Driving device for a document platen and copying machine incorporating a movable document platen

摘要

A document platen on which a document is placed is movably installed on the main body of a copying machine. A motor for producing a driving force is provided. An input gear to which the driving force is transmitted is located in a fixed position. A planetary gear is positioned such that it engages with and moves around the input gear. An endless gear is connected to the document platen. The endless gear has internal teeth in the form of a closed loop which engages with the planetary gear. When the planetary gear, which engages with both the input gear and the endless gear, moves around the input gear once, one reciprocating movement of the document platen is caused. With this configuration, since there is no need to provide a switching mechanism including clutches and solenoids that is used in a conventional device, the number of components is reduced, and thereby decreasing the manufacturing costs.