Abstract: An image forming system includes an image forming apparatus and a sheet laminator. The image forming apparatus forms an image on a sheet being conveyed as an inner sheet. The sheet laminator performs a sheet laminating operation on a two-ply sheet in which the sheet conveyed from the image forming apparatus is inserted between two sheets of the two-ply sheet. The sheet laminator includes a heater and circuitry. The heater heats the two-ply sheet during the sheet laminating operation. The circuitry is to execute a control mode when a specific abnormal event occurs among a plurality of abnormal events that occurs in the image forming apparatus, where the control mode maintains heating by the heater of the sheet laminator for a predetermined time and interrupt the heating by the heater when an abnormal event other than the specific abnormal event occurs.

Abstract: A signal to be measured and a triangular signal are applied to a first mean square value circuit, in which they are added together, full-wave rectified and smoothed and, at the same time, the triangular signal and a measured output are provided to a second mean square value circuit, in which they are added together, full-wave rectified and smoothed. The outputs from the first and second mean square value circuits are subtracted one from the other in a subtractor to obtain the measured output, with the triangular signal component removed. The measured output is applied to the second mean square value circuit to derive therefrom as a measured output an effective value that the root mean square value of the signal to be measured have been extracted.