Portable gauge for measuring thickness variations of thin plastic film
Patent 5030918 Issued on July 9, 1991. Estimated Expiration Date: 
November 17, 2009. 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.
November 17, 2009. 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 ReferencesApparatus for gauging the texture of a conducting surface Capacitance measurement probe Instrument for measuring the moisture content of dielectric objects Wall thickness detector Gap width probe and method Patent #: 4841224 InventorAssigneeApplicationNo. 437628 filed on 11/17/1989US Classes:324/671, To determine dimension (e.g., dielectric thickness)324/674, By frequency signal response, change or processing circuit324/687, Having fringing field coupling324/690Including a probe type structureExaminersPrimary: Wieder, Kenneth A.Assistant: Mueller, Robert W. Attorney, Agent or FirmForeign Patent References
International ClassG01R 027/26AbstractA capacitance gauge system is described for determining the thickness of thin-film non-conducting material (i.e. polyethylene, vinyl, etc.). An elongated capacitance sensing head is applied to one side of the material being measured thereby disturbing the electric field produced by the head. Internal circuitry monitors the effect of the material under test and produces an output proportional to the variation in the material's thickness. A new method of resolving capacitance changes results in the ability to resolve capacitance changes on the order of 5×10-17 Farads in a linear manner with the benefits of simplicity, excellent stability, low power requirement, and small physical size. These factors allow said apparatus to be incorporated into a small hand-held unit. Because of this advancement in portability, accurate measurements can be made more quickly and conveniently than previously possible.Field of SearchWhere a material or object forms part of the dielectric being measuredTo determine dimension (e.g., dielectric thickness) With a capacitive sensing means Including a probe type structure With frequency signal response, change or processing circuit By frequency signal response, change or processing circuit With variable distance between capacitor electrodes To determine dimension (e.g., thickness or distance) Having fringing field coupling | |
