Frequency sensitive level detecting apparatus
Patent 4134022 Issued on January 9, 1979. Estimated Expiration Date: 
August 25, 1997. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
August 25, 1997. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent References 2664556 3384885 3485262 3740563 3882319 3882887 3908129 3908441 InventorAssigneeApplicationNo. 05/827493 filed on 08/25/1977US Classes:250/577, Volume or level137/386, LIQUID LEVEL RESPONSIVE OR MAINTAINING SYSTEMS340/619, Optical sensor73/293With illuminationExaminersPrimary: Grimm, Siegfried H.Attorney, Agent or FirmInternational ClassesG01F 23/284 (20060101)G01F 23/292 (20060101) Foreign Application Priority Data1976-09-03 CAAbstractA level sensing apparatus is disclosed having a source for supplying a signal having a predetermined frequency, a level sensor connected to the source and having an output for supplying an output signal having the predetermined frequency as long as the material, the level of which is being sensed, is not at a predetermined level, a frequency sensitive circuit for receiving the output signal from the level sensor and for providing an output whenever the frequency of the signal is above or below the predetermined frequency, and a load which is connected to be responsive to the output from the frequency sensitive circuit. | |
