Sheet stacking apparatus and image forming apparatus

A sheet stacking apparatus comprising:

• a discharging portion that discharge a sheet;
• a moving portion that moves the sheet to the downstream side in the sheet discharging direction while holding a downstream end portion of the sheet, discharged by the discharging portion, in a sheet discharging direction;
• a stacking portion on which the sheet is stacked;
• a positioning unit that positions a downstream end of the sheet, which is to be stacked on the stacking portion, in the sheet discharging direction;
• and
• a control portion that controls the discharging portion and the moving portion,
• wherein the control portion controls to separate the sheet from the moving portion while moving with the held sheet before a downstream end portion of the sheet, in a sheet discharging direction, reaches the positioning unit.

An image forming apparatus comprising:

• an image forming portion that forms an image on a sheet;
• a sheet stacking apparatus on which the sheet is stacked, the image being formed on the sheet by the image forming portion;
• and
• a control portion that controls the sheet stacking apparatus,
• wherein the sheet stacking apparatus includes
• a discharging portion that discharge a sheet;
• a moving portion that holds a downstream end portion of the sheet, which is discharged by the discharging portion, in a sheet discharging direction and moves the sheet to the downstream side in the sheet discharging direction;
• and
• a stacking portion on which the sheet is stacked, and
• wherein the control portion controls at least one of the discharging portion and the moving portion so that the movement velocity of the moving portion is higher than the sheet discharge velocity of the discharging portion, and separates the sheet from the moving portion by using a velocity difference between the movement velocity and the sheet discharge velocity.

An image forming apparatus comprising:

• an image forming portion that forms an image on a sheet;
• a sheet stacking device on which the sheet is stacked, the image being formed on the sheet by the image forming portion;
• and
• a control portion that controls the sheet stacking device,
• wherein the sheet stacking device includes
• a discharging portion that discharge a sheet;
• a moving portion that holds a downstream end portion of the sheet, which is discharged by the discharging portion, in a sheet discharging direction and moves the sheet to the downstream side in the sheet discharging direction;
• and
• a stacking portion on which the sheet is stacked, and
• wherein the control portion controls to separate the sheet from the moving portion while moving with the held sheet before a downstream end portion of the sheet, in a sheet discharging direction, reaches the positioning unit.