Ink container having dual capillary members with differing capillary pressures for precise ink level sensing

Abstract

A replaceable ink container for providing ink to a printhead of a printing system. The ink container has a fluid outlet configured for connection with the printhead. The ink container includes an ink reservoir having a first capillary member having a first capillary pressure, and a second capillary member having a second capillary pressure that is greater than the first capillary pressure such that the second capillary member has a higher resistance to ink flow than the first capillary member. An ink level sensor senses a low ink condition of the ink reservoir. The ink level sensor includes a C-shaped tube having first and second ports that fluidically communicate with only the second capillary member. The first and second capillary members abut one another at a capillary member interface, and the first port is positioned immediately adjacent to this capillary member interface. Placement of the first port immediately adjacent to the capillary member interface minimizes the ink level variation between an ink drained portion of the second capillary member and an ink filled portion of the second capillary member. A light detector detects when the C-shaped tube is free of ink which defines the low ink condition of the ink reservoir.