E thickness of layers method and apparatus for balancing an apparatus used for measuring th

Claim 3

A method according to claim 1, wherein said measuring circuit comprises a first oscillator the frequency of which is varied by proximity of said probe to said metallic body; and wherein said comparison signal is generated by a second oscillator, said measuring and comparison signals being combined to provide an oscillating signal displaying a beat frequency as a function of the frequency difference of the signals combined.

Claim 4

A method according to claim 2 wherein said null balancing operations are effected by varying the frequencies of each of said oscillators by first and second frequency adjusting means.

Claim 7

A method in accordance with claim 4, wherein during the course of measurement of the layer of said probe is repeatedly positioned beyond the influence range of the part of the layer which is to be measured and balancing at said detection circuit effected.

Claim 8

A method according to claim 5, wherein said measuring circuit comprises a first oscillator the frequency of which is varied by proximity of said probe to said metallic body; and wherein said comparison signal is generated by a second oscillator, said measuring and comparison signals being combined to provide an oscillating signal displaying a beat frequency as a function of the frequency difference of the signals combined.

Claim 9

A method according to claim 6, wherein said null balancing operations are effected by varying the frequencies of each of said oscillators by first and second frequency adjusting means.

Claim 10

A method according to claim 6 wherein the null balancing operation effected with said probe removed from the influence of said body, is carried out while said second oscillator is disconnected from said second frequency adjusting means; whereby said second oscillator signal is at a determinative fixed frequency.

Claim 11

A method according to claim 8, wherein said first adjusting means includes a potentiometer driven by a servo motor, the operating switch for said motor being ganged with the switch connecting said second adjusting means to said second oscillator so that said second adjusting means is disconnected during operation of said servo motor.

Claim 12

Apparatus foR measuring the thickness of insulating layers on metallic bodies in combination: a test probe; a measuring circuit associated with said test probe and generating a measuring signal indicative of the distance of said probe from the said metallic body; a comparison signal generating circuit; a signal combining means for combining said measuring and comparison signals; detection circuit means for examining the output from said combining means; first and second adjusting means connected respectively to said measuring and comparison signal generating circuits, for adjusting the outputs from said circuits to enable a null signal at said detecting circuit; means for impeding adjustment of the one of said adjusting means during adjustment of said other of said adjusting means, said signal from the one of said signal-generating circuits being maintained at a predetermined value during adjustment of the other of said signal-generating circuits, said means also impeding adjustment of said other adjusting means during adjustment of said one adjusting means; means for positioning a metallic calibrating body at a distance equal to the nominal thickness of the insulating layer of the body to be tested from said test probe; means for displacing said probe (1) beyond the range of influence of said calibrating body to enable a nulling of said detection circuit by adjustment of the one of said adjusting means while said probe is thus displaced, (2) to said distance equal to nominal thickness from said calibration body to enable adjustment of said other adjusting means while said distance between probe and body is maintained, thereby re-nulling said detection circuit, and (3) at a predetermined distance from said calibration body for effecting calibration; and means to calibrate said detection circuit upon said displacement of said probe a predetermined distance from said calibration body, whereby to establish calibration for subsequent measuring of layers to be measured by contact with said probe.

Claim 13

Apparatus foR measuring the thickness of insulating layers on metallic bodies in combination: a test probe; a measuring circuit associated with said test probe and generating a measuring signal indicative of the distance of said probe from the said metallic body; a comparison signal generating circuit; a signal combining means for combining said measuring and comparison signals; detection circuit means for examining the output from said combining means; first and second adjusting means connected respectively to said measuring and comparison signal generating circuits, for adjusting the outputs from said circuits to enable a null signal at said detecting circuit; means for impeding adjustment of the one of said adjusting means during adjustment of said other of said adjusting means, said signal from the one of said signal-generating circuits being maintained at a predetermined value during adjustment of the other of said signal-generating circuits, said means also impeding adjustment of said other adjusting means during adjustment of said one adjusting means; means for positioning a metallic calibrating body at a distance equal to the nominal thickness of the insulating layer of the body to be tested from said test probe; means for displacing said probe (1) beyond the range of influence of said calibrating body to enable a nulling of said detection circuit by adjustment of the one of said adjusting means while said probe is thus displaced, (2) to said distance equal to nominal thickness from said calibration body to enable adjustment of said other adjusting means while said distance between probe and body is maintained, thereby re-nulling said detection circuit, and (3) at a predetermined distance from said calibration body for effecting calibration; and means to calibrate said detection circuit upon said displacement of said probe a predetermined distance from said calibration body, whereby to establish calibration for subsequent measuring of layers to be measured by contact with said probe.

Claim 14

Apparatus according to claim 10, wherein said measuring circuit comprises a first oscillator, the frequency of the output signal of which is varied in accordance with the proximity of said probe to the body under test; and wherein said comparison signal generator circuit comprises a second oscillator; and wherein said combining means comprises a mixer for said first and second oscillator outputs for forming a beat frequency signal therefrom constituting the measuring signal for passing toward said detector circuit; said first and second adjusting means being effective to vary the frequency of said first and second oscillators.

Claim 15

Apparatus according to claim 11, further including servo control means for at least the first circuit adjusting means, said servo means including a servo motor and switching means for activating said motor, to in turn activate said first circuit adjusting means to achieve said null.

Claim 16

Apparatus according to claim 11, wherein said first and second circuit adjusting means comprises potentiometers in control circuits including variable capacitor diodes adapted to shift the frequency of the first and second oscillator circuits respectively, the diode of the comparison oscillator circuit being selectively connectable to the potentiometer associated with said circuit and to a fixed circuit and potential respectively, according to the position of a commutator means.

Claim 17

Apparatus according to claim 10 wherein said means for displacing said probe includes at least one adjustable and one stationary carrier, with mechanical measuring means for reading the position and displacement respectively of said carriers with respect to one another, each of said carriers having at least one supporting structure for mounting at least respectively a measuring assembly and a test object thereon.

Claim 18

Apparatus according to claim 14, wherein said adjustable carrier comprises a slide displaceable by means of a mEasuring spindle.

Claim 19

Apparatus according to claim 15 wherein said probe is adapted for mounting on said adjustable carrier.

Claim 20

Apparatus according to claim 16 wherein a plug-in connection is provided for mounting said probe on said adjustable carrier.

Claim 21

Apparatus according to claim 17 wherein the headstock of said slide is adjustable in the direction of movement of the slide and adapted to be fixed at a desired position.

Claim 22

Apparatus according to claim 14, wherein the supporting structure includes a prismatic shaped recess for fixing an object to be measured therein.

Claim 23

Apparatus according to claim 11 further including means for adjusting the sensitivity of said detection circuit means.

Claim 24

Apparatus according to claim 11, further inclduing discriminator means connected between said mixer means and said detection circuit, the slope of the discriminator signal being adjustable thereby to vary the signal to said detecting circuit to a desired level.

Claim 25

Apparatus according to claim 21, wherein the said discriminator includes a periodically chargeable and dischargeable measuring condensor, a plurality of such condensors being present, the slope characteristics of said discriminator being varied by selectively switching in selected of said plurality of condensors.

Claim 26

Apparatus for measuring the thickness of insulating layers on metallic bodies comprising in combination: an inductive test probe; a measuring circuit associated with said test probe and providing a measuring signal indicative of the distance of said probe from the said metallic body; a comparison signal generating circuit; a signal combining means for combining said measuring and comparison signals; detection circuit means for examining the signal derived from said combining means; first and second adjusting means connected respectively to said measuring and comparison signal generating circuits, for adjusting the output from said circuits to enable a null signal at said detecting circuit; means for impeding adjustment of said second adjusting means during adjustment of said first adjusting means, said signal from said comparison signal circuit being maintained at a predetermined value during adjustment of said measuring circuit, said means also impeding adjustment of said first adjusting means during adjustment of said second adjusting means and during subsequent calibration and measurement; means for positioning a calibrating body comprising a metallic body at said apparatus; means for displacing said probe (1) beyond the range of influence of said calibrating object to enable a nulling of said detection circuit by adjustment of said first adjusting means while said probe is thus displaced, (2) into contact with said calibration body to enable adjustment of said comparison circuit signal through said second adjusting means while said contact between probe and body is maintained, thereby re-nulling said detection circuit, and (3) at a predetermined distance from said calibration body for effecting calibration; and means to calibrate said detection circuit upon said displacement of said probe a predetermined distance from said calibration body, whereby to establish calibration for subsequent measuring of layers to be measured by contact with said probe.

Claim 27

Apparatus for measuring the thickness of insulating layers on metallic bodies comprising in combination: an inductive test probe; a measuring circuit associated with said test probe and providing a measuring signal indicative of the distance of said probe from the said metallic body; a comparison signal generating circuit; a signal combining means for combining said measuring and comparison signals; detection circuit means for examining the signal derived from said combining means; first and second adjusting means connected respectively to said measuring and comparison signal generating circuits, for adjusting the output from said circuits to enable a null signal at said detecting circuit; means for impeding adjustment of said second adjusting means during adjustment of said first adjusting means, said signal from said comparison signal circuit being maintained at a predetermined value during adjustment of said measuring circuit, said means also impeding adjustment of said first adjusting means during adjustment of said second adjusting means and during subsequent calibration and measurement; means for positioning a calibrating body comprising a metallic body at said apparatus; means for displacing said probe (1) beyond the range of influence of said calibrating object to enable a nulling of said detection circuit by adjustment of said first adjusting means while said probe is thus displaced, (2) into contact with said calibration body to enable adjustment of said comparison circuit signal through said second adjusting means while said contact between probe and body is maintained, thereby re-nulling said detection circuit, and (3) at a predetermined distance from said calibration body for effecting calibration; and means to calibrate said detection circuit upon said displacement of said probe a predetermined distance from said calibration body, whereby to establish calibration for subsequent measuring of layers to be measured by contact with said probe.

Claim 28

Apparatus for measuring the thickness of insulating layers on metallic bodies comprising in combination: a test probe; a measuring circuit associated with said test probe and generating a measuring signal indicative of the distance of said probe from said metallic body; a comparison signal-generating circuit, said measuring circuit and said comparison signal generating circuit forming signal-generating circuits; a signal combining means for combining said measuring and comparison signals; a detection circuit means for examining the output signal from said combining means; two independent adjusting means associated each with one of saId signal-generaing circuits for continuously adjusting within a limited range the signal generated by said signal-generating circuit; a reference circuit and change-over switch means allowing selective connection of the one of said signal-generating circuits to said adjusting means associated therewith and to said reference circuit respectively, the signal generated by said one of said signal-generating circuits being maintained at a predetermined reference value when connected to said reference circuit; means for positioning a metallic calibrating body at a distance equal to nominal thickness of the insulating layer of the body to be tested from said probe; means for displacing said probe (1) beyond the range of influence of said calibrating body to enable a nulling of said detection circuit by operation of said adjusting means associated with the other signal-generating circuit while said probe is thus displaced, while the signal from said one of said signal-generating circuits is maintained at aaid reference value by positioning said change-over switch means to said reference circuit, and (2) to said distance equal to nominal thickness from said calibration body to enable adjustment of said one signal-generating circuit with said change-over switch means reversed through said adjusting means associated therewith while said distance between probe and body is maintained thereby re-nulling said detection circuit.

Claim 29

Apparatus for measuring the thickness of insulating layers on metallic bodies comprising in combination: a test probe; a measuring circuit associated with said test probe and generating a measuring signal indicative of the distance of said probe from said metallic body; a comparison signal-generating circuit, said measuring circuit and said comparison signal generating circuit forming signal-generating circuits; a signal combining means for combining said measuring and comparison signals; a detection circuit means for examining the output signal from said combining means; two independent adjusting means associated each with one of saId signal-generaing circuits for continuously adjusting within a limited range the signal generated by said signal-generating circuit; a reference circuit and change-over switch means allowing selective connection of the one of said signal-generating circuits to said adjusting means associated therewith and to said reference circuit respectively, the signal generated by said one of said signal-generating circuits being maintained at a predetermined reference value when connected to said reference circuit; means for positioning a metallic calibrating body at a distance equal to nominal thickness of the insulating layer of the body to be tested from said probe; means for displacing said probe (1) beyond the range of influence of said calibrating body to enable a nulling of said detection circuit by operation of said adjusting means associated with the other signal-generating circuit while said probe is thus displaced, while the signal from said one of said signal-generating circuits is maintained at aaid reference value by positioning said change-over switch means to said reference circuit, and (2) to said distance equal to nominal thickness from said calibration body to enable adjustment of said one signal-generating circuit with said change-over switch means reversed through said adjusting means associated therewith while said distance between probe and body is maintained thereby re-nulling said detection circuit.