Non-contacting resistivity instrument with structurally related conductance and distance measuring transducers
Patent 4302721 Issued on November 24, 1981. Estimated Expiration Date: 
May 15, 1999. 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.
May 15, 1999. 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 2640190 3067387 3312893 3890564 InventorsAssigneeApplicationNo. 06/039303 filed on 05/15/1979US Classes:324/226, Combined324/236, Oscillator type414/935ASSOCIATED WITH SEMICONDUCTOR WAFER HANDLINGExaminersPrimary: Strecker, Gerard R.Assistant: Snow, Walter E. Attorney, Agent or FirmInternational ClassesG01S 15/32 (20060101)G01S 15/00 (20060101) G01R 31/265 (20060101) G01R 31/28 (20060101) G01R 31/26 (20060101) G01N 27/02 (20060101) AbstractAn instrument for computing resistivity based upon measurements of thickness and conductance. A conductance transducer is a solenoid in an annular ferrite cup connected to a tank circuit for an eddy current measurement of conductance. Within the center of the annular ferrite cup concentric acoustic wave sending and receiving channels are disposed for making an acoustic pressure wave measurement which is used for a thickness measurement using two gauge heads, spaced on opposite sides of an article to be measured. Each gauge head contains identical conductance and thickness transducers. The thickness measurement is divided by the conductance measurement to derive resistivity.Other References
| |
