Patent ID: 8929751
Filing Date: 2015-01-06
Classification: G03G

Abstract:
1. An image forming apparatus comprising: a buffer configured to temporarily store therein toner supplied from a toner cartridge and to be fed to a developing unit; a magnetic reed switch configured to sense magnet variation occurring in a sensing range and sequentially output signals each indicating a result of the sensing; a toner level indicator plate disposed within the buffer to swing up and down about a fixed edge in response to a change in a level of the toner that remains in the buffer, the toner level indicator plate having a magnet on a free edge thereof, the magnet being made to reach the sensing range in a state where the toner level indicator plate has swung down; a detection unit configured to detect, at equal intervals, each signal output from the magnetic reed switch, each interval being equal to one-Nth of a period of a control pulse signal used for driving a motor positioned within the sensing range, N being an integer two or greater; and a determination unit configured to determine, when a signal detected by the detection unit in a current interval indicates that the magnet reed switch has sensed magnetic variation, whether the signal in the current interval is output due to a toner shortage or the driving of the motor, by comparing the signal in the current interval with signals detected by the detection unit over the last immediately preceding successive N intervals.