METHOD FOR OPERATING A PRINTING DEVICE AND PRINTING DEVICE

Abstract

In the case of a method for operating a printing device (1), wherein a fluid that is provided for a printing procedure is supplied from a fluid storage container (6) by way of a supply line (14) to a printing head (13) so as to be able to be applied by the printing head (13) onto a surface, the fluid in a purification circuit (2) is conveyed through a purification installation (8), and by way of a contamination-measurement installation (11) a key contamination indicator of a fluid-specimen quantity in the purification circuit (2) is determined such that a printing procedure by way of which the fluid is dispensed from the printing head (13) commences only once the key contamination indicator has undershot a first threshold value. The invention also relates to a printing device (1) having a printing head (13) and having a connector installation (12) for a fluid storage container (6), said connector installation (12) being connected to the printing head (13) by way of a supply line (14), wherein the printing device (1) has a purification circuit (2) that is formed from fluid-line portions (3, 4, 5) and has a purification installation (8) and has a contamination-measurement installation (11) in which the fluid that by way of the fluid retrieval installation has been retrieved form the fluid storage container (6) can be purified, and a key contamination indicator of a fluid-specimen quantity in the purification circuit (6) can be determined before the purified fluid is supplied to the printing head (13).

Claims

1. Method for operating a printing device (1), wherein a fluid that is provided for a printing procedure is supplied from a fluid storage container (6) by way of a supply line (14) to a printing head (13) so as to be able to be applied by the printing head (13) onto a surface, characterized in that the fluid in a purification circuit (2) is conveyed through a purification installation (8), and by way of a contamination-measurement installation (11) a key contamination indicator of a fluid-specimen quantity in the purification circuit (2) is determined, and in that a printing procedure by way of which the fluid is dispensed from the printing head (13) commences only once the key contamination indicator has undershot a first threshold value.

2. Method according to claim 1, characterized in that the fluid-specimen quantity that is provided for determining the key contamination indicator is diverted from the purification circuit (2), is supplied to the contamination-measurement installation (11), and upon determining the key contamination indicator is again returned into the purification circuit (2).

3. Method according to claim 1, characterized in that the printing head (13) has a return line (17) into the purification circuit (2), and in that a printing head cleaning fluid quantity that is conveyed into the printing head (13) is again retrieved from the printing head (13) and is returned into the purification circuit (2).

4. Method according to claim 3, characterized in that a key contamination indicator of that printing head cleaning fluid quantity that has been returned from the printing head (13) is determined by the contamination-measurement installation (11), and in that the printing procedure by way of the printing head (13) commences only once the key contamination indicator undershoots a second threshold value.

5. Method according to claim 3, characterized in that the fluid is supplied to the printing head (13) only once a key contamination indicator that is determined in the fluid-purification step of the fluid that is conveyed in the purification circuit (2) undershoots a third threshold value.

6. Method according to claim 1, characterized in that the fluid in the fluid-purification step is conveyed through at least one particle filter (10) and through at least one de-gassing installation (9).

7. Method according to claim 1, characterized in that the key contamination indicator is composed of one of the plurality of key particle-content indicators and of one or a plurality of key gas-content indicators, each being detected by the contamination-measurement installation (11).

8. Printing device (1) having a printing head (13) and having a connector installation (12) for a fluid storage container (6), said connector installation (12) being connected to the printing head (13) by way of a supply line (14) such that the fluid from the fluid storage container (6) can be supplied to the printing head (13) and be applied by the printing head (13) onto a surface, characterized in that the connector installation (12) has a fluid retrieval installation and a fluid refilling installation for the fluid storage container (6), in that the printing device (1) has a purification circuit (2) that is formed from fluid-line portions (3, 4, 5) and has a purification installation (8) and has a contamination-measurement installation (11) in which the fluid that by way of the fluid retrieval installation has been retrieved from the fluid storage container (6) can be purified, a key contamination indicator of a fluid-specimen quantity in the purification circuit (6) can be determined, and the fluid by way of the fluid refilling installation can again be supplied to the fluid storage container (6), and in that the supply line (14) branches off from the purification circuit (2) and connects the purification circuit (2) to the printing head (13) such that the fluid that perfuses the purification circuit (2) can be supplied to the printing head (13).

9. Printing device (1) according to claim 8, characterized in that a return line (17) connects the printing head (13) to the purification circuit (2) such that the fluid that is supplied to the printing head (13) can perfuse the printing head (13) and again be supplied to the purification circuit (2).

10. Printing device (1) according to claim 9, characterized in that the return line (17) on the printing head (13) is connected to the supply line (14) by way of a bypass line.

11. Printing device (1) according to claim 9, characterized in that the return line (17) completely surrounds the supply line (14) at least along one supply line portion.

12. Printing device (1) according to claim 8, characterized in that the printing head (13) is displaceable above an area to be printed, and in that the supply line (14) and the return line (17) are flexible at least along a line displacement portion (19).

13. Printing device (1) according to claim 8, characterized in that the purification installation (8) has at least one de-gassing installation (9) and at least one particle filter (10).

14. Printing device (1) according to claim 13, characterized in that in the flow direction at least one first particle filter (10) is disposed ahead of the de-gassing installation (9), and at least one second particle filter (10) is disposed behind the de-gassing installation (9).

15. Printing device (1) according to claim 8, characterized in that the contamination-measurement installation (11) in the flow direction is disposed behind the purification installation (8).

16. Printing device (1) according to claim 9, characterized in that the return line (17) in the flow direction opens into the purification circuit ahead of the contamination-measurement installation (11).

17. Printing device (1) according to claim 8, characterized in that a bypass-line portion (20) through which the fluid can be conveyed through the contamination-measurement installation (11) such that merely a predefinable fluid-specimen quantity is conveyed through the contamination-measurement installation (11) is disposed in the purification circuit (1).

Description

[0034] Exemplary embodiments of the concept of the invention which are schematically illustrated in the drawing will be explained in an exemplary manner in more detail hereunder. In the drawing:

[0035] FIG. 1 shows a schematic illustration of a printing device according to the invention, having a purification circuit, having a purification installation that is disposed in the purification circuit, and having a contamination-measurement installation, and having a junction with a supply line for a printing head that is disposed so as to be spaced apart from the purification circuit;

[0036] FIG. 2 shows a schematic illustration of a printing device of a deviating design, in which the printing head, in addition to a supply line, is connected to the purification circuit by way of a return line, and in which the printing head can be incorporated into the purification circuit by way of valves;

[0037] FIG. 3 shows a schematic illustration of a printing device of a yet again deviating design, in which the printing head is connected to the purification circuit by way of a flexible line displacement portion, wherein the return line surrounds the supply line and shields the latter in relation to external influences; and

[0038] FIG. 4 shows a schematic illustration of a portion of the purification circuit shown in the region IV in FIG. 3, wherein the contamination-measurement installation is incorporated into the purification circuit by way of a bypass line.

[0039] A printing device 1 that is illustrated in an exemplary manner in FIG. 1 has a purification circuit 2 which is assembled from a plurality of fluid-line portions 3, 4, 5. The fluid-line portion 3 is connected to a fluid storage container 6 that accepts 100 millilitres or 10 litres, for example, such that fluid that is located in the fluid storage container 6 by way of a pump installation 7 can be conveyed from the fluid storage container 6 to a purification installation 8. The fluid can contain organic semiconductor materials, for example OLEO materials, and optionally further additives. The purification installation 8 has at least one de-gassing installation 9 by way of which the gas content in the fluid can be reduced. A particle filter 10, for example a membrane filter having a pore diameter of 1 m, in the flow direction is disposed behind the de-gassing installation 9.

[0040] The fluid is subsequently guided through the fluid-line portion 4 in which a contamination-measurement installation 11 is disposed. A key contamination indicator for the perfusing fluid can be established by the contamination-measurement installation 11. The fluid-line portion 4 transitions into a further fluid-line portion 5 which again opens into the fluid storage container 6, on account of which the purification circuit 2 of the printing device 1 is closed. The fluid-line portions 3 and 5 in the transition region towards the fluid storage container 6 can be combined in one common connector installation 12 which facilitates a rapid and tight connection of the fluid-line portions 3 and 5 of the purification circuit 2 to the fluid storage container 6. A dedicated connector installation for each fluid-line portion 3 and 5 can also be provided instead of one common connector installation 12. The openings of the fluid-line portions 3 and 5 that protrude into the fluid storage container form a fluid retrieval installation and a fluid refilling installation for the fluid storage container 6.

[0041] A printing head 13 of the printing device 1 is connected to the purification circuit 2 of the printing device 1 by way of a supply line 14 which branches off from the purification circuit 2 after the contamination-measurement device. By way of suitable valves 15 and 16, the supply line 14 can be either closed and the purification circuit 2 be opened, or else the supply line 14 can be opened such that fluid that circulates in the purification circuit 2 is diverted from the purification circuit 2 and supplied to the printing head 13. For example, in the case of a minor consumption during a printing procedure, merely a part-quantity of the fluid that circulates in the purification circuit 2 can be supplied to the printing head 13 herein, or else the purification circuit 2 can be shut off by the valve 16 such that the entire fluid quantity that is retrieved from the fluid storage container 6 is supplied to the printing head 13.

[0042] A deviating design embodiment of a printing device 1 according to the invention is illustrated in a merely exemplary manner in FIG. 2. In addition to the supply line 14, the printing head 13 is connected to the purification circuit 2 by way of a return line 17 and of a further valve 18, such that the printing head 13 can be conjointly incorporated into the purification circuit 2 and can be perfused by the fluid which circulates in the purification circuit 2. Depending on the design embodiment of the printing head 13, supply lines to the individual printing head nozzles, and storage chambers, or further components of the printing head 13, can also be perfused and purified, or else the fluid can be guided up to the printing head 13 and then be supplied to the return line 17 without any perfusion of individual components of the printing head 13. Cleaning of the supply line 14 and of the printing head 13 as well as of the return line 17 also takes place herein.

[0043] According to the invention, various method sequences are possible in order for the fluid that is provided for the printing procedure to be purified by way of the printing device 1 according to the invention before the commencement of a printing procedure.

[0044] The fluid can circulate in the purification circuit 2 and be continuously and increasingly purified in the purification installation 8 until a key contamination indicator that has been determined by the contamination-measurement installation 11 undershoots a first threshold value for the maximum permissible contaminant content. The purification circuit 2 can subsequently be shut off by the valve 16, and the purified fluid can be supplied to the printing head 13 by way of the supply line 14 while the printing procedure is being carried out.

[0045] The fluid can initially circulate in the purification circuit 2 without the printing head 13 being connected and being perfused by the fluid also in the case of the printing device 1 schematically illustrated in FIG. 2. A key contamination indicator is continuously established by the contamination-measurement installation 11, and the fluid is recirculated and circulated in the purification circuit 2 until a predefined third threshold value for the contaminant content is achieved or undershot, respectively. Subsequently, the printing head 13 is incorporated into the purification circuit 2 by switching valves 15, 16, and 18, and is perfused by the already purified fluid. Any potential contaminants that are located in the printing head 13 herein are absorbed by the fluid, detected in the contamination-measurement installation 11 disposed downstream in the purification circuit 2, and filtered out in subsequent perfusions of the fluid by the purification installation 8. The circulation of the fluid through the printing head 13 can continue until the key contamination indicator that is determined in the contamination-measurement installation 11 undershoots a second threshold value.

[0046] The second threshold value can correspond to the first threshold value that has been mentioned and used in the exemplary embodiment that has been previously explained. A threshold value deviating therefrom can also be predefined, in order, for example, for a less stringent contaminant content after cleaning of the printing head 13 to be predefined by the contamination-measurement installation 11, since any subsequent contamination of the fluid by the already cleaned printing head 13 can be precluded.

[0047] It is likewise possible for the printing head 13 to be conjointly incorporated and perfused by the fluid and herein purified already as from the first circulation of the fluid through the purification circuit 2.

[0048] It can be achieved in all cases that the contaminations of the actual fluid quantity used for the printing procedure are checked and reduced to below a predefined threshold value before the printing procedure commences. A dedicated preceding check measurement is no longer required.

[0049] In the case of the exemplary embodiment illustrated in FIG. 3 the supply line 14 and the return line 17 are configured so as to be flexible along a line displacement portion 19, such that the printing head 13 is connected to the purification circuit 2 so as to be displaceable relative to the purification circuit 2. Moreover, in the line displacement portion 19, the return line 17 which is configured so as to be hollow-cylindrical surrounds the supply line 14 that is disposed so as to be centric in said return line 17, the latter additionally shielding the supply line 14 in relation to environmental influences and contaminations that are caused on account thereof.

[0050] In the case of the exemplary embodiment illustrated merely in fragments in FIG. 4, the contamination-measurement installation 11 is disposed in a bypass-line portion 20 which by way of a junction 21 branches off from the fluid-line portion 4 and by way of a further junction 22 returns back into the fluid-line portion 5. Only a small fluid-specimen quantity which merely represents a minor proportion of the fluid that circulates in the purification circuit 2 in each case perfuses the contamination-measurement installation 11. The respective proportion of the fluid quantity that perfuses the bypass-line portion 20 and the fluid-line portion 4, routed in parallel with the former, can be detected or checked, respectively, by way of a throughflow-measurement installation 23.

[0051] Independently of the respective design embodiment of the printing devices 1, or of the exemplary embodiments shown merely in an exemplary manner, it is possible for a flexible fluid storage container which can be a bag or a flexible plastics container, for example, to be used instead of a rigid fluid storage container 6 which can be a bottle or a metallic container, for example.