MARKING METHOD AND MARKED RECEPTACLE

Abstract

This method, intended for the marking of a receptacle (2) while it is moved along a conveying path, comprises: moving the receptacle (2) in a marking station along the conveying path; simultaneously marking a first surface region (2A) and a second surface region (2B) of the receptacle (2) while it is moved in the marking station along the conveying path, using a first laser beam (44) and a second laser beam (54) emitted in opposite directions on both sides of the receptacle, transversally to the conveying direction (X.sub.1), the first and second surface regions (2A, 2B) being arranged substantially at 180° from each other with respect to a main axis (X.sub.2) of the receptacle.

Claims

1. A method for the marking of a receptacle while it is moved along a conveying path, the method comprising: moving the receptacle in a marking station along the conveying path in a conveying direction; and simultaneously marking a first surface region and a second surface region of the receptacle while it is moved in the marking station along the conveying path, using a first laser beam and a second laser beam emitted in opposite directions on both sides of the receptacle, transversally to the conveying direction, wherein the first and second surface regions are arranged substantially at 180° from each other with respect to a main axis of the receptacle.

2. The method according to claim 1, wherein the first laser beam is emitted by a first laser device and the second laser beam is emitted by a second laser device, wherein the first and second laser devices each comprise a respective laser source.

3. The method according to claim 2, wherein the first and second laser devices are controlled by a speed at which the receptacle is moved in the marking station along the conveying path and a triggering time, which is the same for both laser devices.

4. The method according to claim 3, wherein the triggering time for both the first laser device and the second laser device is determined by a single sensor configured to detect a position of the receptacle along the conveying path.

5. The method according to claim 1, wherein, for at least one of the first and second surface regions of the receptacle, a ratio of a maximum arc length of a pattern marked on said surface region, taken in a circumferential direction of the receptable, to half a circumference of the receptacle is higher than 30%.

6. The method according to claim 1, wherein, for each of the first and second surface regions of the receptacle, the surface region comprises a polymer resin and an additive that absorbs radiation in a given wavelength range, wherein a wavelength of the laser beam marking the surface region is in the given wavelength range, wherein an energy density in a focal plane for each laser beam avoids material ablation in the corresponding surface region of the receptacle.

7. The method according to claim 1, wherein each laser beam is focused, in a focal plane corresponding to the surface region to be marked, in the form of a laser spot having a spot diameter in a range of between 50 μm and 150 μm.

8. The method according to claim 7, wherein each laser spot is displaced, in a focal plane corresponding to the surface region to be marked, according to a scanning trajectory with a scanning speed in a range of between 2500 mm/s and 5000 mm/s.

9. The method according to claim 7, wherein each laser beam is a pulsed laser beam, wherein its repetition rate and its laser scanning speed are adapted in such a way that a ratio of a length of an overlap zone between two successive positions of the laser spot to a spot diameter of the laser spot is higher than or equal to 0.15.

10. The method according to claim 7, comprising a step of determining, for each of the first and second surface regions of the receptacle to be marked respectively by the first and second laser beams, an optimized scanning trajectory of the laser spot corresponding to an optimized marking order of the characters of the pattern to be marked which minimizes a marking time of the pattern on the surface region.

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14. (canceled)

15. A laser-marked receptacle for use in a packaging filled with sensitive products such as food, nutraceutical products, pharmaceutical products or diagnostic products, wherein said marked receptacle comprises on its outer surface two laser-marked surface regions arranged substantially at 180° from each other with respect to a main axis of the receptacle, wherein each laser-marked surface region comprises a respective marked pattern formed of a plurality of laser marked dots resulting from a color change of material of the outer surface under the effect of a photochemical reaction induced by a laser beam wherein, in each laser-marked surface region, the laser-marked dots are arranged in lines such that a width of each line corresponds to a diameter of one laser-marked dot.

16. The laser-marked receptacle according to claim 15, wherein the patterns marked on the two surface regions of the receptacle result from a color change of the material of the receptacle without material burning or material ablation.

17. The laser-marked receptacle according to claim 15, wherein the patterns marked on the two surface regions of the receptacle are different from one another.

18. The laser-marked receptacle according to claim 15, wherein, for at least one pattern marked on a surface region of the receptacle, a ratio of a maximum arc length of the pattern in a circumferential direction of the receptable to half a circumference of the receptacle is higher than 30%.

19. The laser-marked receptacle according to claim 15, wherein, for each line of each laser-marked surface region, the successive laser-marked dots forming the line are connected to each other in an overlap zone, wherein a ratio of a length of the overlap zone between two successive laser-marked dots in a longitudinal direction of the line to a diameter of each laser-marked dot is higher than or equal to 0.15.

20. The laser-marked receptacle according to claim 15, wherein, for each laser-marked surface region, a surface density of the laser-marked dots for the marked pattern, defined as a ratio of the number of laser-marked dots forming the marked pattern to a surface area of the smallest circumscribing rectangle tangent to the surface region within which the marked pattern is inscribed, is less than 300 dots/mm.sup.2.

21. The laser-marked receptacle according to claim 15, wherein, for each laser-marked surface region, the number of laser-marked dots forming the marked pattern is less than 10000.

22. The laser-marked receptacle according to claim 15, wherein, in each laser-marked surface region, a diameter of each laser-marked dot is in a range of between 50 μm and 150 μm.

23. The laser-marked receptacle according to claim 15, wherein an outer surface of the receptacle comprises a polymeric surface comprising a polymeric resin and an additive that absorbs radiation in a given wavelength range, wherein an amount of the additive is of between 0.5 and 5 wt %.

24. An apparatus for the marking of successive receptacles in a marking station, the apparatus comprising: a conveyor for moving successive receptacles in the marking station along a conveying path; a first laser device and a second laser device each comprising a respective laser source, which are located on both sides of the conveying path and configured to emit two laser beams in opposite directions, transversally to a running direction of the conveyor, wherein the laser beam of the first laser device is focused in a first focal plane corresponding to a first surface region of a receptacle passing in the marking station, and the laser beam of the second laser device is focused in a second focal plane corresponding to a second surface region of a receptacle passing in the marking station, wherein for each receptacle, the first and second surface regions are arranged substantially at 180° from each other with respect to a main axis of the receptacle; and a controller configured to control the first and second laser devices as a function of a speed of the conveyor and a triggering time.

25. The apparatus according to claim 24, wherein the triggering time for both laser devices is determined by a single sensor configured to detect a position of the receptacle transported by the conveyor.

26. The apparatus according to claim 24, wherein the triggering time for both laser devices is computed from a speed of the conveyor in the marking station and a spacing between successive receptacles transported by the conveyor.

27. The apparatus according to claim 24, wherein the controller is configured to control at least one laser parameter of each of the first and second laser devices selected from a group consisting of: a focal laser spot diameter, a laser average power, a laser scanning speed, a repetition rate, a pulse width, a marking direction, and a combination thereof.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0077] Features and advantages of the invention will become apparent from the following description of embodiments of a marked canister and a marking method and apparatus according to the invention, this description being given merely by way of example and with reference to the appended drawings in which:

[0078] FIG. 1 is a side view of a marked canister according to one embodiment the invention, comprising on its outer surface two laser-marked surface regions arranged substantially at 180° from each other with respect to a central axis of the canister;

[0079] FIG. 2 is a perspective view of the marked canister of FIG. 1 on the side of a first laser-marked surface region;

[0080] FIG. 3 is a perspective view of the marked canister of FIG. 1 on the side of a second laser-marked surface region;

[0081] FIG. 4 is a view at larger scale of the detail IV of FIG. 2;

[0082] FIG. 5 is a magnified view of the constitutive lase-marked dots of a marked character of FIG. 4, illustrating appropriate dot diameter and overlap length produced with the marking method according to the invention;

[0083] FIG. 6 is a schematic top view of part of a manufacturing line 30 for producing marked canisters similar to that of FIG. 1, comprising a marking apparatus according to one embodiment the invention; and

[0084] FIG. 7 is a view at larger scale of the detail VII of FIG. 6.

ILLUSTRATIVE EMBODIMENTS OF THE INVENTION

[0085] The figures illustrate a marked canister 2 according to one embodiment of the invention, and a portion of a manufacturing line 30 for producing such marked canisters 2. As shown in FIG. 6, successive operations are performed on the canisters 2 in the manufacturing line 30, i.e. successively: each canister 2 is filled, assembled and closed in a filling station 31; the canisters 2 are separated from one another in a separation station 33; each canister 2 is laser marked in a marking station 35; each canister 2 is controlled with regard to the quality of its laser marking in a control station 37.

[0086] In the example of FIGS. 1 to 3, the marked canister 2 comprises a tubular body 23 and a gas-permeable cap 24. The gas-permeable cap 24 is provided with a plurality of perforations 28 and configured to be fastened on the tubular body 23, e.g. by clipping. The tubular body 23 has a circular cross section and comprises a bottom wall and a peripheral wall delimiting a volume for receiving an active material, which is closed by the gas-permeable cap 24. By way of a non-limiting example, the active material received in the inner volume of the canister 2 may be a dehydrating agent (or desiccant) in a powder or granular form, e.g. selected from molecular sieves, silica gels and/or dehydrating clays. The canister 2 is intended to be dropped in a packaging (not represented) in which sensitive products are stored, so as to regulate the atmosphere inside the packaging.

[0087] As clearly visible in FIG. 1, the tubular body 23 of the canister comprises on its outer surface two laser-marked surface regions 2A and 2B, arranged substantially at 180° from each other with respect to a central axis X.sub.2 of the canister 2. Each laser-marked surface region 2A, 2B comprises a respective marked pattern 21, 22. In this illustrative embodiment, the marked pattern 21 on the surface region 2A is different from the marked pattern 22 on the surface region 2B.

[0088] The combination of the two marked patterns 21 and 22 is configured to satisfy normative requirements, e.g. in terms of content and font size. In particular, the marked pattern 21 on the surface region 2A comprises the inscriptions “DESICCANT” and “DO NOT EAT”, as well as a symbol showing that the canister should not be ingested, whereas the marked pattern 22 on the surface region 2B comprises the inscription “DO NOT EAT” and its translations in French and Spanish languages.

[0089] As visible in the view at larger scale of FIG. 4, each character of the marked patterns 21 and 22 is formed by a plurality of laser-marked dots 26, which are arranged in straight or curved lines 25. In an illustrative embodiment, which is given only by way of example and is not limitative, the tubular body 23 and the cap 24 of the canister are both made of a polymeric material comprising a polyethylene matrix and titanium dioxide (TiO.sub.2) as an additive in an amount of 1 to 3 wt %, which gives a white color to the canister 2. The laser-marked dots 26 of each marked pattern 21, 22 have a grey color which makes them visually distinct from the white background.

[0090] The grey colored laser-marked dots 26 result from TiO.sub.2 reduction in zones where the surface regions 2A and 2B have been irradiated with a pulsed UV laser radiation. The duration and intensity of each dot-producing pulse and the pulse repetition rate are determined according to the surface material to be marked. Advantageously, TiO.sub.2 reduction is a photochemical reaction which absorbs a great quantity of photon energy, so that thermal effects are minimized on the surface regions 2A and 2B and the color change of the laser-marked dots 26 takes place without burning or ablating the surrounding polymer material. Good resolution and good contrast of the laser-marked dots 26 are thus obtained.

[0091] It can be seen in the figures that, for each marked pattern 21 or 22, each segment of line 25 of each character of the marked pattern is formed by a single row of laser-marked dots 26. Then, for each marked pattern 21 or 22, a width W of each line or segment of line 25 corresponds to the diameter D of one laser-marked dot 26. This is due to the specific process used to mark the two surface regions 2A and 2B of the canister, in which a laser beam writes each character of the marked pattern linearly on the corresponding surface region, in the form of a straight or curved line. Such a linear scanning marking is the most efficient method to mark the canister 2 while respecting the marking times imposed by existing production rates for canisters. Advantageously, in this embodiment, the marked patterns 21 and 22 do not contain any segment of line which comprises a matrix of juxtaposed dots in a direction transverse to the longitudinal direction of the segment of line.

[0092] As shown in FIG. 5, for each marked pattern 21 or 22, the successive laser-marked dots 26 in each line 25 are connected to each other in an overlap zone J. By way of example, in this illustrative embodiment, the diameter D of each laser-marked dot 26 is 100 μm and the length L of the overlap zone J in each straight line segment is 30 μm, i.e. there is a 30% overlap. The overlap length L may be higher than 30 μm for curved line segments compared to straight line segments, due to a decrease in the laser scanning speed for the marking of curved line segments. Such a value of the ratio of the overlap length L to the dot diameter D ensures that each line 25 forming a character in the marked patterns 21, 22 appears to be continuous to the human eye.

[0093] In order to reach high marking speed, when the marking method of the invention is used, in which the two surface regions 2A and 2B of the canister 2 are marked simultaneously by two laser beams emitted in opposite directions on both sides of the canister 2, it is possible to calculate a maximum number of laser-marked dots 26 in each of the surface regions 2A and 2B, based on a maximum marking time imposed for the canister 2 and a repetition rate of each laser used to create the laser-marked dots 26. For example, if the canister 2 is to be marked in less than 60 ms, and the lasers used to mark simultaneously the two surface regions 2A and 2B have a repetition rate of 50 kHz, then the number of laser-marked dots 26 constituting each marked pattern 21 or 22 will have to be less than 3000. Knowing a desired length of the pattern to be marked, it is then possible to dimension the values of the dot diameter D and the overlap length L.

[0094] Conversely, if the values of the dot diameter D and the overlap length L are fixed, another parameter that can be calculated, based on a maximum marking time for the canister 2 and a repetition rate of each laser used to create the laser-marked dots 26, is the total linear length of each marked pattern 21 or 22, i.e. the sum of the lengths of all the line segments forming the characters of the marked pattern, where the length of each line segment is taken in the longitudinal direction of the line segment. For example, if the canister is to be marked in less than 60 ms, the lasers used to mark simultaneously the two surface regions 2A and 2B have a repetition rate of 50 kHz, the dot diameter D is 100 μm, then the total linear length of each marked pattern 21 or 22 will have to be less than 300 mm, and even less if an overlap length between successive dots is considered.

[0095] Advantageously, in this embodiment, the surface density of the laser-marked dots 26 for each of the marked patterns 21 and 22 is less than 35 dots/mm.sup.2. The surface density of the laser-marked dots 26 of a marked pattern is defined as the ratio of the number of laser-marked dots 26 forming the marked pattern to the surface area of the smallest circumscribing rectangle tangent to the surface region within which the projection of the marked pattern is inscribed. By way of example, with reference to FIGS. 2 and 3, where the X-direction is parallel to the central axis X.sub.2 and the X- and Y-directions define a plane tangent to each surface region 2A, 2B of the canister 2, the orthogonal projection of the marked pattern 21 on the X-Y plane tangent to the surface region 2A is inscribed within a circumscribing rectangle R1 having a side length a1 of 10 mm along the X-axis and a side length b1 of 9 mm along the Y-axis, while the orthogonal projection of the marked pattern 22 on the X-Y plane tangent to the surface region 2B is inscribed within a circumscribing rectangle R2 having a side length a2 of 8 mm along the X-axis and a side length b2 of 10.5 mm along the Y-axis.

[0096] In this embodiment, for each of the surface region 2A, 2B of the canister 2, a ratio of the maximum arc length of the pattern 21, 22, taken in the circumferential direction of the canister, to half the circumference of the canister is higher than 45%. With such a ratio, the patterns 21, 22 extend over a large portion of the circumference of the canister 2, so that they can be sufficiently complete and legible to provide a clear message to a user. By way of example and without limitation, with reference to FIGS. 2 and 3: the diameter of the canister 2 is 19.35 mm, which corresponds to a half circumference of the canister of 30.40 mm; for the surface region 2A, the maximum arc length 1 of the marked pattern 21 is 14.08 mm, which corresponds to a ratio of the maximum arc length 1 to half the circumference of the canister of the order of 46.3%; for the surface region 2B, the maximum arc length 2 of the marked pattern 22 is 14.84 mm, which corresponds to a ratio of the maximum arc length 2 to half the circumference of the canister of the order of 48.8%.

[0097] As shown schematically in FIG. 6, the manufacturing line 30 for manufacturing filled and marked canisters 2 comprises a conveyor 1 for moving the canisters 2 at a predetermined speed along a conveying path 10. The stations are arranged successively along the conveying path 10, including in the running direction X.sub.1 of the conveyor 1: [0098] the filling station 31, in which the active material is introduced in the inner volume of the tubular body 23 of each canister 2 and the canister 2 is assembled and closed by clipping the cap 24 on the tubular body 23 to avoid escape of the active material; [0099] the separation station 33, in which successive canisters 2, initially grouped in a random way, are separated by a constant spacing d by a separation device 3; [0100] the marking station 35, in which the two surface regions 2A and 2B of each canister 2 are marked simultaneously by two laser devices 4, 5; as shown in FIG. 6, the X-scanning direction of the laser devices 4, 5 is parallel to the central axis X.sub.2 of each canister 2, whereas the Y-scanning direction of the laser devices 4, 5 is parallel to the running direction X.sub.1 of the conveyor 1; [0101] the control station 37, in which the marked patterns on the two surface regions 2A, 2B of each canister 2 are controlled by two cameras 7, 8 positioned on both sides of the conveyor 1, in such a way that the camera 7 faces the surface region 2A of the canister and the camera 8 faces the surface region 2B of the canister. The cameras 7 and 8 ensure independently that each surface region 2A, 2B of the canister 2 is indeed marked with its respective pattern 21, 22 by the laser devices 4, 5. In this embodiment, not only does each camera 7, 8 ensure that the pattern 21, 22 is present on the corresponding surface region 2A, 2B of each canister 2, but each camera 7, 8 also ensures within a certain tolerance that the marked pattern 21, 22 is complete in terms of characters (letters and symbols in the represented example).

[0102] The canisters 2 are moved continuously by the conveyor 1 along the conveying path 10, successively from one station to the following one and within each of the separation station 33, the marking station 35, the control station 37. The speed of the conveyor 1 is advantageously measured by a speed sensor 12, such as an encoder wheel. The spacing d imposed between the successive canisters 2 by the separation device 3 is adjusted according to the speed of the conveyor 1, as measured by the speed sensor 12, and according to the on- and off-delays of the laser devices 4, 5, in such a way that each of the two laser devices 4, 5 can switch back to a ground state between the marking of two successive canisters 2.

[0103] The manufacturing line 30 also comprises two triggering sensors 6 and 9, which are located respectively upstream of the marking station 35 and upstream of the control station 37. Each triggering sensor 6, 9 comprises an emitter 61, 91 and a detector 63, 93 arranged on both sides of the conveying path 10, such that a radiation beam 64, 94 emitted by the emitter 61, 91 is detected by the corresponding detector 63, 93, while crossing the conveying path 10. In this way, each triggering sensor 6, 9 can detect the presence of a canister 2 just upstream of the station 35 or 37, when the canister 2 passes between the emitter 61, 91 and the detector 63, 93, which interrupts the beam 64, 94. The detection of a canister 2 by the marking triggering sensor 6 corresponds to a triggering time which triggers the marking operation for both laser devices 4, 5 of the marking station 35. In the same way, the detection of a canister 2 by the control triggering sensor 9 corresponds to a triggering time which triggers the control operation for both cameras 7, 8 of the control station 37.

[0104] In the marking station 35, the marking apparatus comprises two laser devices 4 and 5 located on both sides of the conveying path 10 and configured to emit two laser beams 44, 54 in opposite directions, transversally to the running direction X.sub.1 of the conveyor, in such a way that the laser beam 44 of the laser device 4 is focused in the surface region 2A of the receptacle 2 when it passes in the marking station 35, and the laser beam 54 of the laser device 5 is focused in the surface region 2B of the receptacle 2 when it passes in the marking station 35.

[0105] Each laser device 4, 5 comprises a laser source 41, 51 coupled to a beam delivery unit 43, 53. In one embodiment, which is given only by way of example and is not limitative, each laser source 41, 51 is a diode-pumped frequency-tripled Nd:YVO4 laser emitting pulses at 355 nm, with a repetition rate of 50 kHz, a pulse width of less than 25 ns and a pulse energy of 160 μJ. Each beam delivery unit 43, 53 is configured to focus the laser beam, in the focal plane corresponding substantially to the surface region 2A or 2B to be marked, in the form of a laser spot 46, 56 having a spot diameter D of 100 μm, and to move the laser spot 46, 56 in the focal plane according to a scanning trajectory corresponding to the desired pattern 21, 22 to be marked.

[0106] To this end, the beam delivery units 43, 53 each comprise a X-scanning mirror and a Y-scanning mirror driven by galvano-scanners, configured to control beam movement respectively in the X-axis and in the Y-axis, as shown in the figures. For each laser device 4, 5, the laser beam emitted by the laser source 41, 51 is reflected by the X-scanning mirror and the Y-scanning mirror to become a scanning laser beam 44, 54, which is focused through at least one lens in the focal plane in the form of the laser spot 46, 56. It is noted that, for the marking of canisters 2 similar to that of FIG. 1, since the marked pattern 21 on the surface region 2A is different from the marked pattern 22 on the surface region 2B, the scanning trajectory for the beam delivery unit 43 of the laser device 4 is different from the scanning trajectory for the beam delivery unit 53 of the laser device 5.

[0107] The marking apparatus also comprises a controller 36 configured to monitor the laser marking in the marking station 35 by controlling the laser devices 4, 5, in particular as a function of the speed of the conveyor 1 and a triggering time determined by the marking triggering sensor 6 located upstream of the marking station 35. In practice, the laser scanning speed of each laser device 4, 5 is adapted as a function of the speed of the conveyor 1 measured by the speed sensor 12, so as to mark each of the desired patterns 21, 22 adequately on the surface regions 2A and 2B. For each surface region 2A, 2B, the laser scanning speed may vary during the marking operation, in particular the laser scanning speed is typically higher for the marking of straight lines, compared to the marking of curved lines.

[0108] The scanning speed is in a range of between 2500 mm/s and 5000 mm/s, preferably between 3000 mm/s and 4500 mm/s. For a given repetition rate of each pulsed source 41, 51, the laser scanning speed can advantageously be adapted in such a way that the ratio of the length L of the overlap zone J between two successive positions of the laser spot 46, 56 to the spot diameter D of the laser spot is higher than or equal to 0.15, preferably higher than or equal to 0.3, corresponding to the marked canister 2 shown in FIG. 1. The overlap length may be higher for curved line segments compared to straight line segments, due to a decrease in the laser scanning speed for the marking of curved line segments.

[0109] By way of example, for a repetition rate of 50 kHz of each laser source 41, 51 and a spot diameter D of 100 μm, a scanning speed of 3500 mm/s at least in straight line segments corresponds to a 70 μm movement per pulse, i.e. an overlap length L of 30 μm, i.e. a 30% overlap for each straight line segment. Another controlled parameter is the energy density in the focal plane, which is a function of the photoactive additive concentration, the pulse energy of the laser and the spot diameter D. In the example of the canisters 2 with surface regions 2A, 2B made of polyethylene with TiO.sub.2 in an amount of 1 to 3 wt %, the energy density in the focal plane is selected to be higher than or equal to 1 J/cm.sup.2, in order to have sufficient marking contrast, and less than or equal to 2 J/cm.sup.2, in order to avoid ablating the material. More generally, the controller 36 is advantageously configured to control parameters of each laser device 4, 5 among: the focal laser spot diameter D, the laser average power, the laser scanning speed, the repetition rate, the pulse width, the marking direction, and a combination thereof.

[0110] The invention is not limited to the examples described and shown.

[0111] In particular, the receptacles may be made of a material other than a polymeric resin. For example, the or each receptacle may be an anodized aluminum can. In this case, the marking of each of the first and second surface regions of the receptacle may be performed using an infrared (IR) laser. For the marking of each surface region according to the invention, the laser source may also not be pulsed. For example, Continuous Wave (CW) or Quasi Continuous Wave (QCW) lasers may be used.

[0112] In addition, in the example of the canister described and shown in the figures, the first and second surface regions of the canister are located on the tubular body of the canister. As a variant, at least one of the first and second surface regions may be on the cap of the canister, e.g. on the periphery or on the top wall of the cap. At least one of first and second surface regions may also extend over both the body and the cap, e.g. overlapping the boundary between the two parts.

[0113] The receptacle may also be other than a canister intended to be dropped in a packaging. For example, the receptacle may be a stopper configured to close a packaging, e.g. for sensitive products. Moreover, whatever its application, the receptacle may have other shapes than a cylindrical shape as shown in the figures, e.g. the receptacle may have a tubular shape with any cross section, or a spherical shape, provided that the receptacle defines an inner volume delimited by at least one peripheral wall, and the first and second surface regions are arranged on two opposite sides of the inner volume.

[0114] Other relative orientations of the receptacle and the laser beams than those represented in the figures can also be considered, as long as the simultaneous marking of the first and second surface regions can take place. For example, it may be considered to have the laser beams oriented vertically facing one another, in the case of a receptacle with the first and second surface regions facing up and down, e.g. when the receptacle is suspended above the conveying path, or when the receptacle is moved in a lying position along the conveying path.