Sheet stacker and image forming apparatus incorporating the sheet stacker

A sheet stacker comprising:

• a sheet stacking tray having an upstream portion in a sheet conveyance direction, the upstream portion being movable in a vertical direction;
• a height adjuster spring configured to apply a biasing force to bias the sheet stacking tray upward, an end of the height adjuster spring being coupled to the sheet stacking tray;
• a slider configured to set an angle of the sheet stacking member in the sheet conveyance direction, relative to a sheet conveying portion, between a first angle and a second angle, the slider including a contact target face configured to contact a contact face of the sheet stacking tray;
• and
• a regulator configured to regulate movement of the sheet stacking member in a case in which the upstream portion of the sheet stacking member is located closer to the sheet conveying portion at either the first angle or the second angle, the regulator including
• an upper limit regulator hook, and
• a tray side hook mounted on the sheet stacking tray and configured to engage with the upper limit regulator hook.

A sheet stacker comprising:

• a sheet stacking tray having an upstream portion in a sheet conveyance direction, the upstream portion being movable in a vertical direction;
• a height adjuster spring configured to apply a biasing force to bias the sheet stacking tray upward;
• a slider configured to set an angle of the sheet stacking member in the sheet conveyance direction, relative to a sheet conveying portion, between a first angle and a second angle;
• and
• a regulator configured to regulate movement of the sheet stacking member in a case in which the upstream portion of the sheet stacking member is located closer to the sheet conveying portion at either the first angle or the second angle.