Sheet feeding apparatus and image forming system

A sheet feeding apparatus comprising:

• a sheet loading unit for loading sheets;
• a lift plate disposed in the sheet loading unit and supported in a vertically movable manner;
• a lift mechanism for moving the lift plate up and down;
• a sheet feeding unit disposed above the lift plate so as to face the same, for contacting and feeding the sheet lifted by the lift plate;
• a sheet detection unit disposed on the lift plate so as to detect whether or not the sheet is placed on the lift plate;
• a remaining amount detection unit for detecting a remaining amount of the loaded sheets based on height of the lift plate;
• and
• a control unit configured to control the up and down movement of the lift plate, wherein
• the control unit controls the lift plate to move upward to a sheet feeding position when feeding the sheet, and after finishing feeding the sheet, moves the lift plate at a waiting position lower than the sheet feeding position during waiting time for waiting for an input of a next print job,
• if the sheet detection unit does not detect the sheet when the lift plate is positioned at the sheet feeding position, the control unit sets the waiting position to a lowest position,
• if the sheet detection unit detects the sheet and if the remaining amount detection unit detects that the remaining amount of the sheets is a predetermined amount or less, the control unit sets the waiting position to a height position between the sheet feeding position and the lowest position, and
• if the sheet detection unit detects the sheet and if the remaining amount detection unit detects that the remaining amount of the sheets is more than the predetermined amount, the control unit sets the waiting position to the lowest position.