected to the exhaust pipe;
an introduction p

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