Image forming apparatus having image forming units that vary pressure against developer image carrier

An image forming apparatus, comprising:

• a developer image carrier that rotates and carries developer images in a carrying direction,
• a first image forming unit and a second image forming unit that are disposed along the carrying direction of the developer image carrier,
• a first transfer part that is arranged sandwiching the developer image carrier with the first image forming unit to transfers a developer image formed in the first image forming unit to the developer image carrier, a first pressing force toward the developer image carrier being generated with the first image forming unit,
• a second transfer part that is arranged sandwiching the developer image carrier with the second image forming unit to transfers a developer image formed in the second image forming unit to the developer image carrier, a second pressing force toward the developer image carrier being generated with the second image forming unit, wherein
• one of the first image forming unit and the first transfer part moves away from the develop image carrier so that the one of the first image forming unit and the first transfer part has two different positions, one position being defined as an image forming position at which the first pressure force is generated therebetween and the developer image is transferred, the other position being defined as a non-image forming position at which no first pressing force is generated therebetween and the developer image is not transferred,
• the image forming apparatus further comprises a pressing force variable mechanism that increases the second pressing force between the second image forming unit and the second transfer part when the one of the first image forming unit and the first transfer part moves from the image forming position to the non-image forming position, and
• when the one of the first image forming unit and the first transfer part is at the non-image forming position that is a position separated from the developer image carrier, the pressing force variable mechanism causes the second pressing force between the second image forming unit and the second transfer part to be increased while moving another of the first image forming unit and the first transfer part in the direction to further stretch the developer image carrier.