There is known, as a printer of the electrophotographic type, such a printer that includes a photosensitive body and a developing cartridge for supplying toner to the photosensitive body. 
Such a type of printer includes a new-product detecting unit for judging information on a developing cartridge mounted in the printer.  For example, the new-product detecting unit is for judging whether or not the cartridge is a new product that is newly mounted in the printer. 
For example, there has been proposed a laser printer.  The laser printer has a main casing, in which a developing cartridge is detachably mountable.  The main casing is provided with an actuator and a photosensor.  The developing cartridge rotatably supports a detection gear.  The detection gear is provided with a protrusion that is for being in abutment contact with the actuator.  When the developing cartridge is mounted in the main casing, the detection gear is driven to rotate.  The protrusion causes the actuator to swing.  The photosensor detects the swinging movement of the actuator.  The laser printer judges information on the developing cartridge based on the detection results by the photosensor.