| 摘要 |
PROBLEM TO BE SOLVED: To provide an incandescent lamp more excellent in light collecting property and impact resistance than a practically used incandescent lamp by defining, in an incandescent lamp including a filament body having a plurality of single coil-shaped light emitting portions that are single coils wound in a flat cylindrical form and used while mounted within a reflector, an optimum range of specification of the filament body. SOLUTION: Each light emitting portion is disposed along an optical axis of the reflector at intervals in a direction intersecting the optical axis. In an x-y orthogonal coordinate system with a flatness [dimensionless] obtained by dividing the long axial length of the inner circumference of the light emitting portion by the short axial length on x-axis and the interval [mm] between light emitting portions on y-axis, the interval between light emitting portions is set to a value within an area vertically sandwiched between lines C5 and S5 (including on the lines C5 and S5) in Fig. 7 when the short axial length is at least 0.5 mm, and the flatness is more than 1 and 5 or less. COPYRIGHT: (C)2008,JPO&INPIT
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