Toner misregistration detection sensor, color image-forming apparatus using the same, and method for toner misregistration detection

摘要

Infrared light emitted from an infrared light-emitting diode and reflected by a toner that is an object to be detected. Then, the reflection light is received by a photodiode. A signal detection circuit is composed of an amplifier for converting an output current into a voltage, an amplifier in which a circuit constant is optimized for detection of color toner density, an amplifier in which a circuit constant is optimized for detection of black toner density and an amplifier in a circuit constant is optimized for detection of toner misregistration. These amplifiers are connected to each other in two steps. The first step amplifier's output is further amplified by the second step amplifiers to output as a color toner detection output voltage Vo1, a black toner detection output voltage Vo2, and a toner misregistration detection output voltage Vo3.