Disclosed are systems, devices and methods for deployment in digital set-top boxes and associated networks to enable t-commerce and other transactions responsive to events generated by peripheral devices. If the ink equal to 5% of containing capacity containable in the ink chamber flows from the outlet port, the liquid container has an area where a fluctuation range of the liquid level of the ink inside the ink chamber becomes 5% or less of the cubic root of the containing capacity. The matrices of the structural portion and of the first machining portion are identical.