Abstract A thickness profile gauging apparatus, particularly for use with metal strip, in which first and second radiation sources irradiate the strip and first and second receivers detect radiation attenuated by the strip and produce signals representative of strip thickness. The receiver signals are converted into pulses having durations representative of signal amplitude and the pulses are integrated to produce a difference signal which is then sampled and held. The pulse converters are sequentially activated so that the respective receivers are gauging portions of the strip along the same transverse line, the sequential activation being controlled by a delay generator responsive to a strip velocity input signal. At least one of the radiation source-receiver pairs is transversely movable to scan the strip width and a center line switch produces a signal when the two gauges are examining portions of the strip on the same longitudinal line of the moving strip. Circuit means responsive to the center line signal causes a sample of the thickness difference information at that line to be held and provided as a drift correction signal. Subsequent difference signals are then combined with this correction signal to produce a continuous profile output, the correction signal compensating for drift in the two converters and detectors.
In a thickness profile determining apparatus for use in examining a longitudinally moving web, the apparatus being of the type having first and second radiation producing means, first and second radiation receiving means, means for supporting the radiation producing and receiving means on opposite sides of a web to be examined thereby, means for transversely moving at least one of said means for supporting to permit transverse scanning of the web, and wherein said first and second receiving means each produce signals representative of the web thickness between the receiving means and its associated source, the improvement comprising first circuit means for sampling and combining the signals representative of web thickness to produce a signal representative of web thickness difference; second circuit means for storing the difference signals produced by said first circuit means between samples and for providing said stored signals as a profile output signal; logic circuit means for controlling the timing of said sampling; means coupled to said means for transversely moving for producing an electrical coincidence signal whenever said pairs of radiation producing and receiving means are in position to examine the web on the same preselected longitudinal portion thereof; circuit means responsive to said coincidence signal and to said logic circuit means for sampling and storing the next difference signal produced by said first circuit means and for providing said signal as a correction to said profile output signal.
Claim 2
Dependent Claim
234 words
In a thickness profile determining apparatus for use in examining a longitudinally moving web, the apparatus being of the type having first and second radiation producing means, first and second radiation receiving means, means for supporting the radiation producing and receiving means on opposite sides of a web to be examined thereby, means for transversely moving at least one of said means for supporting to permit transverse scanning of the web, and wherein said first and second receiving means each produce signals representative of the web thickness between the receiving means and its associated source, the improvement comprising first circuit means for sampling and combining the signals representative of web thickness to produce a signal representative of web thickness difference; second circuit means for storing the difference signals produced by said first circuit means between samples and for providing said stored signals as a profile output signal; logic circuit means for controlling the timing of said sampling; means coupled to said means for transversely moving for producing an electrical coincidence signal whenever said pairs of radiation producing and receiving means are in position to examine the web on the same preselected longitudinal portion thereof; circuit means responsive to said coincidence signal and to said logic circuit means for sampling and storing the next difference signal produced by said first circuit means and for providing said signal as a correction to said profile output signal.
Claim 3
Dependent Claim
75 words
An improved apparatus according to claim 1 wherein said first and second receiving means produce electrical signals having amplitudes representative of web thickness and wherein said first circuit means comprises first and second converters for producing pulses of variable duration proportional to the amplitudes of the scan input signals, and a third converter for integrating in opposite directions the pulses produced by said first and second converters to produce the signal representative of thickness difference.
Claim 4
Dependent Claim
42 words
An apparatus according to claim 1 and further comprising means responsive to the velocity of said longitudinally moving web for sequentially activating said first and second converters to sample their respective signals when examining substantially the same transverse portion of the web.