Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
1999-08-19
2001-10-02
Barlow, John (Department: 2853)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
Reexamination Certificate
active
06296347
ABSTRACT:
RELATED APPLICATION
This application is based on Japanese Patent Application No.10-232748, the content of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an apparatus for recording images on a recording sheet, such as paper, by allowing recording particles to jump and directly attach to the recording sheet.
2. Description of the Related Art
The U.S. Pat. No. 5,477,250 issued on Dec. 19, 1995 discloses a recording apparatus. This recording apparatus comprises a cylindrical toner retaining member, which is rotatable, for retaining charged toner particles (recording particles) on its outer peripheral surface, and a back electrode spaced from the toner retaining member. The back electrode is electrically connected to a power source, and an electric field is formed to attract the charged toner particles on the toner retaining member toward the back electrode. An insulating plate provided with a plurality of apertures, through which the toner particles can pass, is disposed between the toner retaining member and the back electrode. In addition, the insulating plate is provided with a ring-shaped electrode surrounding each of the apertures.
In the above-mentioned recording apparatus, when a signal corresponding to image data is applied to the electrode, the toner particles existing in a position on the toner retaining member opposed to the electrode separate and jump into the corresponding aperture. After passing through this aperture, the toner particles attach to a recording sheet, and an image corresponding to the image data is recorded on the recording sheet.
In the above-mentioned recording apparatus, however, the plurality of apertures in the insulating plate are slightly shifted from one another in the rotation direction of the toner retaining member in some cases in order to raise resolution. In such cases, when two apertures adjacent to each other are viewed in the rotation direction of the toner retaining member, if the ring-shaped electrodes formed around each aperture are positioned so as to overlap with each other although the two ring-shaped electrodes do not make contact with each other, an area on the toner retaining member, wherein the toner particles jumping to one of the apertures located on the upstream side in the rotation direction of the toner retaining member have been retained, may partially overlap with an area on the toner retaining member, wherein the toner particles jumping to the other aperture located on the downstream side thereof. As a result, the amount of the toner particles passing through the other aperture located on the downstream side is less than the amount of the toner particles passing through the aperture located on the upstream side. Consequently, streak-like unevenness in image density may occur on an image to be formed.
To eliminate such unevenness in density, a measure of rotating the toner retaining member at high speed can be used. However, this measure is not desirable since the toner particles become heated, thereby causing another problem of fusing and adhering of the toner particles on the toner retaining member.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide a direct recording apparatus capable of eliminating unevenness in image density without rotating the toner retaining member at high speed, and to provide a PC board used for the recording apparatus.
In order to attain the above-mentioned object, a PC board of the present invention is used for a direct recording apparatus provided with:
transfer means for retaining charged recording particles and transferring the recording particles in a predetermined direction;
a back electrode provided as opposed to the transfer means to electrically attract the recording particles; and
the PC board provided between the transfer means and the back electrode to control the recording particles to jump or not to jump toward the back electrode, and
the PC board comprises:
a first aperture formed in the PC board;
a second aperture formed in the PC board on the downstream side in the predetermined direction and at a position shifted with respect to the first aperture in the direction perpendicular to the predetermined direction;
a first electrode provided corresponding to the first aperture to control the recording particles to jump from the transfer means toward the back electrode through the first aperture depending on an electric signal supplied from an external power source;
a second electrode provided corresponding to the second aperture to control the recording particles to jump from the transfer means toward the back electrode through the second aperture depending on an electric signal supplied from the external power source; wherein
each of the first and second electrodes has a shape wherein a part of a ring shape surrounding the aperture is cut off in the perpendicular direction.
In accordance with the PC board of the present invention, the first electrode may not overlap with the second electrode in the perpendicular direction at all.
Furthermore, the PC board of the present invention may comprise:
a third electrode provided corresponding to the first aperture and formed on the side of the back electrode with respect to the first electrode; and
a fourth electrode provided corresponding to the second aperture and formed on the side of the back electrode with respect to the second electrode.
Furthermore, the direct recording apparatus of the present invention comprises:
transfer means for retaining charged recording particles and transferring the recording particles in a predetermined direction;
a back electrode provided as opposed to the transfer means to electrically attract the recording particles; and
the PC board in accordance with the present invention, provided between the transfer means and the back electrode.
In the PC board or the direct recording apparatus of the present invention, each of the first and second electrodes has a shape wherein a part of a ring shape surrounding the aperture is cut off in the perpendicular direction. When the first electrode receives the electric signal from the external power source and allows the recording particles to jump through the first aperture, a width of a first area of the recording particles to be separated from the transfer means becomes smaller in the perpendicular direction than a width in the case that the first electrode is ring-shaped. In the same way, when the second electrode receives the electric signal from the external power source and allows the recording particles to jump through the second aperture, a width of a second area of the recording particles to be separated from the transfer means also becomes smaller in the perpendicular direction than a width in the case that the second electrode is ring-shaped. Therefore, even when the recording particles are allowed to jump through the second aperture, immediately after the recording particles are allowed to jump through the first aperture, the second area on the transfer means hardly overlaps with the first area thereon. As a result, the amount of the recording particles jumping through the second aperture is not much different from the amount of the recording particles jumping through the first aperture. Consequently, unevenness in image density can be reduced or eliminated substantially.
Furthermore, by disposing the first electrode so as not to overlap with the second electrode in the perpendicular direction, the first separation area corresponding to the first aperture does not overlap with the second separation area corresponding to the second aperture at all. Therefore, the amounts of the recording particles jumping through each of the first and second apertures are made uniform. As a result, the effect of eliminating unevenness in image density can be made more securely.
REFERENCES:
patent: 5477250 (1995-12-01), Larson
patent: 6012801 (2000-01-01), Nilsson
patent: 6074045 (2000-06-01), Bergman et al.
Barlow John
Loper, Jr. Robert D
Minolta Co. , Ltd.
Morrison & Foerster / LLP
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