| 摘要 |
PURPOSE:To detect whether the temperature detecting element of a thermal fixing device is installed or not with a simple structure, minimize the number of input ports such as CPU for fixing temperature control, and simplify the wiring in a control base inner part in an electrophotographic device such as a laser beam printer having the thermal fixing device. CONSTITUTION:An analog switch 36 which is a semiconductor element is connected to both end sides of a thermistor 22 which is the temperature detecting element of a thermal fixing device. The output of a pull-up resistor 33 of short line for detecting the presence of the thermistor unit is inputted to the analog switch 35, and not to a CPU 32 for fixing temperature control. When the thermistor 22 is not installed to a thermal fixing device unit 22, or a connector 25 having the thermistor 22 mounted thereon is not installed, both end sides of the thermistor 22 is short-circuited by the output of the pull-up resistor 33. |
