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1. WO1981003381 - IMPROVEMENTS IN OR RELATING TO MEASUREMENT APPARATUS

Publication Number WO/1981/003381
Publication Date 26.11.1981
International Application No. PCT/GB1981/000089
International Filing Date 19.05.1981
IPC
G01N 27/90 2006.01
GPHYSICS
01MEASURING; TESTING
NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
27Investigating or analysing materials by the use of electric, electro-chemical, or magnetic means
72by investigating magnetic variables
82for investigating the presence of flaws
90using eddy currents
CPC
G01N 27/9046
GPHYSICS
01MEASURING; TESTING
NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
27Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
72by investigating magnetic variables
82for investigating the presence of flaws
90using eddy currents
9046by analysing electrical signals
Applicants
Inventors
Priority Data
801688722.05.1980GB
Publication Language English (EN)
Filing Language English (EN)
Designated States
Title
(EN) IMPROVEMENTS IN OR RELATING TO MEASUREMENT APPARATUS
(FR) AMELIORATIONS APPORTEES OU SE REFERANT A UN DISPOSITIF DE MESURE
Abstract
(EN)
Measurement apparatus receives a signal from an eddy current transducer (20) excited by a generator (24). A signal generator (21) generates a signal at a predeterminable reference level which is combined with the transducer signal to produce a measurable signal at output (23). The output of the signal generator (12) is determined by a set balance control (15) which may be set by amplitude controls (29, 30) in accordance with control coefficients applied via data bus (43). The output of the signal generator (21) may be predetermined iteratively in a calibration phase preceeding measurement. The present invention overcomes the problem of providing an inactive matched eddy current transducer to balance the signal provided by the measurement transducer (20). A second transducer (49) may be switched (50) to replace the signal generator (21) to enable positioning of the measurement transducer (20) with respect to a workpiece.
(FR)
Un dispositif de mesure recoit un signal provenant d'un transducteur (20) de courant parasite excite par un generateur (24). Un generateur (21) de signaux produit un signal a un niveau de reference pouvant etre predetermine, ce signal etant combine avec le signal du transducteur pour produire a la sortie (23) un signal mesurable. La sortie du generateur (12) de signaux est determinee par une commande (15) d'equilibrage preetabli pouvant etre reglee par des commandes d'amplitude (29, 30) conformement a des coefficients de commande appliques via le bus de donnees (43). La sortie du generateur de signaux (21) peut etre predeterminee d'une maniere iterative lors d'une phase d'etalonnage precedant la mesure. La presente realisation resout le probleme de prevoir un transducteur inactif adapte de courant parasite pour equilibrer le signal fourni par le transducteur (20) de mesure. Un deuxieme transducteur (49) peut etre commute (50) pour remplacer le generateur de signaux (21) et permettre le positionnement du transducteur de mesure (20) par rapport a une piece a usiner.
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