Ink cartridge for inkjet printers

An ink cartridge (10) for an inkjet printer having a light-transmitting part (31) and a light-receiving part (32), the ink cartridge comprising:

• a side face (11, 14, 15, 16);
• an ink-receiving space including an extension (33) that projects beyond the side face;
• and
• fill level detection means arranged on the side face, the fill level detection means operative between the light-transmitting part (31) and the light-receiving part (32) when mounted on the ink jet printer, the fill level detection means including,
• a first light-beam-deflecting surface that includes a light beam entry surface (30) which is arranged outside the ink cartridge (10) and faces the light-transmitting part (31),
• a deflecting surface (21) configured to be wetted with ink (34) or dewetted of ink (34) inside the cartridge (10) in dependence upon a fill level of the ink (34) in the ink-receiving space, and
• a second light-beam-deflecting surface that includes a light beam exit surface (35) which is arranged outside the ink cartridge (10) and faces the light-receiving part,
• wherein the first and second light-beam-deflecting surfaces are combined with the deflecting surface (21) to form a common component that is part of the extension (33) of the ink-receiving space.