Sheet stacking apparatus, sheet processing apparatus and image forming apparatus

A sheet processing apparatus comprising:

• a discharging member which is disposed in an upper portion of the sheet stacking apparatus and which discharges sheets;
• a stacking member which stacks the sheets discharged downward from the discharging member;
• a sheet positioning member, located on the downstream side of the stacking member in the discharging direction, which receives ends of the discharged sheets stacked on a stacking surface of the stacking member in a discharging direction of the sheet discharged by the discharging member;
• a pressure member having a pressing surface which presses the sheet received by the sheet positioning member toward the stacking surface of the stacking member, wherein at first a downstream side in the discharging direction of the pressing surface presses the discharged sheets toward the stacking surface of the stacking member, and subsequently an upstream side in the discharging direction of the pressing surface presses the discharged sheets towards the stacking surface sequentially;
• and
• a processing unit which processes sheets stacked on the stacking member and pressed by the pressure member.

An image forming apparatus comprising:

• an image forming portion which forms an image on a sheet;
• a discharging member which is disposed in an upper portion of the sheet stacking apparatus and which discharges sheets formed image by the image forming portion;
• a stacking member which stacks the sheets discharged downward from the discharging member;
• a sheet positioning member, located on the downstream side of the stacking member in the discharging direction, which receives ends of the discharged sheets stacked on a stacking surface of the stacking member in a discharging direction of the sheet discharged by the discharging member;
• and
• a pressure member having a pressing surface which presses the sheet received by the sheet positioning member toward the stacking surface of the stacking member;
• wherein at first a downstream side in the discharging direction of the pressing surface presses the discharged sheets toward the stacking surface of the stacking member, and subsequently an upstream side in the discharging direction of the pressing surface presses the discharged sheets toward the stacking surface sequentially.