Browse Prior Art Database

Full Range Liquid Level Sensor

IP.com Disclosure Number: IPCOM000120172D
Original Publication Date: 1991-Mar-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 1 page(s) / 45K

Publishing Venue

IBM

Related People

Adams, JM: AUTHOR [+3]

Abstract

In the production of semiconductors, the level of the liquid process chemical requires accurate height measurement. Existing continuous (analog) level monitoring systems do not provide the required precision or repeatability. This invention will provide reliable and sensitive level detection.

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Full Range Liquid Level Sensor

      In the production of semiconductors, the level of the liquid
process chemical requires accurate height measurement. Existing
continuous (analog) level monitoring systems do not provide the
required precision or repeatability.  This invention will provide
reliable and sensitive level detection.

      Previous continuous level systems have proven to be unreliable.
Existing reliable systems are not of a technology that will provide a
continuous output.  These non-continuous level systems typically will
monitor one depth of liquid in the process tank.

      The new device is illustrated in the attached drawing. The
system utilizes a tension/compression design load cell attached to a
buoyant force transmitter.  The load cell's housing and diaphragm
provide it protection from aggressive environments.  The diaphragm is
of a flexible design which will allow forces to be transmitted to the
cell.  The force transmitter, diaphragm and housing are of a
fluorocarbon polymer material to provide excellent chemical
inertness.

      The system utilizes Archimedes' principle which gives rise to
the force derived from the force transmitter.  This force is applied
to the load cell whose electrical output is registered on a signal
conditioning circuit to provide an analog output.  This provides for
an accurate indication of the liquid height in the process tank
throughout the tank's depth.

      Disclosed anonymously.