Abstract: Test material (F) such as a textile yarn is illuminated and the light reflected from the test material is measured so that the presence of a foreign substance can be determined from a change in the reflected light. When detecting foreign substances which are darker than the test material (F), an image of the test material in front of a light background (4) is projected onto a sensor (3), and for the detection of lighter foreign substances an image of the test material in front of a dark background is projected onto the sensor. The apparatus and method may be used in combination with an electronic yarn clearer for the purpose of detecting foreign fibers in yarns.

Abstract: For the setting of yarn clearers for fineness control the number of permissible false alarms for a given yarn length, i.e. the permissible alarm frequency, is fixed. During the clearing process measured values of the fineness are recorded continuously, and their distribution is determined. From this distribution of the measured values and from the predetermined permissible alarm frequency, response limits are fixed independently on the basis of statistical regularities. Thus, the yarn clearers can be set automatically in an optimum manner on the basis of actual production circumstances, and mistakes between yarns differing only slightly in their fineness cannot occur.

Abstract: A yarn is wound onto a generally conical yarn package using a cam cylinder to traverse the yarn back and forth between the ends of the package. A first sensor is used to determine the rotational position of an element which is rotating synchronously with the package. The position of the yarn lengthwise of the package is determined using a second sensor. A correction factor is obtained for determining an instantaneous yarn feeding speed from an average yarn speed value obtained from the peripheral speed of the rotating element. The improved yarn speed determination enables on-line spectrograms to be provided on yarns handled in these machines. Also, there is considerably greater accuracy when measuring lengths of yarn defects.

Abstract: The length of fabric is scanned continuously directly at the weaving machine and any defective variations from the texture judged to be normal are determined and displayed. Scanning is performed by an electrical-optical scanning head traversing across the width of the cloth and in the evaluation of the signals of the scanning head those signals are preferentially treated which represent an excessive variation from a specified size or number, or which have a certain periodicity. The variations of the type mentioned are representative of warp stripes and weft bars and consequently are very serious cloth faults. These cloth faults can now by means of scanning be detected directly at the weaving machine sufficiently early for corrective action to be taken in the weaving process before large quantities of fabric are produced with these faults. Thereby the occurrence of fabric of inferior quality is at least considerably reduced.

Abstract: An apparatus controls the titer of synthetic fiber tows by an optical measurement of the cross section of the tow. A ray beam which illuminates the tow from one side is directed towards a photodiode row, on which the tow throws its shadow. The number of photodiode elements of the diode row lying in the shadow produces a measurement for the cross section of the tow. In order to eliminate the form effect of the tows, they may be provided with a false twist by a twisting device or a suitable thread guide may be provided. In order to use the photodiode row in an improved manner, several tows may be guided next to each other and may be measured using one and the same lens system.

Abstract: A method and device for detecting the presence of a running thread takes advantage of the inherent physical irregularities of the thread to generate an alternating current signal as the thread passes through a capacitive element. The variations in capacitance resulting from the running thread are detected and amplified as an alternating current electrical signal, which disappears instantly with thread stoppage or breakage.

Abstract: In a method and apparatus for the detection of yarn defects, which may be effected in combination with a standard yarn clearer or independently thereof, the cross section of the yarn is continuously scanned and an electrical signal is generated representing not only the cross section and length of yarn defects, but also their frequency or periodicity, and these features are used as the criterion for generating a defect signal as an indication of detection of regular or irregular sequences of thick places in the yarn.

Abstract: Faults in produced yarn occurring by fouling of spinning units can be detected by measuring changes in the cross-sectional diameter of the yarn and producing a control signal indicating irregularities. The apparatus of this invention includes a measuring device for measuring the cross-sectional diameter and producing a signal representative thereof, which signal is processed in a discriminator circuit, including at least a correcting circuit with a non-linear characteristic, an integrating circuit and a comparison circuit to compare the integrated signal with a predetermined standard, thereby producing the control signal.