US 8,897,672 B2Granted

Image forming apparatus capable of suppressing belt walk

AssigneeRicoh Company, Ltd.

InventorHiroaki Takagi

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Abstract

An image forming apparatus includes a belt stretched and wound around a driving roller and multiple driven rollers; multiple image formation units arranged in a running direction of the belt including photoconductors to form toner images of different colors; multiple transfer rollers opposed to the photoconductors via the belt; an engagement/disengagement device to bring at least one of the multiple transfer rollers in contact with and separate from the belt in accordance with an image formation mode; a steering controller to correct displacement of the belt in a widthwise direction by inclining one of the multiple driven rollers in a prescribed direction as a steering roller not to change a perimeter of the belt at least in a first image formation mode in which all of the multiple transfer rollers contact the belt; at least one position adjustment roller; and a belt position adjuster.

Claims20

Dependent claims

An image forming apparatus operable in multiple image formation modes, comprising:

a belt stretched and wound around a driving roller and multiple driven rollers;
multiple image formation units arranged in a running direction of the belt including photoconductors to form toner images of different colors on the photoconductors, respectively;
multiple transfer rollers opposed to a corresponding one of the photoconductors via the belt, respectively, the toner images on the photoconductors being successively transferred onto either the belt or a recording medium transported by the belt by the multiple transfer rollers, respectively;
an engagement/disengagement device to bring at least one of the multiple transfer rollers in contact with the belt and separate the at least one of the multiple transfer rollers therefrom in accordance with an image formation mode when the multiple image formation modes are switched;
a steering controller to correct displacement of the belt in its widthwise direction by inclining one of the multiple driven rollers in a prescribed direction as a steering roller not to change a perimeter of the belt at least in a first image formation mode in which all of the multiple transfer rollers contact the belt;
at least one position adjustment roller extending in the widthwise direction of the belt on the same side as the multiple transfer rollers at a region where a stretching posture of the belt varies when the multiple image formation modes are switched, the at least one position adjustment roller contacting the belt at a first given winding angle in a second image formation mode in which one of the multiple transfer rollers separates from the belt;
and
a belt position adjuster to adjust a position of the belt in its widthwise direction by inclining the at least one position adjustment roller in a prescribed direction not to change the perimeter of the belt in the second image formation mode.

5 more elements

A method of forming an image in an image forming apparatus that includes a belt stretched and wound around a driving roller and multiple driven rollers, multiple image formation units arranged in a running direction of the belt including photoconductors to form toner images of different colors on the photoconductors, respectively, multiple transfer rollers facing corresponding one of the photoconductors via the belt, respectively, and at least one position adjustment roller arranged in the widthwise direction of the belt on the same side as the multiple transfer rollers at a region where a stretching posture of the belt varies when multiple image formation modes are switched, the method comprising:

successively transferring the toner images from the photoconductors to either the belt or a recording medium transported by the belt by the multiple transfer rollers, respectively;
bringing at least one of the multiple transfer rollers with an engagement/disengagement device in contact with the belt or separating the at least one of the multiple transfer rollers therefrom in accordance with an image formation mode when the multiple image formation modes are switched;
bringing the at least one position adjustment roller in contact with the belt at a first given winding angle in a second image formation mode in which one of the multiple transfer rollers separates from the belt;
correcting displacement of the belt in its widthwise direction under control of a steering controller by inclining one of the multiple driven rollers in a prescribed direction as a steering roller not to change a perimeter of the belt at least in a first image formation mode in which all of the multiple transfer rollers contact the belt;
and
adjusting a position of the belt in the widthwise direction with a belt position adjuster by inclining the at least one position adjustment roller in a prescribed direction not to change the perimeter of the belt in the second image formation mode.

3 more elements

Dependencies are inferred from the claim text.