Electricity: measuring and testing – Impedance – admittance or other quantities representative of... – Lumped type parameters
Patent
1990-12-17
1992-08-04
Wieder, Kenneth A.
Electricity: measuring and testing
Impedance, admittance or other quantities representative of...
Lumped type parameters
324718, 324724, G01R 2726
Patent
active
051362520
ABSTRACT:
A probe holder mounts a pair of spaced current probes, a pair of spaced primary voltage probes inward of such current probes and a pair of spaced secondary voltage probes outward of such current probes. Each of the secondary voltage probes and the nearer thereto of the primary voltage probes is on the same equipotential contour calculated by assuming that the current probes contact and pass current through a planar homogeneously resistive sheet with infinite boundaries and of infinitesimal thickness. Electroconductive bodies are evaluated for resistive anomalies therein by contacting the body of all the probes and passing current through the body between the current probes. The voltages V.sub.a, V.sub.b and V'.sub.a, V'.sub.b responsively sensed on the surface of such body by, respectively, such two primary probes and such two secondary probes are used to derive first and second signals as functions of the voltage differentials V.sub.a -V.sub.b and V'.sub.a -V'.sub.b respectively. From those signals there is derived a third signal as a function of (V'.sub.a -V'.sub.b)-(V.sub.a -V.sub.b) which is fed to output means to provide an output comprising information about such body. The third signal may additionally be a function of the set value of a bias signal. The output is suppressed by one or more validity checking circuits when a limit is exceeded by one or more of the voltages in the group consisting of the sensed voltages and the voltage differentials. The system may be adapted to operate substantially as described above when one of the four voltage probes is eliminated.
REFERENCES:
patent: 3303418 (1967-02-01), Rose
patent: 3611125 (1971-10-01), Sharon et al.
patent: 3995213 (1976-11-01), Robinson et al.
patent: 4446424 (1984-04-01), Chatanier et al.
patent: 4667149 (1987-05-01), Cohen et al.
"Resistivity Measurements Make a Useful QC Tool", by W. R. Hain, Metal Progress, (Apr. 1986) pp. 27-29.
"The Measurement of Crack Depths By The Direct-Current Conduction Method", by J. G. Buchanan & R. C. A. Thurston, Non-Destructive Testing, Sep.-Oct. 1956, pp. 36-39.
"The Potentials of Infinite Systems of Sources & Numerical Solutions of Problems in Semiconductor Engineering", by A. Uhlir, Jr., Bell System Technical Journal, vol. 34, Jan. 1955. pp. 105-128.
"Measurement of Sheet Resistivities with the Four-Point Probe", by F. M. Smits, Bell System Technical Journal, vol. 37, No. 3 May 1958. pp. 711-718.
"Resistivity Testing for Quality Control", Materials Evaluation, Aug. 1986, pp. 1066-1074.
AT&T Bell Laboratories
Kip, Jr. Ruloff F.
Regan Maura K.
Wieder Kenneth A.
LandOfFree
Apparatus and methods for evaluating resistive bodies does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Apparatus and methods for evaluating resistive bodies, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Apparatus and methods for evaluating resistive bodies will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-780987