Telephone subscriber listing device - is used for telephone installations either as integrated or as auxiliary unit with projection screen

摘要

A subscriber listing system (1) for telephone installations is made either as an auxiliary device or as an integrated unit fitted at telephone exchanges. The system includes a viewing screen onto which the subscriber lists originally duplicated or microfilms or on transparencies are projected using a lens and with either pass-throuh or reflected light. An automatic tip-up frame is used for auxiliary units and an endless band for the integrated unit. Auxiliary units have an external current supply whereas the integrated units have nickel cadmium cells charged through the subscriber's connecting lines.