Tektronix, Inc.

Richard Marantz

Clark W Crawford

James D Buehler

Brian J Wood

Ted E Deur

A discrete ink level sensing system according to the present invention includes a level sensing probe (130) with at least first and second level sensing pads (178, 180) that is placed in an ink reservoir (28). The level sensing system uses electrical conductivity of the ink to detect when the upper surface level of the ink is lower than the lowest points of the level sensing pads. The upper and lower level sensing pads are electrically connected by a sense resistor (182). A voltage sensor (174) detects across the sense resistor a voltage that depends on the ink conductivity and the position of an upper surface level of the ink with respect to the lowest points of the first and second level pads. The value of the voltage is sent to a CPU (154) that signals a user that a predetermined amount of ink should be added to the reservoir.

Ink level sensing probe system for an ink jet printer

A FRU assembly (10) comprises a melt chamber (20) including multiple subchambers (30) in which sticks of phase change ink (38, 40) are inserted and melted. Melted ink flows through apertures (54) to a reservoir (28) comprising multiple compartments (56). Each compartment contains a channel (90) and a siphon plate (114) that allow a siphon action that siphons melted ink in the compartments to an orifice (100) that leads to an ink jet print head (16). Heaters (52, 82, and 142) under the control of a CPU (154) melt the ink and keep the melted ink at a desired temperature during various modes of operation.

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Portland, OR, United States of America

Richard Marantz