Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
1999-08-24
2001-01-23
Pendegrass, Joan (Department: 2852)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S022000, C347S033000
Reexamination Certificate
active
06176567
ABSTRACT:
This application is based on application No. H10-238662 filed in Japan on Aug. 25, 1998, the content of which is hereby incorporated by reference.
FIELD OF THE INVENTION
The present invention relates to a direct printing apparatus for use in a color copying machine and printer.
BACKGROUND OF THE INVENTION
U.S. Pat. No. 5,132,708 discloses a direct printing apparatus. In the direct printing apparatus, four printing stations are disposed on an outer periphery of a drum-like sheet conveying member along a sheet conveying direction. On an outer periphery of a toner carrier in each printing station is retained toner having different colors, for example, magenta, cyan, yellow and black.
Moreover, in the direct printing apparatus, a plurality of aspirators comprising a vacuum cleaner and the like are provided inside the sheet conveying member. Each aspirator sucks the sheet to hold it on the outer periphery of the sheet conveying member and sucks the toner adhering to each printing station to clean the printing station at a cleaning time after printing operation.
However, the direct printing apparatus as described above utilizes the aspirator comprising the vacuum cleaner, thereby there is a disadvantage that a noise is caused when operating the aspirator. The aspirator is provided inside the sheet conveying member, thereby there is an another disadvantage that the apparatus is enlarged. In addition, since the sheet is sucked by the aspirator, it is necessary to form a number of holes in the sheet conveying member. Thereby, there is a further disadvantage that the strength of the sheet conveying member becomes weakened.
SUMMARY OF THE INVENTION
Accordingly, the present invention has been accomplished to solve the aforementioned disadvantages of the prior arts. An object of the present invention is to provide a direct printing apparatus which is possible to remove remaining printing particles to clean the printing station without causing noise, enlargement of the apparatus, and decrease of strength of the sheet conveying member.
In order to achieve the aforementioned object, according to a first aspect of the present invention, there is provided a direct printing apparatus, comprising:
printing means having a bearing member for bearing printing particles thereon, the printing particles being charged to a predetermined polarity, a backing electrode opposed to the bearing member, the backing electrode generating electric field which attracts the printing particles, and a printing head disposed between the bearing member and the backing electrode, the printing head having a plurality of apertures through which the printing particles can propel and a plurality of control electrodes disposed around the plurality of apertures;
an endless belt member disposed between the backing electrode and the printing head of the printing means, the endless belt member receiving the printing particles which are propelled from the printing means; and
cleaning means for cleaning the printing particles adhering to the surface of the endless belt member;
whereby the printing particles adhering to the apertures of the printing head are collected on the endless belt member so that the printing particles are recovered by the cleaning means.
Preferably, the backing electrode is applied with a voltage of opposite polarity to the printing particles adhering to the printing head, whereby the printing particles adhering to the apertures of the printing head is cleaned.
Among the printing particles, there exists wrong-sign printing particles that are charged to a reverse polarity to the predetermined polarity. The wrong-sign printing particles remain on the lower surface of the printing head without propelling to the backing electrode from the printing head under the electric field generated by the backing electrode. In the direct printing apparatus having above described construction, the wrong-sign printing particles adhering to the apertures of the printing head are collected on the endless belt member by applying the backing electrode with a voltage of opposite polarity to the printing particles adhering to the printing head, whereby the wrong-sign printing particles are recovered by the cleaning means. Thus, the apertures of the printing head are surely prevented from clogging off. The cleaning mechanism of the present invention is not based on a suction method by such a vacuum cleaner as the prior art, preventing noise and enlargement of the apparatus. In addition, the cleaning mechanism of the present invention needs not to form a number of holes in the endless belt member, preventing decrease of strength of the sheet conveying member.
According to a second aspect of the present invention, there is provided a direct printing apparatus, comprising:
printing means having a bearing member for bearing printing particles thereon, the printing particles being charged to a predetermined polarity, a backing electrode opposed to the bearing member, the backing electrode generating electric field which attracts the printing particles, and a printing head disposed between the bearing member and the backing electrode, the printing head having a plurality of apertures through which the printing particles can propel and a plurality of control electrodes disposed around the plurality of apertures;
an endless belt member disposed between the backing electrode and the printing head of the printing means, the endless belt member receiving the printing particles which are propelled from the printing means; and
cleaning means disposed on the endless belt member, the cleaning means coming into contact with the printing head to remove the printing particles adhering to the aperture of the printing head as the endless belt member moves.
Preferably, printing particle collecting means for collecting the printing particles which is cleaned by the cleaning means is provided in the vicinity of the endless belt member.
In the direct printing apparatus having above described construction, the printing particles adhering to the aperture of the printing head are removed by directly bringing the cleaning means into contact with the printing head, whereby the wrong-sign printing particles remaining on the printing head are surely removed and recovered.
Preferably, the endless belt means is an intermediate transfer means, and wherein a transfer means for transferring an image of the printing particles formed on the surface of the endless belt means into a print medium is provided. Alternatively, the endless belt means is a conveyance means for conveying a print medium, and wherein the printing means print an image of printing particles directly onto the print medium. As described above, either an intermediate transfer method or a direct printing method can be adopted as a printing method to the printing medium.
Preferably, a plurality of the printing means are provided along the moving direction of the endless belt member in order to implement color print.
REFERENCES:
patent: 4478510 (1984-10-01), Fujii et al.
patent: 4755837 (1988-07-01), Schmidlin et al.
patent: 5132708 (1992-07-01), Schmidlin et al.
patent: 5477250 (1995-12-01), Larson
patent: 3-253879 (1991-11-01), None
patent: 8-281998 (1996-10-01), None
patent: 9-30031 (1997-02-01), None
Hiraguchi Hiroshi
Shibata Yoshifumi
Shimada Hirokatsu
Uno Koji
Yamaki Toshio
Minolta Co. , Ltd.
Morrison & Foerster / LLP
Pendegrass Joan
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