| 摘要 |
797,773. Electric incandescent lamps. INTERNATIONAL POLAROID CORPORATION. Feb. 9, 1956 [March 3, 1955], No. 4066/56. Class 39(2) The bulbs or envelopes of electric incandescent lamps are made either entirely of a polymeric plastic of the vinyl or condensation polymers having a high degree of molecular order and a softening temperature above 80‹C., or comprise a glass envelope with an inner lining or coating of a plastic of the said type. The example shows a "sealed beam" automobile headlamp comprising a front lens portion 12 and reflector portion 14 made entirely of the plastic material, moudded in two parts and force-fitted together around an: interlocking lip configuration A, the leading-in wires 18 having been embedded in the reflector portion 14 during moulding. A reflecting surface, e.g. of vaporized aluminium, may be provided on the inside wall of the reflector portion, or a separate metal reflector may be positioned on the outside surface thereof. The bulb may be evacuated and, if desired, filled with a gas or gaseous mixture. A preferred polymeric plastic is polychlorotrinuoroethylene; other examples are polytetrafluoroethylene, copolymers of chlorotrifluoroethylene and tetrafluoroethylene, vinylidene chloride resins &c., such materials being stated to have the advantage over glass in that they neither adsorb nor absorb gases or water vapour to any significant extent, thereby obviating the cyclical process whereby tungsten from the filament is systematically deposited on the inner wall of the envelope. |
