The invention concerns the cleaning of material jet heads as well as the machines and manufacturing equipment equipped with self-cleaning material jet heads.
“Material jet heads” means here both tinctorial inkjet printing heads and heads for spraying liquids or viscous or powdery products.
In addition, the fields to which the invention applies relate, beyond tinctorial printing with inks, the material jet having medical, biological, genetic, chemical, acoustic, insulating or electrically conductive functions or properties, or the like.
For example, the document WO-A-9919900 shows various uses of the material jet, apart from printing.
The devices employing material jet heads are used for spraying drops of material on a substrate so as to form an image or a three-dimensional structure.
The document FR-A-2790421, filed in the name of the applicant, describes a graphical material jet machine provided with at least one inkjet head.
This document supplies an example of the use of material jet heads for printing patterns on a support such as a chip card.
The document U.S. Pat. No. 5,449,754 describes a method of producing chemical compounds by spraying drops of various liquid solutions onto a substrate.
This document supplies an example of the use of material jet heads for an application in chemistry.
The methods and devices for spraying droplets of material have the characteristic of being sensitive to clogging of the material outlet orifices.
This is because these orifices have a diameter of around a few tens of microns and because of this the least impurity may interfere with the jet of material.
In addition, because of their function of spraying material, these orifices are highly susceptible to being blocked by residues of dry material after use.
Periodic cleaning devices for material jet heads have therefore been developed.
In particular, it is known how to provide a purge phase during which a large quantity of material is expelled through the outlet orifices, a receptacle also being provided to collect the purged material.
This solution has a certain number of drawbacks, including the difficulty of making the receptacle/orifices assembly liquidtight, the receptacle being removable. Moreover, the risk of running is significant in the case of a material jet head which can take various positions.
It is also known how to provide a rubber scraper able to scrape the material outlet orifices during a cleaning phase so as to remove the residual drops of material.
This type of device does not currently give satisfaction because of the difficulty in recovering the scraped material and the need for periodic cleaning of the scraper itself.
It is also known how to provide phases of cleaning the material jet heads by disposing a ribbon under the material jet head, pressing it against the material outlet orifices by means of a pad; and then causing it to move so as to wipe these orifices.
This solution, although more satisfactory than the previous ones, does not leave a sufficiently clean surface state for a quality material jet.
The invention remedies these drawbacks, in particular by supplying a simple cleaning making it possible to ensure a perfect state of cleanliness compatible with the requirements of the precision material jet and/or high rates without using a complex and expensive mechanism.
To this end, a first object of the invention relates to a method of cleaning at least one material jet head of the type comprising an outlet device for material to be sprayed; this method comprising, outside any jet of material through this head, a cleaning cycle comprising the steps making provision for:
The material jet head can belong to the group formed by inkjet printing heads, heads for spraying viscous liquids, dispensing systems and the like.
The material sprayed may belong to the group formed by tinctorial, medical, biological, genetic, chemical, conductive or electrically insulating substances and the like.
The material outlet device mentioned may comprise at least one material outlet orifice.
Moreover, in the first geometrical relationship mentioned, the absorbent member may be generally flat in shape and be disposed in the cleaning plane, opposite the material outlet device.
Likewise, in the second geometrical relationship, the scraper member may be disposed so that the absorbent member is positioned between the material outlet device and the scraper member.
In one embodiment, at step c), the cleaning device is formed by pressing the scraper member and the absorbent member against the material outlet device.
In another embodiment, the cleaning method also comprises, after step b), a purge cycle comprising the steps making provision for:
Also in one embodiment, the cleaning method also comprises, after step b), a jet cycle comprising the steps making provision for:
A second object of the invention relates to a system for cleaning a material jet head comprising a material outlet device, this device comprising:
In the first geometric relationship mentioned, the absorbent member may be generally flat in shape and be disposed in the cleaning plane, opposite the material outlet device.
Likewise, in the second geometric relationship mentioned, the scraper member may be disposed so that the absorbent member is positioned between the material outlet device and the scraper member.
The first movement means can comprise a runner allowing the translation of the scraper member in the direction of movement of the absorbent member.
The second movement means can comprise an actuator with electromagnet.
In one embodiment, the absorbent member is in the form of a ribbon of absorbent material and the third movement means comprise a payout reel and a winding reel as well as two guide spindles, these two reels being able to cooperate in order to make the ribbon of absorbent material pass between the two guide spindles.
The fourth movement means can comprise at least one runner allowing the translation in the elevation direction of at least one of the guide spindles.
In a variant, the fourth movement means can comprise at least one eccentric allowing the translation in the elevation direction of at least one of the guide spindles.
In a preferred embodiment, the control means are able to provide a cleaning cycle during which:
In addition, the control means can be able to provide a purge cycle during which:
Likewise, the control means can be able to provide a jet cycle during which:
A third object of the invention relates to a material jet machine functioning in particular according to the cleaning method in accordance with the invention, and/or comprising a cleaning system according to the invention, this machine comprising:
In one embodiment, the purge means are able, during the cleaning system purge cycle, to control the expulsion of material continuously by the material outlet device for a predetermined period.
In another embodiment, the means of controlling the material jet function are able, during the jet cycle of the cleaning system, to control the isolated execution of the jets of material through the material outlet device at regular intervals during the jet cycle period.
A fourth object of the invention relates to equipment for manufacturing a structure such as an electronic device, this equipment;
A fifth object of the invention relates to a process of manufacturing a structure such as an electronic device, for example an intelligent portable object or electronic component, an information medium, for example an optical or magnetic disc, or the like, characterised in that this manufacture:
Other characteristics and advantages of the invention will emerge in the light of the following description relating to the accompanying drawings, given by way of example:
In the orthogonal reference frames accompanying the figures, the longitudinal direction is represented by the X-axis, the transverse direction is represented by the Y-axis and the elevation direction is represented by the Z-axis.
The machine comprises a material jet head with a material jet 1 supplied by a material reservoir 2. This head is able to move in the transverse direction Y so as to be able to reach the material jet zones on the machine and to be able to be placed above the cleaning system during the cleaning phases as depicted in FIGS. 1 to 5.
This is because the cleaning system is fixed on one side of the material jet machine, on a transverse movement path (in the transverse direction Y) of the material jet head.
The material jet head comprises a substantially plane nozzle plate 11 containing a plurality of material outlet orifices.
The cleaning system comprises a ribbon 3 of absorbent material with a width greater than that of the material jet head 1 (see
The ribbon 3 can have a width (in the transverse direction Y) of 80 mm and a thickness of 0.25 mm, a new payout reel 4 can have a diameter of 70 mm corresponding to a full winding reel diameter 5 of 75 mm, the distance between axes of the reels 4, 5 then being 54 mm.
The ribbon 3 is positioned and guided by two rollers 7, 8 mounted so as to rotate and disposed parallel to the transverse direction Y so as to keep substantially flat a portion of ribbon 3 tensioned under the material jet head 1.
These rollers 7, 8, forming guidance axes, are moreover able to move in the elevation direction. They are mounted on means of translation in the elevation direction Z such as runners or eccentrics, a device for controlling these translation means then allowing the positioning in the elevation direction Z of the portion of ribbon 3 situated between the axes 7, 8.
The rotation of the axis of the payout reel 4 is controlled with respect to the control of the motor 6 so as to afford resistance to the unwinding of the reel 4 in order to keep the tension of the ribbon 3 between the guidance axes 7, 8 and provide a return effect.
In addition, the rotation of the reels 4, 5 is controlled, for example by virtue of a coding wheel, so as to detect any incident such as the breakage of the ribbon 3 or the failure of the motor 6, the purge operation not being performed in the event of detection of such an incident.
The motor 6 also has a control intended to control the speed of rotation of the reel 5 so that the speed of movement of the ribbon 3 remains constant whatever the length of the ribbon 3 wound on the reel 5, the information concerning the instantaneous diameter of the reel 5 being given by any appropriate means, for example a distance meter, a mechanical shoe or a potentiometer.
The mechanism of the rollers 4, 5 described makes it possible to make the ribbon 3 pass continuously under the nozzle plate 11, as depicted schematically in
Under the portion of the ribbon 3 tensioned between the two rollers 7, 8, there is disposed a rubber scraper 9 mounted on a runner 10 enabling the scraper 6 to move in translation along the longitudinal direction X over a distance greater than the length (in the longitudinal direction X) of the nozzle plate 11.
In addition, the scraper 9 extends transversely to the material jet head 1, in the transverse direction Y over a width at least equal to that of the nozzle plate 11.
The scraper 9 is also controlled by an actuator 12 with an electromagnet fixed to the runner 10 and able to press the scraper 9 against the nozzle plate 11 when it is actuated, the scraper 9 being kept separated from the nozzle plate 11 by a spring 13 when the actuator 12 is in the idle state.
The actuator 12 puts the scraper 9 in contact with the nozzle plate 11 with, for example, the following characteristics:
The material jet head is also provided with a purge device arranged so as to put the material reservoir 2 under pressure and thus force the material to emerge continuously through the material outlet orifices, thus providing a purge of the material jet circuit.
The cleaning system described functions as indicated below.
During material jet phases, the material jet head moves parallel to the transverse direction Y, above the substrate to be printed.
During cleaning phases, the material jet head comes to be placed at the end of travel of the transverse direction Y so as to come to be positioned on the side of the machine where the cleaning system is disposed, above the ribbon 3′ (as depicted in
At this stage, the cleaning system is in the idle state, that is to say the scraper 9 is kept separated from the ribbon 3 by the spring 13, the guidance axes 7, 8 are disposed in the elevation direction Z so as to keep the portion of ribbon 3 situated between them at a distance of around 2 mm from the nozzle plate 11.
The cleaning system can then be controlled according to various cycles described with reference to FIGS. 6 to 10 in which, on the Y axis, the time is entered and on the X axis the states (actuated or idle) of the following various members are entered:
The material produced by the purge operation is thus absorbed by the ribbon 3 passing at a sufficient speed so that no running occurs.
With reference to
Contact of the ribbon 3 against the entire surface of the nozzle plate 11 is thus ensured, avoiding, during the purge, the accumulation of material at the reference 14 in
The cleaning sequence in
During this cleaning cycle N, the ribbon 3 is in a position away from the nozzle plate 11 whilst the scraper 9 raises a linear portion against the nozzle plate 11. A cleaning member is thus formed since the linear portion (in the transverse direction Y) of the ribbon 3 formed by the pressure of the scraper 9 constitutes a scraper coated with absorbent material.
The motor control C3 being activated, the ribbon 3 passes under the nozzle plate 11 and the scraper 9, which is mounted in free translation on the runner 10 and which is in contact with the ribbon 3, is then driven in translation so that the cleaning member passes over the entire length (along X) of the nozzle plate 11, thus providing optimum cleaning.
Another embodiment of the invention is depicted by
This purge cycle P combined with an activation of the piezoelectrics C5 corresponds to the following states:
The ribbon 3 is in a position away from the nozzle plate 11 during these operations and fulfils the role of a material jet substrate, this sequence making it possible to keep the material jet heads in a functioning state when the material jet is stopped in order to guarantee their immediate restarting when the material jet is resumed.
In this embodiment, the arrangement of the elements is as follows:
In
Number | Date | Country | Kind |
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01/15519 | Nov 2001 | FR | national |
Filing Document | Filing Date | Country | Kind |
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PCT/FR02/04086 | 11/28/2002 | WO |