JPS646986A - Residual toner detector - Google Patents

Abstract

PURPOSE:To detect the residue of toner in a hopper with slight errors by fitting a piezoelectric sensor on the bottom surface of a hopper. CONSTITUTION:The piezoelectric sensor 13 is fitted on the bottom part of a toner hopper 8 with its detection surface set upward. When the time required for one turn of an agitator 11 is denoted as T, the weight of toner is detected in a time t1, but the sensor does not detect the weight in a time (T-t1), so toner is supplied continuously and the residue reaches a constant value; when the sensor 13 does not detect the weight of the toner continuously any more, a toner end signal is sent out. This sensor 13 is provided where the thin plate member 11a of the agitator 11 passes, and neither the blocking nor the bridge formation of the toner is caused, so a detection error is small. In an actual use state, the toner is supplied to the developing device, so every time the agitator rotates, a value t1/T is read several times continuously and their mean value is calculated to reduce the error.