Fluorescent display device

Claim 1

A fluorescent display device comprising: a casing containing an evacuated chamber; a substrate disposed in said evacuated chamber, said substrate being formed of a thin layer of sheet glass; at least one display section formed on said substrate, said display section having a plurality of segments each comprising anode conductors having a phosphor layer deposited on the surface thereof; and a cathode stretched above said substrate for emitting electrons to be impinged upon said phosphor layer; wherein said casing comprises a front member for permitting external view of said segments and a rear member for forming a rear surface of said casing, said front member and said rear member being formed of a thin layer of limited-heat-treated reinforced glass having a strength of about 3.5 times that of sheet glass after formation of said casing, heat treatment of said glass being limited to that required at least for coating of an external electric field shielding film on said front member and assembling said front and rear members together to form said casing; and wherein said substrate is disposed in said evacuated chamber maintaining spaces between said front member and said substrate and between said substrate and said rear member said spaces allowing deformation of the front member and rear member without touching said substrate so that said substrate is not subject to external forces, said substrate being thinner than said front member.