Title of Invention

A YARN SENSOR

Abstract

The invention relates to a yam sensor for scanning a yam (2), which is moving in its longitudinal direction in a measuring gap (3), with a light beam from a light source (4), having a first receiver (7) for directly transmitted light, at least one second receiver (S, 6) for light reflected by the yam and one element each {8, 9, 10, 11) for transmitting the light between the measuring gap, the light source and a receiver. To keep the overall size and the external dimensions as small as possible, the optical axes !12 - is) of the elements for transmitting the light are disposed together in one plane lying at least approximately at right angles to the yam. PRICE: THIRTY RUPEES

Full Text

YARN SENSOR ? The invention relates to a yarn sensor for scanning a yarn, , which is moving in its longitudinal direction in a measuring gap, with a light beam from a light source, having a first receiver for directly transmitted light, at least one second receiver for light reflected by the yarn and one element each for transmitting the light between the measuring gap, the light source and a receiver. From WO 93/13407 such a yarn sensor is known, in which a receiver for transmitted light and a receiver for reflected light are disposed opposite one another on either side of'a , measuring gap. On one side of the measuring gap, inlet and outlet prisms for the light are moreover lined up alongside one another, viewed in the direction of the yam. ! A drawback of said known yarn sensor is that the various elements, which are provided for transmitting and introducing light in a locally correct manner, take up a great deal of space. Such yarn sensors are however intended for installation in textile machines where there is often very little space available for them. It may therefore happen that in certain textile machines such knovm yarn sensors cannot be installed at all. The subject matter of the invention is t; here fore a yarn sensor, which takes up only a littl© Splice in an outward direction and may also be fitted with a Kelatively small measuring gap. According to the invention, this is achieved in that the optical axes of the elements for transmitting light between the yarn and the receivers together lie ,in the plane, which is situated transversely or preferably at least approxlimately at right angles to the yarn or which is pioroed by the yarn. It is sufficient if two of said optical axes lie in said plane. Said arrangement produces in the measuring gap, for example, , on one side a window for light for exposing the yam to light and, situated alongside, windows for receiving reflected light, which actually lie next to,the yarn and so may receive only light reflected laterally by the yam. The advantages achieved by the invention are in particular that the measuring principle, according to which, for example, impurities or extraneous fibres may be detected in a yarn by evaluating the transmitted light and the reflected light, may be used also with small measuring gaps. In said case, the spatial requirement in the vicinity of the measuring gap may likewise be reduced. Furthermore, the measuring gap may be inserted into a narrow side of the measuring head or yam sensor, which means that the yarn travels only a short distance in the yarn sensor. A further advantage is that, according to the invention, the measuring gap may be small and so the known self-cleaning effect of the measuring gap by the yarn may be used to good effect. With small measuring gaps, the influence of extraneous light, which may enter through the inlet opening for the yarn, is also reduced. With small measuring gaps, the measuring zone also comes to lie close to the yarn, which increases the measuring accuracy and keeps the measuring zone clean. Accordingly the present invention provides a yarn sensor for scanning a yam, which is moving in its longitudinal direction in a measuring gap, with a light beam from a light source, having a first receiver for directly transmitted light, at least one second receiver for light reflected by the yam and one element each for transmitting the light between the measuring gap, the light source and the receiver, characterized in that the optical axes of at least two elements for transmitting the light a1^ situated at right angles to the yarn and intersect in the region of the yam. There follows a detailed description of the invention by way of an example and with reference to the accompanying drawings. The drawings show: Figure 1 a simplified sectional view through part of a yam sensor, Figure 2 a diagrammatic view of part of a measuring gap, Figure 3 and 4 in each case an individual part of the yam sensor. Figure 5 a signal shape of a measuring field characteristic. Figure 6 a section through part of a further construction of a yarn sensor and Figure 7 a diagrammatic view of poseible arrangements of optical axes in a y«rn aenaar. Fig. 1 is a somewhat simplified sectional view of a yarn sensor 1 for a yam 2 having a measuring gap 3 . Disposed in the vicinity of said measuring gap are a light source 4 and receivers 5 and 6 for reflected light as well as a receiver 7 for transmitted light. The light source 4 find the receivers 5, 6 and 7 are known structural element and are therefore not described in detail here. Elements 6, y, 10 and 11 for transmitting the light are disposed between the measuring gap 3, the light source 4 and the receiver!: b, 6, 7. Said elements 8-11 comprise, for example, ii Light shaft which is rectangular in cross section and which may be empty or hollow or filled by a light-guiding or tranaparent body. The walls, which delimit the light shaft, are metalized or designed so as to absorb light. Each of said element - 11 nas an optical axis 12, 13, 14 and 15, which optical axes preferably intersect in the region of the yarn 2 and of which at least two together define a plane, here the drawing plane, which is situated substantially at right angles to the axis of the yarn 2. The points where the elements 8 - 11 or their light shafts open into the measuring gap 3 givtj rise to windows 16, 17, 18 and 19, through which light passes into or out of the f measuring gap 3. Filters which limit the spectrum of the light may also be fitted into the elements 8-11. For example, the windows 16 to 19 may be take the form of such filters. Fig. 2 is a diagrammatic view of part of a measuring gap 20 for a yarn 21, having a window 22 for exposing the yam 21 to light, windows 23 and 24 for receivliig iight reflected by the yarn 21 and a window 25 for receiving residual light from the window 22. Said residual light is the light which passes out' I of the window 22 and is not stopped out, retained or reflected of the yarn sensor according to the inveiit; ,l.o|:i is made very much simpler. Fig. 5 shows two signal shapes 32, 33 which are recorded above, a horizontal axis 34 and alongside a vertical axis 35. Plotted on the horizontal axis 34 are values for a distance corresponding, say, to a distance (::|:om the ihlet or the lateral boundary surface 4 0 (Fig.l) of a measuring gap!3. Plotted on the vertical axis 35 are values of an electric signal of the type supplied by the receivers. Accordingly, the signal shape 3 2 here indicates which values the receiver for transmitted light measures when the yarn is gradually inserted from above (according to Fig.l) deeper into the measuring gap 3. The signal shape 33 correspondingly indicates the values which two receivera of reflected light in the arrangement according to Fig.l measure in said case. The greatest values are measured when the yarn 2 is roughly in the position shown in Fig.l. The signal shape 32 then has a region 32' in which the values remain substantially constant. In the signal shape 33 there arises, in the region 33', a possibly rather non-uniform shape which, as will be explained below, is caused by uneven distribution of the reflected light to two receivers. 41 denotes a signal shape of the type wtlich occurs when only a single receiver for Reflected light is provided. Fig. 6 shows a view of a yarn sensor according to Fig.l, the yarn sensor however comprising, besides the light source 4 and the known receivers 5, 6 and 7, two further light sources 42 and 43 with optical axes 44 and 45. The optical axes of said - compared to Fig.l - additional light wources 44 and 45 or of the associated light-transmitting elements lie preferably substantially in the same plane as the already known optical axes 12, 13, 14 and 15. It is however also conceivable to position some of the known optical liixes :|in a first plane and some in a second plane. The mode of operation of the yarn sensor according to the invention is as follows: A guide which is known per se and not illustrated here ensures' that the yarn 2, as it is drawn in its longitudinal direction in a likewise known manner through the measuring gap 3, stays in the illustrated region in said measuring gap. In the measuring gap 3, the yarn 2 is expoeed to the light beam of the light source 4. Light, which does not strike the yarn 2 and is also not sufficiently deflected by said yarn, strikes the receiver 7 and is converted by said receiver into an electric signal. Light reflected by the yarn strikes the receivers 5 or 6 provided it is reflected at a sufficientli*' large angle 35, 36. The signals from tjie receivers 5, 6, 7 are then processed in a manner which is known per se and is described, for example, in the citwd WO 93/13407. Should the yarn shift out of its pouitiolT Rhown in Fig.l, gaid shift has no effect upon the receiver 7 within a specific « region, as the signal shape 32 in the region 34 reveals. The' receiver 5 receives more reflected light when the yarn 2 is displaced upwards in the measuring gap 3. Said.circumstance finds expression in the signal shape 33 in the hump 37. The receiver 6 receives more light when the yarn 2 is displaced downwards in the measuring gap 3. This produces a hump 38 in the signal shape 33, Ideally, however, the humps 37 and 38 hardly arise. This may be achieved by correctly tuning the width of the light-transmitting elements 8, 9, 10 and 11 in relation to the yam diameter and to the position of the yam 2 in the measuring gap 3, which tuning may be determined, , for example, by means of experimental airangeraents. The slight dip in the signal shape 33 in the .region 34 is attributable to the fact that a portion of the light reflected by the yarn 2 is not detected. Said portion relates |;.D light which is reflected at an angle smaller than the angles 35 and 36. The yarn sensor according to the invention may be provided both with one as well as with two oi moro receivers for reflected light, the construction comparing two receivers 5, 6 or light-transmitting elements 10, 11 disposed symmetrically to the optical axis 12 being however particularly advantageous and giving rise to a more uniform signal shape 33. In the construction according to Fig 6 there is the additional possibility of constructing the light sources 4, 42, 43 in such a way that each light: soun'e emits a different wavelength. It is therefore possible to raoognize whether there is extraneous material such as extraneous fibres or impurities in the yarn. By suitably se Inciting the emitted light, it is possible to effect a targatwii aearch for specific extraneous materials. When all of the light sources emit identical light, it is then possible for each light source to be lit for a limited timfe only and be switched on and off sequentially. Thus, the yarn is exposed to light in each case from a different direction so that it is possible to establish whether theyam is round or whether it has flat points. | ! In a construction according to Fig.7 it is, for example, conceivable to detect a first property of the yam , e.g. its diameter, in the plane 47. In the plane 50 a second property,; e.g. the extraneous material content, may be detected. In the further plane 55 it might be possible, for example, to detect the quality of the surface of the yarn 4(1 and produce information about it, and so on. The yarn sensor according to the invention may naturally also be designed and used for other elongated yam-like formed bodies. The term "yarn sensor" here refers merely to the most frequent application which consists of detecting extraneous 1 1 materials or impurities in such a formed body or yarn or indicating other properties such ae diameter, uniformity, structure, hairiness etc. WE CLAIM; 1. A yarn sensor (1) for scanning a yam (2), which is moving in its longitudinal direction in a measuring gap (3), with a light beam from a light source (4), having a first receiver (7) for directly transmitted light, at least one second receiver (5, 6) for light reflected by the yarn and one element each (S, 9,10,11) for transmitting the light between the measuring gap, the light source and the receiver, characterized in that the optical axes (13,14} of at least two elements for transmitting the light aTe situated at right angles to the yam and intersect in the region of the yam. 2. The yam sensor according to claim 1, wherein the elements for transmitting the light comprise a light shaft (26,27, 28,29). 3. The yam sensor according to claim 1, wherein the elements for transmitting the light comprise a window (16,17,18,19) directed towards the measuring gap. 4. The yam sensor according to claim 3, wherein the windows of the optical elements for transmitting the reflected light to the receiver are situated - viewed at right angles to the direction of motion of the yarn - next to the optical axis (12) of the light source. 3. The yam sensor according to claim 1, wherein the elements for transmitting the light are constmcted together as a single, cohesive body (25,31). 6. The yam sensor according to claim 1, wherein the elements for transmitting the light are light-guiding bodies. 7. The yarn sensor according to claim 1, wherein the elements for transmitting the light comprise filters (16,17,18,19) for limiting the spectrum. 8. A yarn sensor, substantially as herein above described and illustrated with reference to the accompanying drawings.

Documents:

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1324-mas-96 abstract.pdf

1324-mas-96 assignment.pdf

1324-mas-96 claims.pdf

1324-mas-96 correspondence-others.pdf

1324-mas-96 correspondence-po.pdf

1324-mas-96 description (complete).pdf

1324-mas-96 drawings.pdf

1324-mas-96 form-1.pdf

1324-mas-96 form-26.pdf

1324-mas-96 form-4.pdf

1324-mas-96 form-6.pdf

1324-mas-96 form-9.pdf

1324-mas-96 petition.pdf