DE102006037922A1 - Laser beam marking assembly for food or food packaging directs beam through separate paths to overlapping target zones - Google Patents

Abstract

Claimed is a laser beam (2) process and assembly to mark a product e.g. food (10) or its packaging. The laser beam is regulated by a programable laser beam deflector system (30, 31) that direct the beam through two non-overlapping paths. Each beam can be deflected through an angle which overlaps the target area of the other beam. Each beam can reach some or all of the second target area.

Description

The Invention relates to an apparatus and a method for marking, in particular of arched surfaces a food by means of laser marking with at least one freely programmable laser beam deflection system.

Laser marking devices are in industrial production plants and other application areas often used to create individual objects, e.g. Products or their packaging or even food / food directly with different ones To provide information / markings. This is it mostly alphanumeric characters, logos or barcodes, based derer an end customer or an automatic detection system, for example recognize the product, its expiry date or its manufacturer.

In increasing also become products of the daily Life marked by laser, for example, decorative elements on the surface produce a product or its packaging, causing this is upgraded or a clear assignment to the producer learns allowing a user this type and design of the product as possible at a glance can be assigned to the corresponding manufacturer.

The Marking itself takes place through the action of a bundled Laser beam on the product surface or the surface of a Packaging, which either removes a previously applied paint will, the surface is removed and / or melted and / or charred, or by a color change, especially if previously introduced special pigments in the surface to be marked or by a deeper erosion of the surface, so that an engraving is created. The goal is, in any case, the highest possible visual and / or tactile contrast to the surrounding ground to increase readability.

For example, CO ₂ lasers or Nd: YAG lasers are used to carry out this type of marking. The generation of the marking takes place either in the mask weft method, by means of a galvanometer scanner or with crystal-optically deflected lasers. With the exception of the masking method, the said laser marking methods are freely programmable and thus permit a marking which is variable from product to product.

The available here standing freely programmable marking devices such as those with Galvanometer scanner working laser devices point to the deflection unit additional Optics, whereby the laser beam focused in a focal plane becomes. The marking is then expediently carried out in this focal plane, because here the focal spot of the laser radiation is the smallest and thus the power density of the laser radiation becomes maximum, so that in the Essentially, only in this level the material to be marked absorbed laser energy leads to a mark.

ever according to laser power, wavelength, Laser mode and absorption behavior of the material to be marked in the considered wavelength range it is also possible to perform a mark above and below the focal plane, wherein In these areas, the area-related power density the laser radiation from a certain distance to the focal plane decreases so far that no marking is possible. In addition, it is increasing the focal point of the laser radiation with increasing distance from the Focal plane, giving a clear and high-resolution mark even at sufficient power density no longer makes sense. This is limited a laser marking in the area to be marked on an im Essentially flat surface, their roughness or curvature or structure for the reasons mentioned only within narrow limits permissible is.

A larger area Marking, for example, a spherical, or cylindrical or generally an object with one or more strong concave ones or convex curvature is usually only to achieve that the mark image divided into several fields and the object and the marker laser for each Partial image are positioned to each other so that each partial image within the limitations mentioned above and therefore makes sense can be marked. The overall picture then consists of the mentioned sub-images together. It is easy to see that, especially at the border areas the subpictures to each other a high registration accuracy can be achieved must to achieve a self-contained overall picture. For this is for every drawing a precise Alignment of the object to the marking device required, which means a considerable technical and time expenditure.

The advantages of a laser inscription, especially in the food sector, are that in this type of inscription no inks or toners or other coloring substances are applied to the surface to be inscribed, which is especially true for direct labeling of foods such as fruits, vegetables, meat products, baked goods, etc . can lead to an unacceptable contamination. Such inks or toners, as they are applied by means of other marking methods such as inkjet, laser printing, transfer printing, etc., often contain food-legally not authorized and / or partially toxic or karzi Nogene substances, so that in a direct labeling of a food, the consumption of the same is questionable if not dangerous. In contrast to this, only the surface of the foodstuff is changed by means of a laser inscription, which, in particular in the case of a thermal effect, as occurs preferentially when CO ₂ lasers are used, in its effect on the surface to be inscribed is almost identical to the cooking fry used in every kitchen. and baking operations.

task The invention is therefore to eliminate the disadvantages mentioned and to provide a device / method by which it is possible also strongly curved and extensive surfaces to provide foodstuffs with a particularly large-area marking, without any manual or automatic movement neither of the device are still running of the food to be marked during the labeling got to.

According to the invention Problem solved by a device of the generic type, in which at least one first deflecting arrangement is provided, by means of a laser beam dependent on from a distraction by a freely programmable laser beam deflection system in at least two, in particular non-overlapping first solid angle ranges is deflected and still one of the number of first solid angle ranges corresponding number of second deflection arrangements is provided, by means of which a laser beam from each first solid angle range in a respective second solid angle area in the direction of a is distractible to marking food, with the second Solid angle areas at least partially overlap / cross, so that one in the area of the overlap / intersection The second solid angle areas arranged food with laser beams from at least two solid angle ranges markable.

The The object is further achieved by a method in which a laser beam with at least one first deflection arrangement in dependence from a previous deflection by a freely programmable laser beam deflection system in at least two, in particular non-overlapping first solid angle ranges is deflected and a laser beam from every first solid angle area by a second deflection arrangement in a respective second solid angle range is diverted in the direction of a food to be marked, wherein the second solid angle regions at least partially overlap / intersect, so that one in the area of overlap / intersection The second solid angle areas arranged food with laser beams is marked from at least two solid angle areas.

essential The core idea of the invention is with a method according to the invention or a device according to the invention a food to be marked, in particular stationary and stationary not only exclusively to mark out of a solid angle area, but of several Solid angle ranges, in particular at least two solid angle ranges. This can be an optimization of a mark on a curved surface of a to be marked food, without that to be marked Food needs to be realigned.

In the explanations The prior art revealed only one focal plane, since a laser beam essentially from one direction only, or because of the distraction only from a solid angle area to a single object to be marked meets. Does this single object have a strong curvature in the surface, So this is only partially in the focal plane. Through the lighting a single object of several, in particular at least two solid angle areas the position of the surface of a single object to be marked can be better optimized with respect to the then resulting multiple focal planes become. It can be such a larger coherent one Area of the curved surface of a single object, especially if it is is essentially cylindrical or spherical surfaces.

Under A food in the context of the invention is here essentially a grown natural Food understood as e.g. Fruits or vegetables, especially pumpkins, Melons, zucchini, cucumbers, apples etc. as well as produced foods such as sausage, bread etc. This is preferably the direct marking of such food, So not the packaging.

One Laser beam is thus first deflected by a programmable deflection unit to a desired To obtain marking. This can e.g. by a galvanometer scanner device done or any other suitable device.

The image of a mark can be created previously in a higher-level control, for example by means of a graphics program on a computer. Such an image can be stored eg as a vector graphic. The image created on a usually substantially planar monitor may be distorted by software, if desired, depending on a curved surface of a food to be marked such that, after being viewed from the curved surfaces, it is unidirectional without distortion Viewer appears. For this purpose, it may be provided that a concrete curvature or an idealized curvature or the geometric shape of a food to be marked stored in a computer and taken into account, for example, based on a pumpkin or a melon or an apple whose / their diameter and consideration as an idealized ball or eg a cucumber / zucchini their length and diameter and consideration as an idealized cylinder with this data. It may then be provided that the software distorted image is applied to the food to appear when viewed without distortion.

The Image of a mark is thereby by means of a laser beam in Scanned essentially scanned. Depending on a distraction is then the deflected by the deflecting beam by means of a first deflection arrangement in at least two different first solid angle ranges distracted. These different first solid angle ranges become e.g. achieved when passing through the programmable deflection unit deflected beam the first deflection arrangement in different areas meets. If the laser beam strikes e.g. a first area A of the first Deflection arrangement, it is in a first solid angle range A deflected, he meets the deflection arrangement in a region B, so it is deflected into a first solid angle region B and so on.

in this connection It may preferably be provided that all first solid angle ranges do not overlap. For only two solid angle ranges, these may be e.g. essentially be aligned opposite each other.

A first deflection arrangement may e.g. formed by at least two mirrors be, which are arranged at an angle to each other, in particular with the mirrors touching adjacent edges. Everyone the mirror forms a region of the deflection arrangement in the above-mentioned sense. The number of mirrors gives the number of different potential first solid angle ranges. To get two first solid angle ranges For example, a deflection device may be used e.g. be formed by two mirrors, which are arranged at an angle of 90 degrees to each other, in particular where touching two edges of the two mirrors. This edge of the deflection arrangement may point to the programmable deflection unit. For example, 4 first To obtain solid angle ranges, a deflection arrangement by 4 Mirror may be formed, which are arranged in a pyramid, wherein this arrangement with the pyramid tip towards the programmable Deflection unit can be aligned.

There the individual possible first solid angle ranges, which thus originate all in the first Have deflecting, all pointing away from each other it is according to the invention provided, each laser beam from one of the previously defined first space angle ranges in a second solid angle range to redirect. It is thus each of the first solid angle areas in which a laser beam can be deflected by redirecting each a second solid angle range assigned. Here, the deflection takes place by respective second Umlenkanordnungen such that a laser beam located in a second solid angle range moved to a surface of a food to be marked. Such a food will thus depending on the programmed distraction from different second solid angle ranges (at least two) illuminated to introduce a mark in the curved surface. These second solid angle areas will preferably at least partially overlap or overlap.

Around to make the mark is thus advantageously a food positioned so that a surface to be marked in the area an overlap / overlap the different second solid angle ranges is arranged.

According to the invention It may then be provided that a mark, in particular overall marking in the surface of a food by one of the number of the first / second solid angle ranges corresponding number of sub-marks composed, each Partial marker introduced from another solid angle area in the surface becomes.

It may be provided that by means of a higher-level control, e.g. software first breaks down the overall marking into partial markings is then introduced and then given each sub-marks in the surface become.

in this connection can the device of the invention be adjusted so that the part marks directly to each other adjacent to form a self-contained overall marking. In that only a particularly small area of the overall marking by means of one at a different angle (from another solid angle range) It is possible to mark each incident laser beam Partial marking within the permitted depth of field mark and create an overall mark as a whole a contour sharp mark over the entire arched Surface has.

It can also be provided that one of the Number of solid angle areas corresponding number of the same or different respectively individual markers is introduced by means of the invention in the surface of a food. Thus, after a marking, a food may have the same or different images, for example, at different positions.

in this connection it can also be provided, the partial markings of a marker in a parent Interchange and / or mirror control, e.g. when the second solid angle areas above the to be marked, in particular concave surface cross so that the part marks on the surface of the food to be marked in the correct direction to an overall mark put together.

Basically It should be provided the mark with parallel unfocused Perform laser beams. Preferably, however, the laser beams will be focused in such a way in each of the second solid angle regions, the region to be marked the surface of a food to be marked in a depth of field range is arranged around the focal plane around.

This can be done in the Beam path of a laser beam at least one focusing element be arranged, in particular a lens or a curved mirror. It can also for each or each of the first or second solid angle ranges are different be provided focusing elements, in particular with different Focal lengths. Preferably, directly a first and / or second deflection arrangement be designed focusing, in particular as a curved mirror. If a lens is provided as a focusing element, then a Deflection arrangement be designed as a planar deflection mirror.

through The invention provides the possibility of food with any curved Surfaces, especially with concave or convex surfaces. in this connection can the beam paths the laser beams from the first deflection arrangement over the different second deflection arrangements up to the food in the Essentially the same, but also different.

at all versions The invention may also provide that after at least a second deflection arrangement at least one further third and if necessary, the following fourth deflection arrangements, essentially the same Sort are arranged.

at The foods can be essentially those with im Essentially spherical or cylindrical surface act, such as apples, Melons, pumpkins, Cucumbers, zucchini etc. For cylindrical food it can be provided be that lighting with laser beams of two different Solid angle ranges, which are substantially perpendicular to the cylinder axis are arranged. Here, the angle is understood in relation to a ray in the center of the respective solid angle range.

A so on food, especially fruit or vegetables directly applied label may represent an indication of origin to the producer or have decorative purposes. Also, a marker may be a template make up for an intended further processing. For example, can use pumpkins for Halloween Laser markings are provided, such as faces. A Customer, who has acquired such a marked pumpkin, can then even at home cut out the marked face with a knife / carve out.

Of the State of the art, as well as versions of Invention are shown in the following figures. Show it:

1 schematically a laser marking of the known type;

2 : schematically the marking limits for strongly curved surfaces

3 a first embodiment according to the invention with a common focusing optics for marking a convex surface

4 a second embodiment of the invention for marking a concave surface

1 schematically shows a known embodiment of an arrangement for laser marking by means of galvanometer scanner. The one from a laser beam source 1 generated laser beam 2 will be over on the axes 3a and 4a the galvanometer scanner 3 and 4 attached deflecting mirrors 3b and 4b deflected via an unillustrated freely programmable controller so in the X and Y directions that a marker cone 5 can be crossed, creating a marker box 6 is produced.

An in the beam path located focusing optics 7 (Lens) focuses the laser beam 2 also in a focal plane 20 , in which the laser beam has its focal point and thus its minimum extent in the X and Y directions and thus the area-related laser power becomes maximum. Conveniently, a surface to be marked is placed in this plane for a marking, since the contour sharpest and most effective marking takes place here due to the minimum focal spot and the resulting highest power density.

Moving the surface to be marked along the Z-axis away from the focal plane 20 causes an enlargement of the focal point and thus a quadratic reduction of the power density, so that only within a depth of field 20a to 20b passing through an upper interface 20a and a lower interface 20b Certainly still satisfactory marking results are to be achieved. Outside this range, the achievable marking results are unsatisfactory or marking is impossible.

Shall like in 2 schematically shown a strongly curved surface 10 be labeled over a large area, so it is no longer possible to mark all areas of the surface 10 within an acceptable range for a meaningful label 11 , bounded by an upper limit 11a and a lower limit 11b (Depth of field), to hold. Rather, at least one area 12 the surface to be labeled 10 not in the area 11 lie so that it can be labeled only unsatisfactory or not at all or only in accordance with the prior art as already described with partial images in one or more further passes must be labeled.

A first embodiment of the invention shows 3 , The one from a laser beam source 1 generated laser beam 2 will be over on the axes 3a and 4a the galvanometer scanner 3 and 4 attached deflecting mirrors 3b and 4b deflected via an unillustrated freely programmable controller in the X and Y direction and a subsequent focusing optics 7 (Lens) focused in a focal plane. Immediately after the optics 7 there is an optical deflection arrangement 30 , For example, a mirror arrangement 31 which, depending on the previous X and Y deflection at different angles from the optics 7 emerging laser beam 2 in at least two different first space areas 5a and 5b is distracted.

For example, in the mirror arrangement 31 two deflecting mirrors 31a and 31b used, the mutually occupy a certain angle, for example, 90 degrees and form, for example, a prism-like figure, so on the mirrored surface 31a respectively. 31b incident laser beam 2 depending on the previous distraction either in the direction 32a or 32b deflected, resulting in this example, two marker cone 5a and 5b result, which form different first solid angle ranges.

By means of the respectively downstream second deflection arrangement of deflection mirrors 33a and 33b now become these marker cones 5a respectively. 5b so redirected that the surface of the food to be labeled 10 from different second solid angle regions in the partial surfaces 34a respectively. 34b Marked so that the faces to a common marking area 34 complete. Here can be an example as a cylinder 10 Ideally illustrated zucchini or cucumber a food to be marked 10 form.

The distance between the respective partial surfaces 34a and 34b from the focusing optics 7 corresponds to the focal length of the optics used 7 so that every subarea 34a and 34b each lying substantially in the focal plane. For this purpose, the deflection mirror 33a and 33b each be slidably and / or rotatably mounted in a holder, not shown, so as to the respective distances of the partial surfaces to be labeled to the marking optics 7 adapt.

For a label of essentially always the same or similar foods, this setting is unique. In addition, with a suitable choice of Auftreffrichtungen the marker cone 5a and 5b on the surface of the food to be marked 10 the respective partial surfaces 34a and 34b each within the allowed depth of focus, leaving the entire mark in the marking area 34 Overall, within the allowable depth of field and thus a high quality mark is possible. It is of course also possible to split the marking cone into more than the two partial cones mentioned by way of example, for example in three, four or more partial cones in order to label, for example, spherical or conical surfaces.

It is also possible in an alternative embodiment according to the invention to mark extended concave surfaces as in FIG 4 shown. The arrangement is essentially the same as in 3 described arrangement equal to the geometric position of the faces 34a and 34b to each other on the surface 10 of the object to be labeled. In this case, the marking cones (second solid angle ranges) cross each other so that the subareas are also intersected with each other crosswise. A self-contained and right-sided marking picture 34 In this case, too, the respective partial images in the marking software of the marking unit must be exchanged and mirrored.

It may also be appropriate to a marking optics 7 to renounce. In this case, the deflecting mirrors 31a respectively. 31b and or 33a respectively. 33b designed as a camber mirror, causing the laser beam 2 is similarly focused in a focal plane lying substantially on the surface of the object to be labeled. The execution of the curvature mirror can be spherical, parabolic, hyperbolic or similar or as Be off-axis mirror, as needed.

For labeling, all lasers whose laser wavelength, laser power and operating regime make it possible to mark sufficiently in each marking case, for example gas lasers such as CO ₂ lasers, argon lasers, metal vapor lasers, ion lasers, excimer lasers etc. or semiconductor lasers or solid-state lasers such as Nd: solids, are suitable without restriction of generality Laser, ruby laser, alexandrite laser, sapphire laser or free electron laser.

Claims (14)

Device for marking, in particular inscription of convex surfaces of a foodstuff by means of laser inscription with at least one freely programmable laser beam deflecting system, characterized in that a) at least one first deflecting arrangement ( 30 . 31 ) is provided by means of a laser beam ( 2 ) as a function of a deflection by a freely programmable laser beam deflection system ( 3 . 4 ) in at least two, in particular non-overlapping first solid angle ranges ( 5a . 5b ) is deflectable and b) one of the number of first solid angle ranges ( 5a . 5b ) corresponding number of second deflection arrangements ( 33a . 33b ) is provided, by means of which a laser beam ( 2 ) from every first solid angle range ( 5a . 5b ) into a respective second solid angle area in the direction of a food to be marked ( 10 ), wherein the second solid angle regions overlap / intersect at least partially so that c) a food arranged in the region of the overlap / intersection of the second solid angle regions ( 10 ) with laser beams ( 2 ) is markable from at least two solid angle ranges. Device according to claim 1, characterized in that a marking in the surface of a food ( 10 ) by one of the number of the first / second solid angle ranges ( 5a . 5b ) corresponding number of partial markings ( 34a . 34b ) is composable, each sub-mark ( 34a . 34b ) can be introduced into the surface from another solid angle range. Device according to one of the preceding claims, characterized in that in the beam path of a laser beam ( 2 ) at least one focusing, in particular displaceable / rotatable element ( 7 ), in particular a lens ( 7 ) or a curved mirror. Device according to one of the preceding claims, characterized in that a deflection arrangement is designed to focus is, in particular, as a vaulted Mirror. Device according to one of the preceding claims, characterized in that a deflection arrangement ( 30 ) as a planar and / or displaceable / rotatable deflection mirror ( 30 ) is trained. Device according to one of the preceding claims, characterized in that the laser beams ( 2 ) are focused in such a way that in each of the second solid angle regions, the region of the surface of a food to be marked ( 10 ) is disposed in a depth of field around the focal plane. Device according to one of the preceding claims, characterized in that with her convex and / or concave surfaces of a food ( 10 ) are markable. Device according to one of the preceding claims, characterized in that the partial markings ( 34a . 34b ) are arranged reversed in a higher-level control and / or arranged mirrored and cross the second solid angle areas above the to be inscribed, in particular concave surface and the partial markings ( 34a . 34b ) on the surface of the food to be marked ( 10 ) merge in the correct direction to form an overall marking. Method for marking, in particular inscription of convex surfaces of a foodstuff by means of laser inscription with at least one freely programmable laser beam deflecting system, characterized in that a) a laser beam ( 2 ) with at least one first deflection arrangement ( 30 . 31 ) as a function of a previous deflection by a freely programmable laser beam deflection system ( 3 . 4 ) in at least two, in particular non-overlapping first solid angle ranges ( 5a . 5b ) and b) a laser beam ( 2 ) from every first solid angle range ( 5a . 5b ) by a second deflection arrangement ( 33a . 33b ) into a respective second solid angle area in the direction of a food to be marked ( 10 ), wherein the second solid angle regions overlap / intersect at least partially, so that c) a food arranged in the region of the overlap / intersection of the second solid angle regions ( 10 ) with laser beams ( 2 ) is marked from at least two solid angle ranges. A method according to claim 9, characterized in that a mark in the surface of a food by one of the number of first / second solid angle ranges ( 5a . 5b ) corresponding number of partial markings ( 34a . 34b ) too is composed, each sub-marking ( 34a . 34b ) is introduced into the surface from another second solid angle range. Method according to one of the preceding claims 9 or 10, characterized in that the laser beams ( 2 ) in such a way that, in each of the second solid angle regions, the region of the surface of a food to be marked ( 10 ) is disposed in a depth of field around the focal plane. Method according to one of the preceding claims 9 to 11, characterized in that the partial markings ( 34a . 34b ) are arranged reversed and / or mirrored in a higher-level control and the second solid-angle regions intersect above the surface to be marked, in particular the concave surface, so that the partial markings ( 34a . 34b ) on the surface of the food to be marked ( 10 ) merge in the correct direction to form an overall marking. Method according to one of the preceding claims 9 to 12, characterized in that partial markings ( 34a . 34b ) are created completely and successively from a solid angle area. Use of a method or device according to one of the preceding claims for the marking of fruits and / or vegetables, in particular of pumpkins with Halloween-related illustrations, especially as a template for later cut out / cut out.