Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
2002-04-16
2004-04-13
Hsieh, Shih-Wen (Department: 2861)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
Reexamination Certificate
active
06719401
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an ink ejectability maintenance device for maintaining constant ink ejectability of a recording head for ejecting ink droplets toward a recording medium, as well as to an ink jet printer equipped with the ink ejectability maintenance device.
An ink jet printer is usually equipped with a print head mounted on a carriage which travels back and forth in a main scanning direction, and a medium feeder for intermittently feeding a recording medium, such as print paper, in a sub-scanning direction in preset increments. The print head is actuated in the main scanning direction while the recording medium is being fed in the sub-scanning direction, and ink droplets are ejected toward the recording medium from the print head.
A mono-color ink jet printer is usually equipped with one print head. In contrast, a full-color ink jet printer is equipped with a black-ink print head for ejecting black ink, and a plurality of color-ink print heads for ejecting various colors of ink, such as yellow, cyan, and magenta.
A print head of an ink jet printer of such a construction has a pressure generation chamber and a nozzle orifice communicated therewith. Ink is stored in a pressure generation chamber and pressurized at a predetermined pressure, whereby ink droplets of controlled size are ejected from the nozzle orifice to the recording medium. Accordingly, when variations arise in the ink ejectability of the nozzle orifice of the print head, the quality of a recorded image is greatly affected. Hence, the ink ejectability must be maintained constant at all times.
The ink ejectability is changed by various phenomena, such as an increase in viscosity or solidification due to evaporation or drying of solvent in ink by way of the nozzle orifice, clogging due to solid material, adhesion of dust to the nozzles, and intrusion of air bubbles into ink. In order to prevent occurrence of such a change in characteristic, the ink jet printer is equipped with an ink ejectability maintenance device which eliminates the above-described phenomena causing variations to maintain the ink ejectability constant.
The ink ejectability maintenance device is equipped with a capping device, a suction pump, and a wiping device. The capping device is arranged so as to seal a nozzle formation face of a print head when no recording operation is performed, thereby isolating the nozzle orifice from the outside. Thus, the ink ejectability maintenance device has the function of inhibiting evaporation and drying of ink, thereby hindering an increase in viscosity and solidification of ink. Even when the nozzle formation face is sealed with the capping device, there cannot be completely prevented occurrence of clogging due to solid material in the nozzle orifice or intrusion of air bubbles into an ink flow channel. The ink jet printer is further equipped with a suction pump for the purpose of completely preventing occurrence of these problems.
The suction pump is configured so as to exert negative pressure on the nozzle orifice while the nozzle formation face is sealed with the capping device. The suction pump has the function of forcefully causing ink to be discharged from the nozzle orifice through suction, thereby eliminating solid material or air bubbles. Forceful discharge of ink to be performed by the suction pump is usually carried out when a recording operation is resumed after the ink jet printer has remained inoperative for a long time period or when the user has actuated a specifically-designed switch provided in a control panel with the understanding that deterioration of recorded image quality.
When ink is forcefully discharged by the suction pump, ink may splash across a nozzle formation face of the printer head, and in each nozzle orifice an ink meniscus may be disturbed. The nozzle formation face of the print head becomes susceptible to adhesion of extraneous matter with lapse of time. Hence, the print head is equipped with a wiping device for wiping the nozzle formation face, as required.
The wiping device has a wiping member whose base end is caught by a holder, and is constituted of an elastic plate such as rubber. An edge of the extremity of the wiping member is elastically pressed against a nozzle formation face, thereby effecting relative reciprocal movement so as to wipe the nozzle formation face. As a result, ink or extraneous matter adhering to the nozzle formation face is wiped, and ink meniscuses of respective nozzle orifices are made uniform. In short, the wiping device has the function of making the nozzle formation face stable.
Since the cleaning property of the wiping member can be maintained constant by removing ink or extraneous matter adhering to the surface of the wiping member, the wiping device also has a cleaning member. As a cleaning method to be performed by the cleaning member, there has been adopted a general method in which a scraper is placed as a cleaning member in a position perpendicular to the moving direction of the wiping member. The wiping member is caused to come into collision with the scraper, thereby elastically deforming the wiping member. The wiping member is caused to pass through the scraper, thereby removing the ink adhering to the surface of the wiping member.
According to the cleaning method to be performed by such an ink ejectability maintenance device, when the wiping member comes into collision with the scraper, a collision sound arises. Acting as noise, the sound may adversely affect electronic components and induce faulty operation. Moreover, when the wiping member departs from the scraper, the wiping member is restored to its original shape, which may induce splashing of ink and deteriorate recording accuracy.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide an ink ejectability maintenance device capable of preventing occurrence of noise or splashing of ink, which would otherwise be caused when a wiping member is cleaned, as well as an ink jet printer equipped with the ink ejectability maintenance device.
In order to achieve the above object, according to the present invention, there is provided an ink ejectability maintenance device for maintaining an ink ejectability of a print head which ejects ink droplets to a recording medium, comprising:
a wiper, which wipes a nozzle formation face of the print head; and
a wiper cleaner formed with a slit, which removes adhesions on the wiper when the wiper passes through the slit.
Accordingly, the wiper cleaner can scrape away the ink or the like adhering to the wiper without involvement of collision with the wiper. Hence, there does not arise a faulty operation, which would otherwise be caused by noise such as collision sound. Further, the wiper is not subjected to elastic deformation or restoration. Hence, there does not arise deterioration in recording accuracy, which would otherwise be caused by splashing of ink.
Preferably, a width of the slit is substantially identical with a thickness of the wiper. Accordingly, both side surfaces of the wiper where adherents particularly remain when the print head is wiped away can be cleaned.
Preferably, the wiper and the wiper cleaner change their position in cooperation with each other.
Accordingly, adherents adhering to the area where an interference arises between the wiper and the print head can be wiped away completely. The load imposed on the wiper when the wiper passes through the slit of the wiper cleaner can be reduced by minimizing a wiping range.
Here, it is preferable that the wiper is movable between a wiping position and a non-wiping position, and passes through the slit while moving from one of the wiping position and the non-wiping position to the other.
Accordingly, the wiper can be cleaned at all times after the wiper has wiped away the print head.
Further, it is preferable that the wiper cleaner is pivotably held on the device.
Accordingly, the wiper cleaner can readily effect cooperative movement relative to the wiper. Thus, adherents adhering to the wiper can be wiped
Hsieh Shih-Wen
Seiko Epson Corporation
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