Method and apparatus for evaluating yarn signals based on the detection of at least approximately periodic variations in cross section

Claim 1

A method of controlling one or more spinning stations by evaluating yarn signals based on the detection of at last approximately periodic variations in cross section of the yarn comprising the steps of generating signals representative of the cross section or diameter of the yarn by means of detectors, converting the signals to digital form, delaying the digital signals by a time interval τ lying within a predetermined delay interval, producing signals whose absolute values represent the differences between the original yarn signal and the delayed yarn signals, integrating the said absolute value signals to give signals having function values Q(τ) over a time interval T, and obtaining from the maximum and minimum values of Q(τ) appearing within the said delay interval criteria for the presence of at least approximately periodic variations in cross section and/or for the size of the total irregularity of the yarn and controlling said spinning station on the basis of said criteria.

Claim 2

A method of controlling one or more spinning stations by evaluating yarn signals based on the detection of at last approximately periodic variations in cross section of the yarn comprising the steps of generating signals representative of the cross section or diameter of the yarn by means of detectors, converting the signals to digital form, delaying the digital signals by a time interval τ lying within a predetermined delay interval, producing signals whose absolute values represent the differences between the original yarn signal and the delayed yarn signals, integrating the said absolute value signals to give signals having function values Q(τ) over a time interval T, and obtaining from the maximum and minimum values of Q(τ) appearing within the said delay interval criteria for the presence of at least approximately periodic variations in cross section and/or for the size of the total irregularity of the yarn and controlling said spinning station on the basis of said criteria.

Claim 14

An apparatus for controlling one or more spinning stations by evaluating yarn signals based on the detection of at least approximately periodic variations in yarn cross section, comprising an analog-digital converter for converting the yarn signals into digital signals; a microcomputer in which the sum of the differences between the original yarn signal and a yarn signal delayed by a time interval τ is continuously formed, the microcomputer further comprising means for producing specific fault signals from the summed differences and means for checking the fault signals against predetermined reference values; and switching means responsive to said microcomputer for controlling the spinning process at said spinning station if at least one reference value is exceeded.

Claim 15

An apparatus for controlling one or more spinning stations by evaluating yarn signals based on the detection of at least approximately periodic variations in yarn cross section, comprising an analog-digital converter for converting the yarn signals into digital signals; a microcomputer in which the sum of the differences between the original yarn signal and a yarn signal delayed by a time interval τ is continuously formed, the microcomputer further comprising means for producing specific fault signals from the summed differences and means for checking the fault signals against predetermined reference values; and switching means responsive to said microcomputer for controlling the spinning process at said spinning station if at least one reference value is exceeded.

Claim 20

An apparatus according to claims 13 or 16, wherein said microcomputer includes means for storing for later recall, individually or in combination, the intensity of periodicity, period length and size of the irregularity.

Claim 21

A method according to claims 1 or 12, wherein an autocorrelation function is formed from the yarn signals and that criteria for the size of the total irregularity of the yarn are obtained from the maximum and minimum values of the autocorrelation function appearing within the said delay interval.