Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
1999-01-29
2002-12-17
Hilten, John S. (Department: 2861)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S029000, C347S030000
Reexamination Certificate
active
06494560
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to the structure for cleaning a print head of an ink jet printer and a device for driving the cleaning structure.
The present invention is based on Japanese Patent Applications No. Hei. 10-18657 and Hei. 10-339052, which are incorporated herein by reference.
2. Description of the Related Art
In the ink jet printer, liquid ink is supplied from an ink tank to a print head, and forcibly discharged in the form of an ink droplet onto a printing medium, through ink jet nozzles of the print head. Sometimes, one of some of the ink passages ranging from the ink tank to the ink jet nozzles are clogged with air bubbles to possibly obstruct the ink discharging through the passage. To cope with this, the ink jet printer usually has a “clogging-check-pattern printing function”, and a “cleaning function”. When the former function is exercised, the printer prints a preset clogging check pattern by use of all the nozzles of the print head. A user checks the printed preset pattern to locate a clogged nozzle or nozzles if such defective nozzle is present. The latter function, or the cleaning function, is exercised when the clogged nozzle is located, to suck ink from the clogged nozzle to remove its clogging.
Most of the ink jet printers are designed so as to be capable of printing in monocolor or multi-color mode. To this end, the printer uses four (K (black), C (cyan), M (magenta), Y (yellow)) or larger number of color inks. Further, the printer includes ink tanks and a set of nozzles (e.g., 64 or 128 nozzles), which are respectively provided for those color inks. In a printer using four color inks and having 64 nozzles for each color, the total number of required nozzles is 256, and greater.
The clogging check pattern printed out shows the location of a clogged nozzle, if present. Therefore, the user knows which of those nozzles arrayed is clogged. In the event that at least one nozzle is clogged, the user instructs the printer to exercise the cleaning function for removing the clogging. The cleaning operation usually consists of three steps; 1) “flushing” for driving the nozzle to discharge the ink, 2) “wiping” for wiping out the ink from the nozzle surface, and 3) “suction” for sucking the ink from the nozzles by applying negative pressure to the nozzle. Thus, the cleaning operation is complicated. Of those cleaning operation steps, the “suction” process is performed such that 1) the print head is moved to a home position, 2) the entire print surface of the print head is capped with a rubber cap, and 3) the ink is sucked from all the nozzles of the print head thus capped.
As described above, in the event of clogging of the nozzle, to remove the clogging, all the nozzles must be subjected to the suction process although the clogged nozzle is located. Some reasons are present for this. One of the reasons follows. The capping is formed through a complicated mechanism. Therefore, if only the clogged nozzle is sucked, the clogging is not always removed. If so, a natural conclusion is that the sucking of all the nozzles will reliably remove the clogging of the nozzle. However, the sucking of all the nozzles leads to consumption of much ink. The cost of the ink consumption is for the user to bear.
Some places where air bubbles are likely to stay are present in the ink passage ranging from the ink tank to the ink jet nozzle. One of the places is a filter chamber located downstream of and near to the ink tank. In case where a replaceable, ink cartridge is used for the ink tanks, the filter chambers are provided with needle tubes. When the ink cartridge is set to the printer, the needle tubes are thrust into the related ink tanks. During the thrusting, air bubbles possibly enter the filter chamber through a cylinder-piston action by the ink tank and the needle tube.
Generally, one ink tank supplies ink to a number of ink jet nozzles, and an ink supply passage is branched at a location downstream of the filter chamber to have a number of ink passages. The branching of the ink supply passage leads to an increase of its cross section area. The result is that an ink flow rate in each branched ink passage is reduced, and the force acting to drive the air bubbles out of the filter chamber is weak or insufficient.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to minimize the amount of ink consumed by the process of cleaning the ink jet nozzles.
Another object of the invention is to effectively drive air bubbles out of the filter chamber through the branched ink supply passages.
According to one aspect, there is provided an ink jet printer comprising: at least one ink chamber; a print head having a plurality of ink jet nozzles and being connected to the ink chamber; a print controller for driving the print head in order to print; and a capping device for covering the ink jet nozzles of the print head.
The capping device comprises: a cap component having a plurality of cavities for sorting the ink jet nozzles into a plurality of nozzle groups by ink chamber unit, thereby capping all ink jet nozzles corresponding to at least one ink chamber by nozzle group unit; at least one pipe being connected to the cavities of the cap component for supplying negative pressure to the cavities; and a suction controller for controlling the supply of the negative pressure through the pipe to the cavities, thereby supplying the negative pressure independently by every cavity, whereby the suction controller sucks the ink from the ink jet nozzles independently by the nozzle group unit.
In a preferred embodiment of the ink jet printer, the suction controller supplies the negative pressure to one arbitrary cavity of the cap component so as to suck the ink from the ink jet nozzles independently by the nozzle group unit, and all remaining cavities which correspond to one common ink chamber with the arbitrary cavity are sealed.
In another embodiment, the suction controller supplies the negative pressure to all the cavities corresponding to one common ink chamber simultaneously.
In yet another embodiment, a plurality of the ink chambers are provided in the printer, and the cap component has a dimension and number of cavities for capping all of the ink jet nozzles connected to all ink chambers.
In still another embodiment, the cap component comprises one of an integral unit and a plurality of sub-units divided according to the nozzle groups sorted by the ink chamber unit.
In a further embodiment, a plurality of the ink chambers are provided in the printer, and the cap component does not have a dimension and number of cavities for capping all of the ink jet nozzles connected to all ink chambers, and the ink jet printer further comprising a second cap component capping all of the ink jet nozzles at a stretch.
In a still further embodiment, a plurality of the nozzle groups are arranged in a recording medium transporting direction.
In another embodiment, the cap component includes the number of chambers equal to that of the nozzle groups, and caps all the nozzle groups of the print head simultaneously.
In yet another embodiment, one nozzle group is divided into at least two sub-groups of nozzle (in an extreme case, one sub-group consists of one nozzle), and the cap component includes at least two cavities and simultaneously caps those sub-groups.
In still another embodiment, pipes connected to the cavities include valves for closing and opening the pipes. By selectively opening the valves, ink is selectively sucked from the nozzle groups.
In a further embodiment, the pipes connected to the cavities include negative pressure sources, independently operable.
In an additional embodiment, two or larger number of the nozzle groups of the print head are connected to one ink chamber. The cap component includes two or larger number of the cavities so as to simultaneously cap two or larger number of the nozzle groups connected to one ink chamber. Negative pressure is selectively supplied to those cavities. At this time, the remaining cav
Seshimo Tatsuya
Uwai Hikonosuke
Hilten John S.
Hsieh Shih-wen
Seiko Epson Corporation
Sughrue & Mion, PLLC
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