Compact tilt and vibration sensor and method for manufacturing same

A compact tilt and vibration sensor, comprising:

• a case comprising a case body having a hollow portion that is open at a top thereof and a lid that hermetically seals the opening of said hollow portion, a plurality of three-dimensional electrodes formed of at least four electrically conductive coatings that are arranged in equally spaced relationship with each other on inner peripheral wall surfaces of said hollow portion and a conductive metal sphere that is freely movably received in said hollow portion and comes into contact with two adjoining electrodes of said three-dimensional electrodes to electrically interconnect both of the two adjoining electrodes, the case body being formed of a laminated structure constituted by vertically laminating and hermetically sealing a plurality of sheets that are individually made from low thermal expansion glass having a high gas barrier property and a high heat resistance property, and co firing the laminates at a low temperature, wherein when said case is tilted or vibrated, the conductive metal sphere is caused to move in said hollow portion so that the sensor is turned on/off by the moving displacement thereof, wherein:
• said conductive metal sphere comprises a spherical body without plating that is formed from hard gold alloy;
• the lid is formed of a low thermal expansion glass having a high gas-barrier property and a high heat resistance so that a motion of said conductive metal sphere in the hollow portion of said case body is checkable from the outside of said case through said lid with eyes;
• planar conductive coatings are formed on a bottom surface of the hollow portion of the case body and a lower surface of the lid as means for preventing and/or removing a static electricity charge of said conductive metal sphere;
• any impurities, such as moisture and fine dust, which adversely affect the on/off operation by the moving displacement of said conductive sphere, are removed from the hollow portion;
• and
• a gas having a high electrical insulation property is included in said hollow portion under the state in which it is depressurized at least to a predetermined degree of vacuum, wherein said conductive coating disposed on the bottom surface of said hollow portion of said case body is configured to be able to function as a common electrode.

A method for manufacturing a compact tilt and vibration sensor, the method comprising:

• forming a plurality of case bodies in a laminated structure which comprises a plurality of ceramics sheets vertically laminated and co-fired at a low temperature, each of said case bodies having a hollow portion that is open at the top and has electrodes formed of a plurality of conductive coatings arranged therein and flat connecting terminals formed of a plurality of conductive coatings on a lower surface of the bottom of the case body that are individually and electrically connected to the electrodes;
• forming conductive metal spheres of hard gold alloy and freely movably accommodating said spheres into the hollow portions of said case bodies;
• forming a planar conductive coating on a bottom surface of each hollow portion as a means for preventing and/or removing a static electricity charge of the conductive metal sphere;
• hermetically sealing the upper openings of said hollow portions by means of a low temperature expansion glass sheet having a high gas barrier property and a high heat resistance that forms a lid of said case bodies;
• simultaneously with the sealing step, removing moisture and impurities, such as fine dust, which adversely affect the on/off operation by the operation by the moving displacement of the conductive metal sphere from the hollow portion of each case body, and enclosing a gas that has high electrical insulation property and is depressurized at least to a predetermined degree of vacuum in the hollow portion;
• and
• a step of cutting the lid and the laminated ceramics sheets along crisscrossed dicing lines provided on said lid to obtain sensors as individual assemblies, wherein the conductive coating disposed on said bottom surface is configured such that said conductive coating functions as a common electrode.