Discharge type surge absorbing element and method for making the same

A discharge-type surge absorbing element wherein:

• a plurality of discharge electrodes connected to lead wires are disposed opposite to each other within a sealed container filled with discharge gas, thus forming discharge gaps between said discharge electrodes;
• said lead wires from said discharge electrodes are passed through said sealed container so that said lead wires extend externally;
• a layer having good creeping discharge properties is formed on an inner surface of said sealed container at least between said lead wires, said layer being formed from a material used in said discharge electrodes;
• and
• a notch cut out from a part of said layer is formed on said inside surface of said sealed container at least between said lead wires.

A discharge-type surge absorbing element wherein:

• a sealed container is formed by a case having two open ends, each of said openings being connected to a discharge electrode, which also serves as a cover;
• a discharge gap is formed between ends of said discharge electrodes within said sealed container;
• said sealed container is filled with a discharge gas;
• a layer having good creeping discharge properties is formed on an inner surface of said case;
• and
• a very small gap is formed between said discharge electrode and an end of said layer.

A method for making a discharge-type surge absorbing element wherein:

• a plurality of discharge electrodes connected to lead wires are disposed opposite to each other within a sealed container filled with discharge gas, thus forming discharge gaps between said discharge electrodes;
• said lead wires from said discharge electrodes are passed through said sealed container so that said lead wires extend externally;
• a layer having good creeping discharge properties is formed on an inner surface of said sealed container at least between said lead wires;
• a very small gap is formed between said lead wire and an end of said layer;
• said discharge electrode is heated in a depressurized nitrogen atmosphere so that a material making up said discharge electrode melts, scatters and oxidizes;
• said oxidized material covers an inner surface of said sealed container, forming said layer;
• and
• said inner surface of said sealed container is melted in an area where said lead is connected, thus preventing said oxidized material from adhesing to a surface of said connecting area, and forming said very small gap.

A method for making a discharge-type surge absorbing element wherein:

• a plurality of discharge electrodes connected to lead wires are disposed opposite to each other within a sealed glass container filled with discharge gas, thus forming discharge gaps between said discharge electrodes;
• said lead wires from said discharge electrodes are passed through said sealed container so that said lead wires extend externally;
• a layer having good creeping discharge properties is formed on an inner surface of said sealed container at least between said lead wires;
• a notch eliminated from a portion of said layer is formed on said inner surface of said sealed container at least between said lead wires;
• said discharge electrode is heated in a depressurized nitrogen atmosphere so that a material making up said discharge electrode melts, scatters and oxidizes;
• said oxidized material covers an inner surface of said sealed container, forming said layer;
• and
• a laser beam is applied from outside said sealed container to evaporate a portion of said layer formed on said inner surface of said sealed container, thus forming said notch.

A method for making a discharge-type surge absorbing element wherein:

• an emitter material is applied to a surface of a plurality of shaft-shaped electrode bases connected to lead wires;
• said electrode bases are disposed within a container so that said bases are facing each other and are separated by a discharge gap;
• a middle portion of said lead wires is fixed to said container and an end of said lead wires is extended out from said container;
• heat is applied and evacuation of the contents of said container is performed;
• said heat application thermally decomposes said emitter material, forming an emitter layer on a surface of said electrode bases, and melts said surface of said electrode base;
• said evacuation procedure causes depressurization, scattering the material making up said electrode bases;
• of said scattered material from said electrode bases, the material that is oxidized during scattering is adhesed to said inner surface of said container, thus forming a layer on said inner surface of said container at least between said lead wires;
• the material not oxidized during scattering form a plurality of secondary discharge electrodes comprising particles or lumps scattered on a surface of said layer;
• this forms secondary discharge gaps between said lead wires which are more narrow than said discharge gap;
• said container is filled with discharge gas and said container is sealed;
• said emitter material is adhesed to an end of said electrode base to form said emitter layer;
• said emitter material is not present at a surface of an end of said electrode base connected to a lead wire, thus forming an exposed portion;
• said heat application and evacuation melts and scatters the surface of said exposed portion, thus forming said layer and said secondary electrodes.