Differential Pitch Helix Coil for Copier Lamp
Original Publication Date: 1989-Mar-01
Included in the Prior Art Database: 2005-Jan-29
In conventional copier lamps, when the lamp filament is coiled, and then formed into a vertical helix, the spacing of the coils is made uniform, as shown in Fig. 1. The lamp designer makes an attempt to keep the coils close together to form the compact light source needed for copier footprint uniformity. As the lamp operates, the tungsten creeps because of the high temperature that is needed for high light output, as shown in Fig. 2.