APPARATUS FOR SENSING THE LEVEL OF PARTICULATE MATTER OR LIQUID RELATIVE TO A PRESELECTED LEVEL IN A CONTAINER
Original Publication Date: 1994-Oct-31
Included in the Prior Art Database: 2004-Apr-07
Xerox Disclosure Journal
Proposed is an improvement for a container disposed in a printing machine. The container is adapted to dispense toner and capable of maintaining a quantity of toner therein. The improvement comprises a sensor for sensing that the quantity of toner in the container is less than or equal to a predetermined quantity. Referring to the accompanying Figure, sensor 140 is shown having piezoelectric members 142 and 144 mounted in an isolating base 146. The piezoelectric members 142 and 144 are waffer-thin slices of compressed ceramic powder. Inner surfaces, of the members 142 and 144, are separated from and connected operatively to one another by an insulating layer 148. The outer surfaces of the members 142 and 144 are covered with a non-stick coating 150. Ends of the members 142 and 144 are mounted, in cantilever fashion, in an upper portion 152 of the base 146. The upper portion 152 includes a trough 154. Trough 154 is filled with an elastomeric material to dampen the movement of piezoelectric members 142 and 144 with respect to the container in which sensor 140 is placed. Consequently, piezoelectric members 142 and 144 are decoupled from the container. Except for the volume occupied by trough 154, the upper portion 152 is substantially solid. Vibration of the elastomeric-filled trough 154 is minimized when the volume surrounding the trough 154 is solid, rather than hollow. A lower portion 156 of base 146 houses an amplifying/logic circuit 157 of the type that provides an output to a visible display. Line 158 is connected to ground, while lines 159 and 160 are connected respectively to an AC power source and the amplifyingflogic circuit 157.