GB983630A - Projection lamp - Google Patents

Abstract

983,630. Incandescent electric lamps. SYLVANIA ELECTRIC PRODUCTS Inc. March 19, 1963 [March 9, 1962], No. 10849/63. Heading H1F. A lamp, especially for use in projection, has a filament coil acting as a light source and a second filament coil of more open pitch and of smaller diameter wire in series therewith to act as a ballast. The first coil is approximately at the focus of a reflector which may be within the lamp and the second coil is outside the focus. In one form, the first filament 1, Fig. 1, is mounted at the focus of a reflector 2 on support wires 4, 5 carried by a ceramic block 10, the wire 4 being connected by a wire 12 to a contact prong 13 on the lamp base. The second coil 3 is connected between the wire 5 and a support wire 6 connected through a fuse wire 7 to a wire leading to a contact prong 9. Two further prongs 14, 15 support the reflector 2. The fuse wire 7 may be embedded in a glass bead connecting the wires 6, 8, or the wires 6, 8 may be joined by the bead, the fuse wire passing outside the bead from the wire 6 to the prong 9. In another arrangement, the second filament is in two parts, each connected at one end to a lead-in wire and at the other to one of the support wires for the first filament. In the form shown in Fig. 9, the entire mount is supported by a glass bead 30 through which wires pass from the contact prongs 9, 13. The first filament is connected between one of these wires 5 and a wire 4 attached to a tab 40 extending outwards from the reflector 2. A second wire from the tab 40 carries one end of the ballast filament, the other end of which is connected to the second contact prong 13. The reflector is supported by an additional support wire 31 attached to the bead. Specification 906,752 is referred to.