METHOD FOR CIRCULATION OF A LIQUID IN A PRINTER

Abstract

The present invention relates to a method for circulating a liquid in a printer to prevent settling of dispersed particles in the liquid anywhere in said printer by controlling the recirculation of liquid for each printhead in said printer.

Claims

1. A method for circulation of a liquid in a printer, wherein the printer comprises an intermediate liquid reservoir, a controller for controlling the circulation of the liquid, and a first liquid handling system and at least one second liquid handling system, wherein each liquid handling system comprises: a printhead, being in liquid connection with the intermediate liquid reservoir; and a means for circulating a liquid to the intermediate liquid reservoir, and a valve to regulate the circulation, wherein the method comprises the steps of opening the valve to regulate the circulation in the first liquid handling system; closing the valve to regulate the circulation in the at least one second liquid handling system; activate the means for circulating the liquid to the intermediate liquid reservoir to start circulation of the liquid from the printhead in the first liquid handling system back to the intermediate liquid reservoir, while simultaneously drawing liquid from the intermediate liquid reservoir into the printhead in the first liquid handling system,

2. A method according to claim 1, wherein the circulation is regulated during a printing mode of the printer in which the printer is operating to form an image.

3. A method according to claim 2, wherein the circulation of each liquid handling system is dynamically adjusted according to the consumption of liquid of each corresponding printhead.

4. A method according to claim 3, wherein the controller adjusts the settings of any of the valves dependent on the image being printed.

5. A method according to claim 1, wherein the circulation is regulated during a maintenance mode of the printer in which the printer is performing maintenance action and is not operating to form an image.

6. A method according to claim 4, wherein the time of circulation in each liquid handling system is set according to the consumption of liquid of each corresponding printhead between two maintenance actions.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The present invention will become more fully understood from the detailed description given herein below and accompanying schematic drawings which are given by way of illustration only and are not limitative of the invention, and wherein:

[0017] FIG. 1 schematically illustrates a printer having three printheads and three liquid handling systems according to the present invention.

DETAILED DESCRIPTION

[0018] The present invention will now be described with reference to the accompanying drawings, wherein the same reference numerals have been used to identify the same or similar elements throughout the several views

[0019] FIG. 1 schematically shows a printer having three printheads (2a, 2b, and 2c), being in a liquid connection with an intermediate liquid reservoir (1) which enables liquid to be drawn into the printheads by means of valves (4a, 4b, and 4c). Liquid can be drawn out of the printhead by means of valves (3a, 3b, and 3c) back into the liquid connection between the intermediate liquid reservoir (1) and the liquid supply container (5). The valves (3a, 3b, 3c, 4a, 4b, and 4c) are controlled by means of a controller (8) and can be controlled individually and can be set differently from each other. Furthermore the printer shown in FIG. 1 comprises a valve (6) and a pump (7) to regulate the flow from the liquid supply container (5) to the intermediate liquid reservoir (1).

[0020] In an embodiment the printer is in a printing mode, creating images by ejecting an ink onto a print medium, all printheads (2a, 2b, and 2c) are jetting an ink while ink is drawn from the intermediate liquid reservoir (1) by means of valves (4a, 4b, and 4c).

[0021] When one of the printheads (2a, 2b, and 2c), for example printhead (2b), is not ejecting ink for a certain period of time the ink may be recirculated from that particular printhead to the intermediate liquid reservoir (1) to prevent settling of ink in that particular printhead and ink circuit. Valve (3b) will be opened to enable ink to be drawn from printhead (2b) back to the intermediate liquid reservoir (1) and valve (4b) will also be opened to allow ink to be drawn back into printhead (2b). At the same time, valves (3a) and (3c) are closed to prevent ink to be drawn from printheads (2a) and (2c). Thus, ink is circulated through a single printhead while the other printheads are still in a printing mode. It goes without saying that it is possible to randomly select any combination of one or more printheads for circulation of ink. In another embodiment the printer is not in a printing mode, thus all printheads being in a standby mode or a maintenance mode, and all printheads (2a, 2b, and 2c) are not jetting ink.

[0022] As all printheads (2a, 2b, and 2c) are not jetting ink the ink may be circulated through the printheads to prevent settling of ink in those printheads. For sufficient agitation of ink, the ink is circulated through only one printhead at a time. So first ink will be circulated through a first printhead (2a) by opening valves (3a) and (4a) while valves (3b), (4b), (3c), and (4c) are closed to prevent circulation of ink through printheads (2b) and (2c).

[0023] When ink is sufficiently agitated in printhead (2a), valves (3a) and (4a) will be closed and valves (3b) and (4b) will be opened to enable circulation of ink through printhead (2b).

[0024] When ink is sufficiently agitated in printhead (2b), valves (3b) and (4b) will be closed and valves (3c) and (4c) will be opened to enable circulation of ink through printhead (2b). Again it goes without saying that it is possible to randomly select any combination of one or more printheads for circulation of ink.

[0025] This sequence may be repeated as often as needed until the printer goes back into a printing mode.

[0026] Detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention, which can be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriately detailed structure. In particular, features presented and described in separate dependent claims may be applied in combination and any advantageous combination of such claims is herewith disclosed.

[0027] Further, the terms and phrases used herein are not intended to be limiting; but rather, to provide an understandable description of the invention. The terms “a” or “an”, as used herein, are defined as one or more than one.

[0028] The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.