Method and mechanism for contactless cleaning of a nozzle plate

Abstract

A method for contactless cleaning of a nozzle plate of a print head. The method may include: providing a suction element, the suction element causing a fluid to flow along a surface of the nozzle plate and toward the suction element for removing residue from the nozzle plate; sucking-in, by the suction element, the fluid together with the removed residue; and separating the sucked-in fluid from the sucked-in residue. Also, a suction element for cleaning of such a nozzle plate. The suction element may be configured to cause a fluid to flow along a surface of the nozzle plate and toward the suction element for removing residue from the nozzle plate and sucking-in the fluid with the residue. The suction element may include a mouth piece and a wheel, the wheel being arranged such that the mouth piece is spaced away from the surface of the nozzle plate.

Claims

1. A method for contactless cleaning of a nozzle plate of a print head, the method comprising: providing a suction element, the suction element causing a fluid to flow along a surface of the nozzle plate and then toward the suction element for removing residue from the nozzle plate; sucking-in, by the suction element, the fluid together with the removed residue; separating sucked-in fluid from sucked-in residue using a separator connected to the suction element, wherein the separator comprises a cone shaped part in the middle of a cyclone chamber for creating a cyclone in the cyclone chamber; outputting, at a first outlet of the separator, the sucked-in fluid separated from the sucked-in residue; outputting, at a second outlet of the separator, the sucked-in residue separated from the sucked-in fluid; collecting the sucked-in residue separated from the sucked-in fluid in a residue bin connected with the second outlet of the separator; and providing a bypass circuit parallel to the separator for generating underpressure in the residue bin such that the sucked-in residue is sucked into and collected in the residue bin from the separator via the second outlet, the bypass circuit configured to carry fluid from the residue bin, generally free of the sucked-in residue, away from the residue bin.

2. The method of claim 1, wherein the cone shaped part is housed within a substantially cylindrical cavity of the cyclone chamber, causing the sucked-in fluid and the sucked-in residue to move around the cone shaped part between the cone shaped part and the substantially cylindrical cavity to separate the sucked-in fluid from the sucked-in residue.

3. The method of claim 2, wherein the suction element is moved relative to the surface of the nozzle plate during the step of sucking-in the fluid together with the removed residue.

4. The method of claim 3, wherein the suction element is moved relative to the surface of the nozzle plate during the step of sucking-in the fluid together with the removed residue with a speed greater than or equal to about 0.5 mm/s and less than or equal to about 3.0 mm/s.

5. The method of claim 3, wherein the suction element is moved relative to the surface of the nozzle plate during the step of sucking-in the fluid together with the removed residue with a distance from the surface of the nozzle plate larger than or equal to about 0.15 mm and smaller than or equal to about 0.35 mm.

6. A cleaning device for contactless cleaning of a nozzle plate of a print head, the device comprising: a suction element configured to: cause a fluid to flow along a surface of the nozzle plate and then toward the suction element for removing residue from the nozzle plate; and suck-in the fluid together with the removed residue; a separator connected to the suction element, the separator comprising a cone shaped part housed within a substantially cylindrical cavity of a cyclone chamber for creating a cyclone in the cyclone chamber configured to move sucked-in fluid and sucked-in residue around the cone shaped part between the cone shaped part and the substantially cylindrical cavity and separate the sucked-in fluid from the sucked-in residue; a residue bin connected to an outlet of the separator for collecting the sucked-in residue separated from the sucked-in fluid; and a bypass circuit parallel to the separator for generating underpressure in the residue bin such that the sucked-in residue is sucked into and collected in the residue bin from the separator via the outlet, the bypass circuit configured to carry fluid from the residue bin, generally free of the sucked-in residue, away from the residue bin.

7. The cleaning device of claim 6, further comprising a filter device arranged downstream the separator and being connected to the separator, wherein the filter device is configured to remove aerosols from the sucked-in fluid.

8. The cleaning device of claim 7, wherein the filter device comprises an active carbon filter.

9. The cleaning device of claim 7, further comprising a pump arranged downstream the filter device and being connected to the filter device, wherein the pump is configured to discharge the sucked-in fluid to an environment external the cleaning device.

10. The cleaning device of claim 6, wherein the suction element is configured to cause the fluid to flow along the surface of the nozzle plate with a predetermined fluid velocity based on a gap surface between the suction element and the surface of the nozzle plate.

11. The cleaning device of claim 10, wherein the fluid velocity is greater than or equal to about 18 m/s and less than or equal to about 53 m/s.

12. The cleaning device of claim 6, wherein the suction element comprises a mouth piece and at least one wheel, the at least one wheel being arranged such that the mouth piece is spaced away from the surface of the nozzle plate.

13. The cleaning device of claim 6, wherein the suction element further comprises a spring system for pushing the mouth piece toward the surface of the nozzle plate.

14. The method of claim 2, further comprising providing the sucked-in fluid from the first outlet of the separator and fluid from the bypass circuit to a filter device arranged downstream the separator and bypass circuit.

15. The method of claim 2, wherein the suction element is configured for causing the fluid to flow along the surface of the nozzle plate with a fluid velocity greater than or equal to about 18 m/s and less than or equal to about 53 m/s.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) While the specification concludes with claims particularly pointing out and distinctly claiming the subject matter that is regarded as forming the various embodiments of the present disclosure, it is believed that the invention will be better understood from the following description taken in conjunction with the accompanying figures, in which:

(2) FIG. 1 depicts schematically a cleaning device for contactless cleaning of a nozzle plate of a print head according to one embodiment.

(3) FIG. 2 depicts schematically a suction element for contactless cleaning of a nozzle plate of a print head according to one embodiment.

(4) FIG. 3 depicts a flow diagram of a method for contactless cleaning of a nozzle plate of a print head according to one embodiment of the invention.

DETAILED DESCRIPTION

(5) A cleaning device 2 for contactless cleaning of a nozzle plate 11 of a print head 1 according to one embodiment will be described with reference to FIG. 1.

(6) The print head 1 comprises the nozzle plate 11 and a nozzle plate surface 12.

(7) The cleaning device 2 may comprise a suction element 3, a separator 4, a filter device 5, a pump 6, and a bin 7. The separator 4 may be located downstream the suction element 3. The filter device 5 may be located downstream the separator 4. The bin 7 may be located downstream the separator 4. The pump 7 may be located downstream the filter device 5.

(8) An inlet of the separator 4 may be connected to the suction element 3 via a first tubing 81. One outlet 41 of two outlets 41, 42 of the separator 4 may be connected via a second tubing 82 to an inlet of the filter device 5. The other outlet 42 of the two outlets 41, 42 of the separator 4 may be connected via a third tubing 83 to an inlet of the bin 7. An outlet of the bin 7 may be connected to the second tubing 82 via a fourth tubing 84. An outlet of the filter device 5 may be connected to an inlet of the pump 6 via a fifth tubing 85. An outlet of the pump 6 may be operably connected to an environment external the cleaning device 2.

(9) In operation of the cleaning device 2, e.g. when the pump 6 is in operation, fluid 9 may be caused to flow along the nozzle plate surface 12 for removing residue 10 from the nozzle plate surface 12. The residue 10 comprises at least one of ink, cured ink, semi-cured ink, particles, or fibers. The fluid flow is indicated by arrows in FIG. 1, and the residue 10 is depicted by dots. The fluid 9 acts as a carrier for the residue 10 and transports the removed residue 10, e.g. the sucked-in residue 10, via the suction element 3 and the first tubing 81 to the inlet of the separator 4.

(10) The separator 4 may comprise a cone shaped part 43 in the middle of a cyclone chamber 44 for creating a cyclone in the cyclone chamber 44. The separator 4 may be configured to separate that part of the sucked-in fluid 9 from sucked-in fluid not carrying the sucked-in residue 10 by using a cyclone-principle. This part of the sucked-in fluid 9 may be forced to move around by the cone shaped part 43 and may flow from the inlet of the separator 4 upward to the first outlet 41 to leave the separator 4 via the second tubing 82 to the inlet of the filter device 5. The sucked-in fluid 9 cannot, or generally won't, flow from the inlet straight up. Furthermore, under the cone shaped part 43, i.e. between the cone shaped part 43 and the bottom of the cyclone chamber 44, a low wind space 45 may be generated where the part of the sucked-in fluid 9 carrying the sucked-in residue 10 is not swept back up. In operation of the cleaning device 2, the cone shaped part 43 may be wet with sucked-in residue 10 around about a quarter or so of its circumference and halfway or so up the conical shape. This may generally provide an indication of good fluid-residue separation. The part of the sucked-in fluid 9 carrying sucked-in residue 10 may leave the separator 4 via the second outlet 42 located at or near the bottom of the cyclone chamber 44 via the third tubing 83 to the inlet of the bin 7. The fourth tubing 84 may act as a bypass over the cyclone camber 44 to remove the sucked-in fluid 9 carrying the sucked-in residue 10 from the cyclone chamber 44 in to the bin 7. The bypass 84 may use a pressure drop over the cyclone chamber 44 to create an underpressure in the bin 7. This underpressure is used to suck, e.g. remove, the sucked-in fluid 9 carrying the sucked-in residue 10 from the cyclone chamber 44. The use of this bypass 84 allows providing solely the pump 6. Inside the bin 7, separation may be done by using gravity force. Because a flow velocity inside the bin 7 may be relatively or comparatively lower, generally only the sucked-in fluid 9 leaves the bin 7 via its outlet, and generally no splattering occurs that would lead to airborne droplets. The bin 7 may also be called the second stage separator and the separator 4 may also be called the first stage separator. As an alternative solution, or additionally to the bypass 84, an additional underpressure generating device 84′, e.g. a pump, may be provided.

(11) The sucked-in air 9, without the sucked-in residue 10 being collected in the bin 7, may flow from the bin 7 via its outlet, the bypass 84, and the second tubing 82 to the inlet of the filter device 5. The filter device 5 may comprise a housing 52 and a filter, such as but not limited to, an active carbon filter, 51 inside the housing 52. The filter device 5 is provided since aerosols may be generated by high velocity of the fluid during sucking-in thereof. In some embodiments, the filter device 5 may be required to prevent such aerosols from entering the pump 6, due to a possible damage thereof, or exiting the cleaning device 2 into ambient or environmental air, due to health reasons.

(12) The sucked-in fluid 9 generally without aerosols may flow after passing the filter device 5 via the fifth tubing 85 to the inlet of the pump 6 and may be released, e.g. discharged, into the ambient air, e.g. a surrounding environment.

(13) A suction element 3 for contactless cleaning of the nozzle plate 11 of the print head 1 according to one embodiment will be described in detail with reference to FIG. 2.

(14) In FIG. 2, the print head 1 with the nozzle plate 11, the nozzle plate surface 12, and a nozzle 13 is schematically shown. The nozzle plate surface 12 may comprise a recess 14.

(15) The suction element 3 may comprise a mouth piece 32 and one or more, e.g. two, wheels 33. The wheels 33 may be arranged such that the mouth piece 32 is spaced away from the surface 12 of the nozzle plate 11 by predetermined distance d. A spring system 31 may be provided for pushing the mouth piece 32 toward the nozzle plate surface 12.

(16) As described above, the suction element 3 may be configured to cause the fluid 9 (see FIG. 1) to flow along the surface 12 of the nozzle plate 11 with a predetermined fluid velocity. The fluid velocity may be based on, or calculated based on, a gap surface 15 between the suction element 3 and the surface 12 of the nozzle plate 11, as indicated for example by the vertical hatching in FIG. 2. In an example case, the fluid velocity may be greater than or equal to about 18 m/s and less than or equal to about 53 m/s, and in some cases is preferably around 22 m/s.

(17) A method for contactless cleaning of the nozzle plate 11 of the print head 1 according to one embodiment will now be described with reference to FIGS. 1 and 3.

(18) The method for contactless cleaning of the nozzle plate 11 may comprise a first step S1 of providing the above described suction element 3. The suction element 3 may cause the fluid 9 to flow along the surface 12 of the nozzle plate 11 and then toward the suction element 3 for removing residue 10 from the nozzle plate 11.

(19) The method may comprise a second step S2 of sucking-in, by the above described suction element 3, the fluid 9 together with the removed residue 10 and a third step S3 of separating the sucked-in fluid from the sucked-in residue by using the above described first and second stage separators 4, 7. During the second step S2 of sucking-in the fluid 9 together with the removed residue 10, the suction element 3 may be moved relative to the surface 12 of the nozzle plate 11.

(20) The suction element 3 may be moved relative to the surface 11 of the nozzle plate 12 during the second step S2 with a speed, in some cases preferably a constant speed, being greater than or equal to about 0.5 mm/s and less than or equal to about 3.0 mm/s, and in some cases is preferably about 1.0 mm/s. The suction element 3 may be moved relative to the surface of the nozzle plate 11 during the second step S2 with the constant distance d (see FIG. 2) from the surface 12 of the nozzle plate 11 being larger than or equal to about 0.15 mm and smaller than or equal to about 0.35 mm, and in some cases is preferably about 0.2 mm. For separating the sucked-in fluid 9 from the sucked-in residue 10 during the third step S3, the separator 4 may use, as described above, the cyclone-principle.

(21) In a fourth step S4 of the method, the sucked-in residue 10 separated from the sucked-in fluid 9 may be collected in the above described bin 7. The method may further comprise a fifth step S5 of outputting the sucked-in fluid 9 separated from the sucked-in residue 10 by using the above described first and second stage separators via the pump 6 to an external environment or otherwise outside the above described cleaning device 2.

(22) In summary, the above described method, the suction element, and the cleaning device may generally rely on the principle(s) of a vacuum cleaner. The suction mouth may be moved along the print head, causing an airflow along the nozzle plate surface and into the suction mouth. Generally, and in many cases ideally, all or substantially all residue may be removed, but a meniscus inside the nozzle(s) is not, or is not significantly, disturbed. Afterwards, the residue may be separated from the air to enable collection of the residue. Thus, methods and devices are provided allowing cleaning of a print head with a repeatable quality and generally without operator dependency or damage to the print head.

(23) As used herein, the terms “substantially” or “generally” refer to the complete or nearly complete extent or degree of an action, characteristic, property, state, structure, item, or result. For example, an object that is “substantially” or “generally” enclosed would mean that the object is either completely enclosed or nearly completely enclosed. The exact allowable degree of deviation from absolute completeness may in some cases depend on the specific context. However, generally speaking, the nearness of completion will be so as to have generally the same overall result as if absolute and total completion were obtained. The use of “substantially” or “generally” is equally applicable when used in a negative connotation to refer to the complete or near complete lack of an action, characteristic, property, state, structure, item, or result. For example, an element, combination, embodiment, or composition that is “substantially free of” or “generally free of” an element may still actually contain such element as long as there is generally no significant effect thereof.

(24) Additionally, unless otherwise specified, as used herein, the phrases “at least one of [X] and [Y]” or “at least one of [X] or [Y],” where [X] and [Y] are different components that may be included in an embodiment of the present disclosure, means that the embodiment could include component [X] without component [Y], the embodiment could include component [Y] without component [X], or the embodiment could include both components [X] and [Y]. Similarly, when used with respect to three or more components, such as “at least one of [X], [Y], and [Z]” or “at least one of [X], [Y], or [Z],” the phrases mean that the embodiment could include any one of the three or more components, any combination or sub-combination of any of the components, or all of the components.

(25) In the foregoing description various embodiments of the present disclosure have been presented for the purpose of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise form disclosed. Obvious modifications or variations are possible in light of the above teachings. The various embodiments were chosen and described to provide the best illustration of the principals of the disclosure and their practical application, and to enable one of ordinary skill in the art to utilize the various embodiments with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the present disclosure as determined by the appended claims when interpreted in accordance with the breadth they are fairly, legally, and equitably entitled.