Importance

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Abstract

An electric lamp having a coiled filament and at least one intermediate filament support which effectively restrains the filament from excessive swaying or sagging whereby premature lamp failure because of electrical shorting of the filament or thermal shocking of the glass envelope is substantially reduced. The intermediate filament support includes at least one flat segment interposed between two adjacent turns of the outermost coil of the filament. The maximum thickness of the flat segment is less than the winding separation of adjacent turns of the outermost coil. In preferred embodiments of the invention, the intermediate support encloses but does not grasp the filament so that no coil of the filament, inner or outer, is distended in the process of closing the support about the filament. A support in accordance with the invention effectively restrains filament movement in directions along and normal to the filamentary axis. The invention may be employed, singly or in multiples, in any incandescent lamp or any lamp employing an incandescent filament and is particularly appropriate for filaments designed to operate at relatively high voltages as is the situation in many European applications.

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First Claim