Dual sensor scanner for measuring weight of paper and related sheet products
First Claim
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1. Apparatus for measuring the weight of a material, comprising:
- an optical sensor for sensing light shining through a material web portion and generating therefrom a first signal indicative of the weight;
a nuclear sensor mounted adjacent to the optical sensor for sensing particles passing through the material web portion and generating therefrom a second signal indicative of the weight; and
calibrating circuitry for calibrating the optical sensor signal to the nuclear sensor signal as the sensors sense the weight of the same portion of the material web.
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Abstract
A dual sensor scanner includes an optical sensor and a nuclear sensor such as a beta gauge for sensing the basis weight or other parameters of paper as it is being produced by a paper making machine. The nuclear sensor signal is filtered to pass a low frequency portion and the optical sensor is filtered to pass a high frequency portion. The two filtered signals are combined to provide a substantially full frequency signal indicative of the basis weight of the paper. The sensor signals may be manually calibrated or, preferably, the nuclear sensor signal may be used to provide continuous on-line calibration of the optical sensor signal.
18 Citations
20 Claims
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1. Apparatus for measuring the weight of a material, comprising:
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an optical sensor for sensing light shining through a material web portion and generating therefrom a first signal indicative of the weight; a nuclear sensor mounted adjacent to the optical sensor for sensing particles passing through the material web portion and generating therefrom a second signal indicative of the weight; and calibrating circuitry for calibrating the optical sensor signal to the nuclear sensor signal as the sensors sense the weight of the same portion of the material web. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. An apparatus for measuring the weight of a material web, comprising:
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a first sensor having a higher frequency response for sensing the signals passing through a material web portion and generating therefrom a first signal indicative of the weight; a second sensor mounted adjacent to the first sensor and having a lower frequency response for sensing signals passing through the material web portion and generating therefrom a second signal indicative of the weight; a high pass filter for filtering the first sensor signal to pass only a selected high frequency portion thereof; a low pass filter for filtering the second sensor signal to pass only a selected low frequency portion thereof; and a summing junction for adding the low frequency portion of the first sensor signal and the high frequency portion of the second sensor signal to produce a substantially full frequency scanning signal indicative of the weight of the material web. - View Dependent Claims (10, 11, 12, 13, 14)
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15. A method of regulating the weight of a material in a material making process, comprising:
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scanning the same portion of the material web with an optical sensor and a nuclear sensor as the material is being processed; and calibrating the optical sensor signal to the nuclear sensor signal while scanning to produce a scanning signal indicative of the weight of the material web. - View Dependent Claims (16, 17, 18, 19)
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20. A method of measuring the weight of paper in a paper making process, comprising:
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providing a first sensor having a higher frequency response for sensing signals passing through a material web portion and generating therefrom a first signal indicative of the weight; providing a second sensor having a lower frequency response for sensing signals passing through the material web portion and generating therefrom a second signal indicative of the weight; sensing with both sensors the material web portion to sense its weight simultaneously with both sensors; filtering the first sensor signal to pass only a selected high frequency portion thereof; filtering the second sensor signal to pass only a selected low frequency portion thereof; and summing the low frequency portion of the first sensor signal with the high frequency portion of the second sensor signal to produce a substantially full frequency sensor signal indicative of the weight of the material web portion.
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Specification