Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
1997-08-14
2001-10-09
Nguyen, Judy (Department: 2861)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
Reexamination Certificate
active
06299277
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an ink jet printer which is capable of removing thickened ink by cleaning, flushing, or the like.
2. Prior Art
Conventionally, this kind of ink jet printer removes ink (hereinafter referred to as “thickened ink”) which is solidifying through evaporation of a solvent, such as water in the case of a water-soluble ink, by cleaning or flushing.
For example, the thickened ink is removed when printing is started after the lapse of a predetermined time period from termination of the immediately preceding printing operation, or when printing is started after replacement of an ink cartridge, or when the user has found a defective print quality, or on like occasions. In removing the thickened ink, as shown in
FIG. 1
, a head cap
24
is brought into intimate contact with a print head
21
which is arranged at an end of a carriage
23
having an ink cartridge
29
loaded therein, whereby nozzles
22
of the print head
21
are blocked. Then, a pump
28
is operated to collect or draw the thickened ink via an ink absorbent
25
and an ink collecting tube
27
into an ink absorbent
26
. Alternatively, wiping or wrapping of the surface of the print head
21
, that is, cleaning of the same, is carried out.
When the printer has continued to be in an operating state in which the head cap
24
is not in intimate contact with the print head
21
over a predetermined time period, or when printing is terminated, the carriage
23
is returned from a printing area PA to the home position HP to bring the print head
21
into contact with the head cap
24
, and then a slight amount of ink is caused to be delivered through all the nozzles
22
of the print head
21
. In short, flushing is carried out. Further, immediately after the main power supply is turned on, one of or both of the cleaning and flushing operations are carried out. Through these operations, thickened ink formed at openings of the nozzles
22
and ink passages adjacent thereto is removed to thereby prevent the nozzles
22
and the passages from being clogged.
However, according to the conventional ink jet printer, even if the printer is in a non-printing state, i.e. in a state where the print head
21
is in intimate contact with the head cap
24
, if the printer is left unused with the ink cartridge
29
loaded therein for a long time period (e.g. several months), portions of ink not only within the nozzles
22
but also within ink passages extending from the ink cartridge
29
to the nozzles
22
solidify through evaporation of a solvent or water, so that the nozzles
22
and the ink passages are clogged. In such cases, the cleaning and/or flushing normally executed when the printer is started is not sufficient for restoring a normal operative state of the printer in which printing can be properly carried out. To recover from such a malfunction of the printer, it is required to set a new ink cartridge
29
to dissolve the solidified ink, or to carry out the cleaning of the print head
21
several times by the use of the pump
28
, further, if required, to replace the print head
21
by a new one, which prevents the user from using the printer immediately as he desires, and causes him to take the trouble of restoring the normal operative state of the printer.
SUMMARY OF THE INVENTION
It is the object of the invention to provide an ink jet printer which can be used without a hitch even after the ink jet printer is left for a long time period in a non-printing state in which no ink is delivered or drawn from a print head thereof, such as a state in which the print head is in intimate contact with a head cap.
To attain the above object, according to a first aspect of the invention, there is provided an ink jet printer including a print head, and a head cap for being brought into intimate contact with the print head to cover the print head, comprising:
time-measuring means for measuring a time period over which the print head is in intimate contact with the head cap; and
thickened ink-removing means for regularly removing thickened ink adhering to the print head based on a result of measurement by the time-measuring means.
According to this ink jet printer, even when it is in a non-printing state in which the print head is in intimate contact with head cap, the thickened ink is regularly removed. Therefore, even if the ink jet printer is left in the non-printing state for a long time period, it can preserve a condition in which its print head is removed of thickened ink. This enables the printer to perform its normal printing operations without a hitch even after it is left in the non-printing state for a long time. It should be noted that the removal of thickened ink can be executed by cleaning, flushing, or the like.
Preferably, the ink jet printer includes a main power supply for supplying electric power to the ink jet printer for a printing operation thereof, and an auxiliary power supply for supplying electric power to the time-measuring means and the thickened ink-removing means when the main power supply is off.
According to this preferred embodiment, when the main power is off, the time-measuring means and the thickened ink-removing means are supplied with electric power by the auxiliary power supply. Therefore, even if the main power supply is off, the thickened ink can be removed without any problem. This enables the present ink jet printer to preserve the above advantageous features thereof to thereby permit the use thereof immediately as desired by the user.
For example, the auxiliary power supply is a battery.
Preferably, the thickened ink-removing means carries out flushing to remove the thickened ink adhering to the print head.
According to this preferred embodiment, the above advantageous effects can be obtained by execution of the flushing for removing the thickened ink.
Preferably, the thickened ink-removing means carried out the flushing whenever the time period measured by the time-measuring means reaches a predetermined time period.
For example, the time-measuring means is a timer which is reset whenever the flushing is carried out.
To attain the above object, according to a second aspect of the invention, there is provided an ink jet printer including a print head, and a head cap for being brought into intimate contact with the print head to cover the print head, the ink jet printer using an ink in the form of a solution having a solvent, comprising:
time-measuring means for measuring a time period over which the print head is in a state in which the ink is neither delivered therefrom nor drawn therein;
evaporation rate parameter-measuring means for measuring a parameter related to an evaporation rate of the solvent from the ink; and
thickened ink-removing means for removing thickened ink adhering to the print head based on a result of measurement by the time-measuring means and a result of measurement by the evaporation rate parameter-measuring means.
In general, a time period over which an ink for ink jet printers solidifies through evaporation of a solvent of the ink varies with a parameter related to the evaporation rate of the solvent of the ink, which is detected in the environment of the ink jet printer (e.g. relative humidity in the case of a water-soluble ink which uses water as the solvent, and an ambient temperature in the case of an oil-soluble ink which uses e.g. kerosene as the solvent). According to the ink jet printer of the second aspect of the invention, measurements are made not only on a time period over which the ink jet printer is in a non-printing state in which no ink is delivered from or drawn into the print head, such as a state in which the print head is in intimate contact with the head cap, or a state in which printing is inhibited due to other causes, but also on the parameter related to the evaporation rate of the solvent from the ink, and at a timing determined based on results of these measurements, the thickened ink is removed by cleaning or flushing. Therefore, even if the ink jet printer is left in
Hogan & Hartson L.L.P.
Nguyen Judy
Seiko Epson Corporation
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