Incremental printing of symbolic information – Ink jet – Fluid or fluid source handling means
Reexamination Certificate
2001-03-05
2002-08-13
Vo, Anh T. N. (Department: 2861)
Incremental printing of symbolic information
Ink jet
Fluid or fluid source handling means
Reexamination Certificate
active
06431693
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an ink jet recording apparatus for use in recording and printing a character and image, particularly to an ink jet recording apparatus for use in a copying machine, a facsimile machine, an image output machine of a computer, or a printer.
Above all, the present invention relates to an ink supply apparatus to an ink jet head for printing/recording an image, and an ink supply mechanism provided with an ink jet head cleaning and recovering function for pressurizing and supplying an ink during cleaning and recovering of the ink jet head.
2. Related Background Art
A principle of an ink jet print system is disclosed in U.S. Pat. No. 4,723,129. As a printer, an on-demand system product has broadly spread since around 1985.
In a conventional method of supplying ink to an ink jet head of an ink jet printer, a negative pressure system has generally been used. In many cases, the ink jet head consumes ink with which a sponge or another porous material is impregnated. This form is described, for example, in Japanese Patent Application Laid-Open No. 5-270001.
In this method of supplying the ink to the ink jet head, as the ink is consumed, a negative pressure of the sponge increases, and a discharge state of an ink droplet from the ink jet head fluctuates.
In recent years, particularly to record a photographic image, a size of the ink jet droplet has been of the order of 4 to 8 pl (1 p1=1×10
−12
liters), and an influence of the negative pressure has increased.
Moreover, a printing speed of the ink jet printer has increased because of rapid enhancement of a processing speed of an arithmetic operation element inside a computer and printer, and ink consumption has increased. Therefore, an ink supply amount from the sponge is insufficient, the negative pressure temporarily rapidly increases, and image turbulence occurs in accordance with a printing pattern. In order to solve a negative pressure fluctuation, instead of holding the ink in the sponge, the ink is held and supplied in a liquid state so that this problem can be solved. For this, a technique is disclosed, for example, in Japanese Patent Application Laid-Open No. 5-305713.
However, when printing is continuously performed with the ink jet head, dust and foreign particle stick to a surface of the ink jet head as an ink droplet discharge surface, or a slight bubble is generated inside the ink jet head. In this case, it becomes impossible to effectively discharge ink jet droplets via about 300 to 8000 ink jet discharge holes without any defect. Therefore, it is necessary to subject the ink jet head to cleaning and recovery processing after a given number of sheets are printed, or when an image defect is detected by some means. As disclosed in Japanese Patent Application Laid-Open No. 5-008401, this cleaning is performed by scraping dust off the surface of the head with a rubber plate, or by covering the surface with a cap to perform suction recovery. However, when the surface of the ink jet head held in a negative pressure state is wiped with a wiper or another plate, the rubber and foreign particle sticking to the head surface enters the ink jet discharge holes, and a problem occurs that the ink jet discharge holes are closed.
To solve the problem, a method of simultaneously performing suction and surface wiping is necessary.
However, when an apparatus is provided with both a suction mechanism and a surface wiping mechanism, the apparatus is enlarged in size, which is economically disadvantageous in respect of an apparatus manufacturing cost.
Generally considering the aforementioned conventional art problem, an ink supply apparatus and ink supply method in which a constant negative pressure is held during printing in the ink jet head, and cleaning and recovering of the ink jet head can be performed by supplying the ink in a pressurized state and discharging the ink via the ink jet head, and which is simple and small-sized and can be stable in operation have not been technically established yet.
This method is solved to some extent by a method described in Japanese Patent Application Laid-Open Nos. 10-217509 and 10-217510. This technique includes a step of supplying the ink to the ink jet head from an ink tank via ink pressurizing supply means. For a detail constitution, as shown in
FIGS. 9A and 9B
, ink pressurizing supply means
201
is driven by a part of a driving mechanism
804
disposed on a printer main body (not shown) side. When an ink tank
200
is mounted as shown by a dashed line of
FIG. 9A
, a diaphragm
804
a
cam-driven by the driving mechanism
804
is pushed into the ink tank
200
to pressurize an ink storage chamber. Thereby, the ink in the ink storage chamber is supplied under pressure to the ink jet head (not shown) on the printer main body side via a connection port
110
.
A vale which opens to atmosphere at a constant or lower negative pressure is disposed inside the ink tank
200
in such a manner that the ink is supplied.
In this method, however, in order to supply the ink from the ink tank, a combination of two mechanisms is necessary: a mechanical operation mechanism
803
, disposed inside the ink tank
200
, for applying an ink supplying pressure; and the large-sized mechanism
804
disposed on the printer main body side. There is a problem that a complicated apparatus mechanism is necessary for pressurizing and supplying the ink.
As described above, the conventional example has a problem that the apparatus is enlarged in size and complicated in constitution, but in order to supply the pressurized ink to the ink jet head, some ink supply apparatus needs to be added.
Then, the present inventor has studied manufacturing of a small-sized ink supply apparatus, disposed in an outlet of a flexible ink storage baglike member, or midway in an ink supply path, for supplying the ink to the ink jet head, but have found that it is very difficult to manufacture the small-sized ink supply apparatus.
The reason is as follows. In order to print a colored photographic image, the ink jet printer requires at least four colors (black, yellow, magenta, cyan) of ink and/or light colors (light yellow, light magenta, light cyan) of ink or a flesh color of ink. When the ink tank for storing these types of ink, mechanism for pressurizing and supplying these types of ink, and ink jet head as a mechanism for receiving supply of these types of ink are mounted, the ink jet printer is necessarily enlarged, and power consumption also increases. Therefore, the size of the small-sized ink supply apparatus for pressurizing the ink needs to be small. A volumetric size of the apparatus is preferably 8 cm
3
or less, power consumption needs to be one watt or less, and further an independent control operation is necessary. These problems need to be solved.
SUMMARY OF THE INVENTION
An object of the present invention is to solve the aforementioned problem, to provide a liquid pressurizing supply apparatus which is disposed in an outlet of a flexible ink storage bag-like member or midway in an ink supply path so that ink can be supplied to an ink jet head, and which is small in size, little in power consumption and simple in mechanism, and to provide a liquid discharge recording apparatus using the liquid pressurizing supply apparatus.
In order to achieve the aforementioned object, as a result of intensive studies, the present inventor et al. have found that the ink can be pressurized and supplied by manufacturing a small-sized electromagnetic actuator, and disposing a one-way valve on the actuator. The small-sized electromagnetic actuator can operate with an operation power of about one watt or less, but a large problem has further occurred.
That is, when the actuator is small-sized with power consumption of about one watt or less, a driving distance of the actuator is about 0.8 mm or less, and an amount of ink able to be supplied with one operation is small (50 &mgr;liter). Therefore, if the one-way valve is not satisfactorily shielded, ink flo
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Vo Anh T. N.
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