Image forming apparatus, reader writer, and colorant cartridge

A reader writer that reads and writes data from and to a wireless IC tag is installed on/in a colorant cartridge used in an image forming apparatus, comprising:

• an antenna coil for wireless communication with the wireless IC tag;
• and
• plural reader writer contact terminals in positions to contact to plural cartridge contact terminals on the colorant cartridge respectively when the colorant cartridge is mounted to the image forming apparatus;
• wherein the reader writer adjusts a wireless transmission characteristic in accordance with a load installed between the plural cartridge contact terminals, the load electronically connected to the reader writer contact terminals.

A colorant cartridge used in an image forming apparatus, comprising:

• a wireless IC tag;
• plural cartridge contact terminals;
• and
• a load arranged between the cartridge contact terminals;
• wherein the plural cartridge contact terminals are arranged at positions to contact to plural reader writer contact terminals on a reader writer respectively when the colorant cartridge is mounted to the image forming apparatus, the reader writer reading and writing data from and to the wireless IC tag;
• and
• the load has an impedance corresponding to a type of the wireless IC tag and thereby causing the reader writer to adjust a wireless transmission characteristic of the reader writer in accordance with the type of the wireless IC tag.