Printing method and printing device

Abstract

A method and a device as provided for printing a large surface which is situated, in particular, on a substrate which cannot be fed to a printing device. The method is distinguished by the fact that the perpendicular spacing Azo of a reference point of the device at a plurality of points which are distributed over the printing web from the surface to be printed is determined in each case at the points which are distributed over the printing web, and the perpendicular spacing Az of the print head from the surface to be printed is set in accordance with a previously recorded measured value. Here, the plurality of points can be distributed uniformly over the length of the printing web. The device for carrying out the method has a measuring device for contactless measurement of the spacing between a reference point of the device and the surface to be printed. Furthermore, the device has a control unit for evaluating the measured values and producing control pulses for setting the spacing Az of the print head from the surface to be printed.

Claims

1. A method for printing a large surface, in particular a large surface located on a substrate which cannot be moved toward a printing device, wherein a printing head is fastened to a first axis movable along a print track, wherein the print track is at least a portion of the surface corresponding to a printing width of the printing head, wherein the first axis is fastened to a moving frame which can move in a horizontal x-direction, and wherein the surface can be printed by way of sequentially printing at least one print track, wherein a perpendicular distance Azo of a reference point of the printing device is measured by a control unit at a plurality of points distributed over the print track relative to the surface to be printed, and a perpendicular distance Az of the printing head from the surface to be printed is adjusted at each of the plurality of points distributed over the print track according to the measured perpendicular distances Azo, wherein the measured perpendicular distance Azo for each reference point measured along the print track is saved in at least one measurement series, and a trend is determined by the control unit from the measured perpendicular distances Azo of the at least one measurement series, wherein a steering motion of the moving frame which moves in the horizontal x-direction is changed when the trend exceeds a pre-defined threshold.

2. The method according to claim 1, wherein at a beginning of a print process a first print track is traversed without the printing head being activated, wherein the perpendicular distance Azo of the reference point of the printing device to the surface to be printed is determined in advance for the first print track being traversed during a measurement, a determination being made at a plurality of points distributed over the first print track.

3. The method according to claim 1, wherein a start position of the printing head is visually displayed at a beginning of the print track.

4. The method according to claim 1, wherein the printing head is pivoted depending on an alignment of the surface to be printed so that the printing head is always aligned substantially perpendicular to the surface to be printed.

5. The method according to claim 1, wherein the printing is done by applying ink onto the substrate, wherein the ink is maintained at a temperature of about 43° C.

6. The method according to claim 1, wherein the printing head is shaded from UV radiation by way of a device when the printing head is not active.

7. A device for printing a large surface, in particular a large surface located on a substrate which cannot be moved toward a printing device, wherein a printing head is fastened to a first axis movable along a print track, wherein the print track is at least a portion of the surface corresponding to a printing width of the printing head, wherein the first axis is fastened to a moving frame which can move in a horizontal x-direction, and wherein the surface can be printed by way of sequentially printing at least one print track, wherein a distance Az of the printing head from the surface to be printed is adjustable and the printing device comprises a measuring device for measuring in a non-contact manner a distance Azo between a reference point of the printing device and the surface to be printed and that the printing device further comprises a control unit for evaluating the measured distances Azo and for generating control signals for adjusting the distance Az of the printing head from the surface to be printed, wherein the moving frame can move in the horizontal x-direction, wherein the moving frame is designed to be steerable, and wherein the control unit calculates a steering angle of the moving frame.

8. The device according to claim 7, wherein the measuring device for measuring in the non-contact manner the distance Azo between the reference point of the device and the surface to be printed comprises a laser distance meter.

9. The device according to claim 7, wherein the printing head comprises an optical sensor for detecting a starting point of the printing head at a beginning of the print track.

10. The device according to claim 7, wherein the device comprises an extendable first axis for moving the printing head along the print track, wherein the first axis comprises a rack.

11. The device according to claim 7, wherein the device comprises a second axis for adjusting the distance Az of the printing head from the surface to be printed, wherein the second axis comprises a spindle.

12. The device according to claim 7, wherein the device uses a temperature controller for maintaining a temperature of an ink at a temperature of about 43° C.

13. The device according to claim 7, wherein the device uses a movable shading unit for shading the printing head from UV radiation during non-use thereof.

14. A method for printing a large surface, in particular a large surface located on a substrate, the method comprising the steps of: providing a measuring device; providing a printing device including a printing head fastened to a first axis thereof, wherein the printing head is movable along a print track, wherein the print track is at least a portion of the surface, wherein the first axis is fastened to a moving frame of the printing device; providing a control unit in communication with the measuring device and the printing device; measuring, via the measuring device, a perpendicular distance Azo of a reference point of the printing device at a plurality of points distributed over the print track relative to the surface to be printed; adjusting, via the control unit, a perpendicular distance Az of the printing head from the surface to be printed at each of the plurality of points distributed over the print track according to the measured perpendicular distances Azo; generating, via the control unit, at least one measurement series from the measured perpendicular distance Azo for each reference point along the print track; determining, via the control unit, a trend from the measured perpendicular distances Azo of the at least one measurement series; adjusting, via the control unit, a steering motion of the moving frame when the trend exceeds a pre-defined threshold, wherein the moving frame is configured to move in at least one of a horizontal x-direction; and printing, via the printing device, the surface by sequentially printing at least one print track.

Description

(1) Other advantages, unique features and useful improvements of the invention can be found in the dependent claims and the following preferred exemplary embodiments illustrated in the figures.

BRIEF DESCRIPTION OF THE DRAWINGS

(2) Shown in the figures are:

(3) FIG. 1 A device according to the invention in a three-dimensional principle sketch

(4) FIG. 2 The device according to the invention in a top view for printing a wall surface

(5) FIG. 3 The device according to the invention in a top view for printing a wall surface near a wall corner

(6) FIG. 4 shows a printing head 200 according to the invention in a principle sketch

DETAILED DESCRIPTION OF THE INVENTION

(7) FIG. 1 shows a device according to the invention 100 in a three-dimensional principle sketch Device 100 comprises a moving frame 110 movable on four wheels 111 in the horizontal x-direction on the floor 400. A distance measuring device (not shown) is provided at the corners of the moving frame 110 near each wheel. This device optically measures the distance to the floor 400 and forwards the measurement signal to a control unit 402. Each wheel 111 has an adjustable height compensator (not shown). The height compensator of each wheel 111 can be activated depending on the measurement results of each distance measuring device such that the moving frame 110 is self-leveling at all times, in particular when the floor 400 is tiled, for example, and when the floor has joints between the tiles which are lower than the tiles. The device 100 further comprises a first axis 120 in the y-direction. This first axis 120 comprises a rack fastened to the axis in the y-direction. The first axis 120 can be designed in a standard industry profile, wherein the rack is lowered into the profile and protected therein. The first axis 120 can be extended by placing one or more axis modules onto the first axis, the one or more axes likewise being designed in the standard industry profile. The attachable axis modules also comprise a rack. For example, the first axis 120 is about 2.50 m long in the un-extended embodiment, so that it can be used in residential buildings having standard ceiling heights. If higher surfaces 300 are to be printed, for example in a commercial property or an exterior façade, the first axis 120 is extended using corresponding axis modules so that print track of more than 2.50 m in length can be printed.

(8) A second axis 130 is attached to the first axis 120 using a sled 121, the second axis having a primary extension in the z-direction. The sled 121 has a drive in the form of a servomotor and a pinion which engages with the rack of the first axis 120. The upward and downward motion that the second axis 130 and a printing head 200 fastened to the second axis 130 can make can permit a print track to be traversed and printed in the y-direction by the printing head 200. After this print track is prepared, the device 100 can shift in the x-direction by one print track width by way of the device 100 using the moving frame 110 so that the next print track can be printed. A measuring device 190 in the form of a laser distance meter is fastened to the sled 121. This measuring device issues a measurement beam 192 in the direction of the surface 300 to be printed, where the beam hits a measurement point 191. The distance of the measuring device 190 from the surface 300 to be printed in this point is recorded and sent to the control unit 402 of the device 100 as reference distance A.sub.zo which is stored in the control unit 402. The second axis 130 comprises a spindle. In the sled 121, there is a further servomotor for driving the spindle. By evaluating the reference point distance A.sub.zo in the control unit 402, the current distance A.sub.z of print head 200 from the surface 300 to be printed can be determined. This distance can be rapidly and precisely adjusted to a pre-determined set point filed in the control unit 402 by way of the servomotor and the spindle. This allows the distance A.sub.z of the printing head from the surface to be printed to be very precisely and quickly adjusted.

(9) An axis head 131 is attached to the second axis 130 at the end thereof facing the surface 300 to be printed. This axis head 131 hides a servomotor which drives a third axis 140 aligned in the x-direction, i.e. the direction of motion of the moving frame 110. The printing head 200 is fastened to this third axis 140 and is movable in the x-direction. This allows the printing head 200 to be moved independently of the motion of the moving frame 110 in the x-direction.

(10) This provides an advantage when printing is to be done in the corner of a wall, wherein an un-printable area is to be minimized.

(11) The third axis 140 is pivotably mounted at the axis head 131, wherein the pivot range is at least 180°. This allows the printing head 200 to be pivoted both upward, allowing a room ceiling to be printed, for example, and downward, allowing the floor on which the moving frame 110 movably sits to be printed.

(12) For printing a room ceiling, the second axis 130 can also be rotatably attached in the sled 121 together with the axis head 131, the third axis 140 and the printing head 200, wherein the rotating motion covers at least 90° so that a corresponding rotation upward allows the ceiling to be printed.

(13) FIG. 2 shows the device 100 while printing a wall surface 300 in a top view. At least two wheels 111 can be steered so that the moving frame can also follow a curving wall. The device comprises the control unit 402, shown in FIG. 1, for calculating the steering angle of the moving frame 110. The recorded measured values A.sub.zo for each print track for each point measured along the print track are saved as a measurement series, and a trend is determined from the measured values of at least one measurement series, wherein a steering motion of the moving frame 110 which moves in the horizontal direction is changed when the trend exceeds a pre-defined threshold.

(14) FIG. 3 shows the device 100 while printing a wall surface 300 in a top view, wherein the device 100 is located in a corner, formed by two walls. The printing head 200 is moved to the end of the third axis 140 at the corner in order to print into the corners and to minimize or even eliminate areas of the wall 300 in the direction of motion of the moving frame 100 that can't be printed due to the required extension of the moving frame 100 in the direction of motion.

(15) FIG. 4 shows a printing head 200 according to the invention in a principle sketch. The printing head 200 comprises four nozzles 220 which are disposed behind a shading plate 210. The shading plate 210 comprises four slots 211, wherein the shading plate 210 is mounted in a guide 212 which can move in the y-direction so that the nozzles 220 can be shaded against UV radiation by the shading plate when the nozzles are inactive. The printing head 200 further comprises a laser pointer 230 for displaying the position of the printing head 200 at the beginning of a print track on the substrate to be printed. The printing head 200 comprises plates 240 regularly disposed one above the other inside the printing head 200. The plates 240 use a temperature controller. Certain inks are optimally processed at a temperature of about 43° C. The ink is maintained in bags and fed therefrom, wherein the bags are made of an aluminum alloy. The ink bags are kept inside the printing head 200 on individual surface heating devices disposed on the plates 240.

(16) The embodiments shown here only represent examples of the present invention and therefore may not be understood to be limiting. Alternative embodiments considered by a person skilled in the art are also within the protective scope of the present invention.

LIST OF REFERENCE SIGNS

(17) 100 Device for printing large, immovable surfaces 110 Moving frame 111 Wheel 120 First axis, y-axis 121 Sled 130 Second axis, z-axis 131 Axis head 140 Third axis, x-axis 190 Measurement device 191 Measurement point 192 Measurement beam 200 Printing head 210 Shading plate 211 Slot 212 Guide 220 Nozzle 230 Laser pointer 240 Plate 300 Surface to be printed, wall 400 Floor