Textiles: weaving – Weft manipulation – Weaving with stationary weft supply
Patent
1998-12-17
2000-08-01
Falik, Andy
Textiles: weaving
Weft manipulation
Weaving with stationary weft supply
242563, 2423648, 356429, 2505594, G01V 814, D03D 4736, B65H 5122, D04B 1548
Patent
active
060952008
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to an opto-electronic device provided on a storage drum of a yarn feeder for detecting a yarn in a detection zone.
BACKGROUND OF THE RELATED ART
In a device of this kind known from EP-A-0 199 059, the light source and the receiver pointing into the detection zone at the storage drum are provided in a bracket of the housing of the yarn feeder and distant from the surface of the storage drum. Below the detection zone a glass plate is inserted into the surface of the storage drum. At the lower side of said glass plate a full plane reflective coating is provided. The yarn windings wound onto the storage drum in circumferential direction are pushed axially forwards so that each yarn winding passes the detection zone lateral to its longitudinal direction. The device serves as a sensor for the detection of the axial position of at least the first winding of the yarn supply on the storage drum and is responding to the movement, absence or presence of the yarn with a signal which, e.g., is used for the control of the rotational drive of the yarn feeder. The receiver exclusively registers the shade of the yarn or the variation of the light intensity as soon as the yarn is interrupting the light beams directed towards the reflector or coming from the reflector. Independent from the design, only a relatively weak modulation of the signal can be derived from the shadowing, particularly in case of thin yarns, such that in order to generate a useful and clear active signal relatively high efforts are necessary for the evaluation, amplification and discrimination. The device is vulnerable in case of dirt, disturbing light or unavoidable lint or lint bundles. In addition, the frequency of necessary cleaning--or maintenance--cycles is undesirably high.
It is, nevertheless, for similar devices known to provide a diaphragm and/or lenses for an opto-electronic yarn detection between the yarn and the receiver and/or between the light source and the yarn. However, that measure cannot significantly improve the response behavior of the device and does not have a considerable influence on the vulnerability against contamination.
It is an object of the invention to create a device of the kind as disclosed which is apt to derive strong and useful effective signals from the passage of the yarn through or the presence or absence of the yarn in the detection zone, which is relatively insensitive for contaminations, lint and disturbing light.
SUMMARY OF THE INVENTION
The object of the invention is achieved by providing the opto-electronic sensor device of the invention with a reflector having a narrow reflection area which extends in a circumferential direction of the storage drum.
As the yarn, even with its relatively slow forward motion on the storage drum, covers or clears at least one bar-code-shaped reflection-area extending in longitudinal direction of the yarn, relatively quickly, i.e. only very short time is expiring till maximum coverage or complete clearing, very strong and effective use-signals are generated. The narrow but long reflection zone is illuminated during absence of the yarn over its full length and width and is reflecting, due to its large longitudinal extension, much light to the receiver. When the yarn is present between the reflection-strip and the light source, it may happen that the entire reflection strip is covered. Due to the bar-code shape and the small width of the reflection-strip in moving direction of the yam, there is not only a strong difference in the light amount between the covered and the cleared conditions but also a strong and progressive or degressive transition from high light amount to low light amount and vice versa. The strong signal-modulation occurring therewith allows to avoid high electronic efforts for the signal evaluation. The response behavior is hardly changed by uniform and weak contamination. Lint or lint bundles can normally not shadow or clear the reflection zone in the same way as the yarn and for this reason, are al
REFERENCES:
patent: 4083506 (1978-04-01), Mander et al.
patent: 4163158 (1979-07-01), Coughenour et al.
patent: 4865085 (1989-09-01), Ghiardo
patent: 5211121 (1993-05-01), Sakakibara
patent: 5221960 (1993-06-01), Akerlind et al.
Falik Andy
Iro AB
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