Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
2002-02-08
2004-12-14
Hsieh, Shih-Wen (Department: 2861)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S033000, C347S037000, C347S023000, C400S055000
Reexamination Certificate
active
06830311
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention is related to an ink jet recording apparatus operated in such a manner that a moving position of a capping device is changed during both flushing operation and capping operation in accordance with an adjusting amount of a platen gap by a platen gap adjuster, and is also related to a moving position control method of the capping device, and is further related to a flushing control method used in an ink jet recording apparatus operated in such a manner that a flushing operation mode is changed in accordance with an adjusting amount of a platen gap.
For instance, an ink jet recording apparatus of a serial printing system is equipped with an ink jet recording head, and a paper feeding means. While the ink jet recording head is mounted on a carriage, this ink jet recording head is transported along a main scanning direction. The paper feeding means feeds recording paper sheets along a sub-scanning direction located perpendicular to the above-described main scanning direction. Since ink droplets are jetted from the recording head in accordance with print data, a printing operation is carried out with respect to the recording paper sheets.
The above-described ink jet recording head owns the below-mentioned problem in connection with such a printing operation that ink which is pressured in a pressure producing chamber is jetted as ink droplets from nozzle openings onto recording paper sheets. That is to say, the ink viscosity is increased due to evaporation of ink solvent from the nozzle openings, the ink is caked, and dust is attached to the nozzle openings, so that the normal jetting operation of the ink droplets from the nozzle openings is disturbed, resulting in an occurrence of a printing failure.
To avoid this problem, this sort of ink jet recording apparatus are equipped with capping device capable of capping, or sealing nozzle forming surfaces of recording heads while printing operations thereof are set under rest conditions. This capping device may have not only a function of a lid, but also a jetting function recovering means of ink droplets. This lid function is capable of preventing ink of the nozzle openings in the recording head from being dried. The ink droplets jetting function recovering means is capable of solving clogging of the nozzle openings in the case that the ink clogs the nozzle openings in such a manner that the nozzle forming surfaces are capped, and negative pressure is applied from a suction pump so as to suck/eject the ink from the clogging nozzle openings. As a result, clogging problems of the nozzle opening can be solved.
A process operation for forcibly sucking/ejecting ink in order to solve clogging of a recording head is generally referred to as a cleaning operation. This cleaning operation is carried out in the case that a printing operation is restarted after a long rest condition of a recording apparatus, and/or in the case that a user recognizes a printing failure and thus manipulates, for example, a cleaning switch. Then, as previously explained, after the negative pressure is applied by operating the suction pump and the ink is sucked/ejected from the recording head into the capping device, the nozzle forming surfaces are wiped by way of a wiping means which is formed by using, for instance, a rubber material and the like.
On the other hand, the above-described capping device is also equipped with a recovery means of such an ink droplet jetting function, which is provided independent from the above-explained cleaning operation. This ink droplet jetting function may flush ink droplets by applying such a drive signal to the recording head irrespective of printing operation. This recovery means is called as a flushing operation, this flushing operation is carried out every time a constant time period has elapsed in order to achieve an object capable of avoiding such a problem that clogging can be prevented, while this clogging effect occurs due to an increase in viscosity of ink located in nozzle openings from which a few amount of ink droplets is jetted while printing operation is carried out.
On the other hand, most of this sorts of recording apparatus are constructed in such a manner that the ink droplets jetted by the above-explained flushing operation are received by the above-described capping device. In this case, the following problem will occur when an interval between the nozzle forming surface of the recording head and the capping device is extremely narrow. That is, ink droplets jetted from the nozzle openings are rebounded within the capping device, and a portion of these rebounded ink droplets is again flied to the nozzle openings. As a result, meniscus of ink formed in a nozzle opening is destroyed, and thus, the normal jetting effect of the ink droplets from this nozzle opening is disturbed, so that such a printing failure called as “dot skipping” may occur.
Also, in such a case that an interval between the nozzle forming surface of the recording head and the capping device is wide, an occurrence of ink mist may be induced. In this ink mist, ink droplets jetted from the recording head receive air resistance and the like, so that these ink droplets are further distributed in the form of very small ink droplets, and these very small ink droplets are changed under mist state. When such ink mist is produced, various damages are given to the above sort of recording apparatus. That is, while the ink mist may float within the recording apparatus, this floating ink mist not only contaminates recording paper sheets, but also are attached to the respective drive mechanisms and printed circuit boards employed in the recording apparatus and thereafter are caked thereon. As a consequence, when the flushing operation is carried out, the above-described interval between the nozzle forming surface and the capping device should be properly controlled.
On the other hand, in this sort of recording apparatus, a platen gap adjuster is provided. This platen gap adjuster is capable of adjusting a platen gap between the recording head and the platen in correspondence with a thickness of a recording paper sheet. Then, the platen gap adjusters are generally constructed as follows. That is, when the platen gap adjuster is manipulated, the position of the recording head may be changed with respect to the platen which is arranged on a fixed position. As a result, in the case that the platen gap is adjusted, the above-described distance between the nozzle forming surface and the capping device is changed.
More specifically, nowadays, since various printing needs are made, considerably thick paper sheets are required to be used as printing paper sheets. In accordance with such a requirement, the gap adjustable range by the above-explained platen gap adjuster should be necessarily and considerably increased, as compared with the gap adjustable range of the prior art. As a consequence, the move amount of the recording head with respect to the platen is accordingly increased by manipulating the platen gap adjuster. Since such a move amount is increased, the increased move amount extremely exceeds the proper interval range between the nozzle forming surface of the recording head and the capping device, which may induce the above-described printing failure such as dot skipping, or may induce the mechanical trouble and the electrical trouble, which are caused by the occurrence of the above-described ink mist.
Also, as described above, since the platen gap is changed, the positional relationship between the nozzle forming surface of the recording head and the capping device for capping the nozzle forming surface, so that abutting pressure of the capping device with respect to the nozzle forming surface is changed. As a consequence, for instance, in such a case that the abutting pressure of the capping device with respect to the nozzle forming surface is brought into overpressure condition, another problem occurs. That is, the capping member which abuts on the nozzle forming surface is deformed. Then, in the case that
Fukasawa Shigenori
Yoshida Atsushi
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