Image reading device

An image reading device comprising:

• a supply tray configured to support a sheet to be supplied, the supply tray including a movable plate that is configured to be movable from a first position to a second position according to a decrease in the number of the sheet to be supported by the supply tray, the second position being higher than the first position;
• a discharge tray positioned below the supply tray, the discharge tray being configured to support the sheet to be discharged;
• a conveyance guide configured to convey the sheet from the supply tray to the discharge tray;
• a reading sensor configured to read an image on the sheet to be conveyed on the conveyance guide;
• a discharge guide including a discharge opening for discharging the sheet conveyed by the conveyance guide to the discharge tray, the discharge guide being configured to be movable from a third position to a fourth position according to the decrease in the number of the sheet to be supported by the supply tray, the fourth position being higher than the third position;
• a discharge roller configured to discharge the sheet through the discharge opening;
• a first drive source configured to generate a drive force;
• and
• a first drive train configured to transmit the drive force from the first drive source to the discharge roller,
• wherein the first drive train transmits the drive force from the first drive source to the discharge roller when the discharge guide moves from the third position to the fourth position, the discharge roller being configured to discharge the sheet through the discharge opening by receiving the drive force from the first drive source
• wherein the discharge roller is rotatable around a first axis center whose position changes according to movement of the discharge guide from the third position to the fourth position, and
• wherein the first drive train includes:
• a first rotation body that is rotatable around the first axis center together with a rotation shaft of the discharge roller;
• and
• a second rotation body that is rotatable around a second axis center which is parallel to the first axis center and whose position is constant, the second rotation body being configured to transmit the drive force from the first drive source to the first rotation body, and
• wherein the discharge guide is rotatable around the second axis center, and
• wherein the second rotation body is rotatable independently of the discharge guide.