Reed switches and process for making them

The method of making a reed switch comprising forming a glass tube of substantially uniform, non-circular internal cross sectional configuration with precisely predetermined effective internal heightwise and widthwise dimensions and having at least one open end;

• forming an elongated reed element with an end-bearing portion at both ends, at least one of said ends being a contact section, said reed element ends having a maximum width to fit slidably but closely within said effective widthwise internal dimension of said tube, of a thickness less than half the effective heightwise internal dimension of said tube and of a length less than the length of said tube;
• bending said reed element intermediate its said ends beyond the memory of said reed element to form a sealing-bearing section displaced entirely from a reference plane defined by said end-bearing portions an amount to make the distance between the said reference plane and the farthest surface of said sealing-bearing section greater than the said effective heightwise internal dimension of the tube, said sealing-bearing section having a maximum width to fit slidably but closely within said effective widthwise dimension of said tube;
• forcing said reed element into said tube until both said end-bearing portions and said farthest surface of said sealing-bearing section bear upon the internal surface of said tube;
• softening the glass of said tube in the area of said sealing-bearing section of the reed element while maintaining the glass in the area of the end-bearing portions unsoftened to seal at least a part of said sealing bearing-section in said tube and to permit the said sealing-bearing section to move a part of said softened tube away from the said reference plane and to relieve at least part of the bearing force of the contact section end-bearing portion of the reed element, said reed element and tube constituting the sole means for positioning the reed element and tube with respect to one another during the sealing and relieving process.

The method of making a reed switch comprising forming a glass tube substantially rectangular in cross section and of uniform effective heightwise and widthwise dimensions throughout an envelope-forming length of said tube and having at least one open end;

• forming an elongate reed element of uniform cross section throughout its length with two end portions, at least one of which is a part of a contact section and an intermediate sealing section between and entirely out of a reference plane defined by said end portions, a bearing surface of said sealing section being displaced from said plane a distance greater than said effective internal heightwise dimension of said tube, said reed element being of a width to fit slidably but closely within the effective widthwise dimension of said tube;
• inserting said reed element into said open end of said tube sufficiently far to cause both of said end portions and said sealing section bearing surface to bear against the inside wall of said tube, the contact section end portion of said reed element bearing with a force greater than the force ultimately to be exerted by said portion in the finished switch;
• heating the full circumference of said tube through at least the full initial bearing area of said sealing section of the reed element to soften the glass of said tube in said area to cause said tube to collapse against and seal to said reed element sealing section and to cause the said sealing section to move away from said reference plane against the bias of said softened glass to relieve at least a part of the bearing pressure of said end-bearing portions on said tube wall, the tube wall at the said end-bearing portions being unsoftened, and thereafter cooling said glass, the said reed element and tube constituting the sole means for positioning the reed element and tube with respect to one another during said sealing and relieving process.