Title of Invention

A SYSTEM FOR ONLINE YARN THICKNESS MEASUREMENT FAULT DETECTION AND CLEARING

Abstract

ABSTRACT A System for on-line yarn thickness measurement and fault detection with , monochromatic polarised light for imaging light interference pattern of an yarn using CCD array and means for analyzing the interference pattern and thereby detecting the yarn thick and thin faults A system for on-line yarn fault clearing provided with or without said system for yarn thick/thin fault detection comprising laser means of desired power adapted to selectively remove thick and thin faults on the yarn. The system provides for on-line precise measurement of thickness of yarn and on-line removal of yarn faults thereby avoiding problems of averaging/approximation of yarn thickness and bring about improvement in uniformity in yarn character. Being an on¬line system the same does not affect the production line and is also cost-effective and easy to operate.

Full Text

The present invention relates to a system for yarn fault detection and in particular to a system for yarn fault detection and removal of thick faults. Faults in the yarn, like thick and thin places affect the quality of the fabric, as well as disturb the subsequent process like weaving, knitting etc. It is thus essential to detect thick and thin faults in yarn for possible rectification and ensuing good quality fabric. Conventionally it is known to use either capacitance or optic shadow principles to detect the thick and thin place faults. However, such conventional devices suffer from disadvantages in that it was not possible to carry out precise measurement of thickness and is basically dependent on averaging and approximation which failed to effectively cater to the requirement of quality maintenance of yarn. Moreover, under the known system irrespective of the nature of the fault it was always essential to cut the fault areas and rejoin the correct parts of the yarn which affected both quality of the yarn produced and also productivity. It is thus the basic objective of the present invention to provide a system for precise measurement of thickness of yarn and avoid need of averaging or approximation as in the case of the known systems such as capacitive measuring head. Another object of the present invention is to provide a system for on-line thick fault removal and/or trimming of hairiness of yarn thereby avoiding the present cutting and rejoining system which resulted in non uniforming of the yarn and lower productivity and also affected the life span of the splicing mechanism. Another object of the present invention is to provide a system for measurement of yarn thickness and fault detection which would be simple to operate, will maintain uniformity in yarn fault detection and will be extremely reliable. Yet further object of the invention is to provide an online clearing system for removal of thick faults and/or trimming the hairiness of the yarn to provide for quality yarn and also improve productivity. Yet further object of the invention is directed to provide a system for determining yarn thickness wherein errors due to wobbling and tension differences of the yarn because of the speed variations of the winding machine can be minimized. Thus according to one aspect of the present invention there is provided a system for online yarn thickness measurement, fault detection and clearing comprising: at least one polarized monochromatic light source ; at least one aperture means through which the yarn to be tested is fed ; at least one means for imaging light interference pattern of said yarn including CCD array ; at least one means for analyzing the interference pattern and detecting the yarn thick and thin faults; and at least one means for online removal of thick faults and/or trimming the hairiness of the yarn. In the above disclosed system of the invention laser is preferably used as the light source which is monochromatic, unipolar and of even intensity. Importantly, a single laser source can be used as a light source for more no. of measuring locations by use of optical fibre. The aperture means can be of fixed slit type if yarn under clearing is only in one range and in cases where regular count (indicating the yarn diameter) change occur there can be provided a manually adjustable type slit. A fully automatic slit with motorized movement is also possible as an added modification. A micromotor adjustment or manually adjusted setting of the slit can be provided. According to another aspect of the present invention there is provided a system for online clearing of yarn faults comprising means for online removal of thick faults and/or trimming the hairiness of the yarn. The above system for on-line clearing of yarn faults can be used as an independent system or can be operatively connected to the system for measuring yarns thickness and detecting yarn faults. The above disclosed means for online removal of thick faults and/or trimming the hairiness of the yarn in accordance with the system of the invention can comprise use of laser beam of suitable power with necessary optical gadgets. Alternatively, such means for online removal of thick faults and/or trimming the hairiness of the yarn in accordance with the system of the invention can comprise cut generator circuitry with necessary logic operatively connected to the CCD array means to generate a cut signal and activate a cutter. The yarn cutter used can be a knife activated by magnet or any other type of yarn breaker which can do the breaking of yarn without adding tension on yarn and also which can break the yarn instantly after the detection of the fault. An yarn cutter amplifier can also be used in case the signal from the processor is very weak and hence has to be suitably amplified to cut yarn. This can be a current amplifier or a voltage switch normally. Known electric gadgets may be used to active such amplification. The means for analyzing the CCD array image data comprise any conventional microprocessor having means to carry out diffraction equation calculations and fault detection cut generator by performing necessary logical operations depending upon yarn thickness and related parameters. For the purpose necessary software logic is built in the Read Only Memory content of the microprocessor. A Central Monitoring Station can be provided using a dedicated processor, shared processor or even with a PC dedicated for achieving or facilitating the above cut operations and/or trimming the hairiness. The system of the invention is explained hereunder in greater details with reference to non-limiting exemplary embodiments in relation to the accompanying figures wherein - Fig. 1 is a schematic illustration of the system for detection of yarn faults and removal of thick faults in accordance with the present invention ; Fig. 2 illustrates the use of a single common light source for plurality of different measuring/cleaning heads used of the system of the invention ; Fig. 3 illustrates an embodiment of online clearing system for removal of thick faults and/or trimming hairiness of yarn of the invention ; Fig. 4 illustrates another embodiment of the online clearing system for removal of thick faults and/or trimming hairiness of yarn of the invention. Reference is first invited to figure 1 which illustrates schematically a preferred embodiment of the system of the present invention having both said means for measuring the yarn thickness for identification of yarn faults and also the online clearing system for removal of thick faults and/or trimming the hairiness of the yam. As would be evident from Fig. 1, the system basically comprises of the polarized monochromatic light source preferably a laser source, the aperture means, the images system comprising said CCD array means, an array control and data A/D controller means, a processor means adapted to calculate diffraction equation to favour fault detection and a cut generator for removal of thick faults and/or hairiness trimming as may be required. In particular, in the above system of the invention CCD array means detects the light falling pixels. By identifying the presence of light at one pixel and the absence of light in the nearby pixel and the no. of pixels in between it is possible to calculate the gap between the bright and dark fringes, just by multiplying the no. of pixels in between by the size of a pixel in micrometer. The CCD array which works as a digital sensor provides for reliability of the system. In particular, the array control and A/D converter means acquires the data from the pixels. The diffraction equation calculations are done by the processor to find the thickness of the yarn at that sampling point. All these are Digital manipulations which work similar irrespective of the processor, temperature and other ambient conditions, depending upon the logic used. The cut generator provides for necessary removal of thick faults and/or trimming the hairiness of the yarn. The hardware/software and algorithm are preferably selected for speedy processing of the imaged diffraction pattern and for the computation of the diffraction equations. Reference is now invited to figure 2 which illustrates an arrangement of the system of the invention wherein a common light source (1) is used for different measuring/clearing heads (2) utilizing optical fibres (3). The cutter generator actuates the a laser beam means for removal of thick faults or trimming the hairiness of yarn an embodiment of which is illustrated in figure 3. As shown in figure 3 laser beam (4) of suitable power with necessary optics can be used for removing yarn thick areas. Yarn for clearing (5) is passed through the laser beam means and cleared yarn (6) is achieved. In particular for trimming the hairiness of yarn the laser may preferably be pointed at such a way that it encircles the yarn so that the trimming takes place on all the sides of the yarn. Such an embodiment is shown in Fig. 4. It can be a hexagonal fixture with its inside faces made into mirrors (7). The laser (8) is allowed to enter through a hole on one face and it gets reflected around the yarn (9). Yarn for clearing (10) passes through system and cleared yarn (11) is achieved. This can be manually or automatically adjustable for different yarns of different diameter and hairiness. This system can also act as an equivalent of singing or reduce hairiness of yarn. In the above system of the invention the laser light intensity will vary if dust is accumulating at the entry point. This can be avoided by providing means for passing compressed air passing through the sensor area, A suitable housing is also provide for the system so that effect of ambient light is reduced. Importantly, in accordance with the invention an online clearing system may or may not have the laser detection system itself and a diffraction based detection system need not have a laser clearing system. The laser clearing system and the diffraction based thick/thin detection system can work together or separately or even fitted with other type of clearers and sensors. We claim: 1. A system for online yarn thickness measurement, fault detection and clearing comprising: at least one polarized monochromatic light source at least one aperture means through which the yarn to be tested is fed ; at least one means for imaging light interference pattern of said yarn including CCD array ; at least one means for analyzing the interference pattern and detecting the yarn thick and thin faults; and at least one means for online removal of thick faults and/or trimming the hairiness of the yarn. 2. A system as claimed in claim 1 wherein laser is used as the monochromatic, unipolar and even intensity light source. 3. A system as claimed in anyone of claims 1 or 2 wherein a single laser source is used for plurality of said aperture and yarn measuring locations. 4. A system as claimed in anyone of claims 1 to 3 wherein aperture means comprise fixed slit aperture for the yarn. 5. A system as claimed in anyone of claims 1 to 3 wherein said aperture means comprise adjustable type slit. 6. A system as claimed in claim 5 wherein said adjustable slit is manually and/or ' automatically operated. 7. A system as claimed in anyone of claims 5 or 6 wherein a micromotor adjustment means is provided for said adjustable slit. 8. A system as claimed in claim 1 wherein said means for online removal of thick faults and/or trimming the hairiness of the yarn comprises laser beam of suitable power and online clearing generating circuitry with necessary logic means. 9. A system as claimed in any preceding claim wherein said means for online removal of thick faults and/or trimming the hairiness of the yarn comprise use of laser beam of suitable power with necessary optical gadgets operatively connected to said means for measuring and detecting yarn faults. 10. A system as claimed in any of claims 1 to 8 wherein said means for online removal of thick faults and/or trimming the hairiness of the yarn comprise online clearing generating circuitry with necessary logic means operatively connected to the CCD array means to generate a cut signal and activate a cutter. 11. A system as claimed in any of claim 10 wherein said yarn cutter used comprise knife activated by magnet. 12. A system as claimed in claim 11 wherein said yarn cutter comprise a yarn breaker adapted to break the yarn instantly after the detection of the fault. 13. A system as claimed in claim 12 comprising an yarn cutter amplifier to facilitate yarn cut. 14. A system as claimed in claim 13 wherein said yarn cutter amplifier comprise current amplifier or a voltage switch amplifier. 15. A system as claimed in anyone of claims 1 to 14 wherein said means for analyzing comprise microprocessor means. 16. A system as claimed in anyone of claims 1 to 15 wherein said microprocessor is provided with necessary software logic. 17. A system as claimed in anyone of claims 1 to 16 comprising Central Monitoring Station to provide user interface. 18. A system as claimed in anyone of claims 16 to 17 wherein said processor means is adapted to calculate diffraction equation for fault detection and generate cut generation signals for removal of thick faults and/or hairiness trimming. 19. A system as claimed in anyone of claims 1 to 18 wherein said CCD array means comprising means for detecting the light falling pixels for identifying the presence of light at one pixel and the absence of light in the nearby pixel and the number of pixels in between and means to calculate the gap between the bright and dark fringes, and micrometer means for determining the size of the pixel. 20. A system as claimed in any one of claims 1 to 19 wherein said microprocessor with necessary hardware/software and algorithm is selected for speeding processing of the imaged diffraction pattern and for the computation of the diffraction equations. 21. A system as claimed in anyone of claims 1 to 20 wherein said laser is adapted to be pointed such that it encircles the yarn so that the trimming is effected on all the sides of the yarn. 22. A system as claimed in claim 21 wherein said laser is adapted to enter through a hole on one face and get reflected around the yarn. 23. A system as claimed in claim 22 wherein the said laser is adapted for the purpose manually and/or automatically for different yarns of different diameter and hairiness. 24. A system as claimed in anyone of claims 1 to 23 wherein there is provided means for passing compressed air through the sensor area. 25. A system as claimed in anyone of claims 1 to 24 wherein a housing is provided to reduce effect of ambient light. 26. A system as claimed in anyone of claims 1 to 25 wherein there is provided means for sensing the speed of a winding machine for identifying the feed rate of said yarn which is operatively connected to said means for analyzing the thickening and fault detection and/or said means for online clearing. 27. A system for online yarn thickness measurement, fault detection and clearing substantially as hereindescribed and illustrated with reference to accompanying figures.

Documents:

1018-mas-1999 abstract-duplicate.pdf

1018-mas-1999 abstract.pdf

1018-mas-1999 claims-duplicate.pdf

1018-mas-1999 claims.pdf

1018-mas-1999 correspondence-others.pdf

1018-mas-1999 correspondence-po.pdf

1018-mas-1999 description(complete)-duplicate.pdf

1018-mas-1999 description(complete).pdf

1018-mas-1999 drawings-duplicate.pdf

1018-mas-1999 drawings.pdf

1018-mas-1999 form-1.pdf

1018-mas-1999 form-19.pdf

1018-mas-1999 form-26.pdf

1018-mas-1999 form-3.pdf