Device for printing one or several objects moving in a feed direction

Description of the invention

The subject of the invention is a device for printing one or more objects moving in the direction of travel, in particular labels, packages, parts of packages, a carrier tape or labels adhered to a carrier tape.

Such a device is known, for example, from DE 19507892 A1. In this known apparatus, the label tape, which is a carrier tape with labels adhered to and separated from it, is guided between the thermal printing head and the pressure roller and is printed by thermal or thermal transfer. The labels are then detached from the carrier tape by means of a separator, the tape passing over the trailing edge. The print head is fixedly fixed in the device and, in the case of a thermal printing method, is held during transport and printing execution against the label or the carrier tape.

Moreover, such devices are known in which the print head is moved away from the label and from the carrier tape when printing is not taking place.

The thermal printer speed is limited due to the print quality. Moreover, as the speed increases, the wear of the thermal bar increases.

U.S. Patent No. 6,331,773 B1 discloses an apparatus for printing an object moving in the direction of advance, having a printhead and means for delivering the object to the printhead. In the described embodiments, the device is designed as a plotter having a print head. One of the possible embodiments of the printhead mentioned in this description is a thermal imaging head. The device comprises a frame serving as the working contact surface as well as means for continuously transporting the strip material to be printed in a first coordinate direction along the longitudinal direction of the material through the working contact plane. The longitudinal support with the first and second ends is coupled to the frame and extends transversely through the working contact plane. The printhead is connected to the support such that it is movable between the first and the second ends. The control system in which the graphic data is stored gives commands to the device to control the relationship between the position of the print head and the support and the working material. In use, such combined movement of the printhead and work material as instructed by the control system results in the printhead printing successive line segments of graphics that are nearly perpendicular to the first coordinate direction.

The object of the invention is to improve a device of the type specified in the introduction so that it has a higher printing or labeling speed without reducing the print quality and / or increasing the wear of the thermal bar.

A device according to the invention for printing one or more objects moving in the feed direction, in particular labels, packages, packaging fragments, a carrier tape or labels adhered to a carrier tape, having a thermal printing head and means for feeding the printed object to the thermal printing head, wherein the thermal printing head is equipped with a drive unit, by means of which the thermal printing head is displaceable in the direction of the printed object feed, as well as in the direction opposite to the feed of the object, characterized in that this drive unit has an articulated-sliding mechanism or a piezoelectric actuator and constitutes a system moving the thermal printing head parallel to the travel path the object being printed in the same direction as well as in the opposite direction, wherein the thermal printing head has a means for moving the thermal printing head towards and away from the object to be printed, the drive means being connected to a control system, the thermal printing head being displaceable during the movement parallel to the advance of the object at the same speed as the moving object or with lower speed, and during the movement opposite to the advance of the object, the thermal imaging head is displaceable away from the object or from labels adhered thereto.

Particularly fast reciprocating movements of the print head parallel to the direction of the strip advance are reliably realized by means of such an articulated-sliding mechanism. The same is true for the piezo actuator.

PL 205 179 B1

Advantageously, the device according to the invention has sensors for detecting the feed rate of a moving object, which are signal-connected to the control system, whereby the measurement signals sent are proportional to the feed rate, and the control system controls the movement of the thermographic head depending on the detected feed rate.

Preferably, the stroke length with which the thermal imaging head moves in the feed direction and against the feed direction of the printed item is adjustable. This configuration makes it possible to adjust the forward and reverse movement of the print head parallel to the direction of tape advance depending on the length of the label and / or the spacing of the labels to be printed on the tape.

Preferably, the thermal printing head is placed on a support mounted on the sliding guide, which also carries another unit for moving the thermal printing head towards and away from the object to be printed. A cam disk or a circular disk with an eccentric axis of rotation is preferably assigned to the thermal printing head, and by means of such disk the thermal printing head is brought into contact with the printed object by overcoming the reaction of a spring element, preferably a helical spring.

Preferably, the unit for moving the thermal printing head to and from the printed object has at least one piezoelectric actuator.

Instead of a pinch roller, as is the case with traditional devices of this type having a fixed print head, the device according to the invention preferably has a plate-like abutment opposite the thermal printing head, on which the printed object slides with its reverse side during its advance.

The subject of the invention is illustrated in the drawings in which Fig. 1 shows schematically, not to scale of the drawing, the device according to the invention in the first embodiment, and Fig. implementation.

Fig. 1 shows a device for printing labels 2 adhered to a carrier tape 1, which are arranged on the carrier tape 1 at a substantially uniform distance from each other. The carrier tape 1 is unwound from the web roll 3 and fed to the printing section. The printing section consists of a printing head in the form of a thermal printing head 4 and a plate-shaped support 5 having a smooth surface, on which the carrier tape 1 slides with its rear side during the advance. The thermal imaging head 4 is in the form of a bar and extends transversely to the advancing direction of the carrier tape 1 substantially over its width or over the width of the labels. The thermal printing head 4 presses the labels with sufficient force against the fixed plate support 5 and prints them by the thermal method or the thermal transfer method. In the direction of the tape run, a sudden change of direction is provided on the trailing edge 6 after the printing section, on which the printed labels 2 are detached in a known manner from the carrier tape 1 and are taken out through an opening in the device housing and can then be placed on the marked object. The carrier tape 1, after being reversed on the trailing edge 6, is wound onto a stepper motor-driven 7 roller 8 of a winder.

The thermal imaging head 4 is held on a plate support 9, which is mounted on the sliding guide 10. The shown sliding guide 10 can also be formed, for example, of roller bearings. The support 9 is connected to a drive unit by means of which the support and hence the thermal printing head 4 can move parallel in the feed direction and against the feed direction of the carrier tape 1. This is indicated by a double arrow. In the embodiment shown, the drive unit of the bracket comprises a stationary motor 11, preferably an electric motor, whose motor shaft 12 drives the circular disk 13. The disk has an eccentrically arranged pivot pin 14 to which one end of the pin rod 15 is articulated. it is hingedly connected to a hinge pin 16 located on the support 9. The circular disk 13 with an eccentrically arranged pivot pin 14, a pin rod 15 connected thereto and a bracket 9 bearing on the sliding guide with a pivot pin 16 arranged thereon form an articulated-sliding mechanism. The distance between the axis of rotation of the motor shaft 12 and the center of the pivot pin 14 arranged on the circular disk 13 determines the stroke length of this articulated-slide mechanism.

In order to be able to move the thermal printing head 4 with different stroke lengths in the feed direction and in the opposite direction to the feed direction of the carrier web 1, if necessary, the following options are provided.

The distance between the pivot pin 14 and the axis of rotation of the motor shaft 12 is adjusted so that the pivot pin 14 can be appropriately moved and retained on the circular disk 13.

A control system 17 is assigned to the motor 11, which controls the drive unit so that the thermal printing head 4, when moving in the advance direction of the carrier tape 1, has the same speed as the carrier tape or has a lower speed than the carrier tape 1. Part of the control system for speed detection for the advance of the carrier strip 1 are sensors 18, 19 in the form of a light-emitting transmitting diode and a light-responsive receiving diode, respectively. Substantially equidistant labels 2 or other uniformly spaced marks on the carrier tape 1 interrupt the reception of light emitted from the emitting diode sensor 18 by the receiving diode sensor 19 when the ribbon is transparent. If the receiving diode is to receive the light emitted from the transmitting diode reflected on the tags 2 or on the unlabeled sections 20 of the carrier tape 1, it is placed - contrary to the illustration - together with the transmitting diode on the label side of the carrier tape 1.

As an alternative to the transmitting diode and the receiving diode, other means for detecting the speed of the carrier tape may also be provided, for example a measuring generator running on the carrier tape or the like.

A receiving diode or a measuring generator generate measurement signals that are proportional to the speed of the carrier tape 1. These signals are sent to the measurement and control system 17, which controls the rotational speed of the motor shaft 12 and thus the linear movement of the support 9 and the thermal printing head 4 in depending on the detected conveyor belt advance speed 1.

The support 9 is provided with a device that enables the thermal printing head 4 at the carrier tape 1 to be moved towards and away from the carrier tape 1. This device is also connected by a signal line 21 to the control circuit 17 and has an electric motor 26, preferably a stepper motor. and a circular disc 27 with an eccentrically situated axis of rotation. On the support 9 there is a support 28 of the electric motor 26. The support 9 is shown in longitudinal section in the drawing. The thermal printing head 4 is equipped with bars 29, 30 extending parallel to each other, which are guided in slide bearings formed on the support 9. The upper ends of the bars 29, 30 are connected to each other by a crossbar 31. A spring element 32 in the form of a helical spring which moves the thermal printing head 4 away from the ribbon. By means of an eccentrically mounted circular disc 27 which acts on the upper side of the crosspiece 31, the thermal printing head 4 can be brought into contact with the carrier strip 1 or in each case the printed label 2 against the action of the spring element 32.

The control system 17 controls the drive unit in such a way that the thermal printing head 4 rests against the printed label 2 stuck to the tape during the advance of the carrier tape 1, and moves at a distance from the carrier tape during the movement opposite to the conveying direction of the carrier tape 1. or labels attached to it 2.

The embodiment shown in Fig. 2 differs from the embodiment according to Fig. 1 only in that instead of an electric motor 26, an eccentrically mounted circular disk 27, a support 28, a parallel guide made of rods 29, 30 and a crossbar 31 and a spring element 32 are used. at least one piezoelectric actuator 33 to raise and lower the thermal printing head 4. Thermal printing head 4 in Fig. 2 it is mounted on at least one piezoelectric actuator 33, which is fastened on the underside of the plate-shaped support 9. The support 9, in turn, is mounted on the slide guide 10. However, instead of this slide guide 10 - as already mentioned - also a roller bearing can be used.

The invention in its implementation is not limited to the examples described above. Several variants are conceivable which, even with a substantially different construction, make use of the idea of ​​the invention as disclosed in the claims. In particular, the invention is not limited to printing labels adhered to the carrier tape. The invention is also applicable to the printing of single-sided linerless (so-called linerless) paper, single-fed carrier paperless labels and partially printed paper or cardboard packages.