EP2861427B1 - Method and device for printing patterns on three-dimensional articles - Google Patents

Description

Technical field of the invention

The invention relates to the printing of patterns on three-dimensional articles, and more particularly to printing on articles mounted on rotary receiving elements.

State of the art

Bottles, tubes, jars used for inkjet printing are generally made of plastic, because they are particularly inexpensive, unbreakable, light, and colorable. The bottles can also be formed of glass.

In order to print a pattern, especially in color, on a plastic article, it is preferable to subject the surface to be printed to a treatment, for example by corona, flame, plasma, or any appropriate surface treatment. , in order to give the surface a better adhesion of the ink. A white background is then optionally printed which is dried, for example with ultraviolet radiation, before printing a four-color process (black, magenta, cyan, yellow). In general, printing machines are used which have a plurality of fixed ink jet printheads, and an article is moved relative to the heads. The machines include a drive mechanism for rotating the articles to print a pattern. Regardless of the printing device used, printing defects may occur due to misalignment, article, or printheads. Indeed, when the article is rotated more than expected, due in particular to variations in the operation of the drive mechanism, the pattern is spread over the article.

It is said then that there is an error of development of the motif on the article. The defects of the printing machines, however small, add to each other cause variations of position of the article with respect to the printheads, and developed, which are incompatible with the extreme precision required for a high quality impression. In addition, the high rate in an industrial environment requires repeated printing and quickly causes printing defects. Moreover, these machines are complex and require maintenance operations and settings that can be long and can reduce the rate of printing patterns.

For example, the English patent application GB 2376920 which discloses a method for printing a pattern on a cylinder (or cone) of any size using several printheads. The printheads are radially disposed with respect to the center of the article for printing on curved objects. The printheads can be fixed or movable along an axis. For example, the cylinder is rotated about its axis while a print head moves in translation along a generatrix of the cylinder. In other words, the relative trajectory of the print head relative to the cylinder is helical. In addition, a software managing the printing takes into account the parameters of the helix to correct the printed image. The software can perform image processing to print an image of the rectangular type on an article of the conical type. The software uses a modified print file to adapt the rectangular image to the conical shape of the article. But this process only allows to print a single pattern on one object at a time, it is unsuited to an industrial process where it is desired to print several patterns on several items with a high rate. The document US 2006/137548 A1 discloses the technical features of the preamble of claim 1 and claim 4.

Object of the invention

An object of the invention is to overcome these disadvantages, and more particularly to provide a means for printing patterns with a high print timing and high accuracy.

Another object is to be able to provide a means for correcting printing errors due, in particular, to variations in pattern development.

According to one aspect of the invention, there is provided a method of pattern printing on three-dimensional articles respectively mounted on rotary receiving elements, comprising a step of producing, for each receiving element, a set of plural digital images intended to print respectively parts of the same pattern on an article mounted on the receiving element, and a step of successive impressions of the parts of the same pattern on the same article respectively from the digital images of the set associated with the receiving element of the article.

The digital images of the same set have the same length, the method comprising a step of simultaneous printing of several parts of distinct patterns on respectively several articles, each simultaneous printing of a part of a pattern on an article being performed at from a digital image of the set associated with the receiving element of the article.

By such a method, the rate of printing of the patterns on several articles is increased. In addition, the length of the digital images associated with each receiving element is adapted to obtain an accurate impression of the patterns. Thus, we print several patterns on different items with a high cadence while guaranteeing a high precision of the printing of the reasons.

Each digital image can represent a monochromatic part of a pattern.

The length of the digital images of the same set associated with a receiving element can be determined from the length of an arc described by the rotation of the article mounted on the receiving element.

Thus, the differences in rotation between the receiving elements are taken into account in order to obtain an even more precise impression of the patterns on the articles. Indeed, there may be variations in rotation between two receiving elements due to a machining defect of the elements, or to a positioning error of the elements. Thus, the printing of the patterns is adapted according to the rotational variations between two receiving elements.

• un poste d'impression muni de plusieurs têtes d'impression à jet d'encre ;
• un plateau de support muni sur sa périphérie d'une pluralité d'éléments de réception d'articles, chaque élément de réception étant monté à rotation sur le plateau de support ;
• des moyens de traitement d'images configurés pour élaborer, pour chaque élément de réception, un ensemble de plusieurs images numériques destinées à imprimer respectivement des parties d'un même motif sur un article monté sur l'élément de réception ; et
• des moyens de mise en rotation du plateau de support configurés pour placer chaque article monté sur un élément de réception successivement face à chaque tête d'impression de manière à imprimer successivement les parties d'un même motif sur un même article à partir respectivement des images numériques de l'ensemble associé à l'élément de réception de l'article.

Les images numériques d'un même ensemble ont une même longueur, et les têtes d'impression sont configurées pour imprimer simultanément plusieurs parties de motifs distincts sur respectivement plusieurs articles, chaque tête d'impression imprimant une partie d'un motif sur un article à partir d'une image numérique de l'ensemble associé à l'élément de réception de l'article.According to another aspect of the invention, there is provided a device for printing patterns on three-dimensional articles comprising:

• a printing station provided with a plurality of inkjet printing heads;
• a support plate provided on its periphery with a plurality of article receiving members, each receiving member being rotatably mounted on the support plate;
• image processing means configured to develop, for each receiving element, a set of plural digital images for respectively printing portions of a same pattern on an article mounted on the receiving member; and
• means for rotating the support plate configured to place each article mounted on a receiving element successively facing each print head so as to successively print the parts of the same pattern on the same article respectively from the digital images of the set associated with the receiving element of the article.

The digital images of the same set have the same length, and the printheads are configured to simultaneously print several parts of distinct patterns on respectively several articles, each print head printing a part of a pattern on an article to from a digital image of the set associated with the receiving element of the article.

The image processing means can produce monochromatic digital images.

The image processing means can determine the length of the digital images of the same set associated with a receiving element from the length of an arc described by the rotation of the article mounted on the element of reception.

Brief description of the drawings

• La figure 1 illustre schématiquement une vue en perspective d'un mode de réalisation d'un dispositif d'impression selon l'invention ;
• la figure 2 illustre schématiquement une vue de dessus du dispositif d'impression de la figure 1 ;
• la figure 3 illustre de façon schématique les principales étapes d'un mode de mise en oeuvre d'un procédé d'impression selon l'invention ;
• la figure 4 illustre de façon schématique un mode de mise en oeuvre d'une étape de détermination de la longueur des images numériques; et
• la figure 5 illustre de façon schématique un autre mode de mise en oeuvre du procédé d'impression.

Other advantages and features will emerge more clearly from the following description of particular embodiments and implementation of the invention given by way of non-limiting example and represented in the accompanying drawings, in which:

• The figure 1 schematically illustrates a perspective view of an embodiment of a printing device according to the invention;
• the figure 2 schematically illustrates a top view of the printing device of the figure 1 ;
• the figure 3 schematically illustrates the main steps of an embodiment of a printing method according to the invention;
• the figure 4 schematically illustrates an embodiment of a step of determining the length of the digital images; and
• the figure 5 schematically illustrates another embodiment of the printing process.

detailed description

The figure 1 schematically represents an embodiment of a printing device on three-dimensional articles A1 to A32, making it possible to ensure accurate printing at a high rate.

Articles A1 to A32 may be generally cylindrical in shape (eg bottles, bottles, jars, etc.). The shape of an article A1 to A32 may deviate slightly from that of a cylinder; it can be slightly conical (eg cups), concave, or convex. It can also have an elliptical or ovoid section.

The printing device comprises a support plate 1. This support plate 1 can be rotated, about an axis substantially perpendicular to the plane of the plate, by rotating means such as a main motor 2 (FIG. figure 2 ) coupled to the support plate 1. The rotation of the support plate 1 makes it possible to place the latter in different indexed positions for printing or processing articles A1 to A32. The support plate 1 is provided on its periphery with a plurality of receiving elements P1 to P32 of articles A1 to A32. As illustrated in figures 1 and 2 , the printing device comprises thirty-two articles A1 to A32 mounted respectively on thirty-two receiving elements P1 to P32. The receiving elements P1 to P32 can be angularly distributed homogeneously on the periphery of the support plate 1 which has the general shape of a disk. As illustrated in figure 2 , the reception elements P1 to P32 are distributed along a circle C ₁ equidistant from the center of the support plate 1 coinciding with the center of the circle C ₁ . Each receiving element P1 to P32 is rotatably mounted about its longitudinal axis B, for example by means of ball bearings. In other words, each receiving element can turn on itself. Rotating a receiving element P1 to P32 rotates an article A1 to A32. Thus, an article A1 to A32 can both rotate about itself about the longitudinal axis B of the receiving member on which it is mounted, and be displaced by the rotation of the support plate 1 along the circle. C ₁ . Preferably, the axis of rotation B of the receiving elements P1 to P32 is substantially perpendicular to the longitudinal plane of the support plate 1, that is to say the plane of the sheet of the figure 2 . In the present description, by substantially perpendicular is meant perpendicular to plus or minus 10 degrees from a right angle.

Preferably, the receiving elements P1 to P32 are arranged to axially receive the respective articles A1 to A32, an article A1 to A32 being associated with a receiving element P1 to P32 carrying it. By "axially" is meant that the articles A1 to A32 are arranged on the receiving elements P1 to P32 with their longitudinal axis oriented substantially perpendicular to the plane of the support plate 1.

The reception elements P1 to P32 are provided to ensure stable and sufficiently accurate maintenance of items A1 to A32 during the various treatments. For example, in the case where the articles A1 to A32 are pot-shaped, the receiving elements P1 to P32 may have a shape that fits inside the pots, the pots being arranged on the receiving elements P1 to P32 with their opening facing the support plate 1. In the case where the items A1 to A32 are bottles, the receiving elements P1 to P32 may have a cylindrical shape to the diameter of the inside of the necks of the bottles. The receiving elements P1 to P32 may be provided with an expansion system that allows the shape to be shaped inside the necks. A tailstock, not shown here for simplification purposes, supported in the bottom of an article A1 to A32 may be provided to complete the alignment of the longitudinal axis of the article A1 to A32.

The printing device comprises a printing station 30 comprising four inkjet printing heads 22a to 22d. Furthermore, the printing device may comprise another printing station 6 comprising one or two print heads 5a, 5b. The printing device may further comprise one or more printing stations each provided with at least one print head. The printing device may also comprise other items processing stations A1 to A32, such as a loading station 17 of items A1 to A32 on the receiving elements P1 to P32, and an unloading station 18 articles A1 to A32. The loading station 17 may be equipped with a gripping arm capable of gripping an article A1 to A32 from a workstation, and fitting the gripped article A1 to A32 with a receiving element P1 to P32 proximal to the workstation. loading 17. The unloading station 18 may comprise a gripping arm for recovering an article A1 to A32 disposed opposite the unloading station 18. Among the processing stations, one station can be found successively from the loading station 17. anti-static treatment unit 19, a surface treatment station 20 (corona, flame or plasma type), the additional printing station 6, a drying station 21 by ultraviolet radiation, the printing station 30, and a another drying station 23 by ultraviolet radiation.

The printing station 30 is preferably a color printing station where the four print heads 22a, 22b, 22c, 22d are respectively associated with the four colors cyan, magenta, yellow and black. Each head 22a, 22b, 22c, 22d is preferably associated with a single color to print part of a pattern on an item A1 to A32, especially a monochrome portion of a polychrome pattern. Each head 22a, 22b, 22c, 22d may have an independent adjustment in inclination relative to the vertical of the support plate 1 so as to follow the profile of an article A1 to A32, especially when the latter is tapered. Each print head 22a to 22d, 5a, and 5b has a plurality of nozzles 40 which are preferably perpendicular to the plane of the support tray 1. The printing heads 22a, 22b, 22c, 22d are adjacent to each other. at each rotation of the support plate 1, in particular when the support plate 1 passes from one indexed position to the other, an article A1 to A32 passes successively from one print head to the other. The printing heads 22a to 22d, 5a, and 5b are fixedly mounted on the same base 101. The base 101 forms a perforated support plate so as to pass the support plate 1. The plane of the support plate 1 and the plane of the support plate 101 is preferably parallel (or substantially parallel).

As illustrated on the figure 1 , the printing device further comprises image processing means 31 coupled to the printing heads 22a to 22d, respectively by connections 32 to 35. In general, the processing means 31 are configured to produce at least a digital image for printing, via a print head, a part of a pattern on one or more articles. Preferably, the processing means 31 elaborate several digital images, for example monochromatic images, intended to print respectively the parts of the same pattern, for example a polychromatic pattern. For example, the print heads of the station 30 can print the monochrome parts of the same initial pattern on the same article, so that the superposition, the mixture or the juxtaposition of the four monochrome parts on the article restores the initial pattern . More particularly, the processing means 31 produce four monochrome digital images respectively cyan, magenta, yellow and black, respectively representing four monochrome portions of a four-color process to be printed on an article. Monochrome digital images are transmitted by means of processing 31 to the print heads 22a to 22d so that each print head prints the portion of the pattern from the digital image having the color corresponding to that of the print head.

On the figure 3 schematically shows the main steps of an embodiment of a printing process for ensuring accurate printing at high speed. The printing process can be implemented by the printing device defined in the figures 1 and 2 . The method comprises a production step S1 in which, for each receiving element P1 to P32, an article is produced, a set of several digital images intended to print parts of the same pattern respectively on the article mounted on the receiving element P1 to P32. For example, to print a four-color process, an associated set of cyan, magenta, yellow, and black digital images for printing the pattern on an article A1 to A32 is produced for each receiving element. Then, during a second step S2, successively prints the parts of the same pattern on the same article from respectively digital images of the set associated with the receiving element of the article.

Thus one prints on an article mounted on a receiving element, all the parts of a pattern from respectively the digital images of the assembly associated with the receiving element of the article. For example, using the device defined in figures 1 and 2 , the support plate 1 has a first article A1 facing a first printing head 22a, the first printing head 22a prints a first part of a pattern of a first color on the article A1, in particular simultaneously with a rotation of the receiving element P1 on itself. After printing the first part of the pattern on the first article A1, the main motor 2 drives the support plate 1 in rotation to present the first article A1 facing another print head 22b to print another part of the pattern another color. Successive impressions on an article overlap, mixtures or juxtapose the parts of the motif on the article, which restores the motif on the article.

In order to increase the printing rate, at the time of each successive printing, S3 is simultaneously printed with several parts of several distinct patterns on several articles respectively. In particular, each simultaneous printing of a part of a pattern on an article is performed from a digital image of the set associated with the item receiving element.

Preferably, the color print heads 22a to 22d are positioned relative to one another at an angle to the center of the disk equal to the angle between two adjacent receiving members P1 to P32 or a multiple thereof. of seperation. This allows, when one of the print heads 22a is facing a receiving element P1 provided with an associated article A1, to place other articles A3 to A4 respectively opposite the other print heads 22b to 22d. In particular, the four printing heads 22a to 22d simultaneously print respectively four monochrome portions of respectively four distinct patterns on respectively four items. The four patterns may be the same or different from each other. In addition, each successive printing of a part of a pattern on an article using a first print head 22a, three other parts of three other patterns are respectively printed on three other articles at the same time. using the other three printheads 22b to 22d. In particular, the printing device is particularly suitable for printing several four-color process patterns on several items A1 to A32 from the four print heads 22a to 22d.

In other words, four items A1 to A4 are placed in front of the four color printing heads 22a to 22d, respectively. Then we simultaneously print four parts of four patterns on the four respectively items. In particular, a first part of a first pattern in cyan color is simultaneously printed on the first article, a second part of a second pattern in magenta color on the second article, a third part of a third pattern in yellow on the third article, and a fourth part of a fourth pattern in black color on the fourth article. Then, the four articles are moved to place each article in front of another print head to print another part of pattern on each article. In particular, with each movement of the articles from one head to the other, there is carried out on each article, an impression of a part of pattern, called successive printing. In addition, at each successive printing, several patterns are simultaneously printed on several articles respectively. It is also possible, for example, to carry out a step of drying an article, preferably by ultraviolet radiation, after the step of successive impressions of the parts of the same pattern on the article. One can also consider performing a partial drying step of each article between two simultaneous printing steps, that is to say between two impressions respectively of two parts of the same pattern on the article.

Moreover, in order to take into account the rotation variations between the different reception elements P1 to P32, digital images S1 are produced with a printing format adapted to each of the reception elements. Indeed, every time a part of a pattern is printed on an item, the rotating article is driven via the rotary receiving element. The same receiving element performs the same rotation in front of each print head. Thus, for each receiving element, an associated set of images having the same length determined from the rotation of the receiving element is developed. Furthermore, the receiving elements may have rotations different from each other. In particular, the length of the images of the same set associated with a receiving element is determined from the length of an arc defined by the rotation of the article mounted on the receiving element. Indeed, when rotates the receiving element, the article described, for example a complete revolution, or a circular arc. In order to obtain a sufficiently accurate impression, all the digital images of the same set associated with a receiving element have the same length. The length of a set of images associated with a receiving element may therefore be different from that of another set of images associated with another reception element.

• CoefPi : le coefficient de correction associé à l'élément de réception Pi ;
• eMi : l'erreur d'impression associée à l'élément de réception Pi ; et
• Lref : la longueur de l'image de référence Iref.

In order to determine the precise length of the images of each set of images, an image length determination step is carried out prior to the successive printing step S2. Diagrammatically shown on the figure 4 an embodiment of the step of determining the length of images. During the step of determining the length of images, reference articles Aref1 are placed at Aref32 on the reception elements P1 to P32, respectively. The reference articles may all be different from each other, preferably they are all identical. A reference article may be, for example a cylinder, preferably a right cylinder. At least one digital reference image Iref is produced, having a reference format Fref used by the print heads 22a to 22d. The reference digital image Iref comprises two marks r1 and r2, and the reference format Fref comprises a reference length Lref and a reference height Href. Then, on each reference article Aref1, Aref2 is printed with a pattern M1, M2 from the reference digital image Iref. Then, each printed pattern is analyzed on each of the reference articles and it is determined whether a printing error has occurred. For example, a print error with respect to a mark in the pattern printed on the reference article can be determined, or it can relate to a mark on the reference article itself. For example, if the pattern is spread over the article, there is an overlap of the edges of the pattern on the article. In this case the length of the image is too long. If, moreover, the pattern is not printed on the entire outline of the article, an unprinted strip appears on the reference article. In this case, the length of the digital image is too short. Once the error has been determined, the determined error associated with the reception element, for example via a software interface of a computer, is recorded using image processing means 31 for each reception element. . Then, for each receiving element Pi, an associated correction coefficient CoefPi is calculated from the determined printing error associated with the reception element Pi, that is to say from the developed length. of the reception element Pi. Note that the reference Pi designates a particular reception element among the reception elements P1 to P32. Each correction coefficient is calculated by the following relation: CoefPi = (Lref - eMi) / Lref
with

• CoefPi: the correction coefficient associated with the reception element Pi;
• eMi: the printing error associated with the receiving element Pi; and
• Lref: the length of the reference image Iref.

We can note in the example shown at figure 4 , that the first pattern M1 is correctly printed because the two marks r1 and r2 are aligned with the pattern M1 printed. In particular, the lengthwise development Lm1 of the first pattern M1 is identical to the reference length Lref. The developed in length of a pattern printed on an article corresponds to the length of the arc described by the outline of the reference article during the rotation of the receiving element of this reference article. The second pattern M2 is not correctly printed, since the developed length Lm2 is greater than the reference length Lref. In this case, a printing error eM2 associated with the second receiving element P2 is determined. It may be noted that each receiving element P1 to P32 has a developed in defined length, that is to say a determined, mechanically reproducible rotation that is specific to it. In other words, the lengthwise development of a receiving element is constant regardless of its position in the operating cycle of the printing device, that is to say whatever the indexed position of the tray 1. Thus, the printing error associated with a The receiving element is identical for all printed patterns regardless of the print head used.

• Darticleref = 60 mm : le diamètre de chacun des articles de référence Aref1 à Aref32, et où chaque article de référence a une forme globalement cylindrique à base circulaire;
• Lref = Dartideref · π = 188,49 cm : la longueur de référence de l'image de référence Iref à imprimer, par exemple la longueur de référence est égale au périmètre des articles de référence Aref1 à Aref32 ; et
• eM17 = +0,72 mm : l'erreur d'impression associée à l'élément de réception P17.

For example, we can take:

• Darticleref = 60 mm: the diameter of each of the reference articles Aref1 to Aref32, and where each reference article has a globally cylindrical shape with a circular base;
• Lref = Dartideref · π = 188.49 cm: the reference length of the reference image Iref to be printed, for example the reference length is equal to the perimeter of reference articles Aref1 to Aref32; and
• eM17 = +0.72 mm: the printing error associated with the receiving element P17.

In this example, the error eM17 is positive because it corresponds to a printed pattern that is too long compared to the desired reference pattern that should have a length equal to Lref = 188.49. In general, the printing error eMi is equal to the difference between the length of the pattern printed on the reference article and the length Lref of the reference image Iref. It may be noted that the error eMi can be positive, in the case where the developed in length of the printed pattern is greater than the length Lref, or negative in the case where the developed in length of the printed pattern is less than the length Lref. Furthermore, in this example, for the receiving element P17, the associated correction coefficient CoefP17 = (Lref - eM17) / Lref = (188.49 - 0.72) / 188.49 = 0.9962 is calculated.

• LCPi : la longueur des images numériques de l'ensemble associé à l'élément de réception Pi (Pi étant la référence d'un élément de réception parmi les trente-deux éléments de réception P1 à P32) ;
• LM : la longueur d'une image à imprimer ;

Ainsi, à partir des coefficients de correction CoefPi, on peut imprimer un motif à partir d'une image numérique de longueur quelconque LM sur un article A1 à A32 de longueur quelconque.Then, for each reception element P1 to P32, a length LCPi of the associated digital images is determined from the correction coefficient CoefPi associated with the reception element. The length LCPi of the images of the set associated with a reception element Pi is determined by the relation LCPi = LM · CoefPi
with

• LCPi: the length of the digital images of the set associated with the reception element Pi (Pi being the reference of a reception element among the thirty-two reception elements P1 to P32);
• LM: the length of an image to print;

Thus, from the correction coefficients CoefPi, a pattern can be printed from a digital image of any length LM on an article A1 to A32 of any length.

In the example shown in figure 4 , the length LCP1 associated with the first receiving element P1 is equal to the length LM of the image to be printed, because no printing error has been determined, in this case, the correction coefficient CoefP1 = 1. The length LCP2 associated with the second reception element P2 is determined as follows: LCP2 = LM · CoefP2. Since the error eM2 is positive, the length LCP2 is less than the length LM of the image to be printed. In order to automatically determine the lengths of the digital images of each set associated with a receiving element, using the processing means 31, the length LM of the digital image intended to print a pattern on the articles A1 to A32. Then, the processing means 31 determine, for each receiving element, the length LCPi of the digital images of the set associated with the reception element Pi, starting from the length LM of the digital image and the correction coefficient CoefPi associated with the reception element Pi.

On the figure 5 schematically shows a print file FI comprising the different digital images intended to print the same pattern, or different patterns, on the different items A1 to A32. Each digital image is referenced by the general references IMiC_LCPi, IMiM_LCPi, IMiJ_LCPi, and IMiN_LCPi, where i is an integer which varies from 1 to 32. IMi corresponds to the reference of the pattern to be printed on an article mounted on a reception element Pi , LCPi corresponds to the length of the digital images of the set associated with the receiving element Pi. Therefore, the reference IMiC_LCPi corresponds to the digital image intended to print the cyan portion of the pattern IMi having the length LCPi, the reference IMiM_LCPi corresponds to the digital image intended to print the magenta part of the IMi pattern having the length LCPi, the reference IMiJ_LCPi corresponds to the digital image intended to print the yellow part of the pattern IMi having the length LCPi, and the reference IMiC_LCPi corresponds to the digital image intended to print the black part of the pattern IMi having the length LCPi. For example, the reference IM32J_LCP32 corresponds to the digital image intended to print the yellow part of a thirty-second IM32 pattern having the length LCP32 associated with the receiving element P32 which supports the article A32. The first line I1 of the FI file comprises four digital images IM1C_LCP1, IM2M_LCP2, IM3J_LCP3, and IM4N_LCP4. The first digital image IM1C_LCP1 is used by the first print head 22a to print the first cyan portion of the first pattern IM1 on the item A1. It may be noted that the four digital images IM1C_LCP1, IM1M_LCP1, IM1J_LCP1 and IM1N_LCP1 of the set associated with the receiving element P1 all have the same length LCP1.

The printing station 30 simultaneously prints four parts of patterns IM1C, IM2M, IM3J and IM4N, respectively from the first four digital images of the first line I1, respectively on the first four articles A1 to A4. The rotating means 2 move the support plate 1 into another indexed position, and the four articles A32, A1 to A3 are opposite the adjacent print head. As a result, the thirty-second article A32 is facing the print head 22a associated with the cyan color, and the third article A3 is found in front of the fourth print head 22d associated with the black color. Then, the printing station 30 simultaneously prints four other parts of patterns IM32C, IM1M, IM2J and IM3N from the four images respectively. number of the second line I2 of the FI file. In order to print all the parts of all the patterns IM1 to IM32, the printing station successively prints the lines of the print file FI at each new indexed position of the support plate 1.

The printing method which has just been described can be implemented by the printing device defined in FIG. figure 1 . In order to provide simultaneous printing of the parts of several distinct patterns and successive impressions of all parts of the same pattern, it is possible, for example, to use the printing device illustrated in FIG. figure 2 .

On the figure 2 schematically is a top view of the printing device of the figure 1 . The printing device comprises the rotating means 2 of the support plate 1 and a system for rotating the receiving elements P1 to P32. In an initial position, the rotation means 2 of the support plate 1 are configured to place four articles A1 to A4, mounted on their respective receiving elements P1 to P4, respectively facing the four printing heads 22a to 22d of FIG. printing station 30. By "face to face" is meant that a receiving element P1 is proximal to the print head 22a so that the surface of the article A1 mounted on the receiving element P1 can be printed by the print head 22a.

The printing device further comprises means for generating a relative translational movement between the base 101 and the support plate 1. Advantageously, this movement can be constrained according to a vector between two staggered points along an axis substantially parallel to the axes B rotation of the articles, to allow a helical pattern printing on items A1 to A32, during the rotation of the receiving elements P1 to P32. In other words, the means for generating the translation movement cooperate with the rotating system of the receiving elements P1 to P32 so as to allow helical printing.

According to another embodiment, the support plate 1 can be fixed, the base 101 is then equipped with a motor adapted to move it relative to the support plate 1. If the support plate 1 is fixed, it can be mounted by a total connection on a frame of the printing device. If the base 101 is fixed, it can be mounted by a total connection to the frame of the printing device. By total connection between two elements, it is understood that these two elements behave in their movements as a single piece.

The rotation system of the receiving elements P1 to P32 comprises a single secondary motor 7 arranged to drive all the receiving elements P1 to P32 in rotation, by means of a single belt, or several belts. Each receiving element P1 to P32 comprises a pinion geared by a belt.

According to a particular embodiment, the support plate 1 comprises separate assemblies 8 staggered at the periphery of the support plate 1, and coupled to the secondary motor 7.

Each set 8 comprises a series of reception elements P21 to P24, and a first driving element 9 rotatably mounted on the support plate 1 and coupled to the secondary motor 7. The first driving element 9 has preferably , an axis of rotation substantially perpendicular to the support plate 1. Each assembly 8 further comprises an end transmission element 10 in the form of a closed loop, for example a belt. The end transmission element 10 is integral with the receiving elements P21 to P24 of the series and the first driving element 9 of the assembly concerned, allowing the implementation simultaneous rotation of the first driving element 9, coupled to the secondary motor 7, and the series of receiving elements P21 to P24. The division in the form of assemblies 8 makes it possible in particular to facilitate the coupling to the secondary motor 7 by limiting the number of transmission elements required, while maintaining a high timing. Furthermore, the return to an initial position of the receiving elements P1 to P32 is much faster without having to reverse the direction of rotation of the secondary motor 7. Preferably, the end transmission element 10 of each set 8 is arranged so that at each turn of the latter, the receiving elements P21 to P24 of the series, and the first associated driving element 9, resume an identical initial position. To improve the coherence between the different sets 8 and the timing, when an end transmission element 10 of a set 8 has taken a turn, all the end transmission elements 10 of the different sets 8 have, preferably , also made a loop tour. In other words, at each turn of an end transmission element 10, the receiving elements P21 to P24 of each series and the first associated driving elements 9 take up an identical initial position. By identical initial position, it is meant that a driving element 9 or receiving element P1 to P32 has made at least one complete revolution on itself, or an integer multiple of revolutions on itself, and is found in the same position he had before starting his turn.

Each receiving element P1 to P32 preferably comprises a pinion whose axis of rotation is preferably substantially perpendicular to the plane of the support plate 1. The first driving element 9 is a toothed wheel, and the end transmission element 10 is a toothed belt whose number of teeth is an integer multiple of the number of teeth of each associated gear, and the number of teeth of the associated toothed wheel. Thus, the teeth of the toothed belt 10 cooperate with the teeth of the toothed wheel 9 and pinions.

Preferably, the assemblies 8 are connected in pairs to form separate unit elements 12. In each unit element 12, the first driving elements 9 of two combined assemblies are connected to a second driving element 13, preferably rotatably mounted on the support plate 1, by an intermediate transmission element 14, in the form of closed loop such as a toothed belt, so that each turn of the intermediate transmission element 14 corresponds to a turn of the end transmission elements 10 of the two connected sets. The second driving element 13 is coupled to the secondary motor 7. The second driving element 13 resumes a position identical to each revolution of the intermediate transmission element 14. Preferably, the second driving element 13 comprises a wheel notched wheel associated with the intermediate transmission element 14. The toothed wheel may comprise an axis of rotation substantially perpendicular to the plane of the support plate 1. Preferably, when an intermediate transmission element 14 makes a turn, all the transmission elements intermediaries 14 of the printing device also make a loop turn. The second drive element 13 preferably has an axis of rotation substantially perpendicular to the support plate 1.

The support plate 1 is preferably a disk, the first driving elements 9 are preferably arranged in a second circle C ₂ concentric to the first circle C ₁ , and of smaller diameter than the first circle C ₁ . The second drive elements 13 are preferably arranged in a third circle C ₃ concentric with the second circle C ₂ and of smaller diameter than the second circle C ₂ . The first, second and third circles C ₁ , C ₂ and C ₃ each have their center coinciding with the center of the support plate disk 1. In other words, starting from the periphery of the support plate, one finds successively in the direction of center of the support plate 1 the reception elements P1 at P32, the first driving elements 9, the second driving elements 13.

The coupling of the unit elements 12 to the secondary motor 7 can be achieved by connecting them in pairs by a main transmission element 15, in the form of a closed loop. Each main transmission element 15 is coupled on the one hand to a third driving element 16 fixed to a central axis driven by the secondary motor 7 and on the other hand to two second driving elements 13 of the unit elements 12. preferably the central axis is a shaft of the secondary motor 7. The unit elements 12 are connected so that each turn of a main transmission element 15, corresponds to a turn or a half-turn of the intermediate transmission elements 14 of the the connected unit elements 12, and preferably all intermediate transmission elements 14. The third drive element 16 resumes an initial position identical to each revolution of a main transmission element 15. Preferably, at each turn an intermediate transmission element 14 corresponds to an integer multiple of revolutions of the associated main transmission element 15. The third drive element 16 preferably has an axis of rotation substantially perpendicular to the support plate 1.

A main transmission element 15 may be formed by a toothed belt. The driving element 16 may comprise a toothed wheel whose axis of rotation is substantially perpendicular to the plane of the support plate 1.

The transmission elements, end 9, intermediate 14 and main 15, being in the form of closed loop, by "turn" made by the latter, is meant a loop turn. The transmission elements may be in the form of belts, preferably notched, or chains.

Preferably, between a first and a second indexed position of the support plate 1, the receiving elements P1 to P32 have performed at least one complete revolution on themselves. In the first and second indexed positions, in addition to the transmission elements 10, 14, 15, all the driving elements 9, 13, 16 are in their initial position.

According to one embodiment, the printing device comprises eight sets 8 angularly distributed at the periphery of the plate 1, and four distinct unit elements 12. Each set 8 comprises four reception elements P21 to P24. Each receiving element P1 to P32 is provided with a gear 11 having 25 teeth, and the first driving element 9 of an assembly 8 is formed by a notched wheel of 25 teeth. The associated end transmission element 10 is a toothed belt comprising about 150 teeth. In other words, when the toothed belt 10 of a set makes a turn, all the receiving elements P1 to P32, and all the first driving elements 9, do exactly six turns on themselves. Each second driving element 13 may comprise two notched wheels whose axis of rotation is preferably perpendicular to the support plate 1. These two notched wheels are interconnected by a total connection, that is to say they are fixed relative to each other, they have the same angular velocity. A first toothed wheel of the second drive member 13 is coupled to the intermediate transmission member 14 formed by a toothed toothed belt of 150 teeth. A total of four unit elements 12 are then obtained. The four unit elements 12 are coupled two by two to the central axis. Each coupling can be achieved by a main transmission element 15 in the form of a toothed toothed belt 150 coupled on the one hand to the second 50-toothed wheels of the second drive elements 13 respectively of the two connected unit elements 12, and other part of the third drive element 16 arranged, preferably, in the form of at least a toothed wheel of 50 teeth fixed to the central axis. Belts The notches forming the main transmission elements are only two in number.

When the belts forming the end transmission elements 10 turn, the belts forming the intermediate transmission elements 14 turn around, and the belts forming the main transmission elements make two turns.

Such a printing device makes it possible to ensure the reproducibility of the rotational movements of an article on its receiving element at each indexing of the support plate 1.

In particular, in the embodiment where the receiving elements P1 to P32 are driven by means of a single belt, the secondary motor 7 is a motor brushless type ("brushless" in English). Such an engine avoids fluctuations in the electrical and mechanical losses associated with other types of engines which would have the consequence of introducing non-reproducible offsets at each turn of the main transmission end, intermediate transmission 14 and transmission transmission elements 15 .

When using the printing device, each receiving element may have a variation of rotation with respect to another receiving element of the device. Such variations may be due to manufacturing variations of the belts and sprockets of the drive system of the receiving elements. The printing device defined in the figures 1 and 2 is particularly adapted to take these variations into account and improve the printing accuracy of the patterns.

Claims (6)

1. Method for printing patterns onto three-dimensional articles respectively mounted on rotary receiving elements, including a step of generating (S1), for each receiving element, a set of several digital images for respectively printing parts of a same pattern onto an article mounted on the receiving element, a step (S2) of printing successively parts of a same pattern onto a same article respectively from the digital images of the set associated with the receiving element for the article, a step (S3) of printing simultaneously several parts of distinct patterns respectively onto several articles, characterized in that the digital images of a same set have a same length, each simultaneous printing of a part of a pattern onto an article being performed from a digital image of the set associated with the receiving element for the article.
2. Method according to claim 1, wherein each digital image represents a monochromatic part of a pattern.
3. Method according to claim 1 or 2, wherein the length of the digital images of a same set associated with a receiving element is determined from the length of a circular arc described by the rotation of the article mounted on the receiving element.
4. Device for printing patterns onto three-dimensional articles including:

   - a printing station (30) provided with several ink jet print heads (22a to 22d) being configured to print simultaneously several parts of distinct patterns respectively onto several articles (A1 to A32);

   - a support plate (1) provided on its periphery with a plurality of receiving elements (P1 to P32) for articles (A1 to A32), each receiving element (P1 to P32) being rotatingly mounted on the support plate (1);

   - image processing means (31) configured to generate, for each receiving element (P1 to P32), a set of several digital images for respectively printing parts of a same pattern onto an article (A1 to A32) mounted on the receiving element (P1 to P32); and

   - means (2) for rotating the support plate (1) configured to place each article (A1 to A32) mounted on a receiving element (P1 to P32) successively opposite each print head (22a to 22d) so as to print successively the parts of a same pattern onto a same article (A1 to A32) respectively from the digital images of the set associated with the receiving element (P1 to P32) for the article (A1 to A32);

   characterized in that the digital images of a same set have a same length, each print head (22a to 22d) printing a part of a pattern onto an article (A1 to A32) from a digital image of the set associated with the receiving element (P1 to P32) for the article (A1 to A32).
5. Printing device according to claim 4, wherein the image processing means (31) generate monochromatic digital images.
6. Printing device according to claim 5, wherein the image processing means (31) determine the length of the digital images of a same set associated with a receiving element (P1 to P32) from the length of a circular arc described by the rotation of the article (A1 to A32) mounted on the receiving element (P1 to P32).

Images