Liquid residual-amount detecting device

A liquid residual-amount detecting device detecting a residual amount of a liquid contained in a liquid cartridge, the detecting device comprising:

• an optical sensor having a pair of a light emitting portion and a light receiving portion;
• and
• a plurality of liquid cartridges each having a respective one of a plurality of light shielding portions, each of the plurality of liquid cartridges having a containing portion that contains the liquid, a float disposed in the containing portion and receiving buoyancy of the liquid, and a respective one of the plurality of light shielding portions which is displaced on a path that crosses an optical path of detection light emitted by the light emitting portion in synchronization with displacement of the float,
• wherein the plurality of light shielding portions each has a size such that a light amount of the detection light, which the light receiving portion receives, cannot be made smaller than a predetermined light amount by any of the light shielding portions acting alone, and
• wherein when the float is at a highest position in each of the plurality of liquid cartridges, the plurality of light shielding portions are disposed to be aligned in a direction crossing the optical path and shield the optical path, so that the light amount of the detection light, which the light receiving portion receives, is made smaller than the predetermined light amount.