Pressure applying mechanism for fixing rollers of a copying apparatus

Claim 1

A pressure device for applying pressure between an upper fixing roller and a lower fixing roller of an image forming apparatus, said pressure device comprising: a holding arm member for supporting a rotary shaft of said lower fixing roller at each end thereof, said holding arm member including a bearing portion and two vertical arm elements projecting from said bearing portion of said holding arm member such that said holding arm member substantially resembles a "U", each of said vertical arm elements having an inwardly protruding portion formed on an inner wall thereof, said inner walls of said arm elements facing each other such that said protruding portions prevent said rotary shaft of said lower fixing roller from being inadvertently detached from said holding arm member; two horizontal stationary support plates located at each end of said lower fixing roller juxtapositioned to said rotary shaft adjacently disposed on respective sides of said vertical arm elements of said holding arm member, each support plate being provided with a shoulder portion substantially at the central portion thereof such that siad holding arm member is positioned between said support plates within said shoulder portions; biasing means located immediately below said respective bearing portions of said holding arm members for biasing said holding arm members upward so that said respective holding arm members may be engaged with said respective shoulder portions of said support plates; and means for preventing said biasing means from moving in a horizontal direction, said pressure applying device being provided at each end of said lower fixing roller whereby said upper and lower fixing rollers are held in pressure contact with each other through depression of said upper fixing roller towards and with said lower fixing roller.