FR2999981A1 - Device for cleaning of e.g. single pass inkjet printhead of printer, has support surface locally convex toward plate, on level of contact zone of longitudinal portion, so that portion includes two sides located outside of contact zone - Google Patents

Abstract

The device (7) has an assembly (33) for moving a plug (25) and each of inkjet printheads (13, 13') one with respect to another. Another assembly (31) tightens a longitudinal portion (29) of a band (23) on a support surface of the plug during cleaning, and moves the band in the direction along length diretion. The support surface is locally convex toward a plate (19), on a level of a contact zone of the longitudinal portion, so that the portion includes two longitudinal sides located outside of the contact zone. An independent claim is also included for a method for realizing a cleaning of an inkjet printhead.

Description

Absorbent band device for cleaning at least one corresponding inkjet print head, printer and method. The present invention relates to a device for cleaning at least one inkjet printing head, the or each print head comprising a plate having orifices adapted to eject an ink to form said jets, the orifices substantially aligning in an alignment direction, the apparatus comprising: - a strip adapted to absorb the ink, - a pad having a support surface of a longitudinal portion of the strip for wiping the or each plate, - a first set for moving the pad and the or each print head relative to each other, to contact the or each plate respectively with a contact area of the longitudinal portion of the strip, and sliding the or each contact zone on the or each plate substantially in the alignment direction during cleaning, and - a second assembly for tensioning the longitudinal portion of the strip on the support surface during cleaning, and to move the web in the direction of its length to bring a new longitudinal portion of the web after the cleaning onto the support surface.

The invention further relates to a printer incorporating such a device, and a method implemented by such a device. In an inkjet printer, the orifices are connected to an ink supply for ejecting drops on demand and forming a printed pattern on an object. The ejection of the drops is for example caused by a piezoelectric system.

In normal operation, the print heads eject rows of perfectly parallel drops. To maintain this function, it is necessary to keep the lower plate of the heads perfectly clean. However, especially in an industrial environment, dust or other debris sometimes mix with a drop of ink ready to exit and stick against the plate This partially blocks an ejection orifice. In this case, the ejection of the drop is deviated or even not done. The drops concerned do not arrive at the intended place on the object to be printed and the quality of the printed image is degraded. There are cleaning devices to limit the presence on the plate of debris or clumps of ink likely to disturb the ejection of the drops.

Documents US Pat. No. 6,733,106 and US Pat. No. 7,004,560 describe a purging of the orifices carried out by a capsule which sticks against the orifices and into which the ink is sucked. It is also known to wipe the plate with a flexible squeegee, as described in US 5,583,548, or with a brush, as described in US 6,869,161. the need arose to clean the doctor blade or the brush, as described in US 8 186 804. US 6 692 100 discloses the use of a strip of absorbent material for wiping the printing heads. , with renewal of the band. In order to clean all heads at once, the band used must have a fairly large width.

It has been noted that this type of cleaning device does not, however, address the entire problem of the implementation of the printheads, especially that of single-pass heads (known as single pass in English). . In this technology, the printheads are fixed and the object on which the pattern is to be printed is moved beneath the printheads, unlike technologies in which the printheads are mounted on a trolley that sweeps across the printheads. object to print. Thus, the slightest deviation of an ink jet causes a printing defect. The tape cleaning device has sufficient efficiency to avoid these printing defects. An object of the invention is to provide an improved efficiency band cleaning device, specially adapted for cleaning at least one, preferably more than one, printing head (s), in particular the printing heads. in a single pass. To this end, the subject of the invention is a device for cleaning at least one inkjet printing head, of the type described above, in which the support surface is locally, at the or each zone contact, curved towards the or each plate, so that the longitudinal portion of the strip comprises two longitudinal edges located outside the or each contact zone. In what follows, the terms "cleaning device" and "device for cleaning" are considered equivalent. According to particular embodiments, the device comprises one or more of the following characteristics, taken in isolation or in any technically possible combination: the tape that is suitable for absorbing the ink has a transverse elasticity greater than or greater than its length; equal to 5 times the longitudinal elasticity of said band; the first assembly brings the pad into contact with the or each print head so that the sliding of the or each contact zone on the or each plate is substantially perpendicular to the direction of the length of the strip; the buffer support surface has, at the or each contact zone, in a plane parallel to the alignment direction and perpendicular to the or each plate, a substantially circular arc section having a radius of between 10 mm and 50 mm, preferably about 20 mm; the buffer comprises an outer layer of elastomeric material, preferably of flexible silicone, the outer layer comprising the support surface; the outer layer of the buffer has a hardness of between 5 and 50 Shore A; the device is intended for cleaning at least two printing heads arranged radially from an axis substantially parallel to the alignment direction, the two or each plates being substantially parallel to the axis, the buffer having a general shape circular projection on a plane perpendicular to the axis, and being centered on an axis substantially parallel to the axis; - The first set is adapted to move the buffer of a cleaning position in which the axis of the buffer is substantially coincident with the axis, at a rest position, in which the axis of the buffer is spaced from the axis ; the device is intended for cleaning at least one printing head, the or each plate extending substantially in a plane, the buffer extending along an axis parallel to the plane, and the support surface having a substantially cylindrical shape according to a generator parallel to the axis; - The first set is able to move the or each print head, to approach or approach the buffer before cleaning, and away or away from the buffer after cleaning; the strip comprises an absorbent material; the second set is capable of moving the pad relative to the or each print head with a relative sliding speed of between 1 and 20 meters per minute; the strip has a first elasticity in the direction of the length of the band and a second elasticity in a transverse direction of the band, preferably perpendicular to the direction of the length of the band, the second elasticity being greater than the first elasticity by a factor of 10. The the invention also relates to a printer comprising at least one ink-jet printing head, the or each printing head comprising a plate having orifices adapted to eject an ink to form said jets, the orifices substantially aligning with one another; alignment direction, characterized in that the printer comprises a cleaning device as described above. The invention finally relates to a method for performing a cleaning of at least one ink jet printing head, the or each print head comprising a plate having orifices adapted to eject an ink to form said jets, orifices substantially aligning in a direction of alignment, characterized in that it comprises the following steps: - one tends on a support surface of a buffer a longitudinal band portion adapted to absorb the ink, - one moves the buffer and the or each print head relative to each other to contact the or each plate respectively with a contact zone of the longitudinal portion of the strip, and to achieve a sliding of the or each zone contacting the or each plate substantially in the alignment direction, and - moving the strip in the direction of the length of the strip to bring a new longitudinal portion of the strip to the support surface, erected in that the support surface is locally, at the or each contact zone, curved towards the or each plate, so that the longitudinal portion of the strip comprises two longitudinal edges located outside the or each contact area.

The invention will be better understood on reading the description which follows, given solely by way of example, and with reference to the appended drawings, in which: FIG. 1 is a front view of a printer according to a first embodiment of the invention, with radial printing heads, the printing heads being in a closed position and the cleaning device being at rest, - Figure 2 is a right view of the printer shown. 1, the elements 13 'and 15' of FIG. 1 not being shown in FIG. 2; FIG. 3 is a view from above of the printer shown in FIGS. 1 and 2; FIG. 4 is a front view of the printer stamp shown in FIGS. 1 to 3, the pad being in contact with the printheads; FIG. 5 is a vertical section along a median plane of the printer buffer shown; In FIGS. 1 to 4, FIG. 6 is a right view of the print. 1 to 3, the printheads being in a closed position and the cleaning device being active, the elements 13 'and 15' of FIG. 1 not being shown in FIG. 7 is a perspective view of a printer according to a second embodiment of the invention, with parallel print heads, FIG. 8 is a sectional view of the buffer of the printer shown in FIG. With reference to FIGS. 1 to 3, a printer 1 according to the invention is described. The printer 1 comprises an inkjet printing device 3 for printing a pattern (not shown) on an object 5 (FIG. 1), and a cleaning device 7. The object 5 has, for example, a shape general circular cylindrical axis D parallel to a horizontal axis Ox pointing forward. The object 5 advantageously has a radius R1 between a printable minimum diameter of 30 mm and a maximum printable diameter of 60 mm. For example, R1 is about 57 mm.

In addition, an axis Oz pointing upwards and an axis Oy horizontal and perpendicular to the axis Ox is defined, the reference Ox, Oy, Oz being direct. The printing device 3 is advantageously in a single pass. The printing device 3 comprises a frame 11, four printing heads 13, 13 'arranged radially from the object 5, four supports 15, 15' of the printing heads 13, 13 ', and an actuator 17. fixed on the frame 11 to actuate the supports 15, 15 '. The print heads 13, 13 'are for example similar to each other. The printing heads 13, 13 'are fixed on the supports 15, 15' in a radial orientation from the axis D. The printing heads 13, 13 'each comprise a plate 19 intended to be turned towards the object 5.

The print heads 13, 13 'are for example spaced one of the following at an angle of about 60 °. The supports 15, 15 'are slidably mounted on the frame 11 to support the printing heads 13, 13'. The supports 15, 15 'are movable between a closed position, in which the printing heads 13, 13' are radially close to the object 5, and an open position, in which the printing heads 13, 13 'are radially spaced apart from the object 5. The frame 11 extends for example substantially perpendicular to the Ox axis. The frame 11 defines a notch 16 located near the object 5 and opening downwards.

Each plate 19 extends substantially along the Ox axis. Each plate 19 comprises at least one row of nozzles or orifices 21 capable of ejecting ink toward the object 5. In the closed position, the plates 19 are advantageously tangent to a cylinder of axis D and of radius R2 (Figure 4) between 5 mm and infinity. The plates 19 are either substantially vertical or directed downwards. The radius R2 is for example between the minimum printable diameter and the maximum printable diameter above. The orifices 21 extend in an alignment direction D2 substantially parallel to the axis D. The actuator 17 is adapted, for example by a rack and pinion system (not shown), to move the supports 15, 15 'radially. The cleaning device 7 is, in the example shown, generally above the printing device 3 and behind it.

The cleaning device 7 comprises a strip 23 capable of absorbing the ink, a buffer 25 comprising a support surface 27 (FIGS. 4 and 5) of a longitudinal portion 29 of the strip 23 intended to wipe the plates 19. cleaning system 7 further comprises a first assembly 33 for moving the buffer 25 relative to the printing heads 13, 13 ', and a second assembly 31 for tensioning the longitudinal portion 29 on the support surface 27 and for moving the strip 23 in the sense of its length, and. The first assembly 33 comprises a frame 35 extending vertically, a carriage 37 (FIGS. 2 and 3) mounted to move in vertical translation on the frame 35, two guide bars 39 fixed on the carriage 37, the two guide bars 39 making protruding in the alignment direction D2 to the printing device 3. The first assembly 33 comprises a support plate 41 slidably mounted on the two bars 39 and advantageously perpendicular to them, and a pole 43 extending towards the device of printing 3 from the support plate 41 to carry the buffer 25.

The first assembly further comprises a jack 45 fixed to the frame 35 for moving the carriage 37 vertically relative to the frame 35, and an actuator 47 (FIG. 2) for moving the support plate 41 relative to the carriage 37 in the direction of D2 alignment. The carriage 37 is movable between a high position visible in FIG. 1, in which the buffer 25 is situated vertically above the axis D, and a low position visible in FIGS. 2 and 6, in which the buffer 25 is situated. vertically at the level of the axis D. The support plate 41 is movable between a retracted position visible in Figure 2, wherein the buffer 25 is in the alignment direction D2 of the side of the frame 11 relative to the plates 19, and an outward position visible in Figure 6, wherein the pad 25 is in the alignment direction D2 of the side opposite the frame 11 relative to the plates 19. The pole 43 extends for example vertically downward. The pole 43 comprises, for example, a substantially vertical proximal portion 49 and a distal portion 51 forming a right angle with the proximal portion 51. As can be seen in FIGS. 4 and 5, the pad 25 has the general shape of a substantially D3 axis wheel. parallel to the alignment direction D2. The pad 25 has for example a radius R3 of between 30 mm and 60 mm. The pad 25 comprises a hub 53 mounted, for example by ball bearing, on the distal portion 51 of the pole 43, and an outer layer 55 disposed around the hub 53. The pad 25 and the cleaning device 7 are in a position rest (Figure 1) when the carriage 27 is in the up position and the support plate 41 is in the retracted position. The pad 25 and the cleaning device 7 are in a cleaning start position (Figure 2) when the carriage 27 is in the down position and the support plate 41 is in the retracted position. The pad 25 and the cleaning device 7 are in an end cleaning position (FIG. 6) when the carriage 27 is in the low position and the support plate 41 is in the extended position. Finally, the buffer 25 and the cleaning device 7 are in an intermediate position when the carriage 27 is in the high position and the support plate 41 is in the extended position. The outer layer 55 is elastomeric material, for example flexible silicone. Advantageously, the outer layer 55 has a hardness of between 5 and 50 Shore A. The outer layer 55 defines the support surface 27.

The support surface 27 (FIG. 5) has, in a plane of section passing through the axis D3, a section 57 bulging outwardly of the buffer 25, for example substantially in an arc having a radius of curvature R4 of between 10 mm. and 50 mm, preferably about 20 mm. The second assembly 31 (FIGS. 1 and 3) comprises a coil 59 for unwinding the strip 23, a final winding coil 61, return rollers 63, a drive roller 65, a motor 67, all mounted on the plate support 41, and a pressure roller 69. The pressure roller 69 is mounted on a fork 71 biased by a spring 73. The movement of the drive roller 65 is returned to the spool 61 by a belt pulley assembly 75. The second assembly 31 further comprises guides 77, 79 of the strip 23 fixed on the pole 43. The strip 23 is for example made of an absorbent material, lint-free and not rough. The material is for example a fabric.

Alternatively, the material is nonwoven. The band 23 advantageously has a flat width, in the unstretched state, of between 10 mm and 50 mm. The band 23 advantageously has a first elasticity in a longitudinal direction and a second elasticity in a transverse direction, the second elasticity being greater than the first elasticity by a factor greater than or equal to 5, for example about 10. The band 23 s extends in its longitudinal direction between the coil 59 and the spool 61, passing on the drive roller 65 and the support surface 27 of the buffer 25. Advantageously, the strip 23 wraps around the buffer 25 on at least 50% of the circumference of the pad 25, preferably at least 80% of the circumference of the pad 25. In the cleaning position (FIG. 4), the longitudinal portion 29 of the strip 23 has four contact zones 81 with the plates 19 The contact areas 81 cover all the rows of nozzles or orifices 21.

The longitudinal portion 29 comprises two longitudinal edges 83 (FIG. 5) located outside the contact zones 81. In other words, the contact zones 81 do not go as far as the longitudinal edges 83. The operation of the device 1 will now be described.

During printing on the object 5 (Figure 1), the printheads 13, 13 'are in the closed position. The plates 19 are vis-à-vis the object 5 and project ink jets (not shown) from the orifices 21. The cleaning device 7 is then in the rest position shown in FIG. at the second assembly 31, the band 23 is stretched between the unwinding reel 59 and the winding reel 61. In particular, the longitudinal portion 29 of the strip 23 is wound and stretched on the support surface 27 of the buffer 25. The strip 23 is then stationary relative to the second assembly 31. When the printing is complete, the actuator 17 acting on the supports 15, 15 'moves the print heads 13, 13' from the closed position to the open position. The object 5 is then removed by means not shown. The first assembly 33 then moves the buffer 25 from the rest position to the cleaning start position (FIG. 2), and brings the longitudinal portion 29 of the strip 23 into contact with the plates 19, as soon as the heads of 13, 13 'are moved in the closed position corresponding to the diameter of the buffer 25. For the aforementioned displacement of the buffer 25, the cylinder 45 moves the carriage 37 from the high position to the low position. The strip 23 is then in contact with the plates 19 by the four contact zones 81. Advantageously, the contact areas 81 have an extension less than or equal to 3 mm parallel to the plate 19 with which they are respectively in contact. Then, the assembly 33 moves the pad 25 from the cleaning start position to the end cleaning position (Figure 6). To do this, the actuator 47 moves the support plate 41 from the retracted position to the extended position. The contact areas 81 then slide along the plates 19 in the alignment direction D2. The slippage is substantially distinct from a slippage in the direction of the length of the strip 23. In other words, the sliding direction of each contact zone 81 is angularly offset with respect to the direction of the length of the strip 23. sliding is actually in the alignment direction D2, that is to say substantially perpendicular to the direction of the length of the strip 23.

The second assembly 31 immobilizes the longitudinal portion 29 relative to the support surface 27 during sliding. The sliding is at a speed between 1 and 20 meters / minute. The buffer 25 has a double curvature, represented by the rays R3 and R4 (Figure 5). The radius curvature R3 allows the pad 25 to be in contact with all the radially arranged print heads 13, 13 '. The second curvature of radius R4 limits the extension of the contact areas 81, so that the edges 83 of the longitudinal portion 29 remain outside the contact areas 81. Then, the print heads 13, 13 'pass again from the closed position to the open position by the actuator 17. The buffer 25 passes from the end cleaning position to the intermediate position through the cylinder 45 passing the carriage 37 from the low position to the high position.

Finally, the buffer 25 moves from the intermediate position to the rest position thanks to the actuator 47 passing the support plate 41 from the extended position to the retracted position. After the cleaning, for example when the pad 25 is again in the rest position, the second set 31 circulates the strip 23 in the direction of the length of the strip 23, so as to bring on the support surface 27 a new longitudinal portion 85 of the strip 23. To do this, the motor 67 acts on the drive roller 65 for a predetermined time to move the strip 23 to a length greater than or equal to a length to present in front of each plate 19 a strip portion 23 unsoiled ink by the previous cleaning. Thanks to the characteristics described above, the device 7 implements contact areas 81 away from the longitudinal edges 83 of the strip 23 and slides in a direction transverse to the strip 23. This allows cleaning , if necessary, several printing heads 13, 13 ', whatever the width of the band 23. This also limits the risk that, by capillarity, a part of the ink being inside a openings 21 is sucked during the separation of the strip 23 of the plate 19 after cleaning and that the meniscus of the ink, instead of being at the entrance to the orifice 21, goes back inside the print heads 13, 13 '. As a result, the cleaning is faster if there are several printheads 13, 13 'and leaves the plates 19 in a state for better print quality. Referring to Figures 7 and 8, will now be described a device 100 constituting a second embodiment of the invention. Unless otherwise indicated, the device 100 is similar to the device 1 shown in Figures 1 to 6. The like elements retain the same references in Figures 7 and 8 and will not be described again. The device 100 comprises a printing device 103 and a cleaning device 107 located for example below the printing device 103. The printing device 103 comprises four printing heads 113 mounted parallel to each other. The print heads 113 are also similar to the print heads 13, 13 ', except that the plates 19 are for example turned downwards. The print heads 113 are mounted on a not shown mobile support. The cleaning device 107 is fixed in the local coordinate system (Ox, Oy, Oz). The cleaning device 107 comprises a pad 125 of oblong appearance, extending parallel to the plates 19 and perpendicular to the alignment direction D2 of the orifices 21. The cleaning device 107 further comprises a first assembly 133 comprising the movable support not shown, and a second assembly 131 for tensioning the band 23. The pad 125 is fixed on the support plate 41.

The buffer 125 (FIG. 8) comprises an upper flexible silicone layer 155 defining a support surface 127 for the strip 23. The support surface 127 is, for example, substantially cylindrical with a generatrix parallel to the axis Oy and of circular cross-section. radius R4. The operation and advantages of the device 100 are similar to those of the device 1. The operation of the device 100 differs in that the second set 133 moves the print heads 113 to bring them into contact with the longitudinal portion 129 of the strip 23. , the buffer 125 being fixed. Then, the first set 133 prints a translational movement to the printing heads 113 in the alignment direction D2, which wipes the plates 19 on the longitudinal portion 129 of the strip 23. Next, the first set 133 moves the heads away. 113 of the longitudinal portion 129.

Claims (12)

REVENDICATIONS1. A device (7; 107) for cleaning at least one ink jet print head (13,13 '; 113), the or each print head (13,13'; plate (19) having orifices (21) adapted to eject an ink to form said jets, the orifices (21) substantially aligning in an alignment direction (D2), the device (7; 107) comprising: - a strip (23) adapted to absorb the ink, - a buffer (25, 125) having a support surface (27; 127) of a longitudinal portion (29, 129) of the strip (23) for wiping the each plate (19), - a first set (33; 133) for moving the buffer (25; 125) and the or each print head (13,13 '; 113) relative to each other; in order to contact the or each plate (19) respectively with a contact zone (81) of the longitudinal portion (29; 129) of the strip (23), and to effect a sliding of the or each contact zone (81) on the or each plate (19) substantially in the alignment direction (D2) during cleaning, and - a second set (31; 131) for tensioning the longitudinal portion (29; 129) of the strip (23) on the support surface (27; 127) during cleaning, and for moving the strip (23) in the direction of its length to bring about the support surface (27; 127) a new longitudinal portion (85) of the strip (23) after cleaning, characterized in that the support surface (27; 127) is locally at the or each contact zone (81), curved towards the or each plate (19), so that the longitudinal portion (29; 129) of the strip (23) comprises two longitudinal edges (83) located outside the or each contact zone (81). 2. Device (7; 107) according to claim 1, characterized in that the band (23) adapted to absorb the ink has a transverse elasticity to its length greater than or equal to 5 times the longitudinal elasticity of said strip. 3. Device (7; 107) according to claim 1 or 2, characterized in that the first assembly (33; 133) contacts the buffer (25; 125) and the or each print head (13, 13 '). 113) so that the sliding of the or each contact zone (81) on the or each plate (19) is substantially perpendicular to the direction of the length of the strip (23). 4. Device (7; 107) according to any one of claims 1 to 3, characterized in that the support surface (27; 127) of the buffer (25; 125) has, at the or each contact zone ( 81), in a plane parallel to the alignment direction (D2) and perpendicular to the or each plate (19), a substantially arcuate section (57) having a radius (R4) of between 10 mm and 50 mm, preferably equal to about 20 mm. 5. Device (7; 107) according to any one of claims 1 to 4, characterized in that the buffer (25; 125) comprises an outer layer (55; 155) of elastomeric material, preferably flexible silicone, the outer layer (55; 155) having the support surface (27; 127). 6. Device (7; 107) according to claim 5, characterized in that the outer layer (55; 155) of the buffer (25; 125) has a hardness of between 5 and 50 Shore A. 7. Device (7) according to any one of claims 1 to 6, characterized in that it is intended to clean at least two printing heads (13, 13 ') arranged radially from an axis (D ) substantially parallel to the alignment direction (D2), the two or each plate (19) being substantially parallel to the axis (D), the buffer (25) having a generally circular shape in projection on a plane perpendicular to the axis (D), and being centered on an axis (D3) substantially parallel to the axis (D). 8. Device (7) according to claim 7, characterized in that the first assembly (33) is able to move the buffer (25) of a cleaning position in which the axis (D3) of the buffer (25) is substantially coincides with the axis (D), at a rest position, in which the axis (D3) of the buffer (25) is spaced from the axis (D). 9. Device (107) according to any one of claims 1 to 6, characterized in that it is intended to clean at least one printing head (113), the or each plate (19) extending substantially in a plane, the pad (125) extending along an axis (Oy) parallel to the plane, and the support surface (127) having a substantially cylindrical shape along a generatrix parallel to the axis (Oy). 10. Device (107) according to claim 9, characterized in that the first assembly (133) is adapted to move the or each print head (113), to approach or approach the buffer (125) before the cleaning, and away from or away from the pad (125) after cleaning. A printer (1; 100) comprising at least one ink jet printhead (13,13 '; 113), the or each printhead (13,13'; 113) including a plate (19); ) having orifices (21) capable of ejecting an ink to form said jets, the orifices (21) aligning substantially in an alignment direction (D2), characterized in that the printer (1; cleaning device (7; 107) according to one of the preceding claims. 12. A method for cleaning at least one ink jet print head (13, 13 '; 113), the or each print head (13, 13'; 113) comprising a plate (19); ) having orifices (21) capable of ejecting an ink to form said jets, the orifices (21) aligning substantially in an alignment direction (D2), characterized in that it comprises the following steps: on a support surface (27; 127) of a buffer (25; 125) a longitudinal portion (29; 129) of a strip (23) adapted to absorb the ink; - the buffer (25; and the or each print head (13, 13 '; 113) relative to each other for contacting the or each plate (19) respectively with a contact area (81) of the longitudinal portion (29; 129) of the web (23), and for sliding the or each contact zone (81) on the or each plate (19) substantially in the alignment direction (D2), and - moving the band (23) in the direction of the length of the strip (23) to bring on the support surface (27; 127) a new longitudinal portion (85) of the strip (23), characterized in that the support surface (27; 127) is locally, at the or each contact zone (81), curved towards the or each plate (19), so that the longitudinal portion (29; 129) of the strip comprises two longitudinal edges (83) located outside the or each contact zone (81).