When a first roller is in an operation state, a driving device displaces a second displacement member in a first direction. This displaces a second locking portion of a slide portion to a position to lock a first projection portion of a first roller support member and a second projection portion of a second roller support member, while a first displacement member is held at a first position. The driving device further displaces the second displacement member in a second direction and stops the second displacement member. This allows the first displacement member to be displaced from the first position to a second position, and the second displacement member is further displaced and stopped at a position where the second projection portion is inserted in the recessed portion of the slide portion. This allows a second roller to enter an operation state.

A controller can select and execute a full color mode of performing image formation in a first state in which each primary transfer member is in contact with an intermediate transfer belt, and a monochrome mode of performing image formation in a second state in which only a primary transfer member is in contact with the intermediate transfer belt. The controller determines which state of the first state and the second state is formed, based on a detection result obtained by a current detection circuit when a photosensitive drum is charged by a charging roller, and voltage is applied to the primary transfer member from a primary transfer power source.

An example method of printing images in an electrophotographic printer is provided. The method includes developing a first image on a first portion of an intermediate transfer member by receiving a first sequence of color separations from a photo imaging member, and developing a second image on a second portion of the intermediate transfer member by receiving a second sequence of color separations from the photo imaging member. A voltage is applied to the intermediate transfer member during receipt of each color separation from the photo imaging member. During development of the second image at least one null separation is inserted into the second sequence of color separations. During a period for the null separation, a voltage applied to the intermediate transfer member is reduced and the first image is transferred to a conductive substrate.

An image forming apparatus includes a transport belt, a first intermediate transfer belt, and a second intermediate transfer belt. The transport belt is disposed along a transport path extending in a vertical direction. The transport belt is configured to transport a recording medium while coming into contact with one surface of the recording medium. The first intermediate transfer belt is configured to sandwich the recording medium together with the transport belt. An image is transferred from the first intermediate transfer belt to the recording medium. The second intermediate transfer belt is disposed above the first intermediate transfer belt. The second intermediate transfer belt is configured to sandwich, together with the transport belt, the recording medium which is in a state where the recording medium is sandwiched between the first intermediate transfer belt and the transport belt. An image being transferred from the second intermediate transfer belt to the recording medium.

An image forming apparatus includes an image carrier, a transfer member, a registration roller pair, and a conveyance guide which includes a first conveyance guide and a second conveyance guide. The second conveyance guide has a main body portion and a shaft member. The shaft member is held by a shaft holding portion of the main body portion so as to be reciprocatable between a first position which is a most downstream-side position and a second position on an upstream side of the first position. When a first recording medium is conveyed, the shaft member is arranged at the first position such that a distance between the shaft member and the first conveyance guide is a predetermined distance. When a second recording medium is conveyed, the shaft member is arranged at the second position such that the distance between the shaft member and the first conveyance guide is increased.

A pressing device includes a cam member 120, a bearing 120a, a cam portion 120b, a cam engaging portion 120c of snap fit fashion. The bearing 102a is rotatably supported by a fixation frame 115. The cam portion 120b is provided on one side of the bearing 120a and contacts a pressing lever. The cam engaging portion 120c is provided on the other side of the bearing 120a and engages with a hole 123a formed on an outer surface of a cam shaft 123. The cam engaging portion 120c engages with the hole 123a at a position away from a maximum load portion of the cam portion 120b by not less than 90 degrees phase different.

An image forming apparatus includes a plurality of image forming portions, an intermediate transfer belt, a primary transfer member, a secondary transfer roller, a counter roller, and a charge eliminating device. The counter roller is pressed against the secondary transfer roller via an intermediate transfer belt to thereby form a secondary transfer nip portion. The charge eliminating device includes a charge eliminating needle that is disposed with an end part thereof pointing to a downstream side in a conveyance direction of the recording medium, and that is grounded, and a charge eliminating needle protection cover that has a guide surface that is opposed to the recording medium having passed through the secondary transfer nip portion. The guide surface is formed of a conductive material having a resistance value of 10.sup.6 or lower, and is in a floating state.

An image forming apparatus includes a transport belt, a first intermediate transfer belt, and a second intermediate transfer belt. The transport belt is disposed along a transport path extending in a vertical direction. The transport belt is configured to transport a recording medium while coming into contact with one surface of the recording medium. The first intermediate transfer belt is configured to sandwich the recording medium together with the transport belt. An image is transferred from the first intermediate transfer belt to the recording medium. The second intermediate transfer belt is disposed above the first intermediate transfer belt. The second intermediate transfer belt is configured to sandwich, together with the transport belt, the recording medium which is in a state where the recording medium is sandwiched between the first intermediate transfer belt and the transport belt. An image being transferred from the second intermediate transfer belt to the recording medium.

A position of a stretch roller, where the stretch roller stretches an intermediate transfer belt upstream of and adjacently to a most upstream primary transfer roller in a rotational direction of the intermediate transfer belt, is apart from a photosensitive drum with respect to a primary transfer surface. Further, the most upstream primary transfer roller is larger in outside diameter than other primary transfer rollers, and the most upstream primary transfer roller has a transfer pressure larger than the transfer pressure of the other primary transfer rollers. This arrangement inhibits the most upstream primary transfer roller from deforming and a defective transfer due to waving of the intermediate transfer belt, while inhibiting an increase in size of an apparatus.

In an image forming apparatus of a direct transfer system, when in a region where a transfer nip portion of a photosensitive drum is formed, a region in which the toner image can be formed is defined as a first region, and a region where the recording medium does not pass while the recording medium is conveyed by the transfer nip portion is defined as a second region, in forming the toner image on the recording medium, the photosensitive drum enters the transfer nip portion in a state where the second region of the photosensitive drum includes a region in which an absolute value of a surface potential is smaller than an absolute value of a surface potential of a region in which the toner image is not formed in the first region.