Fixing unit and image forming apparatus

An image-forming apparatus having a function of fixing a toner image onto a sheet, comprising:

• a fixing belt threaded on at least two of supporting rollers;
• and
• a temperature-equalizing member equipped in a vicinity of a supporting roller, serving as one of said supporting rollers, to equalize a temperature distribution of said fixing belt in its width direction;
• a sheet-size detecting section to detect a size of said sheet currently selected;
• a temperature detecting section to detect a temperature of said temperature-equalizing member;
• and
• a controlling section to control a moving action of said temperature-equalizing member so that, when said sheet-size detecting section detects that said size of said sheet is small, said temperature-equalizing member pressure-contacts said fixing belt at a first contacting position, and to change a contact angle of said fixing belt, when said temperature detecting section detects that said temperature of said temperature-equalizing member exceeds a reference value.

An image forming apparatus having a function of fixing a toner image onto a sheet, comprising:

• a fixing roller, including a heater and a base body on which an elastic layer is formed;
• and
• a temperature-equalizing roller to equalize a temperature distribution of said fixing roller in its width direction;
• wherein said temperature-equalizing member can pressure-contact said fixing roller with a pressure-contacting force, and can be released from a pressure-contacting state;
• and
• wherein a value of said pressure-contacting force is selectable in a plurality of step values.

An image-forming apparatus having a function of fixing a toner image onto a sheet, comprising:

• a fixing roller, including a heater and a base body on which an elastic layer is formed;
• and
• a temperature-equaling roller unit, including a temperature-equalizing roller, and a shaft serving as a rotating axis of said temperature-equalizing roller;
• wherein said temperature-equalizing roller pressure-contacts said fixing roller at a pressure-contacting area, being equivalent to a partial length of said fixing roller, so as to equalize a temperature distribution of said fixing roller in its width direction;
• and
• wherein said temperature-equalizing roller is movably coupled to said shaft, so that said temperature-equalizing roller can move in a longitudinal direction of said shaft in order to change a length and/or a position of said pressure contacting area.

An image-forming apparatus having a function of fixing a toner image onto a sheet, comprising:

• a fixing roller, including a heater and a base body on which an elastic layer is formed;
• and
• a temperature-equalizing roller unit to equalize a temperature distribution of said fixing roller in its width direction;
• wherein said temperature-equalizing roller unit includes two temperature-equalizing rollers, a shaft serving as a rotating axis of said two temperature-equalizing rollers and a phase deviation preventive member to fix a mutual phase relationship between said two temperature-equalizing rollers in respect to said shaft;
• and
• wherein said two temperature-equalizing rollers are movable in a longitudinal direction of said shaft.

An image-forming apparatus having a function of fixing a toner image onto a sheet, comprising:

• a fixing roller, including a heater and a base body on which an elastic layer is formed;
• and
• a plurality of temperature-equalizing roller units, each of which includes a temperature-equalizing roller fitted on a shaft serving as a rotating axis of said temperature-equalizing roller, said temperature-equalizing roller pressure-contacting said fixing roller at a pressure-contacting area, being equivalent to a partial length of said fixing roller, so as to equalize a temperature distribution of said fixing roller in its width direction;
• wherein each of said temperature-equalizing roller units, pressure-contacts said fixing roller at a pressure contacting area, wherein said pressure-contacting areas are different relative to each other in length and/or position, corresponding to a plurality of pressure-contacting modes.

A fixing unit, comprising:

• a fixing roller;
• and
• a temperature-equalizing roller to equalize a temperature distribution of said fixing roller in its width direction;
• wherein said temperature-equalizing member can pressure-contact said fixing roller, and can be released from a pressure-contacting state;
• and
• wherein an angle, at which a rotating axis of said temperature-equalizing roller is inclined to that of said fixing roller, is changeable.