Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
1999-06-03
2002-11-19
Yockey, David F. (Department: 2861)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S030000
Reexamination Certificate
active
06481824
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 also relates to an ink jet recording apparatus having a recording head which moves in the direction of width of recording paper, and discharges ink droplets onto recording paper in accordance with print data for printing images, and more specifically relates to a control technology for the recording head cleaning operation to recover from inferior printing of the recording head by absorbing ink through nozzle openings of the recording head.
The present invention is based on Japanese Patent Applications Nos. Hei. 10-18657, Hei. 10-154852 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, 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 great.
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 operations 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.
In order to solve these problems the ink jet recording apparatus has capping means for sealing the nozzle openings of the recording head in a non-print mode and a cleaning mechanism for cleaning a nozzle plate as the need arises. This capping means functions as a cover preventing ink at said nozzle openings from drying. Said capping means also has a function to solve clogging of the nozzle openings with absorbing ink through the nozzle openings by sealing the nozzle plate with a capping member and applying negative pressure from a suction pump when clogging occurs at the nozzle openings.
The forcible ink suction and discharge process executed to solve clogging of the recording head is generally called the cleaning operation. The cleaning operation is performed when resuming the printing operation after a long halt or when the user turns on a cleaning switch in order to solve clogging of the recording head. Said operation is followed by the wiping operation with a wiping member comprised of elastic plates such as rubber after discharging ink droplets by applying negative pressure.
In this kind of recording apparatus, said recording heads for black ink and color inks are also disposed on one nozzle plate. A black ink cartridge and a color ink cartridge are provided on each recording head for supplying ink. With regard to this kind of recording apparatus for public use, said each cartridge is mounted directly to the top of each recording head respectively.
FIG. 32
is a cross section showing the state that an ink cartridge is mounted on the top of the recording head and the nozzle plate of the recording head is sealed with capping means ascended form the lower part of the recording head.
Specifically, reference numeral
308
in
FIG. 32
denotes the ink cartridge. A film member (not shown) is adhered to an ink supply port
308
a
of the ink cartridge
308
so as to prevent ink solvent form vaporizing while ink is stored.
When a new cartridge is installed, the cartridge
308
can be mounted just by thrusting in a manner in which an ink supply port
308
a
of the ink cartridge
308
is placed downward in the opposite side of a supply needle
331
, which is hollow and set up upward beyond the back of the recording head
307
. With this operation, said ink supply needle penetrates said film adhered to the ink supply port
308
a.
Thus, rubber seal member
308
b
disposed inside the ink supply port is closely connected with the ink supply needle, thereby ink is supplied to the recording head
307
from the cartridge
308
.
The capping member
310
arranged in a non-print section of the apparatus ascends from the lower part so as to seal the nozzle plate of the recording head
307
after the carriage mounting said recording head
307
moves to the non-print section. An ink suction port
324
connected to a suction pump (not shown) and an air opening
325
connected to an air valve (not shown) are disposed on the bottom of said capping member
310
. When the suction pump operates with the air valve connected to the air opening
325
closed, the cleaning operation is executed for sucking ink from the nozzle openings of the recording head. When the suction pump operates with the air valve open, discharged ink within the capping means
310
can be discharged into a discharge ink tank (not shown).
In the recording apparatus as described above, when replacing an ink cartridge, said capping means seals the nozzle plate of the recording heads and the suction operation is performed for absorbing ink through the nozzle openings by applying negative pressure from the suction pump (the cleaning operation for replacement). Thereby bubbles entered at the time of connecting the ink cartridge and the ink supply needle, are removed. This suction operation discharges said bubbles entered into the recording head during replacement of the cartridge, so that poor printing, such as the so called missing dots, can be avoided.
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 even if the clogged nozzle is located. This is due to several reasons.
One of the reasons is as follows. The clogging 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.
For example, when a black ink cartridge is replaced, ink suction is executed not only through the nozzle openings for discharging black ink but from the nozzle openings for jetting cyan, magenta, and yellow inks as well. Thus, there was a problem that color inks were unnecessarily consumed
Moreover, since each nozzle opening absorbs ink equally, rise of negative
Hayakawa Hitoshi
Seshimo Tatsuya
Uwai Hikonosuke
Seiko Epson Corporation
Yockey David F.
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