Image forming apparatus having a setting device for setting a recording medium size

1. An image forming apparatus comprising:

a fixing device that is attachable to and detachable from an apparatus body and fixes a developer image onto a recording medium;

a setting unit that is provided in the fixing device and in which a size of a recording medium to be used in the fixing device is set;

an acquiring unit that is provided in the apparatus body and acquires size information of a recording medium onto which the developer image is to be fixed;

a determining unit that compares the size of the recording medium set in the setting unit with the size of the recording medium acquired by the acquiring unit so as to determine whether or not a fixing process is performable by the fixing device; and

a notifying unit that at least provides notification of a negative determination result obtained by the determining unit,

wherein the setting unit is a variable resistor in which sizes of recording media are set in correspondence with different resistance values and in which the resistance values are switchable in the variable resistor by actuation of an operation knob.

2. The image forming apparatus according to claim 1 , wherein the notifying unit is a display that is provided in the apparatus body and displays a determination result.

3. The image forming apparatus according to claim 1 , wherein the apparatus body is provided with a selecting unit that is used by a user to select whether or not to use the fixing device attached to the image forming apparatus when the negative determination result is obtained by the determining unit.

4. The image forming apparatus according to claim 1 , wherein the acquiring unit is configured to detect a width of the recording medium to determine the size of the recording medium.

5. The image forming apparatus according to claim 4 , wherein the width of the recording medium is detected by using sensors.

6. An image forming method comprising:

setting a size of a recording medium to be used in an attachable/detachable fixing device by using a variable resistor in which sizes of recording media are set in correspondence with different resistance values and in which the resistance values are switchable in the variable resistor by actuation of an operation knob, the variable resistor being disposed on the fixing device;

acquiring size information of a recording medium onto which a developer image is to be fixed;

comparing the set size of the recording medium with the acquired size of the recording medium so as to determine whether or not a fixing process is performable by the fixing device; and

at least providing notification of a negative determination result.