Coating of Surfaces using the Drop-on-Demand Method

Abstract

The invention relates to a method for coating an application surface (11) of a component (10), in particular of a building, within an application area (12) with a coating agent, in particular with a building paint, comprising a step of edge application to the application area (12) and a step of surface application to the application area (12), which does not include the edge application, characterised in that a first application method on the basis of the drop-on-demand method is used in the edge application step, and a second application method, which has a higher surface coating output than the first application method, is used in the surface application step.

Claims

1. A coating method, comprising an edge application step, wherein a coating agent, in particular a wall paint, is applied to a wall (11) of a building within an application area (12) by using a first application method, which works according to a drop-on-demand application method, the edge application step comprising successive application of one or more coating agent strips (20), each of which include an edge portion (12a) of the application area (12), and a surface application step, wherein a portion of the application area (12) is coated, which does not include the edges (12a), by using a second application method, wherein the second application method has a higher surface coating rate than the first application method.

2. Method according to claim 1, characterized in, a) that in the step of edge application, the one or more coating agent strips (20) are applied by means of a first drop-on-demand applicator (1) having an application width of 5-200 mm, or preferably 5-100 mm, b) that the coating agent strip (20) is applied in such a way, that the lateral edge (21) of the coating agent strip (20) comes to coincide with an edge (12a) of the application area (12), c) that the coating agent strip (20) is formed of coating agent drops or jets (23) which are discharged onto the wall (11) from drop-on-demand nozzles (3) located on the underside of the first drop-on-demand applicator (1), d) that the coating agent drops or jets (23) are deposited on the wall (11) as coating agent dots (19), and e) that adjacent coating agent dots (19) bond together to form a coherent layer.

3. Method according to claim 2, characterized in, that the application of a coating agent strip (20) for edge application comprises the following steps: a) placing the first DOD applicator (1) on the wall (11) at the location of an edge (12A) of the application area (12), b) thereby aligning the first DOD applicator (1) in such way, that the row (4) of nozzles (3) are directed perpendicularly to the edge (12a) of a predetermined or overall arbitrary application area (12), c) carrying out an application movement of the first DOD applicator (1) on the coating surface (11) along the edge (12a) with an acceleration phase and a deceleration phase, d) during the application movement, maintaining the contact of the first DOD applicator (1) with the wall (11) and discharging coating agent drops or jets (23) onto the wall (11) through one or more nozzles (3), f) wherein the discharge of the coating agent drops or jets (23) takes place at equidistant distances A in the direction of movement (18), and g) wherein the distances A are constant and independent of the speed of the first DOD applicator (1) on the wall (11).

4. Method according to claim 3, characterized in, a) that the edge (12a) of the application area (12) corresponds to the intersection curve (16) of the application area (12) with a further surface (13) and, in order to carry out the edge coating, the first DOD applicator (1) is moved along the further surface (13) in contact therewith, or b) that the edge (12a) of the application area (12) corresponds to the intersection curve (16) of the wall (11) with a guide rail (17) and the first DOD applicator (1) is moved along the guide rail (17) in contact therewith in order to carry out the edge coating, or c) that the placement of the first DOD applicator (1) additionally includes the alignment of the front side (8) of the first DOD applicator (1) with a third surface (14), with the edge (21, 22) of a previously applied coating agent strip (20) or with a free edge (12a) of the coating area.

5. Method according to claim 1, characterized in that an edge application of a wall (11) in an inner corner (15) of a room in a building is carried out, wherein a) the further surface (13) corresponds to the area of a side wall, a ceiling or a floor, and b) the application area (12) on the wall surface is delimited by edges (12) corresponding to the inner edges between the wall (11) and the side wall, the wall (11) and the ceiling or the wall (11) and the floor.

6. Method according to claim 2, characterized in that after or during the application of a coating agent strip (20) a) coating agent in the region of the edge (21) of the coating agent strip (20), which is facing away from the edge (12a), is distributed manually over said edge (21) by using a brush, a cloth, a sponge or a roller, and/or b) coating agent is manually added, distributed or levelled at the edge (12a) of the application area (12) with a brush, cloth, sponge or roller, and/or c) coating agent which has been applied unintentionally beyond the edge (12a) is removed manually with a brush, a cloth, or sponge.

7. Method according to claim 1, characterized in a) that, during the application movement, the distance covered by the first DOD applicator (1) over the wall (11) is measured and/or that the speed of the first DOD applicator (1) relative to the wall (11) is continuously measured and that measurement data are formed therefrom, b) that in a control unit (32), which is located within the first Drop-on-Demand applicator (1) or in a supply unit (31), the measurement data are converted into control signals for controlling a Drop-on-Demand head (2, 2a, 2b), the conversion being based on an algorithm which provides for firing of the nozzles (3) of the drop-on-demand head (2, 2a, 2b) at equidistant intervals (A), c) that the control signals are being transmitted to the drop-on-demand head (2, 2a, 2b), and d) that one or more nozzles (3) are being triggered for the discharge of coating agent drops or jets (23).

8. Method according to claim 1, characterized in that the edge application is carried out by means of a first Drop-on-Demand applicator (1) without prior masking and/or masking of the edges (12a) of the application area (12).

9. Method according to claim 1, characterized in that the second application method comprises the use of a paint roller, a brush or a paint spraying device.

10. Method according to claim 1, characterized in that the second application method comprises the use of a second DOD applicator (50) whose operating principle is based on the drop-on-demand method, the second application method comprising a) a first step of surface application, in which the application of coating agent to the coating area (12) is carried out by means of the second DOD applicator (50) without obtaining a closed and/or uniform layer, and b) a second surface application step in which the coating agent applied in the first step is spread and/or leveled using a brush, cloth or paint roller.

11. Method according to claim 10, characterized in that in the first step of the surface application the second DOD applicator (50) is moved one or more times over a section of the wall (12) at a distance of 1 cm-500 cm, or 1 cm-150 cm in parallel (51) and/or rotating (52) and/or pivoting (53) movements, wherein on actuation of a key or a switch the DOD coating agent application takes place with constant or variable drop frequency and/or constant or variable drop size.

12. Method according to claim 1, characterized in, that the discharge of the coating agent drops and/or jets (23) are determined by a first set of influencing variables, which include, a) that the nozzles (3) of the nozzle row (4) each have a diameter of 0.1 mm-1 mm or 0.2 mm-0.5 mm and/or b) that the nozzles have a distance to their neighboring nozzles of 0.5 mm-5 mm or of 1 mm-3 mm, and/or c) that the distance of the nozzle outlets to the coating surface is 3 mm-50 mm or 5 mm-20 mm or 50 mm-300 mm and/or d) that the distances A between coating agent dots (19) applied sequentially in the direction of movement (18) are in a fixed relationship to the nozzle distance D and correspond to 0.2-5 times or 0.5-2 times or 1 time the nozzle distance D or are 0.5 mm-5 mm or 1 mm-3 mm and/or e) that the liquid overpressure in relation to the environment during a drop ejection from a nozzle (3) is 0.2 bar-20 bar or 0.5 bar to 10 bar or 1 bar to 5 bar and/or f) that as coating agent a building dispersion paint is used which is configured for application by brush, roller or spraying device, wherein the paint is diluted by addition of 2%-40% or 5%-20% or 5%-10% water and/or, by addition of 0.01%-10% or −0.1-2% or 0.1-0.5% of a thickening agent acting predominantly in the shear rate range below 1000 1/s, the rheology is modified in such a way that the possible run-off of the paint on non-horizontal coating surfaces (11) as a result of the dilution is prevented.

13. Method according to claim 12, characterized in a) that the nozzles (3) of the nozzle row (4) are cleaned with a cloth, tissue or sponge in recurring sequence, and/or b) that the nozzles (3) of the nozzle row (4) are wiped in recurring sequence with a cloth, tissue or sponge soaked with water, a solvent or a drying retarding agent such as glycol or glycerine, and/or c) that in case of an interruption of the application, a cover is applied to the nozzles (3) which closes them and thus prevents the drying of the coating material in the nozzles (3), and/or d) that, when application is interrupted, a cover is applied to the nozzles (3), which cover contains a sponge impregnated with water, with solvent or with a drying-retarding agent such as glycol or glycerine, preferably in a closed environment, and/or e) that during an interruption of the application the nozzles (3) are flushed with water or a solvent, and/or f) that during an interruption of the application the part of the applicator (1, 50) containing the nozzles (3) is removed and cleaned or disposed of externally.

14. A DOD application system for coating a wall (11) of, a building within an application area (12) with a coating agent according to claim 1, comprising a) a first DOD applicator (1) for carrying out an edge application of the application area (12), having a first drop-on-demand head (2) which is provided for the discharge of coating agent drops or jets (23), and b) a supply unit which supplies the first DOD applicator (1) with fluid and electrical power, and c) one or more supply lines (9) designed for connecting DOD applicators to supply units (31).

15. A DOD application system according to claim 14, comprising b) a second DOD applicator (50) for applying coating agent to the application area (12) for performing surface coating of the application area (12) excluding edge application, having a second drop-on-demand head (2) provided for the discharge of coating agent drops or jets (23).

16. A DOD application system according to claim 15, characterized in, a) that the first and/or second drop-on-demand head (2) comprises a liquid-carrying part (2b) with one or more mechanically or pneumatically actuated coating agent valve elements (38) and a row (4) of nozzles, and b) that the first and/or second drop-on-demand head (2) comprises a control part (2a) for controlling the liquid-carrying part (2b), and c) that the liquid-carrying part (2b) is connected to the control part with a quick-release connection and a change of the liquid-carrying part (2b) takes place in 5 seconds to 15 minutes.

17. A DOD application system according to claim 16, characterized in, a) that between the control part (2a) and the fluid-carrying part (2b) there is an elastic sealing membrane (41) connected to the control part (2a) and formed in such a way b) that it can transmit the mechanical actuating movements of the mechanical actuators to the corresponding one or more mechanically actuated coating agent valve elements (38) of the liquid-carrying part (2b) and/or c) that it can transmit the pneumatic control pressures to the valve diaphragms (44) of the one or more pneumatically operated coating agent valve elements (38) d) and that it ensures, together with the housing (37), protection against dust and moisture in accordance with one of the protection classes IP65 to IP 69.

18. DOD application system according to claim 14, characterized in, a) that the nozzles (3) of the first DOD applicator (1) are arranged equidistantly within the row of nozzles (4) and the distance D between the nozzles (3) is 0.5-5 mm and the diameter of the nozzles is from 0.05 mm to 1 mm, b) that the nozzles (3) of the first DOD applicator (1) are parallel and directed towards the wall (11), c) that the row of nozzles (4) of the first DOD applicator (1) extends to the width of the first DOD applicator (1), the distance of the edge nozzles of the row of nozzles (4) from the respective side surface (7) of the first DOD applicator (1) being 0.5 times to 2 times the nozzle distance D, and d) that the nozzle row (4) is located inside the first DOD applicator (1) at the front side (8) of the first DOD applicator (1), wherein the distance of the nozzle row (4) from the front side (8) of the first DOD applicator (1) equals 0.5 to 2 times the nozzle distance D.

19. A DOD application system according to claim 15, characterized in, a) that the first (1) and second DOD applicator (50) are identical, and/or b) that the first (1) and the second DOD applicator (50) are identical and the second DOD applicator (50) is operated in such a way that the step of surface coating takes place at a higher coating rate than the step of edge coating, in particular with a coating rate of 1-2, 1-5 or 1-10 times, and/or c) in that the second DOD applicator (50) is operated with a liquid-carrying part (2b) which enables a higher coating performance than the liquid-carrying part (2b) of the first DOD applicator (1), by a larger number of nozzle rows (4) and/or of nozzles (3) per nozzle row (4) and/or by using longer actuation times and/or by applying a higher fluid pressure, and/or by using wider nozzle rows (4) and/or by using coating agent valve elements (38) with a higher fluid throughput in total.

Description

LIST OF FIGURES

[0059] FIG. 1 shows aspects of the application method according to the invention in connection with DOD applicators according to the invention.

[0060] FIG. 2 shows the application of a first DOD applicator 1 to a corner of a room 15 for the application of a coating agent strip 20, as the first strip of a corner coating.

[0061] FIG. 3 shows the application of a first DOD applicator 1 for coating a corner 15 of a room to a previously applied coating agent strip 20a for continuing the corner coating on an edge (14a) of a third surface 14.

[0062] FIG. 4 shows the application of a coating agent strip 20 along a stop rail 17.

[0063] FIG. 5 shows a side view of essential components of a first DOD applicator 1.

[0064] FIG. 6 shows a first DOD applicator 1 at the edge 12a of an application area 12 with various auxiliary means (34, 35) and reference surfaces (7, 8) that predict the frontal and lateral edges of a coating agent strip 20 and facilitate the movement of the applicator along lines or surfaces.

[0065] FIG. 7 shows a first DOD applicator 1 with rollers (5, 6) in the case of coating corners with an uncomfortable sharp angle in two different ways.

[0066] FIG. 8 shows a surface application using a) a second DOD applicator in a first step and b) a paint roller for levelling the applied coating agent in a second step.

[0067] FIG. 9 shows a side view of essential components of a second DOD applicator 50. The reference labels correspond to those of the first DOD applicator 1, but it is pointed out that many of the components can be designed or constructed differently.

[0068] In the following, the composition of the components of the first DOD applicator 1 and the second DOD applicator 2 is illustrated with reference to the figures. Thereby a) a first DOD applicator 1 with a first drop-on-demand head 2, which is provided for the discharge of coating agent drops or jets 23, and b) a supply unit, which supplies the first DOD applicator 1 fluidically and electrically, and c) one or more supply lines 9, designed for the connection of DOD applicators with supply units 31 represent essential basic components of a DOD application system for coating an application surface 11 of a component 10, in particular a building within an application area 12, with a coating agent.

[0069] The application system may have one or more of these basic components respectively.

[0070] For example, different first DOD applicators 1 can be part of a modular system, which are used within the application system, with different configurations and designs, for example with regard to the following features: (a) application width AB, (b) viscosity range of compatible coating agents, (c) droplet size range, (d) nozzle diameters and distances D, (e) materials and designs of the liquid-carrying parts, (f) heatability, (g) exit angle of the coating agent drops or jets 23, (h) design as front shooter (not shown, droplet exit at front side 8) or bottom shooter (as shown in FIG. 5), i) type of path or speed measurement.

[0071] For example, different versions of supply units 31 can be part of the application system alternatively or in a complementary manner, sorted here according to different criteria. According to the type of supply unit: a) supply unit 31 as a stand-alone device, b) as a device that can be worn on the body, for example on the hip or as a backpack. The supply unit can also be divided into two parts: a stand-alone unit with a larger ink tank+intermediate storage and control unit on the body, ink filtering close to the applicator.

According to the type of coating agent supply to the supply unit: a) pressurised coating agent tank; b) coating agent pump with suction line to external coating agent bucket, c) recirculation supply.
According to the area of application: a) Variants for large construction sites and coating areas, b) Variants for use in confined spaces.
By industry: a) variants for the construction industry, b) for shipbuilding, aircraft construction, automotive construction, c) for refinishing, etc.

[0072] Furthermore, various supply lines 9 can be part of the DOD application system, which have couplings 56 to the individual DOD applicators 1 or 50 and supply units 31.

[0073] Another DOD application system, especially designed for surface application according to the method of the invention, comprises a) a second DOD applicator 50 with a second drop-on-demand head 2, which is intended for the discharge of coating agent drops or jets 23, and b) a supply unit, which supplies the second DOD applicator 1 fluidically and electrically, and c) one or more supply lines 9, designed for the connection of DOD applicators with supply units 31.

[0074] It is advantageous if a drop-on-demand application system enables both a drop-on-demand edge application and a drop-on-demand surface application. Thus, a DOD application system according to the invention comprises

a) at least one first DOD applicator 1 for carrying out an edge application of the application area 12, with a first drop-on-demand head 2, which is provided for the discharge of coating agent drops or jets 23,
b) a supply unit which supplies the first DOD applicator 1 fluidically and electrically,
c) one or more supply lines 9, designed for the connection of DOD applicators with supply units 31 and additionally
d) at least one second DOD applicator 50 for carrying out a edge application of the application area 12, with a second drop-on-demand head 50, which is provided for the discharge of coating agent drops or jets 23.

[0075] The design of the first and second drop-on-demand head 2 can in principle be of any type for carrying out the method according to the invention, as long as coating agent drops or jets can be discharged in a suitable way. Preferably, a suitable drop-on-demand head 2 consists of two parts, a) a liquid-carrying part 2b comprising one or more mechanically or pneumatically actuated coating agent valve elements 38 and a row 4 of nozzles, and b) a control part (2a) for controlling the liquid-carrying part 2b. The connection of the liquid-carrying part 2b to the control part (2a) is advantageously made by means of a quick-release connection, so that a quick change of the liquid-carrying part 2b is possible within 5 seconds to 15 minutes.

[0076] The aforementioned fluid-carrying part 2b contains, for example, one or more coating agent valve elements 38 which are operated by mechanical actuating forces or which are operated by pneumatic control pressures acting on valve diaphragms 44. The coating agent valve elements 38 are connected on the outlet side to one or more nozzles 3 and on the inlet side to a coating agent supply line 40 through which coating agent is supplied under pressure. The individual coating agent valve elements 38 contain, for example, a fixed valve seat and a movable closing element corresponding to the sealing element.

[0077] The aforementioned coating agent valve elements 38 contain, for example, one or more fluid connections 39 on the outlet side consisting of fluid channels and/or cavities which are connected to the one or more nozzles 3. Furthermore, it is advantageous if the one or more coating agent valve elements 38 are set back from the row 4 of nozzles 3 by a distance d.sub.4 of 0 mm-20 mm. In this way, the row 4 of nozzles 3 can be placed close to the leading edge. The length of the fluid connections is typically from 0.1 mm-10 mm, and the cross-sectional dimensions are 0.2 mm-2 mm.

[0078] The control parts contain, for example, one or more electro-mechanical actuators (piezo, coil) which, via actuating elements performing actuating movements, respectively actuate one or more coating agent valve elements 38 of the liquid-carrying part 2b, or one or more pneumatic valves 42, preferably micro-pneumatic valves, which are connected to a compressed air supply 43 and generate the control pressures for respectively actuating one or more pneumatically operated coating agent valve elements 38 of the liquid-carrying part 2b.

[0079] It is advantageous if between the control part (2a) and the fluid-carrying part 2b there is an elastic sealing membrane 41 which is connected to the control part (2a) and which is designed in such a way that it can transmit the mechanical actuating movements of the mechanical actuators to the corresponding one or more mechanically actuated coating agent valve elements 38 of the fluid-carrying part 2b, that it can transmit the mechanical actuating movements of the mechanical actuators to the corresponding one or more mechanically actuated coating agent valve elements 38 of the liquid-carrying part 2b and/or which is designed in such a way that it can transmit the pneumatic control pressures to the valve diaphragms 44 of the one or more pneumatically actuated coating agent valve elements 38.

[0080] With regard to the first DOD applicator 1, it is advantageous if the width of the first drop-on-demand head (2, 2a, 2b) is greater than the application width (AB) by at most 2 nozzle spacings (D), and/or if the width of the first DOD applicator 1 is greater than the application width (AB) by at most 2 nozzle spacings (D). For the area of edge application in the interior of buildings, it is advantageous if the first DOD applicator 1 has an application width (AB) of 5 mm-50 mm or 5 mm-150 mm.

[0081] Furthermore, it is advantageous, particularly for the first DOD applicator 1,

a) if the nozzles 3 are arranged equidistantly within the nozzle row 4, and/or
b) if the distance D between the nozzles 3 is 0.5-5 mm, and/or
c) if the nozzles 3 are parallel and directed towards the application surface 11, and/or
d) when the nozzle row 4 extends to the width of the first DOD applicator 1, the distance of the edge nozzles of the nozzle row 4 from the respective side surface 7 of the first DOD applicator 1 being 0.5 times to 2 times the nozzle distance D,
f) if the diameter of the nozzles is from 0.05 mm to 1 mm and/or
g) when the nozzle row 4 is located inside the first DOD applicator 1 at the front side 8 of the first DOD applicator 1, wherein the distance of the nozzle row 4 to the front side 8 of the first DOD applicator 1 is from 0.5 times to 2 times the nozzle distance D.

[0082] To enable clean drop tear-off at the nozzles 3, it is advantageous if the coating agent valve elements 38 of the first drop-on-demand head and second drop-on-demand head are configured to be able to perform switching times of 0.1 ms-5 ms or 0.1 ms-2 ms or 0.1 ms to 0.5 ms.

[0083] With regard to the materials of the liquid-carrying part 2b of the DOD head of the first DOD applicator 1 or second DOD applicator 50, it should be noted that these must be inert to the coating agent. In the case of water-based wall paints or basecoats, the following materials are suitable, for example: POM, PA, PC, PS, PP, PE, PMMA, PEEK, PVDF, PEEK, PET, PMMA, TPFE, PFA, stainless steel, nickel, aluminium.

[0084] Furthermore, it is advantageous for the liquid-carrying part 2b of the DOD head 2, but also of the housing 17 of the first DOD applicator 1 or second DOD applicator 50, if these exhibit a contact angle of >450 or >1200 in combination with the coating agent (wall paint, building paints, water-based paints and other paints in the automotive sector). This can be favoured on the one hand by a suitable choice of material or also by suitable surface treatments such as the hydrophobisation of the surfaces, for example by sol-gel methods.

[0085] In practice, DOD applicators must be highly robust—also with regard to dirt and moisture. In particular, it should be possible to clean the entire DOD applicator under running water or in an ultrasonic basin. This requires that the at least one first DOD applicator 1 and/or the at least one second DOD applicator 50 is designed to be dust and water protected according to one of the protection classes IP65 to IP69. In particular, attention should also be paid to complete tightness and sealing of the sealing membrane 41 towards the control part.

[0086] Finally, it should be noted that if the first DOD applicator 1 is designed accordingly, it can also be used instead of the second DOD applicator for the purpose of surface application according to the method described above,

a) in that the first DOD applicator 1 and the second DOD applicator 50 are identical or of the same design or the first applicator is operated in the same way as a second applicator 50 in the surface application step, and/or
b) in that the first DOD applicator 1 is operated like a second DOD applicator 50, so that the coating agent application in the surface application step takes place at a higher coating rate than in the edge coating step, in particular at a 1-2, 1-5 or 1-10 times the coating rate, and/or
c) in that the first DOD applicator 1 is operated like a second DOD applicator 50, wherein the first DOD applicator 1 is operated for this purpose with a liquid-carrying part 2b which differs from that used for edge application and which has a higher coating agent output than the liquid-carrying part 2b of the first DOD applicator 1. This can be achieved by
i) a larger number of nozzle rows 4, and/or
ii) a larger number of nozzles 3 per nozzle row 4, and/or
iii) longer actuation times of the coating agent valve elements 38, and/or
iv) applying a higher fluid pressure, and/or
v) using wider nozzle rows 4, and/or
vi) using coating agent valve elements 38 with a higher total fluid throughput.

[0087] The invention is not limited to the embodiments described above. The invention also claims protection for the subject-matter and features of sub-claims independently of the respective references back to the aforementioned claims or even the main or side claim.

LIST OF REFERENCE LABELS

[0088] 1 First DOD applicator [0089] 2 Drop-on-demand head [0090] 2a Control part of the drop-on-demand head [0091] 2b Replaceable liquid-carrying part of the drop-on-demand head [0092] 3 Nozzle [0093] 4 Nozzle row [0094] 5,6 Reference surfaces on the underside, here as wheels [0095] 7 Side of the applicator, lateral sliding and reference surface [0096] 8 Front side, front reference surface [0097] 9 Supply line to a supply unit with electrical control signals and/or sensor signals, coating [0098] agent supply, rinsing agent supply [0099] 10 Component to be coated [0100] 11 Application area, wall area [0101] 12 Application area (can also be selected spontaneously) [0102] 12a Paint edge of the application area [0103] 13 additional surface, side wall surface [0104] 14 third surface, front wall surface [0105] 14a Inner edge (intersection curve) of application area 11 and front wall area 14 [0106] 15 Room corner [0107] 15a Inner edge (intersection curve) of lateral wall surface 13 and third, or front wall surface [0108] 14 [0109] 16 actual or extrapolated intersection curve of application surface 11 and further 13, or lateral wall surface [0110] 17 (temporary) guide rail, auxiliary tool [0111] 18 Direction of movement [0112] 19 Coating centre point, has a diameter, the position of the coating point always refers to the centre of the point [0113] 20 Coating agent strip [0114] 21 Lateral edge of the coating agent strip [0115] 22 Front edge of the coating agent strip [0116] 23 Coating agent drop or jets [0117] 30 Sensors for measuring the movement of the applicator in relation to the application surface. [0118] 31 Supply unit with coating agent container, pumps or compressor, control system [0119] 32 Electronic control [0120] 33 Attachment or handle/knob [0121] 34 Mechanical (e.g. pointers, gauges) or optical (e.g. a light beam) aids for edge detection, front side [0122] 35 Mechanical (e.g. pointers, gauges) or optical (e.g. a light beam) aids for edge detection, lateral [0123] 36 Control unit [0124] 37 Applicator housing [0125] 38 Coating agent valve elements [0126] 39 Fluid line or cavity to nozzles [0127] 40 Coating agent supply line [0128] 41 Sealing diaphragm [0129] 42 Pneumatic valve [0130] 43 Compressed air supply [0131] 44 Valve diaphragm [0132] 50 Second DOD applicator [0133] 51 Parallel movements of the second DOD applicator [0134] 52 Rotating movements of the second DOD applicator [0135] 53 Swivelling movements of the second DOD applicator [0136] 55 Button, switch [0137] 56 coupling [0138] 57 Electrical connections [0139] 60 Paint roller or brush [0140] D Nozzle spacing [0141] d.sub.1 lateral distance between first/last nozzle of a row and an edge 12a of the application area 12 [0142] d.sub.3 frontal distance of a nozzle 3 from the nozzle row 4 to a frontal edge of a coating sheet or an existing coating strip [0143] d.sub.4 back offset of the coating agent valve elements 38 behind the vertical plane of the nozzle outlets [0144] d.sub.10 Application distance second DOD applicator [0145] A Distance between adjacent nozzles 3 [0146] AB Application width of a DOD head/DOD applicator [0147] E Plane perpendicular to the row of nozzles 4 and to the application surface 11