Ushio Denki Kabushiki Kaisha

Minoru Asao

Hiroshi Sugahara

Kenzo Kai

Masashi Dan

Katuhiko Miyahara

Yutaka Yamanizu

Katsuhiko Miahara

In order to provide an incandescent lamp in which an unlit state of the lamp caused by a hang-out of the coil as well as a short lifetime thereof are prevented using a simple construction and its lifetime in practical application is long, a coil ( )-like filament ( ) is held in a bulb ( ) by upholding parts ( &prime;) with an axis of the coil ( ) being oriented in a vertical direction, and a coil pitch of the coil ( ) at the upper part thereof is made narrow as compared with that of the lower part of the filament ( ). Or the filament ( ) of the incandescent lamp ( ) is constituted by the coil ( ) of a conical shape or that of a frustum of a circular cone, and the filament is arranged within the bulb ( ) in such a way that it may be held by upholding parts ( &prime;) with an axis of the coil ( ) of the filament ( ) being oriented in a vertical direction and the one end of the oil ( ) having a smaller diameter being positioned upward.

Coil filament structure for an incandescent lamp

In order to prevent a short lifetime of a lamp experiencing an extending downward of the coil under application stress when the coil is in a vertical configuration, there is provided an incandescent lamp in which a filament is stored in a bulb, and the filament is arranged in a vertical orientation and held by supporting element, where the filament is composed of a double coil in which a primary coil having a strand wound thereon is doubly wound, and the primary coil is more closely wound at the upper part of the filament than at the lower part of the filament.

Incandescent lamp filament

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Tatsuno, Japan

Minoru Asao