Device for inscribing or marking of objects using laser beam

The invention relates to a device for labeling or marking articles by means of laser beam according to Claim first

The marking of articles, in particular of packaging materials with Laser has long been known. For this scanning systems can be used be or masks working systems. In the former case, two rotatable Mirrors arranged at right angles to each other, so that the deflected laser beam can cover every point of a two-dimensional surface. In the screening method A laser beam pulse-like manner is passed through a mask for Production of writing or marking in one go.

To achieve higher power densities and resultant better Caption qualities is known to the light beam on the workpiece surface focus. So-called F-theta lenses are used. These have a planar focal surface, so that especially at the edges of the label plane the change in distance from the normally spherically symmetric focus area is balanced.

Another possibility, the focal length in dependence on the solid angle of the to change the deflected laser beam, is mechanically the focal length of the lens system to change. For this, the lenses must be moved mechanically, which is connected to a corresponding apparatus complexity.

The invention has for its object to provide a device for labeling or creating marking objects having a cylindrical surface can.

This object is achieved by a lens system, in which the Focal plane represents a weggekrümmte by the lens system face.

There are different ways conceivable to design such a lens system. According to one embodiment of the invention the lens system comprises a first defocusing and a second focusing lens. According to another embodiment the invention, the defocusing lens a weak concave / plane Lens and the second lens is a plan / convex or slightly concave / convex Lens. According to another embodiment of the invention, the second Lens preferably designed as a cylindrical lens. The marking of cylindrical Surfaces, the distance between the surface and lens system with the curvature of the cylindrical surface. Perpendicular thereto forms the cylindrical surface each in one direction is a straight line. It is understood that the lens system reflects this fact.

The invention is explained in detail using a drawing.

The sole figure shows a lens arrangement according to the invention with two laser beams for labeling or marking of a cylindrical surface.

A non-illustrated object such as a bottle, has an area 10, the curvature of which lies in the plane of the drawing. From a laser or a Deflecting mirror are two outgoing laser beams represented 12 and 14 respectively. The X-axis may be, for example, in the area of ​​the deflection mirror. The laser beam 12 and 14 has a certain extension in width. He passes through a lens system 16 through which focuses the laser beams 12, 14 on the surface 10, as shown at 18 and 20 respectively. If the deflection of the laser beams 12, 14 However, not only in the plane of the drawing, but also perpendicular thereto. such Distraction for labeling or marking with the aid of a deflection mirror is However, generally known.

The lens system 16 has a first slightly concave / planar lens 22 and behind a second plan / convex lens 24, in the section shown as a cylindrical lens is vertically but molded to a normal convex lens. Of the Refractive index of the lens 22 is smaller than that of the lens 24. The first lens 22 has defocusing and the second a focusing effect. In each case, the arrangement of the lenses 22, 24 so that regardless of the spatial angle of the Laser beams 12, 14 they are respectively focused on the surface of the tenth

The principle illustrated in the above description is in principle also applicable to so-called mask systems in which the beam path of the laser a mirror image punched mask shapes the object to be marked. After all is also possible to on a cylindrical surface moving surfaces label. Here, when labeling is the speed of the moving marking field control technology, balanced on the scanner.