Optics: measuring and testing – Inspection of flaws or impurities – Textile inspection
Patent
1998-04-13
1999-10-12
Rosenberger, Richard A.
Optics: measuring and testing
Inspection of flaws or impurities
Textile inspection
57265, 57 81, 356429, D01H 1316
Patent
active
059662115
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to an optoelectronic sensor device having a light source and detector for detecting a yarn passing through a scanning zone, and to a weft-yarn measuring and storing device wherein the optoelectronic sensor device detects yarn being withdrawn from weft yarn measuring and storing device.
BACKGROUND OF THE INVENTION
In an optoelectronic sensor device which is known from GB-C-1 283 528, the transverse passage of a spun yarn is detected in a ring spinning machine, with the unwinding running yarn orbiting in an opening. The opening has a light beam passing diametrically therethrough, the light beam being emitted from a light source, which is arranged in an opening wall, and through the opening onto an opposite receiver. A slit aperture is arranged in front of the receiver. The receiver responds to light variations or to the shadow of the yarn which passes over the slit aperture. Disturbing factors, such as vibrations, extraneous light, or the like, can prompt the receiver to output a wrong signal, despite the fact that the yarn has not properly passed through the slit aperture in the scanning zone.
In weft-yarn measuring and storing devices, as typically used on weft looms for providing weft yarn, exact information as to when and that the weft yarn passes through a scanning zone upon withdrawal is required for controlling and monitoring the feed operation of each weft yarn. To this end, at least one withdrawal sensor is provided which is equipped with a receiver that is oriented towards the illuminated scanning zone and is responsive to light variations. Since vibrations, the effect of extraneous light, or other unwanted factors that are observed during practical operation also prompt the receiver to respond, the significance of the signals gained from the weft-yarn passages is not to be relied on. Therefore, a method has been adopted in practice in which two receivers which are closely arranged one after the other in the axial direction of the storage body are oriented towards the same scanning zone and in which a significant signal for the yarn passage is derived from the response of the two receivers in a differential circuit, the signal being distinguishable from signals produced by unwanted factors because of the fact that an unwanted factor is observed on both receivers at the same time and in the same manner, whereas the yarn is recorded by the two receivers such that the record is offset in time. Nevertheless, this known scanning sensor with the two receivers does not reliably operate for several reasons. The receiving surface of each receiver is approximately circular as a rule. The yarn which moves relative to the receiving surface is only gradually imaged by its reflective light or its shadow because of the circular form of the receiving surface and due to transitional imaging. In addition, the response sensitivity of the receiver in the edge portions of the receiving surface is weaker than near the center. The signal which is evaluated in the differential circuit is therefore weak because of the gradual signal increase and the also gradual signal decrease and requires considerable amplification efforts which, however, are undesirable in the case of unwanted factors. Furthermore, such measuring and storing devices imperatively operate with a distinctly axial reciprocating movement of the yarn supply border at the withdrawal side of the yarn supply on the storage body, especially with when yarn separation and/or when a lively pattern is being weaved. This results in a yarn withdrawal geometry in which yarn withdrawn from the last winding of the yarn supply varies its longitudinal orientation in the scanning zone between approximately axial and approximately circumferential, respectively related to the axis of the storage body. With an approximately axial orientation of the yarn in the scanning zone the yarn is perceived by both receivers at the same time and in a similar manner, which renders a distinction difficult, or even excludes it, with res
REFERENCES:
patent: 3772524 (1973-11-01), Erbstein
patent: 4112665 (1978-09-01), Werst
Iro AB
Picanol N.V.
Rosenberger Richard A.
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