Liquid level sensor using thick film substrate

US7596998B2 · kind B2 · utility

Assignee

• Therm-O-Disc, Incorporated · US

Inventors

• Bernd Zimmermann · Rodenberg, DE
• Tung-Sheng Yang · Mansfield, US
• Thomas C. Anderson · Lakemoor, US

Key dates

• Filing date: Jul 19, 2006
• Grant date: Oct 6, 2009
• Expiry date: Jun 13, 2027

Classification

• Technology area (CPC G): Physics
• CPC primary: G05D9/12
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

In many applications, where the level of a liquid needs to be monitored (and possibly controlled), it is not necessary to provide a continuous (analog) liquid level signal, but limit sensing to one (or two) discrete levels over a small level range. In this case, a ceramic substrate sensor with discrete thermistor/heater pairs provides necessary information to control the level of the fluid. Protection of the substrate from liquid (and potential contaminants) is accomplished by coating the surface with an inert glass (“glaze”) layer and/or polymer layer (e.g., “Parylene”). Packaging of the coated substrate is accomplished by protective base, epoxy, and slosh shield. Cost can be significantly reduced over a prior art multiple thermocouple based sensor design, since discrete electronic components are avoided or reduced. Also, the number of pins, and therefore electrical connections, can be significantly reduced.