Patent Number: 6,612,173

Title: Stepped plunger for use with an ultrasonic sensor

Abstract: An improved plunger for fluid dispensing cartridges used in automated dispensing systems. The plunger helps control the reflection of ultrasonic signals used to sense the position of the plunger as it moves within the cartridge tube. The plunger has a convex bottom, ink-facing surface and a top surface comprising one or more flat, horizontal surfaces. In the preferred embodiment, the horizontal surfaces are concentric steps.

Inventors: Lawson; Rebecca A. (Florence, SC), Lowry; James W. (Florence, SC)

Assignee: Sonoco Development, Inc.

International Classification: G01N 29/04 (20060101); G01N 029/04 ()

Expiration Date: 09/02/2020