Patent ID: 7054585

Claim:
An image forming apparatus, comprising: a belt-formed member supported by a plurality of supporting rollers; a plurality of opposing members arranged side by side in a line so as to oppose said belt-formed member and to be contacting or in close proximity to said belt-formed member; and a separation device configured to change a position such that said belt-formed member and a part of said plurality of opposing members, contacting or in close proximity each other, are separated; and a relative distance changing device configured to change a relative distance between at least one of the plurality of supporting rollers and other of the plurality of supporting rollers so as to suppress a change in a tension of said belt-formed member in said separation of said belt-formed member from a part of said plurality of opposing members, wherein: said relative distance changing device changes the relative distance between at least one of the plurality of supporting rollers and other of the plurality of supporting rollers such that said belt-formed member is spanned with a tension applied, and that a sum of (1) a length of said belt-formed member windingly in contact with a plurality of contacting members and (2) a non-contacting length of said belt-formed member between said contacting members where said belt-formed member is not in contact with any contacting member, does not change in said separation of said belt-formed member from a part of said plurality of opposing members.