Patent attributes
Ink cartridges 1a to 1c for storing light-transmissive inks include a shutter arranged therein so that the shutter is movable depending on the ink residual amount, and a projection 51 having light transmittance and passing the shutter therethrough. An ink cartridge 1d for storing a nontransparent ink includes a projection 51 having light transmittance. Optical sensors 21a to 21c, which detect the shutter at the projection 51 of the ink cartridges 1a to 1c respectively, are arranged at a position higher in the vertical direction than a position of arrangement of an optical sensor 21d detecting the ink at the projection 51 of the ink cartridge 1d. It is possible to use both an ink cartridge for storing a light-transmissive ink and an ink cartridge for storing a nontransparent ink, and the ink amount is correctly detected for any one of the cartridges.
