| 摘要 |
PURPOSE:To provide a residual toner detector in a small size and capable of lessening wrong detection by providing a temp. detecting means for generating the output in proportion to a detected temp. and the detection circuit for detecting the residual toner based on the output from the temp. detecting means. CONSTITUTION:A developing chamber 23 is provided with the magnet roll 26 for transporting magnetic toner and the doctor blade 27 for regulating the toner layer thickness of the magnet roll 26. The thermistor (temp. detecting sensor) 30 is disposed in the position allowed to contact to the toner of the agitation chamber 22. The magnetic toner filling in the agitation chamber 22, is gradually consumed corresponding to the developing operation. Therefore, the periphery of the thermistor 30 in a state filled with the toner is changed into the state hardly allowed to contact to the toner. As a result, the air comes into contact with the thermistor 30, thereby the thermal resistance of the thermistor 30 is changed, thus the presence or absence of the toner (toner empty) can be detected. |
