Abstract: Premising a duplex imaging apparatus having an image carrier provided with a plurality of image carrying regions, the image deterioration phenomenon (i.e., the so-called “oil ghost phenomenon”), as might otherwise accompany the local transfer of a releasing agent from a fixing unit to the image carrier, is effectively avoided.

Abstract: Image deterioration (so-called oil ghost) due to local transfer of a release agent from a fuser to an intermediate transfer body is effectively prevented. The fuser has a pair of fixing members, a release supply mechanism, an interlocking mechanism, and an interlocking control mechanism. The fixing members are in contact with each other and roll over each other, thus nipping a sheet. The fixing members fix unfixed images on the sheet. The release agent supply mechanism is mounted to at least the fixing member located on the surface of the sheet carrying an unfixed image. The release agent supply mechanism supplies a release agent to this fixing member at a constant rate. The interlocking mechanism interlocks the fixing members and release agent supply mechanism with each other such that the fixing members are kept in contact with each other and roll over each other and that a release agent is supplied to the fixing members.

Abstract: A toner image fixing device which has a satisfactory self-stripping ability to suppress the formation of creases of an envelope, and to prevent the abrasion of the elastic layers of a pair of toner image fixing rollers. In the fixing device, surface strain .di-elect cons.h in the circumferential direction of the first elastic layer of a first toner image fixing roller which comes in contact with a non-fixed toner image on a recording medium, and surface strain .di-elect cons.p in the circumferential direction of the second elastic layer of a second toner image fixing roller are defined by:.di-elect cons.h.gtoreq.0.0583 (.DELTA..di-elect cons.).sup.4 -0.6 (.DELTA..di-elect cons.).sup.3 +2.1917(.DELTA..di-elect cons.).sup.2 -3.65(.DELTA..di-elect cons.)+6where .di-elect cons.h<6%, .DELTA..di-elect cons..ltoreq.3% and .DELTA..di-elect cons.=.di-elect cons.h-.di-elect cons.p.