Image forming apparatus including grooved cam and link mechanism engaging with grooves of the grooved cam

An image forming apparatus having an intermediate transfer member to which a toner image developed on a photosensitive material is transferred while the intermediate transfer member rotates plural times, and a transfer roller that is provided to be able to move into contact with and apart from the intermediate transfer member and transfers the toner image on the intermediate transfer member to a paper sheet while conveying the paper sheet pressed to the intermediate transfer member, the apparatus comprising:

• a grooved cam having different grooves formed respectively in front and back surfaces of the grooved cam, wherein
• a link mechanism for color image printing and a link mechanism for monochrome printing are reciprocated independently from each other, with ends of the link mechanism engaged respectively in the grooves of the grooved cam, thereby to control contact and separation of the transfer roller and the intermediate transfer member,
• wherein
• each of the link mechanism includes:
• a link member having one end engaged in one of the grooves of the grooved cam;
• and
• a lever member having one end pivoted, to be swingable, on the link member and the other end attached to an end of an axle of the transfer roller.