Image forming apparatus and image forming method in which distances between image bearing members and transfer belt vary depending on mode

An image formation apparatus, comprising:

• a first image bearing member on which a toner image of a first color is to be formed;
• a second image bearing member on which a toner image of a second color is to be formed;
• a belt member onto which the toner images borne on the first image bearing member and the second image bearing member are to be transferred;
• a first transfer member configured to transfer the toner image formed on the first image bearing member onto the belt member;
• a second transfer member configured to transfer the toner image formed on the second image bearing member onto the belt member;
• a first moving unit configured to move the first transfer member so as to displace the belt member between a contact state, in which the belt member is in contact with the first image bearing member, and a separated state, in which the belt member is separated from the first image bearing member;
• a second moving unit configured to move the second transfer member so as to displace the belt member between a contact state, in which the belt member is in contact with the second image bearing member, and a separated state, in which the belt member is separated from the second image bearing member;
• and
• a controller configured to:
• control, in a monochrome image forming mode for forming the toner image of the second color without forming the toner image of the first color, the first moving unit and the second moving unit such that the belt member is in a separated state from the first image bearing member by a first distance and in a contact state with the second image bearing member;
• control, in a color image forming mode for forming the toner image of the first color and the toner image of the second color, the first moving unit and the second moving unit such that the belt member is in a contact state with the first image bearing member and the second image bearing member;
• and
• control, in a standby mode for standing by for the image formation to start, the first moving unit and the second moving unit such that the belt member is in a separated state from the first image bearing member by a second distance, which is shorter than the first distance, and in a contact state with the second image bearing member.

A method to be executed by an image forming apparatus,

• the image forming apparatus comprising:
• a first image bearing member configured to bear a toner image;
• a second image bearing member configured to bear a toner image;
• a belt member onto which the toner images borne on the first image bearing member and the second image bearing member are to be transferred;
• a first transfer member configured to transfer the toner image borne on the first image bearing member onto the belt member;
• a second transfer member configured to transfer the toner image borne on the second image bearing member onto the belt member;
• a first moving unit configured to move the first transfer member;
• the first image bearing member and the second image bearing member capable of being abutted against the first transfer member and the second transfer member, respectively, through intermediation of the belt member, to thereby transfer the respective toner images onto the belt member,
• the image forming apparatus being operable in an image forming mode in which an image is formed and a standby mode in which an image is not formed, and further being operable in a color mode for forming a color image and a monochrome mode for forming a monochrome image when operating in the image forming mode,
• wherein the method comprises:
• controlling the first moving unit to move the first transfer member such that:
• in the monochrome mode, the belt member is located at a first position at which the belt member is separated from the first image bearing member;
• in the color mode, the belt member is located at a second position at which the belt member is in contact with the first image bearing member;
• and
• in the standby mode, the first transfer member is located at a predetermined position between the first position and the second position, and
• wherein the belt member is in contact with the second image bearing member in the image forming mode and the standby mode.

A method to be executed by an image forming apparatus,

• the image forming apparatus comprising:
• a first image bearing member on which a toner image of a first color is to be formed;
• a second image bearing member on which a toner image of a second color is to be formed;
• a belt member onto which the toner images borne on the first image bearing member and the second image bearing member are to be transferred;
• a first transfer member configured to transfer the toner image formed on the first image bearing member onto the belt member;
• a second transfer member configured to transfer the toner image formed on the second image bearing member onto the belt member;
• a first moving unit configured to move the first transfer member so as to displace the belt member between a contact state, in which the belt member is in contact with the first image bearing member, and a separated state, in which the belt member is separated from the first image bearing member;
• and
• a second moving unit configured to move the second transfer member so as to displace the belt member between a contact state, in which the belt member is in contact with the second image bearing member, and a separated state, in which the belt member is separated from the second image bearing member;
• wherein the method comprises:
• controlling the first moving unit to move the first transfer member and controlling the second moving unit to move the second transfer member such that:
• in a monochrome image forming mode for forming the toner image of the second color without forming the toner image of the first color, the first moving unit and the second moving unit are controlled such that the belt member is in a separated state from the first image bearing member by a first distance and in a contact state with the second image bearing member;
• in a color image forming mode for forming the toner image of the first color and the toner image of the second color, the first moving unit and the second moving unit are controlled such that the belt member is in a contact state with the first image bearing member and the second image bearing member;
• and
• in a standby mode for standing by for the image formation to start, the first moving unit and the second moving unit are controlled such that the belt member is in a separated state from the first image bearing member by a second distance, which is shorter than the first distance, and in a contact state with the second image bearing member.