Hinge mechanism for platen cover

摘要

A hinge mechanism of an image forming apparatus supporting a platen cover for holding an original at a fixed position on a platen glass includes a hinge unit for supporting the platen cover in such a manner that the platen cover can be opened and closed by swinging it up and down, a compression coil spring for biasing the platen cover in its opening direction, and a hinge holder attached to a housing of the apparatus for accommodating the compression coil spring. The hinge unit is provided with a hinge torque keeping mechanism which causes the compression coil spring to produce a specific amount of hinge torque to bias the platen cover in its opening direction even when the platen cover is closed.