Patent ID: 6493525
Filing Date: 2002-12-10
Classification: G03G

Abstract:
An image forming apparatus comprising:an image forming section including at least a photoconductive element, a fixing unit, a developing unit, and a heat discharge fan; and a controller for selectively stopping a rotation of said heat discharge fan for a moment or controlling a rotation speed of said heat discharge fan, and for selectively raising or lowering a fixing temperature in each of a sheet feed mode and a standby mode, wherein said controller causes, when a thin sheet is to be fed after an ordinary sheet fed last time, sheet feed to wait until the fixing temperature has been lowered, rotates said heat discharge fan at a higher speed than during sheet feed for a preselected period of time to thereby rapidly lower said fixing temperature to a preselected temperature or stops, when an ordinary sheet is to be fed after a thin sheet fed last time, the rotation of said heat discharge fan to thereby raise said fixing temperature as rapidly as possible, and wherein when said heat discharge fan is rotating at a usual speed when the sheet feed mode is replaced with the standby mode, the fixing temperature in said standby mode is T in the event of a replacement of said standby mode with said sheet feed mode, said fixing temperature in said sheet feed mode is t, when said temperature T is higher than said temperature t occurring when said fixing temperature is lowered at the time of transition from said standby mode to said sheet feed mode, an allowable temperature difference is tdown, and when said temperature T is lower than said temperature t occurring when said fixing temperature is to be raised at the time of transition from said standby mode to said sheet feed mode, an allowable temperature difference is tup, then said controller rotates said heat discharge fan at a higher speed than during usual sheet feed when a difference Tâˆ’tdown is greater than t, or rotates said heat discharge fan at a usual speed when said difference Tâˆ’tdown is equal to or smaller than t, which is in turn equal to or smaller than a sum T+tup, or stops the rotation of said heat discharge fan for a moment when said sum T+tup is smaller than t.