Image forming apparatus having moving mechanisms to move developing rollers to be in contact with and separated from photosensitive drums

An image forming apparatus comprising:

• a conveyor configured to convey a sheet along a conveyance path in a conveyance direction;
• a sheet tray configured to support a sheet;
• a pick-up roller configured to pick up the sheet supported on the sheet tray;
• a first photosensitive drum arranged along the conveyance path;
• a second photosensitive drum arranged along the conveyance path, the second photosensitive drum disposed downstream of the first photosensitive drum in the conveyance direction;
• a first developing roller being movable between a first contact position at which the first developing roller contacts the first photosensitive drum and a first separated position at which the first developing roller is separated from the first photosensitive drum;
• a second developing roller being movable between a second contact position at which the second developing roller contacts the second photosensitive drum and a second separated position at which the second developing roller is separated from the second photosensitive drum;
• a first moving mechanism configured to move the first developing roller from a first contact position to a first separated position and from the first separated position to the first contact position;
• a second moving mechanism configured to move the second developing roller from a second contact position to a second separated position and from the second separated position to the second contact position;
• and
• a controller configured to perform:
• a color print process for printing a color image on a sheet by using both the first developing roller and the second developing roller;
• a monochrome print process for printing a monochromatic image on a sheet by using only the second developing roller;
• in a first case where the color print process is executed for printing a color image on a sheet conveyed from the sheet tray:
• controlling the first moving mechanism to start moving the first developing roller from the first separated position toward the first contact position;
• controlling the pick-up roller to start picking up the sheet supported on the sheet tray after the controlling the first moving mechanism is executed;
• and
• controlling the second moving mechanism to start moving the second developing roller from the second separated position toward the second contact position after the controlling the pick-up roller is executed;
• and
• in a second case where the monochrome print process is executed for printing a monochromatic image on a sheet conveyed from the sheet tray:
• controlling the pick-up roller to start picking up the sheet supported on the sheet tray;
• and
• controlling the second moving mechanism to start moving the second developing roller from the second separated position toward the second contact position after the controlling the pick-up roller is executed.

An image forming apparatus comprising:

• a sheet tray;
• a pick-up roller configured to pick up a sheet on the sheet tray;
• a first photosensitive drum;
• a second photosensitive drum;
• a first developing roller being movable between:
• a first contact position at which the first developing roller contacts the first photosensitive drum;
• and
• a first separated position at which the first developing roller is separated from the first photosensitive drum;
• a second developing roller being movable between:
• a second contact position at which the second developing roller contacts the second photosensitive drum;
• and
• a second separated position at which the second developing roller is separated from the second photosensitive drum;
• and
• a controller configured to perform:
• when printing image on a sheet picked up from the sheet tray by using both the first developing roller and the second developing roller:
• starting moving the first developing roller from the first separated position toward the first contact position;
• after starting moving the first developing roller, starting picking up the sheet supported on the sheet tray by the pick-up roller;
• and
• after starting picking up the sheet, starting moving the second developing roller from the second separated position toward the second contact position;
• and
• when printing image on a sheet picked up from the sheet tray by using only the second developing roller:
• starting picking up the sheet supported on the sheet tray by the pick-up roller;
• and
• after starting picking up the sheet, starting moving the second developing roller from the second separated position toward the second contact position.