Patent ID: 8393722

Claim:
A set of cartridges comprising: a first cartridge having a small capacity and comprising a first tank configured to store liquid therein, wherein a liquid level in the first tank is at a first position when an amount of liquid stored in the first tank is a predetermined amount; and a second cartridge having a large capacity and comprising a second tank configured to store liquid therein, wherein the second tank has a larger capacity than the tank of the first cartridge, and a liquid level in the second tank is at a second position which is below the first position when an amount of liquid stored in the second tank is the predetermined amount, wherein each of the first cartridge and the second cartridge comprises: a detection region configured to receive an optical signal emitted from an exterior of the first tank or the second tank, wherein the detection region of the first cartridge is positioned at a same height as the detection region of the second cartridge; a float positioned in the first tank or the second tank, and configured to move based on the amount of liquid stored in the first tank or the second tank; and a light-blocking portion connected to the float and configured to move relative to the detection region based on a movement of the float, wherein the light-blocking portion is configured to block the optical signal when the light-blocking portion is in the detection region and the optical signal is allowed to pass through the detection region when the light-blocking portion is out of the detection region, wherein the first cartridge is configured such that the light-blocking portion moves out of the detection region when the liquid level in the first tank lowers and reaches the first position, and the second cartridge is configured such that the light-blocking portion moves out of the detection region when the liquid level in the second tank lowers and reaches the second position.