Abstract: An embodiment of the present invention discloses a method for determining the layer thickness of an electrically conductive coating which is applied on an electrically conductive substrate of a test object. First, the induced voltage of an eddy current sensor is collected in the air as a function of the frequency of an exciter field. The majority of coated reference objects which have been provided each contains a substrate and coating from the same materials, such as the substrate and coating of the test object. The reference objects display various known layer thicknesses. A reference voltage can be detected for each reference object as a function of the frequency of the exciter field with the eddy current sensor. Subsequently, a material induced voltage can be determined from the reference voltage and the induced voltage of the eddy current sensor in the air for each reference object. Afterwards, standard amplitude of the material induced voltage can be generated for each reference object.

Abstract: Disclosed is a device for detecting defects which are deep in electrically conductive materials in a non-destructive manner, comprising an excitation device provided with induction coils which are used to produce low frequency eddy currents in the material, and a receiving device for the magnetic field of the eddy currents, the magnetic field being modified by the defects, and the receiving device comprising a gradiometer magnetic field sensors with an integrated bridge circuit.

Abstract: An apparatus for detection of the gradient of a magnetic field includes at least four antenna elements (11, 12, 13, 14) composed of a ferromagnetic material, which are arranged in pairs, and a bridge circuit having at least four resistance elements (1, 2, 3, 4), which are associated with the antenna elements (11, 12, 13, 14) or antenna element pairs. Each antenna element pair has at least one associated resistance element (1, 2, 3, 4) whose resistance value is dependent on the field strength and on the direction of the magnetic field, and which resistance element (1, 2, 3, 4) is arranged in a field area (19) which extends between the two antenna elements (11, 12, 13, 14) of the antenna element pair. The invention also relates to a method for production of an apparatus which is intended for detection of the gradient of a magnetic field.

Abstract: The invention relates to a device for detecting defects which are deep in electrically conductive materials in a non-destructive manner, comprising an excitation device provided with induction coils which are used to produce low frequency eddy currents in the material, and a receiving device for the magnetic field of the eddy currents, said magnetic field being modified by the defects, and said receiving device comprising a gradiometer magnetic field sensors with an integrated bridge circuit.

Abstract: An apparatus for detection of the gradient of a magnetic field includes at least four antenna elements (11, 12, 13, 14) composed of a ferromagnetic material, which are arranged in pairs, and a bridge circuit having at least four resistance elements (1, 2, 3, 4), which are associated with the antenna elements (11, 12, 13, 14) or antenna element pairs. Each antenna element pair has at least one associated resistance element (1, 2, 3, 4) whose resistance value is dependent on the field strength and on the direction of the magnetic field, and which resistance element (1, 2, 3, 4) is arranged in a field area (19) which extends between the two antenna elements (11, 12, 13, 14) of the antenna element pair. The invention also relates to a method for production of an apparatus which is intended for detection of the gradient of a magnetic field.

Abstract: In a motion detector according to the Ferraris principle, an excitation element applies an inhomogeneous time-dependent alternating magnetic field to an induction element. A motion of the induction element induces in the induction element an eddy current with a temporal characteristic that depends both on the velocity and the acceleration. A sensor element measures the temporal characteristic of the eddy current and supplies the temporal characteristic to a signal processing circuit which determines at least one useful signal that is proportional to the velocity and acceleration, respectively.

Abstract: In order to compensate for a drop in sensitivity at high rotational speeds, an acceleration sensor having an inductive measuring head (T) which cooperates with a moving Ferraris disk (F) essentially over a main magnetic field and which supplies an acceleration-dependent variable (Vdet; V?) is expanded by an additional DC magnetic field excitation circuit (13, 14, IK, RK) with a means for driving the latter with the effect that the additional DC magnetic field acts in a compensating fashion on an eddy-current DC field, starting from a relatively high rotational speed (?) of the Ferraris disk (F). This can be performed by amplifying the main magnetic field or by reducing the eddy-current DC field. A control signal (V?), dependent on rotational speed, which both can be generated outside the sensor via a characteristic curve, and can be derived in the form of a control loop from the sensor signal (V?), serves as a drive.

Abstract: A device for measuring a motion of a moving electrically conducting body is disclosed. A magnetic field generated by, for example, electromagnets or permanent magnets, penetrates at least a partial area of the moving body. Two or more measuring devices are arranged outside the magnetic field to measure a measurement magnetic field that is induced by electrical currents in the moving body. The measuring devices are arranged essentially symmetrically with respect to the magnetic field generating means or the moving body. The measurement magnetic field represents at least one motion variable of the moving body. The measuring device is thereby no longer subjected to the temperature-dependent variations of the exciting field.

Abstract: A method and measuring device for the in situ detection of the &ggr;-&agr; phase transformation of strip steel. The detection takes place on the basis of the eddy currents of the nonmagnetic phase, which are caused from the workpiece when an electromagnetic excitation field is applied, and on the basis of response fields which are generated by the magnetic phase which may be present. At least one electromagnetic excitation field which acts on the workpiece is generated by means of at least one excitation coil, and a response field which results from the application of the excitation field is measured by means of at least one detector measurement coil. The resulting measurement signal, which is dependent on the distance between the measuring device and the workpiece, is used to detect the degree of transformation.

Abstract: A motion parameter of an at least partially conducting moving body is measured with a measuring device having at least one coil with a coil axis tangential to the motion direction of the moving body. A primary magnetic field induces electrical currents in the moving body that generate a motion-dependent measuring magnetic field which is measured by the measuring device. The tangential coil(s) has/have a greater distance from the moving body than the primary magnets.

Abstract: In a motion detector according to the Ferraris principle, an excitation element applies an inhomogeneous time-dependent alternating magnetic field to an induction element. A motion of the induction element induces in the induction element an eddy current with a temporal characteristic that depends both on the velocity and the acceleration. A sensor element measures the temporal characteristic of the eddy current and supplies the temporal characteristic to a signal processing circuit which determines at least one useful signal that is proportional to the velocity and acceleration, respectively.

Abstract: In the inductive motion sensor, there are provided magnetic field generating means (4, 5, 7, 8) for generating a magnetic exciting field and a measuring device for measuring a mutually induced measurement magnetic field as a measure of the motion. The measuring device is arranged with an offset from the magnetic field generating means in the motion direction and is thereby no longer subjected to the temperature-dependent variations of the exciting field.

Abstract: A motion parameter of an at least partially conducting moving body is measured with a measuring device having at least one coil with a coil axis tangential to the motion direction of the moving body. A primary magnetic field induces electrical currents in the moving body that generate a motion-dependent measuring magnetic field which is measured by the measuring device. The tangential coil(s) has/have a greater distance from the moving body than the primary magnets.

Abstract: The invention relates to a method for the in situ determination of the degree of conversion of a non-magnetic phase in a ferromagnetic phase of a metallic work piece comprising an eddy current measuring method wherewith two distance measuring coils measure different distances to a work piece are measured using two distance measuring coils and distant dependent signals are determined. A distance dependent calculated value is determined therewith. A further measuring signal pertaining to a detector measuring coil is measured and a response field resulting from the application of an excitation field to a work piece is measured. A measured value for the degree of conversion is determined.

Abstract: A scanning head for eddy-current testing includes a probe coil configuration disposed on a film on a film base. The film base is matched to a shape of an object to be tested. This allows quick, low-interference eddy-current testing. A method for producing a scanning head for an eddy-current test and an eddy-current test method are also provided.

Abstract: In order to compensate for a drop in sensitivity at high rotational speeds, an acceleration sensor having an inductive measuring head (T) which cooperates with a moving Ferraris disk (F) essentially over a main magnetic field and which supplies an acceleration-dependent variable (Vdet; V&agr;) is expanded by an additional DC magnetic field excitation circuit (13, 14, IK, RK) with a means for driving the latter with the effect that the additional DC magnetic field acts in a compensating fashion on an eddy-current DC field, starting from a relatively high rotational speed (&ohgr;) of the Ferraris disk (F). This can be performed by amplifying the main magnetic field or by reducing the eddy-current DC field. A control signal (V&ohgr;), dependent on rotational speed, which both can be generated outside the sensor via a characteristic curve, and can be derived in the form of a control loop from the sensor signal (V&agr;), serves as a drive.