CH616882A5

CH616882A5 - Method and device for inking printing characters

Info

Publication number: CH616882A5
Application number: CH1327277A
Authority: CH
Inventors: Vraj Abhechand Lathiya; Bruce William Maskell
Original assignee: Dymo Industries Inc
Priority date: 1976-11-01
Filing date: 1977-11-01
Publication date: 1980-04-30
Also published as: NO147206B; ES464671A1; NO147206C; FR2369096A1; GB1570545A; ATA879077A; IT1125800B; FR2369096B1; DK143840C; JPS61120560U; AT371065B; AU508777B2; NO773660L; BE860420A; JPS6334937Y2; DE2748600A1; DK486277A; AU3024377A; SE7712183L; SE433475B

Abstract

The object of this method is to provide an improvement in the inking of printing characters. It consists in forming a microporous wall, a first surface of which contacts an ink reserve, and a second surface of which supplies this ink to the printing characters via an elastic element which contacts it, and of which one portion is compressed against the said second surface in order to collect the ink, then expanded in order to create a partial vacuum in the wall and to attract the ink into the latter, whereas ambient air enters the ink reserve through the wall in order to re-establish the pressure balance. The device comprises an inking roll (11) formed of a hollow cylinder (12) with a microporous wall, whose ends are sealed (13) in order to form a closed vessel in which a load of ink (17), is housed while elastic means (18) are in contact with the cylidner (12) in order to transfer the ink (17) from the surface of the cylinder (12) to the printing characters. <IMAGE>

Description

40 L'invention a également pour objet un dispositif d'encrage de caractères d'impression, comprenant un rouleau encreur, caractérisé en ce qu'il comporte un cylindre creux à paroi microporeuse, des moyens de scellement des extrémités de ce cylindre creux pour former dans le cylindre une enceinte close, une charge d'encre de 45 viscosité choisie logée dans cette enceinte close, et des moyens élastiques en contact avec le cylindre pour transférer l'encre de la surface dudit cylindre aux caractères d'impression. 40 The invention also relates to an inking device for printing characters, comprising an inking roller, characterized in that it comprises a hollow cylinder with a microporous wall, means for sealing the ends of this hollow cylinder to form in the cylinder a closed enclosure, an ink charge of 45 viscosity chosen housed in this closed enclosure, and elastic means in contact with the cylinder to transfer the ink from the surface of said cylinder to the printing characters.

Par ces moyens, on assure un encrage permettant une densité d'impression uniforme sur toute la durée du dispositif et l'on évite so le surencrage ainsi que les taches après une période de repos. En outre, on supprime les problèmes de contrôle d'évent ainsi que les risques de suintement ou de fuite usuellement présents avec les dispositifs connus, du fait qu'il n'y a pas de trous d'évent. Le dessin annexé représente à titre d'exemple, deux formes 55 d'exécution du dispositif selon l'invention. By these means, an inking is ensured allowing a uniform printing density over the entire duration of the device and so over-inking as well as stains are avoided after a rest period. In addition, it eliminates the problems of vent control as well as the risks of seepage or leakage usually present with known devices, because there are no vent holes. The accompanying drawing shows, by way of example, two embodiments 55 of the device according to the invention.

La fig. 1 est une perspective de la première forme d'exécution ; les fig. 2 à 5 en montrent le fonctionnement; Fig. 1 is a perspective of the first embodiment; fig. 2 to 5 show how it works;

la fig. 6 est une perspective de la deuxième forme d'exécution; les fig. 7 et 8 en montrent le fonctionnement. 60 Le dispositif représenté sur la fig. 1 comprend un rouleau d'encrage 11 adapté à fournir de l'encre directement aux caractères d'impression. Le rouleau 11 comporte un cylindre 12 fait d'un matériau microporeux tel que, par exemple, un polyéthylène fritté à poids moléculaire élevé. D'autres matériaux microporeux 65 peuvent évidemment être utilisés, qu'ils soient métalliques ou autres. fig. 6 is a perspective of the second embodiment; fig. 7 and 8 show how it works. The device shown in FIG. 1 includes an inking roller 11 adapted to supply ink directly to the printing characters. The roller 11 comprises a cylinder 12 made of a microporous material such as, for example, a sintered polyethylene of high molecular weight. Other microporous materials 65 can obviously be used, whether metallic or otherwise.

Lorsque le matériau utilisé est un polyéthylène, l'épaisseur de la paroi du cylindre est approximativement de 1,65 mm et le When the material used is polyethylene, the thickness of the cylinder wall is approximately 1.65 mm and the

diamètre des micropores est uniforme, compris entre 2 et 70 jx. Si du métal est utilisé, l'épaisseur de paroi peut être réduite jusqu'à environ 0,25 mm, les diamètres des micropores étant alors de 10 n environ. Pour des matériaux plus tendres, l'épaisseur de paroi peut excéder 1,8 mm et les diamètres des micropores dépasser 40 n. micropore diameter is uniform, between 2 and 70 µm. If metal is used, the wall thickness can be reduced to approximately 0.25 mm, the micropore diameters then being approximately 10 n. For softer materials, the wall thickness can exceed 1.8 mm and the micropore diameters exceed 40 n.

Les extrémités du cylindre 12 sont scellées par des bouchons d'extrémité 13 pour former dans le cylindre ime enceinte close. Chaque bouchon d'extrémité est pourvu d'un axe extérieur 14 arrangé axialement par rapport au cylindre 12, lesquels axes 14 s'engagent dans les bras 16 prévus usuellement pour supporter les rouleaux distributeurs d'encre. The ends of the cylinder 12 are sealed with end caps 13 to form a closed enclosure in the cylinder. Each end plug is provided with an external axis 14 arranged axially with respect to the cylinder 12, which axes 14 engage in the arms 16 usually provided for supporting the ink distributor rollers.

A l'intérieur du cylindre 12 est disposée une réserve ou charge 17 d'encre d'impression ayant une viscosité d'environ 1000 cPo à 21°C. Suivant la nature du matériau microporeux, Inside the cylinder 12 is disposed a reserve or charge 17 of printing ink having a viscosity of approximately 1000 cPo at 21 ° C. Depending on the nature of the microporous material,

cette viscosité peut être comprise entre 100 et 5000 cPo. this viscosity can be between 100 and 5000 cPo.

Autour du cylindre 12 est disposé un manchon 18 formé d'un matériau microporeux tel qu'un élastomère ou du caoutchouc. La paroi de ce manchon a environ 1,03 mm d'épaisseur, sa porosité est choisie de façon que l'encre puisse passer à travers et sa dureté est de l'ordre de 5 à 45 degrés Shore. Ce manchon 18 couvre presque la totalité de la paroi du cylindre 12, laissant libres deux portions 15 de celle-ci. Il est adapté à heurter directement les caractères d'impression. Around the cylinder 12 is disposed a sleeve 18 formed of a microporous material such as an elastomer or rubber. The wall of this sleeve is approximately 1.03 mm thick, its porosity is chosen so that the ink can pass through and its hardness is of the order of 5 to 45 degrees Shore. This sleeve 18 covers almost the entire wall of the cylinder 12, leaving two portions 15 of the latter free. It is suitable for directly striking printing characters.

Comme visible sur les fig. 2 et 3, lorsqu'une tête d'impression 23 translate tangentiellement au rouleau 11, les caractères d'impression 21 heurtent le manchon 18 du rouleau et se trouvent ainsi encrés. La vitesse tangentielle de la tête d'impression communique un mouvement rotatif au rouleau 11 et la composante radiale de la vitesse tangentielle de la tête d'impression comprime la portion 22 du manchon 18 qui a contacté les caractères. As seen in fig. 2 and 3, when a print head 23 translates tangentially to the roller 11, the print characters 21 strike the sleeve 18 of the roller and are thus inked. The tangential speed of the print head communicates a rotary movement with the roller 11 and the radial component of the tangential speed of the print head compresses the portion 22 of the sleeve 18 which has contacted the characters.

Comme la portion 22 se dilate et revient à sa forme originale par suite de son élasticité naturelle, il se créé une succion qui aspire l'encre hors de la paroi du cylindre 12. Cette encre est remplacée dans la paroi du cylindre 12 par l'action capillaire des micropores de la paroi. Lorsque plusieurs cycles d'impression ont été effectués, cette sortie d'encre de l'intérieur du rouleau provoque une diminution de la pression dans le cylindre et, quand cette réduction de pression devient suffisante pour surmonter la résistance de l'encre dans la paroi du cylindre, de l'air pénètre dans le rouleau à travers la paroi frittée jusqu'à ce que l'équilibre de pression soit rétabli. Les fig. 4 et 5 illustrent cette action à l'aide des flèches tremblées montrant la sortie d'encre (fig. 4) et l'entrée d'air (fig. 5). As the portion 22 expands and returns to its original shape due to its natural elasticity, a suction is created which sucks the ink out of the wall of the cylinder 12. This ink is replaced in the wall of the cylinder 12 by the capillary action of the micropores of the wall. When several printing cycles have been carried out, this ink output from the inside of the roller causes a reduction in the pressure in the cylinder and, when this reduction in pressure becomes sufficient to overcome the resistance of the ink in the wall from the cylinder, air enters the roller through the sintered wall until the pressure balance is restored. Figs. 4 and 5 illustrate this action using the shaky arrows showing the ink outlet (fig. 4) and the air inlet (fig. 5).

Des essais ont montré que le rouleau 11 marque une chute brutale d'intensité d'impression à la fin de sa durée de vie normale, alors que l'intensité d'impression reste constante jusqu'à ce moment-là. Par exemple, des rouleaux ont effectué avec succès plus de 140000 cycles d'impression en produisant une intensité d'impression uniforme, puis ils ont faibli jusqu'au point d'illisibi-lité durant les 5000 cycles suivants. Cette chute rapide facilite grandement la détermination du moment où le rouleau doit être remplacé. Tests have shown that the roller 11 marks a sudden drop in printing intensity at the end of its normal service life, while the printing intensity remains constant until that time. For example, rollers have successfully completed more than 140,000 print cycles producing uniform print intensity, and then have weakened to the point of illegibility during the next 5,000 cycles. This rapid fall makes it much easier to determine when the roller should be replaced.

Un autre avantage du rouleau 11 est que les micropores du manchon et du cylindre sont saturés d'encre et toujours prêts à l'impression. En outre, cette structure ne nécessite pas de rouleau de transfert pour appliquer l'encre aux caractères. Ainsi, il n'est pas nécessaire de prévoir un temps de mise en action pour amener Another advantage of the roller 11 is that the micropores of the sleeve and of the cylinder are saturated with ink and always ready for printing. In addition, this structure does not require a transfer roller to apply ink to the characters. Thus, it is not necessary to provide an activation time to bring

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le système d'encrage au point où la densité d'impression est uniforme. Enfin, même après une longue période d'inactivité, le rouleau 11 permet des caractères imprimés denses, sans taches ni surencrages. the inking system at the point where the print density is uniform. Finally, even after a long period of inactivity, the roller 11 allows dense printed characters, without stains or inking.

Le dispositif représenté sur la fig. 6 comprend un rouleau d'encrage 31 comportant un cylindre 32 fait d'un matériau microporeux tel que, par exemple, un polyéthylène fritté de haut poids moléculaire. La paroi du cylindre a une épaisseur comprise entre 1,5 et 1,8 mm, et sa porosité est de l'ordre de 2 à 70 p.. Les extrémités du cylindre 32 sont obturées par une paire de bouchons 33 comportant chacun un axe central 34. Le cylindre 32 ainsi que les bouchons 33 définissent ainsi un rouleau d'encrage pourvu d'une enceinte scellée unique dans laquelle est logée une charge d'encre d'impression 39. Cette encre a une viscosité de l'ordre de 100 à 5000 cPo à 21°C. The device shown in fig. 6 comprises an inking roller 31 comprising a cylinder 32 made of a microporous material such as, for example, a sintered polyethylene of high molecular weight. The wall of the cylinder has a thickness of between 1.5 and 1.8 mm, and its porosity is of the order of 2 to 70 p. The ends of the cylinder 32 are closed by a pair of plugs 33 each having an axis central 34. The cylinder 32 and the plugs 33 thus define an inking roller provided with a single sealed enclosure in which is housed a charge of printing ink 39. This ink has a viscosity of the order of 100 at 5000 cPo at 21 ° C.

Le dispositif comporte une paire de bras porte-rouleau 36, pourvus chacun d'une rainure 37 destinée à loger l'un des axes 34 des bouchons 33. A l'extrémité libre des bras 36 est monté rota-tivement un rouleau de transfert 38. Ce rouleau de transfert 38 est formé d'un cylindre épais 42 de caoutchouc tendre ou d'un élastomère similaire (dureté: 10-45 degrés Shore), monté sur un axe 43 dont les extrémités sont pivotées dans les extrémités des bras 36. Une paire de ressorts 41 disposés dans les rainures 37 applique le rouleau d'encrage contre le rouleau de transfert. The device comprises a pair of roller support arms 36, each provided with a groove 37 intended to accommodate one of the axes 34 of the plugs 33. At the free end of the arms 36 is rotatably mounted a transfer roller 38 This transfer roller 38 is formed from a thick cylinder 42 of soft rubber or of a similar elastomer (hardness: 10-45 degrees Shore), mounted on an axis 43 whose ends are pivoted in the ends of the arms 36. A pair of springs 41 arranged in the grooves 37 presses the inking roller against the transfer roller.

L'action capillaire des micropores de la paroi du cylindre 32 fait pénétrer l'encre dans les micropores. En dépit de cela, on a constaté que le cylindre reste sec au toucher et ne transfère pas facilement l'encre sur la peau. Lors de chaque cycle d'impression, le rouleau de transfert heurte les caractères de la tête d'impression pour les encrer. Au même moment (fig. 7), le rouleau de transfert est mis en rotation par la tête d'impression et forcé contre le rouleau d'encrage pour s'imbiber d'encre. Le caoutchouc tendre du rouleau de transfert se comprime dans la région 44 (fig. 8) qui heurte le rouleau encreur. Comme la tête d'impression s'éloigne du rouleau de transfert, la région 44 se dilate par élasticité naturelle, ce qui crée une zone locale de pression réduite dans la paroi du cylindre. La réduction de pression fait pénétrer l'encre dans la surface du rouleau encreur pour remplacer l'encre prise par le rouleau de transfert. Après plusieurs cycles d'impression et une réduction concomitante de la quantité d'encre dans le cylindre, la pression dans ce dernier se trouve réduite. L'air pénètre alors dans les micropores par suite de la différence de pression, et cela jusqu'à ce que l'équilibre de pression soit rétabli. The capillary action of the micropores of the wall of the cylinder 32 causes the ink to penetrate into the micropores. Despite this, it has been found that the cylinder remains dry to the touch and does not easily transfer ink to the skin. During each print cycle, the transfer roller hits the characters on the print head to ink them. At the same time (fig. 7), the transfer roller is rotated by the print head and forced against the ink roller to soak up ink. The soft rubber of the transfer roller compresses in region 44 (fig. 8) which strikes the ink roller. As the print head moves away from the transfer roller, region 44 expands by natural elasticity, which creates a local area of reduced pressure in the cylinder wall. The pressure reduction causes the ink to penetrate the surface of the ink roller to replace the ink taken up by the transfer roller. After several printing cycles and a concomitant reduction in the amount of ink in the cylinder, the pressure in the cylinder is reduced. The air then enters the micropores as a result of the pressure difference, and this until the pressure balance is restored.

Une caractéristique significative de cette forme d'exécution est que, bien que le rouleau d'encrage paraisse sec au toucher, le rouleau de transfert arrive à attirer l'encre à la surface du rouleau encreur pour ensuite la collecter. A significant characteristic of this embodiment is that, although the inking roller appears dry to the touch, the transfer roller succeeds in attracting ink to the surface of the inking roller and then collecting it.

En outre, le dispositif selon cette forme d'exécution permet aussi une densité d'impression uniforme sur toute sa durée de vie, celle-ci étant suivie d'une chute abrupte de la densité d'impression lorsque la charge d'encre est terminée. Par exemple, de tels dispositifs d'encrage ont effectué 100000 cycles d'impression sans aucune variation appréciable dans l'intensité de l'image obtenue, puis ils ont faibli jusqu'au point d'illisibilité au cours des 5000 cycles suivants. Ici également, ce maintien d'une densité uniforme et cette chute d'intensité brutale sont hautement désirables dans nombre d'applications pour l'impression. In addition, the device according to this embodiment also allows a uniform print density over its entire lifetime, this being followed by an abrupt drop in print density when the ink charge is completed. . For example, such inking devices performed 100,000 printing cycles without any appreciable variation in the intensity of the image obtained, then they weakened to the point of illegibility during the following 5000 cycles. Here too, this maintenance of uniform density and this drop in abrupt intensity are highly desirable in many printing applications.

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Claims

616,882

2

1. Method for inking printing characters, characterized in that a microporous wall is formed, a first surface of which is brought into contact with an ink supply and a second surface of which is intended to supply ink for printing characters, in that one puts an elastic element in contact with this second surface to ink the printing characters, in that one compresses a portion of this elastic element against said second surface to collect of the ink from the wall, in that one expands the elastic element against the second surface to create a partial vacuum in the wall and attract a portion of the ink in said wall, and in that one then infiltrates the ambient air into the ink reserve through the microporous wall to replace said portion of ink.

2. Device for inking printing characters for implementing the method according to claim 1, comprising an ink roller, characterized in that it comprises a hollow cylinder with a microporous wall, means for sealing the ends of this hollow cylinder to form in the cylinder a closed enclosure, an ink charge of selected viscosity housed in this closed enclosure, and elastic means in contact with the cylinder to transfer the ink from the surface of said cylinder to the printing characters.

3. Device according to claim 2, characterized in that the cylinder wall has pores with a diameter between 2 to 70 n.

4. Device according to claim 2, characterized in that the ink charge has a viscosity between 100 to 5000 cPo at 21 ° C.

5. Device according to claim 2, characterized in that the means for transferring the ink from the surface of the cylinder to the printing characters comprise a microporous elastic sleeve surrounding the cylinder.

6. Device according to claim 5, characterized in that the sleeve is formed of a microporous elastomer of hardness between 5 to 45 degrees Shore.

7. Device according to claim 5, characterized in that the sleeve is shorter than the cylinder, for exposing a portion of said cylinder to ambient air.

8. Device according to claim 2, characterized in that the cylinder consists of a sintered material having pores with a diameter between 2 to 70 | i.

9. Device according to claim 2, characterized in that the means for transferring the ink from the surface of the cylinder to the printing characters comprise a transfer roller in contact with the cylinder.

10. Device according to claim 9, characterized in that the transfer roller consists of a soft elastomer of hardness between 10 to 45 degrees Shore.

In recent developments in the printing arts, the traditional inking arrangement comprising an ink distribution roller partially immersed in ink has been replaced by a hollow ink distribution roller filled with ink. These hollow dispensing rollers are generally provided with holes distributed around their circumference and with a permeable outer coating which limits the flow of ink to the outside to ensure uniform transfer of the ink to a transfer roller or directly to the characters. These rollers are also provided with a venting device which allows air to enter the roller to replace the ink as it is used.

However, these hollow ink distribution rollers have significant drawbacks which seriously limit their use. Thus, a material which provides an appreciable print density in repeated use generally saturates during prolonged periods of non-use. By reusing the roller after such periods of non-use, you get severely inked and stained images. In addition, during extended rest periods, leakage occurs through the vent holes of these traditional vent device rollers.

In addition to this, the print density offered by these rollers gradually declines over their normal service life, so that the printed image degrades and becomes more and more difficult to decipher. While the human being usually manages to adapt to read a degraded image, the machines to decipher or read, known by the English designation of Optical Character Recognition (OCR) generally cannot. As a result, the limit at which the machine begins to misread degraded images is difficult to determine until significant errors have occurred.

In an attempt to overcome the vent control problems, attempts have been made to make use of sintered solid plastic rollers, open cell sponge rubber rollers and the like. These constructions are however subject to the same problems of degradation of the printing density as those mentioned above. In addition, many of them are leaking and causing stains.

25 In order to remedy these drawbacks, the present invention relates to a method for inking printing characters, characterized in that a microporous wall is formed, a first surface of which is brought into contact with a reserve of ink and a second surface of which is intended to supply ink for the printing characters, in that an elastic element is brought into contact with this second surface for inking the printing characters, in that a portion of this elastic element is compressed against said second surface to collect ink from this wall, in that the elastic element is expanded against the second surface to create a partial vacuum in the wall and attract a portion of the ink in said wall and in that the ambient air is then infiltrated into the ink reserve through the microporous wall to replace said ink portion.