Electrophotography – Document handling – Copy
Reexamination Certificate
2001-01-30
2003-03-11
Ngo, Hoang (Department: 2852)
Electrophotography
Document handling
Copy
C270S040000
Reexamination Certificate
active
06532356
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to image-forming devices, and particularly to a paper feed mechanism of an image-forming device that employs continuous paper. The present invention is suitable, for example, for an output device for use with a computer system that needs to print large amounts of data.
Hereupon, the phrase, “continuous paper”, is intended to denote continuous-form paper in a folded stack, roll or other shapes, and an OHP film, or other types of recordable media that permit a user's discretionary setting of a recording length. The width of the continuous paper has a standardized or predetermined dimension.
The electrophotographic image-forming device that uses continuous paper as a recordable medium (continuous paper printer) is utilized for printing (outputting) large amounts of data. In recent years, high-speed continuous paper printers that can create a printed output for a short time by printing out processed information received from networked small processors or main frames have become commercially practical. The continuous printer generally comprises a printing part, a paper feeder part, a conveyor part, and a collecting part.
The printing part, which adopts the electrophotographic method employing a photoconductive insulator (e.g., photosensitive drum, and photosensitive belt), follows the procedural steps of charging, latent image formation, development, transfer, and fixing. The charging step uniformly electrifies the photosensitive drum (e.g., at −700 V). The latent image formation step irradiates a laser beam or the like on the photosensitive drum based upon print data, and changes the electrical potential at the irradiated area down, for example, to −50 V or so, forming an electrostatic latent image. The development step electrically deposits a developer onto the photosensitive drum using, for example, the reversal process, and visualizes the continuous electrostatic latent image. The transfer step brings the photosensitive drum into continuous contact with continuous paper conveyed at the same speed as a circumferential velocity of the photosensitive drum, and continuously forms a toner image corresponding to the electrostatic latent image on the continuous paper using a transfer unit. The fixing step fuses and fixes the toner image on the continuous paper by the application of heat or pressure, or light irradiation by a fixing unit, thereby obtaining a printed matter.
The paper feeder part includes a hopper accommodating folded continuous paper. The conveyor part conveys the continuous paper from the paper feeder part to the collecting part through the printing part. The conveyor part typically includes an automatic loading part, and a conveyor roller. At both sides of the continuous paper are provided, for example, round apertures (sprocket holes), and the conveyor part includes conveyor pins and a pin roller (or belt with teeth) that corresponds to the apertures and moves in synchronous with rotation of the photosensitive drum, to convey continuous paper at high speed by fitting pins into the apertures of the continuous paper. During conveyance of continuous paper, the continuous paper is subjected to the processes in the transfer and fixing steps, and precisely synchronized operations between the conveyance of the continuous paper and the rotation of the photosensitive drum make a high-quality transfer possible. The collecting part includes a stacker that stores continuous paper that has been printed. The stacker also serves to eject the continuous paper that has been printed out of the device. The continuous paper that has been ejected out of the device undergoes a variety of processes such as cutting in a post-processor electrically connected with the continuous paper printer.
However, a conventional continuous paper printer is disadvantageously susceptible to a jam and image degradation. To be more specific, in the conventional continuous paper printer, an irregular load that would be applied to continuous paper when the conveyor part draws out the continuous paper from the hopper would pull the continuous paper in a direction opposite to the drawing direction. Accordingly, a conveyance speed of the continuous paper would vary, and thus a poor transfer results, or a local application of the above load would cause the continuous paper to swerve from a conveyance route, and produce a jam. A description will now be given of loads applied to the continuous paper, with reference to
FIGS. 7 through 9
.
Continuous paper P is stored in a hopper
1
so that each folded side may come into contact with wall surfaces of the hopper
1
so as to prevent the continuous paper P from moving in the hopper
1
, and affecting the conveyance. When the continuous paper P is drawn out from the hopper
1
, if the uppermost fold of the continuous paper P were not in contact with the wall of the hopper
1
as shown in
FIG. 7
, the continuous paper P would be conveyed with no irregular load applied thereto.
Faster printing processes demanded in recent years require increased speed at conveying the continuous paper P. Fast conveyance would generate vibrations in the continuous paper P, and often cause the continuous paper P to be drawn out with the fold kept in contact with the wall surface of the hopper
1
. If the continuous paper were conveyed with the fold kept in contact with the wall surface of the hopper
1
, space formed with the wall surface of the hopper
1
and the continuous paper P would decompress as shown in
FIG. 8
, and thereafter, part of the continuous paper P would be adhered closely to the wall surface of the hopper
1
as shown in FIG.
9
. This phenomenon would occur more frequently particularly when the amount of the continuous paper P stored in the hopper
1
becomes small. The closely adhered continuous paper P to the hopper
1
would cause an irregular load to be applied to the continuous paper P partially or entirely. Such a load would pull the continuous paper in a direction opposite to a drawing direction, and thus reduce the conveyance speed of the continuous paper that is being drawn out. Accordingly, the conveyance speed of the continuous paper P would vary. Consequently, a jam due to misaligned continuous paper P, or deteriorated image quality due to a poor transfer caused by loss of synchronism with the photosensitive drum would result. Hereupon,
FIG. 8
is a schematic sectional view for illustrating decompressed space formed with the continuous paper P and the wall surface of the hopper
1
.
FIG. 9
is a schematic sectional view for showing the continuous paper P adhered closely to the hopper
1
.
In order to prevent such adhesion of the continuous paper P to the hopper
1
, holes that allow air to flow through the wall of the hopper
1
might possibly be formed to prevent the decompression. However, this would be impractical due to disadvantages such as a possible increase in costs of hoppers as accompanied by recent year's diversification of recordable media, and continuous printers' incapability of using a variety of hoppers.
As shown in
FIG. 10
, a roller pair might be provided directly above the continuous paper P stored in the hopper
1
to regulate a conveyance route of the continuous paper P.
FIG. 10
is a schematic sectional view for showing a conventional swing prevention mechanism for continuous paper P. The roller pair includes an immovable roller unit
2
and a movable roller unit
3
. The immovable roller unit
2
is anchored perpendicularly on a main body housing of the continuous paper printer, and includes at a distal end thereof a roller portion
2
a
, which may rotate while keeping in contact with the continuous paper P. The movable roller unit
3
is joined via a joint
4
to the housing of the continuous paper printer, and is manually pivotable about the joint
4
as indicated by a dotted line and a solid line. The movable roller unit
3
also includes at a distal end thereof a roller portion
3
a
, which may rotate while keeping in contact with
Armstrong Westerman & Hattori, LLP
Fujitsu Limited
Ngo Hoang
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