US 6,324,358 B1Granted

Image forming apparatus with multi-speed intermediate transfer member

AssigneeCanon Kabushiki Kaisha

InventorHiroshi Sahara

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Abstract

An image forming apparatus includes a plurality of image bearing members for bearing an image of plural colors, respectively, an intermediate transfer member and a controller for controlling the peripheral speed of the transfer member. For this apparatus, selection is made possible between a first mode of sequentially transferring the image of plural colors onto the intermediate transfer member by use of the plurality of image bearing members for the transfer of the image of plural colors on the intermediate transfer member to a transfer material, and a second mode of transferring a monochromatic image onto the intermediate transfer member by use of a predetermined image bearing member for the transfer of the monochromatic image to a transfer material. When the second mode is selected and the length of the monochromatic image in the moving direction of the intermediate transfer member is shorter than the distance from a first position of transferring the monochromatic image on the predetermined image bearing member onto the intermediate transfer member to a second position of transferring the monochromatic image on the intermediate transfer member to the transfer material in the moving direction of the intermediate transfer member, the controller switches the peripheral speed of the intermediate transfer member from a first speed of transferring the monochromatic image from the image bearing member to the intermediate transfer member to a second speed higher than the first speed during a predetermined time period.

Claims31

Dependent claims

An image forming apparatus comprising:

a plurality of image bearing members for bearing images of plural colors, respectively;
an intermediate transfer member;
and
control means for controlling a peripheral speed of said intermediate transfer member,
wherein a first mode in which the images of plural colors are sequentially transferred onto said intermediate transfer member by use of said plurality of image bearing members and the images of plural colors on said intermediate transfer member are transferred to a transfer material and a second mode in which a monochromatic image is transferred onto said intermediate transfer member by use of a predetermined image bearing member among said plurality of image bearing members and the monochromatic image on said intermediate transfer member is transferred to a transfer material are selectable, and
wherein when said second mode is selected and when a length of the monochromatic image along a moving direction of said intermediate transfer member is shorter than a distance along the moving direction of said intermediate transfer member from a first position in which the monochromatic image on said predetermined image bearing member is transferred onto said intermediate transfer member to a second position in which the monochromatic image on said intermediate transfer member is transferred to the transfer material said control means switches the peripheral speed of said intermediate transfer member from a first speed at which the monochromatic image is transferred from said image bearing member to said intermediate transfer member to a second speed higher than said first speed during a time period between a time when a transfer of a trailing end of the monochromatic image from said predetermined image bearing member to said intermediate transfer member is completed and a time before a leading end of the monochromatic image on said intermediate transfer member arrives at said second position.

3 more elements

An image forming apparatus comprising:

a plurality of image bearing members for bearing images of plural colors, respectively;
an intermediate transfer member;
and
control means for controlling a peripheral speed of said intermediate transfer member,
wherein a first mode in which the images of plural colors are sequentially transferred onto said intermediate transfer member by use of said plurality of image bearing members and the images of plural colors on said intermediate transfer member are transferred to a transfer material and a second mode in which a monochromatic image is transferred onto said intermediate transfer member by use of a predetermined image bearing member among said plurality of image bearing members and the monochromatic image on said intermediate transfer member is transferred to a transfer material are selectable, and
wherein when said second mode is selected and a length of a transfer material along a conveying direction is shorter than a distance along the moving direction of said intermediate transfer member from a first position in which the monochromatic image on said predetermined image bearing member is transferred onto said intermediate transfer member to a second position in which the monochromatic image on said intermediate transfer member is transferred to the transfer material, said control means switches the peripheral speed of said intermediate transfer member from a first speed at which the monochromatic image is transferred from said image bearing member to said intermediate transfer member to a second speed higher than said first speed during a time period between a time when a transfer of a trailing end of the monochromatic image from said predetermined image bearing member to said intermediate transfer member is completed and a time before a leading end of the monochromatic image on said intermediate transfer member arrives at said second position.

3 more elements

Dependencies are inferred from the claim text.