EP0252109A1 - Device for detecting the beginning of a tear on a sheet during its manufacture - Google Patents

Device for detecting the beginning of a tear on a sheet during its manufacture

Info

Publication number
EP0252109A1
EP0252109A1 EP87900172A EP87900172A EP0252109A1 EP 0252109 A1 EP0252109 A1 EP 0252109A1 EP 87900172 A EP87900172 A EP 87900172A EP 87900172 A EP87900172 A EP 87900172A EP 0252109 A1 EP0252109 A1 EP 0252109A1
Authority
EP
European Patent Office
Prior art keywords
cell
sheet
source
light
light source
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
EP87900172A
Other languages
German (de)
French (fr)
Inventor
Jacques Sabater
Serge Bauduin
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
CENTRE TECHNIQUE DE L'INDUSTRIE DES PAPIERS CARTONS ET CELLULOSE
Original Assignee
CENTRE TECHNIQUE DE L'INDUSTRIE DES PAPIERS CARTONS ET CELLULOSE
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by CENTRE TECHNIQUE DE L'INDUSTRIE DES PAPIERS CARTONS ET CELLULOSE filed Critical CENTRE TECHNIQUE DE L'INDUSTRIE DES PAPIERS CARTONS ET CELLULOSE
Publication of EP0252109A1 publication Critical patent/EP0252109A1/en
Ceased legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/84—Systems specially adapted for particular applications
    • G01N21/88—Investigating the presence of flaws or contamination
    • G01N21/89—Investigating the presence of flaws or contamination in moving material, e.g. running paper or textiles
    • G01N21/8901—Optical details; Scanning details

Definitions

  • the present invention relates to a device for detecting tear primers which can be present on the edges of a sheet during its manufacture, in particular on a sheet of paper, cardboard or the like.
  • the manufacture of a sheet of paper is done on a paper machine which allows successively to form the sheet, to dry it and finally to wind it.
  • this sheet is subject to a large number of tensions resulting either from shrinkage during drying, or from variations in speed of the numerous cylindrical organs responsible for driving and drying the sheet, organs which are complex to regulate speed.
  • the sheet of paper very often undergoes a wet surface treatment which momentarily weakens it, so that the manufacturing speeds are generally of the order of several hundred meters per minute.
  • This device of the invention overcomes these drawbacks.
  • This device for detecting incidences of breakage or tearing on the edge of a sheet of moving paper of the type comprising:. a light source,
  • a receiving cell for capturing the light transmitted by the source through the sheet which passes between the source and the cell is characterized: - on the one hand, in that the light source is a laser source; and on the other hand, in that the receiving cell is an optoelectronic cell arranged in such a way that the solid angle at which one sees, the useful surface of said cell, or its image by an optical system, from the sheet of paper is less than 0.01 steradian.
  • the invention consists in combining the laser source as a light source with an optoelectronic receiving cell, provided that the solid angle at which the useful surface of this cell is seen from the sheet of paper is less than 0.01 steradian.
  • the amount of light scattered by the sheet and received by the cell that is to say the amount of light scattered in said solid angle, would be more important, and consequently the difference in the light fluxes received by the cell, when there is a tear initiation and when there is none, would be smaller. This would affect the accuracy of the measurement.
  • the floor value results from the surface of the cell which is of the order of a few square millimeters.
  • the moving sheet As the light beam from the laser source is perfectly cylindrical, the moving sheet is illuminated at a single point. " It follows that the studied area receives all the light emitted by this source. So, when there is a tear initiation on this sheet, the light beam encounters no obstacle, and the cell then receives all the light emitted by However, when the leaf is intact, the transmitted light is scattered in all directions included in a solid angle cone of T (pi) steradians.
  • the solid angle at which the cell or its optical image can be seen from the sheet is S / d2.
  • the quantity of light collected being proportional to the solid angle, the cell will therefore only receive (S / d2) the quantity of light scattered.
  • the solid angle under which we see the cell from the sheet is 0.003 steradian and the cell does not receive that less than a thousandth of the light scattered by the sheet.
  • the device according to the invention therefore makes it possible to detect with very high precision tear primers on a sheet being scrolled, in particular on a sheet of paper during manufacture.
  • the laser source is a gas laser or a semiconductor laser
  • the opto-electronic cell is a cell with a very small surface, that is to say of the order of a few square millimeters
  • the useful surface of the opto-electronic cell is as already said the smallest possible in order to have a very precise device but nevertheless greater than the size of the light spot on the sheet of paper, increased by the divergence of the laser beam; preferably, this surface is such that the solid angle at which one sees said cell, or its image by an optical system, from the sheet of paper, is less than 0.01 steradian and advantageously 0.003
  • dry compressed air is sent into the device at the orifices intended to allow the light beam to pass; in this way, thanks to the overpressure, the deposit of fibers or of charges on the optical surfaces is avoided.
  • the device according to the invention consists of a U-shaped box, the two branches of which respectively contain the laser source and optoelectronic cell.
  • the power supply of the laser source is housed in the part of the box connecting the two branches of the U.
  • This box includes a supply of dry compressed air which is evacuated through the orifices intended to allow the light beam to pass. The optical surfaces are thus protected from surrounding dust.
  • the compressed air is also used simultaneously to cool the laser tube and its power supply.
  • the two branches of the U are tubular.
  • an additional diaphragm is inserted between the sheet of paper and the cell or the image of said cell by an optical system.
  • This device for detecting the initiation of rupture essentially takes a case (1) on which is fitted two parallel tubular branches (2,3) between which the edge (4) of a sheet of moving paper passes ( 5).
  • the set (1,2,3) therefore has the general shape of a U.
  • the upper branch (2) contains a source la ⁇ ser (6), for example a helium-neon laser, powered by a suitable member (7) connected by connections (8) to an inlet (9) of the housing.
  • This laser (6) emits a light beam (10) which is reflected by a mirror prism (11) on the sheet (5) through the opening (12).
  • the transmitted ray (13) then passes through another opening (14) formed in the parallel branch (3) to be reflected on a mirror (15), passes through a diaphragm (16) and arrives on an optoelectronic cell.
  • (17) for example a silicon cell.
  • This silicon cell is electrically powered by a connection (18) also connected to the inlet (9).
  • the cell (17) is connected to an electronic card (19) which is in turn connected via a power relay (20) to one or more alarm devices (21), such as an indicator light, a buzzer or a display counter.
  • the solid angle is close to 0.002.
  • the housing (1) also has an inlet (22) for compressed air connected to a source not shown.
  • This compressed air which passes through a baffle (23) is used on the one hand, to cool the laser source (6) and on the other hand, by evacuating via (12) and (14), to clean these two passage orifices of the laser beam (10,13) and thus avoid clogging of the optical elements (11,15,17).
  • This detection device is particularly advantageous: on the one hand, because of its structural simplicity which does not comprise any moving part;

Landscapes

  • General Health & Medical Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Textile Engineering (AREA)
  • Biochemistry (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Length Measuring Devices By Optical Means (AREA)
  • Investigating Or Analysing Materials By Optical Means (AREA)
  • Geophysics And Detection Of Objects (AREA)
  • Paper (AREA)

Abstract

Dispositif pour détecter les amorces de rupture ou de déchirure sur les bords (4) d'une feuille (5) en mouvement, du type comprenant: une source lumineuse (6) et une cellule réceptrice pour capter la lumière transmise par la source (6) au travers de la feuille (5) qui défile entre la source (6) et la cellule; caractérisé: d'une part, en ce que la source lumineuse (6) est une source laser, et d'autre part, en ce que la cellule réceptrice (17) est une cellule opto-électronique disposée de telle façon que l'angle solide sous lequel on voit la surface utile de cette cellule (17) ou de son image par un système optique, depuis la feuille de papier (5) est inférieur à 0,01 stéradian.Device for detecting the beginnings of rupture or tearing on the edges (4) of a sheet (5) in motion, of the type comprising: a light source (6) and a receiving cell for picking up the light transmitted by the source (6 ) through the sheet (5) which passes between the source (6) and the cell; characterized: on the one hand, in that the light source (6) is a laser source, and on the other hand, in that the receiving cell (17) is an opto-electronic cell arranged such that the angle solid under which one sees the useful surface of this cell (17) or of its image by an optical system, since the sheet of paper (5) is less than 0.01 steradian.

Description

DISPOSITIF POUR DETECTER UNE AMORCE DE DECHIRURE SUR UNE FEUILLE LORS DE SA FABRICATION.DEVICE FOR DETECTING A TEAR PRIME ON A SHEET DURING ITS MANUFACTURE.
La présente invention concerne un dispositif pour détecter les amorces de déchirure qui peuvent se présen¬ ter sur les bords d'une feuille lors de sa fabrication, notamment sur une feuille de papier, de carton ou analo¬ gues.The present invention relates to a device for detecting tear primers which can be present on the edges of a sheet during its manufacture, in particular on a sheet of paper, cardboard or the like.
La fabrication d'une feuille de papier se fait sur une machine à papier qui permet successivement de former la feuille, de la sécher et enfin de l'enrouler. En cours de fabrication, cette feuille est l'objet d'un grand nombre de tensions résultant soit des retraits durant le séchaqe, soit des variations de vitesse des nombreux organes cylindriques chargés d'entraîner et de sécher la feuille, organes qui sont complexes à réguler en vitesse. De plus, la feuille de papier subit très souvent un traitement de surface par voie humide qui momentanément la fragilise,d' autanb que les vitesses de fabrication sont généralement de l'ordre de plusieurs centaines de mètres à la minute.The manufacture of a sheet of paper is done on a paper machine which allows successively to form the sheet, to dry it and finally to wind it. During manufacture, this sheet is subject to a large number of tensions resulting either from shrinkage during drying, or from variations in speed of the numerous cylindrical organs responsible for driving and drying the sheet, organs which are complex to regulate speed. In addition, the sheet of paper very often undergoes a wet surface treatment which momentarily weakens it, so that the manufacturing speeds are generally of the order of several hundred meters per minute.
Dans de telles conditions, on comprend aisément que ce matériau dont l'épaisseur n'est que de quelques dizaines de microns et qui est relativement fragile, subisse des ruptures ,voire des casses qui per¬ turbent la fabrication et finalement coûtent très cher.Under such conditions, it is understandable that material whose thickness is q ue of a few tens of microns and is relatively fragile, suffer fractures or breakages which per¬ turbent manufacturing and ultimately very expensive.
II est donc important de pouvoir détecter avec le plus de précision possible les amorces de déchirure qui peuvent naître sur le bord d'une feuille durant sa fa¬ brication et qui sont le signe avant courreur d'une cas¬ se prochaine. Il existe déjà des dispositifs très simples, constitués d'une source lumineuse, en qénéral une lampe à incandescence, et d'une cellule disposée de l'autre côté de la feuille. La feuille de papier passe alors entre la source lumineuse et la cellule, qui caote alors la lumière transmise à travers cette feuille. Tant que la feuille de papier passe normalement entre la source et la cellule, l'intensité lumineuse transmise est faible. En revanche, lorsqu'on est en présence d'une amorce de riipture, la cellule reçoit alors toute l'intensité lumineuse émise par la source, ce qui déclenche un moyen d'alarme.It is therefore important to be able to detect with as much precision as possible the tear incidences which may arise on the edge of a sheet during its manufacture and which are the early warning sign of an upcoming case. There are already very simple devices, consisting of a light source, usually an incandescent lamp, and a cell placed on the other side of the sheet. The sheet of paper then passes between the light source and the cell, which then coots the light transmitted through this sheet. As long as the sheet of paper passes normally between the source and the cell, the transmitted light intensity is low. On the other hand, when we are in the presence of an initiation of rupture, the cell then receives all the light intensity emitted by the source, which triggers an alarm means.
Ce dispositif, bien que larqement utilisé, présente encore toutefois de nombreux inconvénients. Tout d'abord, la lumière émise par la source diffuse dans to tes les directions. Il s'ensuit que la quantité de lumière reçue en un point de la feuille est donc très faible, ce qui perturbe la détection. Ensuite, I35 cel- Iules de détection sont affectées par les radiations lumineuses environnantes,car leur anqle de réception est trop important. Enfin, à la lonque, le dispositif de dé¬ tection s'encrasse, car des fibres et des charges se dé¬ posent sur les surfaces optiques destinées à laisser passer le faisceau lumineux, ce qui rend alors le disoo- sitif inutilisable.This device, although widely used, still has many disadvantages, however. First of all, the light emitted by the source diffuses in all your directions. It follows that the quantity of light received at a point on the sheet is therefore very low, which disturbs detection. Then, I35 detection cells are affected by the surrounding light radiation, because their reception angle is too great. Finally, when it is long, the detection device becomes clogged, because fibers and charges settle on the optical surfaces intended to allow the light beam to pass, which then makes the device unusable.
Pour obtenir les meilleures conditions possibles de détection, il faudrait donc que la quantité de lumiè- re reçue par la cellule soit très faible lorsque la feuille de paoier passe entre la source et la cellule, et très importante lorsque la lumière émise par la sour¬ ce atteint directement la cellule, ce que l'on ne sait faire jusqu'alors. Le dispositif de l'invention pallie ces inconvé¬ nients. Ce dispositif pour détecter les amorces de rup¬ ture ou de déchirure sur le bord d'une feuille de pa¬ pier en mouvement, du type comprenant : . une source lumineuse,To obtain the best possible conditions for detection, the quantity of light received by the cell should therefore be very low when the sheet of paper passes between the source and the cell, and very large when the light emitted by the source. this directly reaches the cell, which we did not know how to do until then. The device of the invention overcomes these drawbacks. This device for detecting incidences of breakage or tearing on the edge of a sheet of moving paper, of the type comprising:. a light source,
. et une cellule réceptrice pour capter la lumière transmise par la source au travers de la feuille gui défile entre la source et la cellule, se caractérise : - d'une part, en ce_ que la source lumineuse est une source laser ; et d'autre part, en ce que la cellule réceptrice est une cellule opto-électronique disposée de telle fa¬ çon que l'angle solide sous lequel on voit, la surface utile de ladite cellule, ou son image par un système optigue, depuis la feuille de papier est inférieur à 0,01 steradian.. and a receiving cell for capturing the light transmitted by the source through the sheet which passes between the source and the cell, is characterized: - on the one hand, in that the light source is a laser source; and on the other hand, in that the receiving cell is an optoelectronic cell arranged in such a way that the solid angle at which one sees, the useful surface of said cell, or its image by an optical system, from the sheet of paper is less than 0.01 steradian.
En d'autres termes, l'invention consiste à combiner la source laser comme source lumineuse avec une cellule réceptrice opto-électronique, sous réserve que l'angle solide sous lequel on voit, depuis la feuille de papier, la surface utile de cette cellule est inférieure à 0,01 steradian.In other words, the invention consists in combining the laser source as a light source with an optoelectronic receiving cell, provided that the solid angle at which the useful surface of this cell is seen from the sheet of paper is less than 0.01 steradian.
En effet, on a observé que si cet angle solide était supérieur à 0,01 steradian, la quantité de lumière diffusée par la feuille et reçue par la cellule, c'est- à-dire la quantité de lumière diffusée dans ledit angle solide, serait plus important, et par conséquent la dif¬ férence des flux lumineux reçus par la cellule, quand il y a une amorce de déchirure et quand il n'y en a pas, serait plus faible. Cela affecterait alors la précision de la mesure. En pratique, la valeur plancher résulte de la sur¬ face de la cellule qui est de l'ordre de quelques milli¬ mètres carré.Indeed, it has been observed that if this solid angle was greater than 0.01 steradian, the amount of light scattered by the sheet and received by the cell, that is to say the amount of light scattered in said solid angle, would be more important, and consequently the difference in the light fluxes received by the cell, when there is a tear initiation and when there is none, would be smaller. This would affect the accuracy of the measurement. In practice, the floor value results from the surface of the cell which is of the order of a few square millimeters.
De même, on a observé que si l'on utilisait une autre source lumineuse qu'une source laser, on perdrait alors le bénéfice de la cohérence spatiale du faisceau lumineux, en particulier le bénéfice d'une différence considérable du faisceau lumineux reçu par la cellule en présence d'une amorce de rupture.Similarly, it has been observed that if a light source other than a laser source were used, the benefit of the spatial coherence of the light beam would be lost, in particular the benefit of a considerable difference in the light beam received by the cell in the presence of a rupture primer.
Comme le faisceau lumineux de la source laser est parfaitement cylindrique, on éclaire en un seul point la feuille qui défile . "Il s'ensuit que la zone étudiée reçoit toute la lumière émise par cette source. Ainsi, quand il y a une amorce de déchirure sur cette feuille, le faisceau lumineux ne rencontre aucun obstacle, et la cellule reçoit alors toute la lumière émise par la source. En revanche, lorsque la feuille est intacte, la lumière transmise est diffusée dans toutes les directions comprises dans un cône d'angle solide de T (pi) stéradians.As the light beam from the laser source is perfectly cylindrical, the moving sheet is illuminated at a single point. " It follows that the studied area receives all the light emitted by this source. So, when there is a tear initiation on this sheet, the light beam encounters no obstacle, and the cell then receives all the light emitted by However, when the leaf is intact, the transmitted light is scattered in all directions included in a solid angle cone of T (pi) steradians.
Si la feuille se trouve à une distance cl de la cel- Iule ou de son image optique, et que la surface utile de la cellule est S, l'angle solide sous lequel on voit la cellule ou son image optique depuis la feuille est S/d2. La quantité de lumière recueillie étant proportionnelle à l'angle solide, la cellule ne recevra donc que ( S/d2) de la quantité de la lumière diffusée. "If the sheet is at a distance cl from the cell or its optical image, and the useful surface of the cell is S, the solid angle at which the cell or its optical image can be seen from the sheet is S / d2. The quantity of light collected being proportional to the solid angle, the cell will therefore only receive (S / d2) the quantity of light scattered. "
Si dans un exemple de réalisation correspondant à la pratique S = 5 mm2 et la distance d = 5 cm, l'angle solide sous lequel on voit la cellule depuis la feuille est de 0,003 steradian et la cellule ne reçoit alors que moins d'un millième de la lumière diffusée par la feuille.If in an exemplary embodiment corresponding to practice S = 5 mm2 and the distance d = 5 cm, the solid angle under which we see the cell from the sheet is 0.003 steradian and the cell does not receive that less than a thousandth of the light scattered by the sheet.
Le dispositif selon l'invention permet donc de détecter avec une très grande précision des amorces de déchirure sur une feuille en cours de défilement, notam¬ ment sur une feuille de papier en cours de fabrication.The device according to the invention therefore makes it possible to detect with very high precision tear primers on a sheet being scrolled, in particular on a sheet of paper during manufacture.
Avantageusement, en pratique : - la source laser est un laser à gaz ou un laser à semi-conducteur ; la cellule opto-électronique est une cellule de très petite surface, c'est-à-dire de l'ordre de quelques millimètres carré ; - on peut placer devant la cellule opto-électroni¬ que un diaphragme, de façon à réduire la surface utile de la cellule à la taille voulue ; la surface utile de la cellule opto-électronique est comme déjà dit la plus petite possible afin d'avoir un dispositif très précis mais néanmoins supérieure à la taille de la tache lumineuse sur la feuille de papier, augmentée de la divergence du faisceau laser ; de préfé¬ rence, cette surface est telle que l'angle solide sous lequel on voit ladite cellule, ou son image par un sys- tème optique, depuis la feuille de papier, est inférieur à 0,01 steradian et avantageusement de 0,003 ; on envoie dans le dispositif de l'air comprimé sec au niveau des orifices destinés à laisser passer le faisceau lumineux ; de la sorte, grâce à la surpression, on évite la formation de dépôt de fibres ou de charges sur les surfaces optiques.Advantageously, in practice: - the laser source is a gas laser or a semiconductor laser; the opto-electronic cell is a cell with a very small surface, that is to say of the order of a few square millimeters; - one can place in front of the optoelectronic cell as a diaphragm, so as to reduce the useful surface of the cell to the desired size; the useful surface of the opto-electronic cell is as already said the smallest possible in order to have a very precise device but nevertheless greater than the size of the light spot on the sheet of paper, increased by the divergence of the laser beam; preferably, this surface is such that the solid angle at which one sees said cell, or its image by an optical system, from the sheet of paper, is less than 0.01 steradian and advantageously 0.003; dry compressed air is sent into the device at the orifices intended to allow the light beam to pass; in this way, thanks to the overpressure, the deposit of fibers or of charges on the optical surfaces is avoided.
Dans un mode de réalisation préféré, le dispositif selon l'invention est constitué d'un boitier en forme de U dont les deux branches contiennent respectivement la source laser et la cellule opto-électronique. L'alimen¬ tation de la source laser est logée dans la partie du boitier reliant les deux branches d.u U. Ce boitier com¬ prend une alimentation en air comprimé sec qui s'évacue par les orifices destinés à laisser passer le faisceau lumineux. Les surfaces optiques sont ainsi à l'abri des poussières environnantes. L'air comprimé sert en outre et simultanément à refroidir le tube laser et son alimentation. Pour éviter les angles vifs qui risqueraient de provoquer des cassures de la feuille lors de vibrations intempestives, les deux branches du U sont tubulaires.In a preferred embodiment, the device according to the invention consists of a U-shaped box, the two branches of which respectively contain the laser source and optoelectronic cell. The power supply of the laser source is housed in the part of the box connecting the two branches of the U. This box includes a supply of dry compressed air which is evacuated through the orifices intended to allow the light beam to pass. The optical surfaces are thus protected from surrounding dust. The compressed air is also used simultaneously to cool the laser tube and its power supply. To avoid sharp angles which could cause breakage of the sheet during untimely vibrations, the two branches of the U are tubular.
Pour affaiblir l'influence des radiations lumineu- ses environnantes, on intercale un diaphragme supplémen¬ taire entre la feuille de papier et la cellule ou l'ima¬ ge de ladite cellule par un système optique.To weaken the influence of surrounding light radiation, an additional diaphragm is inserted between the sheet of paper and the cell or the image of said cell by an optical system.
La manière dont l'invention peut être réalisée et les avantages qui en découlent ressortiront mieux de l'exemple de réalisation qui suit donné à titre indica¬ tif et non limitatif, à l'appui de la figure unigue an¬ nexée qui montre, vu en coupe, un exemple de réalisation avantageux conforme à l'invention.The manner in which the invention can be implemented and the advantages which result therefrom will emerge more clearly from the embodiment which follows, given by way of non-limiting indication, in support of the attached single figure which shows, seen in section, an advantageous embodiment according to the invention.
Ce dispositif de détection d'amorce de rupture com¬ prend essentiellement un boitier (1) sur lequel est em¬ manché deux branches tubulaires parallèles (2,3) entre lesquelles passe le bord (4) d'une feuille de papier en mouvement ( 5) .This device for detecting the initiation of rupture essentially takes a case (1) on which is fitted two parallel tubular branches (2,3) between which the edge (4) of a sheet of moving paper passes ( 5).
L'ensemble (1,2,3) a donc la forme générale d'un U. La branche supérieure (2) contient une source la¬ ser (6), par exemple un laser hélium-néon, alimenté par un organe approprié (7) relié par des connections (8) à une arrivée (9) du boitier.The set (1,2,3) therefore has the general shape of a U. The upper branch (2) contains a source la¬ ser (6), for example a helium-neon laser, powered by a suitable member (7) connected by connections (8) to an inlet (9) of the housing.
Ce laser (6) émet un rayon lumineux (10) qui est réfléchi par un prisme miroir (11) sur la feuille (5) en traversant l'ouverture (12). Le rayon transmis (13) tra¬ verse alors une autre ouverture (14) ménagée dans la branche parallèle (3) pour être réfléchie sur un miroir (15), traverse un diaphragme (16) et arrive sur une cel¬ lule opto-électronique (17), par exemple une cellule au silicium. Cette cellule au silicium est alimentée élec¬ triquement par une connection (18) également reliée à l'arrivée (9). La cellule (17) est reliée à une carte électronique (19) qui est reliée à son tour par l'inter¬ médiaire d'un relais de puissance (20) à un ou plusieurs organes d'alarme (21), tel qu'un voyant lumineux, une sonnerie ou un compteur d'affichage.This laser (6) emits a light beam (10) which is reflected by a mirror prism (11) on the sheet (5) through the opening (12). The transmitted ray (13) then passes through another opening (14) formed in the parallel branch (3) to be reflected on a mirror (15), passes through a diaphragm (16) and arrives on an optoelectronic cell. (17), for example a silicon cell. This silicon cell is electrically powered by a connection (18) also connected to the inlet (9). The cell (17) is connected to an electronic card (19) which is in turn connected via a power relay (20) to one or more alarm devices (21), such as an indicator light, a buzzer or a display counter.
Dans l'exemple de réalisation décrit, l'angle soli¬ de est voisin de 0,002.In the example of embodiment described, the solid angle is close to 0.002.
Le boitier (1) présente également une arrivée (22) d'air comprimé reliée à une source non représentée. Cet air comprimé qui traverse une chicane (23) sert d'une part, à refroidir la source laser (6) et d'autre part, en s'évacuant par (12) et (14), à nettoyer ces deux orifices de passage du rayon laser (10,13) et ainsi d'éviter l'encrassement des éléments optiques (11, 15,17).The housing (1) also has an inlet (22) for compressed air connected to a source not shown. This compressed air which passes through a baffle (23) is used on the one hand, to cool the laser source (6) and on the other hand, by evacuating via (12) and (14), to clean these two passage orifices of the laser beam (10,13) and thus avoid clogging of the optical elements (11,15,17).
Lors d'une rupture ou d'une déchirure, la quantité de lumière reçue par la cellule (17) augmente brutale- ment. Il s'ensuit que grâce à l'électronique (19), on provoque un déclenchement de l'alarme (21). Le conduc¬ teur marque alors la feuille (5) qui continue à défiler pour repérer ce défaut.During a rupture or a tear, the quantity of light received by the cell (17) suddenly increases. It follows that thanks to the electronics (19), we triggers the alarm (21). The driver then marks the sheet (5) which continues to scroll to identify this defect.
Ce dispositif de détection est particulièrement avantageux : d'une part, du fait de sa simplicité de structu¬ re qui ne comporte aucune pièce en mouvement ;This detection device is particularly advantageous: on the one hand, because of its structural simplicity which does not comprise any moving part;
- par la simplicité de sa construction et de sa mi- se en place et la sécurité de son fonctionnement.- by the simplicity of its construction and its installation and the safety of its operation.
Il est donc parfaitement adapté aux machines pape- tières. It is therefore perfectly suited to papermaking machines.

Claims

REVENDICATIONS
1/ Dispositif pour détecter les amorces de rupture ou de déchirure sur les bords (4) d'une feuille (5) en mouvement, du type comprenant : . une source lumineuse (6),1 / Device for detecting the beginnings of rupture or tearing on the edges (4) of a sheet (5) in movement, of the type comprising:. a light source (6),
. et une cellule réceptrice pour capter la lumière transmise par la source (6) au travers de la feuille (5) qui défile entre la source (6) et la cellule, caractérisé :. and a receiving cell for capturing the light transmitted by the source (6) through the sheet (5) which passes between the source (6) and the cell, characterized:
- d'une part, en ce que la source lumineuse (6) est une source laser ; et d'autre part, en ce que la cellule réceptrice (17) est une cellule opto-électronique disposée de toile façon que l'angle solide sous lequel on voit la surface utile de cette cellule (17) ou de son image par un sys¬ tème optigue, depuis la feuille de papier (5), est inférieur à 0,01 steradian.- on the one hand, in that the light source (6) is a laser source; and on the other hand, in that the receiving cell (17) is an optoelectronic cell arranged in a canvas so that the solid angle at which the useful surface of this cell (17) or of its image is seen by a system ¬ optic head, from the sheet of paper (5), is less than 0.01 steradian.
2/ Dispositif selon la revendication 1, caractérisé en ce que la source lumineuse (6) et la cellule récep¬ trice (17) sont logées respectivement dans chacune des deux branches (2,3) d'un ensemble en forme de U, reliées à un boitier (1) .2 / Device according to claim 1, characterized in that the light source (6) and the receiver cell (17) are housed respectively in each of the two branches (2,3) of a U-shaped assembly, connected to a case (1).
3/ Dispositif selon l'une des revendications 1 et 2, caractérisé en ce que le boitier (1) comporte une alimentation (22) en air comprimé destiné à refroidir la source lumineuse (6) et à maintenir par surpression l'état de propreté des surfaces optiques en circulant par les orifices (12,14) de passage du rayon lumineux (10) et du rayon réfléchi (13) . 4/ Dispositif selon l'une des revendications 1 à 3, caractérisé en ce que la source laser (6) est un laser à gaz.3 / Device according to one of claims 1 and 2, characterized in that the housing (1) comprises a supply (22) of compressed air intended to cool the light source (6) and to maintain the state of cleanliness by overpressure optical surfaces circulating through the orifices (12,14) for passage of the light ray (10) and the reflected ray (13). 4 / Device according to one of claims 1 to 3, characterized in that the laser source (6) is a gas laser.
5/ Dispositif selon l'une des revendications 1 à 5, caractérisé en ce que la source laser (6) est une source laser à semi-conducteur.5 / Device according to one of claims 1 to 5, characterized in that the laser source (6) is a semiconductor laser source.
6/ Dispositif selon l'une des revendications 1 à 5, caractérisé en ce qu'il comporte un diaphragme supplé¬ mentaire (17) intercalé entre la feuille (5) et la cel¬ lule (17) ou l'image de ladite cellule par un système optique.6 / Device according to one of claims 1 to 5, characterized in that it comprises an additional diaphragm (17) interposed between the sheet (5) and the cell (17) or the image of said cell by an optical system.
7/ Dispositif selon la revendication 1, caractérisé en ce que l'angle solide est voisin de 0,003 steradian. 7 / Device according to claim 1, characterized in that the solid angle is close to 0.003 steradian.
EP87900172A 1985-12-31 1986-12-23 Device for detecting the beginning of a tear on a sheet during its manufacture Ceased EP0252109A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8519569 1985-12-31
FR8519569A FR2592487B1 (en) 1985-12-31 1985-12-31 DEVICE FOR DETECTING A TEAR PRIME ON A SHEET DURING ITS MANUFACTURE.

Publications (1)

Publication Number Publication Date
EP0252109A1 true EP0252109A1 (en) 1988-01-13

Family

ID=9326427

Family Applications (1)

Application Number Title Priority Date Filing Date
EP87900172A Ceased EP0252109A1 (en) 1985-12-31 1986-12-23 Device for detecting the beginning of a tear on a sheet during its manufacture

Country Status (6)

Country Link
US (1) US4788442A (en)
EP (1) EP0252109A1 (en)
JP (1) JPS63502613A (en)
FI (1) FI873750A (en)
FR (1) FR2592487B1 (en)
WO (1) WO1987004248A1 (en)

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FI88828C (en) * 1991-02-06 1993-07-12 Valmet Paper Machinery Inc Method and apparatus for photoelectric identification of a material path
US5389789A (en) * 1992-05-20 1995-02-14 Union Camp Corporation Portable edge crack detector for detecting size and shape of a crack and a portable edge detector
DE19510753A1 (en) * 1995-03-24 1996-09-26 Will E C H Gmbh & Co Device for measuring sheets of paper
US5994712A (en) * 1997-07-29 1999-11-30 Mack; John Edward Belt flaw detector
US6219136B1 (en) 1998-03-03 2001-04-17 Union Underwear Company, Inc. Digital signal processor knitting scanner
JP3524888B2 (en) 2001-05-30 2004-05-10 三菱重工業株式会社 Monitoring device
TWM330197U (en) * 2007-05-08 2008-04-11 Tsc Auto Id Technology Co Ltd Sheet sensor for tab printer
EP2186624B1 (en) * 2008-11-18 2015-08-26 Tetra Laval Holdings & Finance S.A. Apparatus and method for detecting the position of application of a sealing strip onto a web of packaging material for food products

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DE1573497A1 (en) * 1965-11-23 1970-03-05 Feldmuehle Ag Device for testing and sorting of web or sheet products
GB1320898A (en) * 1969-07-07 1973-06-20 British Steel Corp Strip measuring unit and split edge detector
US3710129A (en) * 1971-02-16 1973-01-09 H Gibson Methods of and apparatus for detecting minute holes in objects
US3840302A (en) * 1971-06-01 1974-10-08 D Brunton Oscilloscope presentation of sheet profile from a scanning gage
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Also Published As

Publication number Publication date
FI873750A0 (en) 1987-08-28
FR2592487A1 (en) 1987-07-03
FR2592487B1 (en) 1988-03-11
JPS63502613A (en) 1988-09-29
WO1987004248A1 (en) 1987-07-16
FI873750A (en) 1987-08-28
US4788442A (en) 1988-11-29

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