Device and method for manufacturing layered sheet

A layered sheet manufacturing method comprising:

• a conveyance process in which a layered body containing at least one continuous sheet, and another sheet or layer is conveyed along a predetermined path;
• a thermal fusion process in which an anvil roll and an energy applying device are disposed so as to sandwich the predetermined path and an energy for thermally fusing layers of the layered body together is applied from the energy applying device to a part of the layered body passing through a space between the anvil roll and the energy applying device;
• a detection process in which a nip stage is provided where first and second members are included, the first and second members sandwiching the layered body in a thickness direction upstream of the space between the anvil roll and the energy applying device and at least one of the first and second members is a displacement member displaced in accordance with a thickness of the part of the layered body sandwiched between the first and second members, and whether the thickness has deviated from a predetermined reference range or not is determined on the basis of a displacement of the displacement member;
• and
• a retreat process in which when it is determined that the thickness has deviated from the reference range in the detection process, the energy applying device is caused to retreat in the direction going away from the anvil roll,
• wherein in the detection process,
• by using a lever that swings according to the displacement of the displacement member and having a predetermined part displaced more largely than the displacement member and
• a sensor that detects a displacement of the predetermined part of the lever,
• it is detected whether the thickness has deviated from the reference range or not.