Sheet stacking device, image forming apparatus, control method, and recording medium

A method of controlling a sheet stacking device, the sheet stacking device including a mounting table on which a pallet is mounted, the mounting table having a lift,

• the method comprising:
• detecting, by a sensor, at least one of an upper surface of sheets stacked on the pallet or an upper surface of the pallet, the sensor including light emitters and light receivers each arranged in the lateral direction of the sheet stacking device so as to face with each other;
• causing the lift to lower the mounting table by a predetermined amount in response to the detecting;
• and
• determining that the sheets have been stacked abnormally when the sensor is not in a non-detection state after the mounting table has been lowered by the predetermined amount.

A non-transitory recording medium storing a plurality of instructions, which, when executed by one or more processors, causes the processors to perform a method of controlling a sheet stacking device, the sheet stacking device including a mounting table on which a pallet is mounted, the mounting table having a lift,

• the method comprising:
• detecting, by a sensor, at least one of an upper surface of sheets stacked on the pallet or an upper surface of the pallet, the sensor including light emitters and light receivers each arranged in the lateral direction of the sheet stacking device so as to face with each other;
• causing the lift to lower the mounting table by a predetermined amount in response to the detecting;
• and
• determining that the sheets have been stacked abnormally when the sensor is not in a non-detection state after the mounting table has been lowered by the predetermined amount.